Patent Application
20190270779
The instant application contains a Sequence Listing submitted via EFS-Web and hereby incorporated by reference in its entirety. Said ASCII copy, created on Oct. 26, 2015, is named 20151026_01131000100US_SeqList.txt, and is 86,211 bytes in size.
The present invention relates to immunotherapeutic agents. In particular, it relates to agents that can be used to prevent or treat a condition characterised by the presence of unwanted cells, such as tumours or other disease causing cells.
Immunotherapeutic strategies for targeting malignant disease are an active area of translational clinical research, and have been for several decades. The current models dictate that cancer represents either a functional or constitutional immunodeficiency which can be treated with immunotherapeutic manipulation of the host. These efforts can be broadly classified into 2 groups. The first serves to augment or support endogenous anti-tumour immunity through measures such as vaccination, cytokine support (IL-2, IFNγ) or reducing immunosuppressant environment (ipilimumab) whilst the second seeks to restore an absolute deficiency with components of a functional immune response (passive immunotherapy with antibodies, TCR transfer, Stem Cell Transplantation and adoptive immunotherapy). These approaches are unified by the argument that a highly effective functional anti-tumour immune response is indeed possible. Although irrefutable evidence exists for an effective anti-tumour immune response in some cases, this central pillar of tumour immunology is overwhelmingly countered by the current clinical reality that despite great efforts, no effective immunotherapeutics are available for the majority of patients with cancer. Almost all cancer vaccination trials have provided negative results, with those providing positive data most frequently demonstrating a small effect. The reality is that therapeutic antibodies, with a few exceptions, offer very modest clinical benefit in the area of oncology.
If a therapeutic strategy could be developed which can efficiently molecularly re-direct an endogenous cytotoxic anti-viral immune response to instead target malignant tissue, this may afford a new powerful and safe approach to treat malignant disease.
The majority of cytotoxic therapeutic antibodies rely on immunological effector mechanisms to deliver their anti-cancer effect such as complement dependent cytotoxicity (CDC) and Antibody Dependent Cellular Cytotoxicity (ADCC). Importantly, all cells (both healthy and malignant) have numerous mechanisms to limit attack by the immune response to avert autoimmunity. This is evident in the context of autoimmune disease where high levels of tissue-reactive antibodies, which although frequently evoke organ inflammation, rarely induce complete organ destruction. Indeed, autoimmune diseases where complete tissue destruction is observed, such as diabetes mellitus, are known to be dependent on CTL responses rather than antibody-directed mechanisms.
To improve upon the poor efficacy of therapeutic antibodies, immunoconjugates (radionuclides/toxins) and engineered antibodies which better engage with the cytotoxic effector mechanisms (e.g. glycoengineering) have been used. However clinical trials of such agents remain largely disappointing and are plagued by toxicity. One example is antibody-drug conjugates (ADCs) that have been developed to selectively target anti-tumour agents to tumours (see U.S. Pat. Nos. 5,773,001; 5,767,285; 5,739,116; 5,693,762; 5,585,089; US 2006/0088522; US 2011/0008840; U.S. Pat. No. 7,659,241; Hughes (2010) Nat Drug Discov 9: 665, Lash (2010); In vivo: The Business & Medicine Report 32-38; Mahato et al (2011) Adv Drug Deliv Rev 63: 659; Jeffrey et al (2006) BMCL 16: 358; Drugs R D 11(1): 85-95). ADCs generally comprise a monoclonal antibody against a target present on a tumour cell, a cytotoxic drug, and a linker that attaches the antibody to the drug. However, only a few ADCs are currently in the late stage of clinical development, and of those that are, clinical success has proven elusive.
Thus, there remains a demand for more effective immunotherapeutic agents with greater efficacy and lower toxicity.
The agents of the invention are an example of re-directed immunotherapy. This refers to the concept of re-directing an existing immune response that normally target cells harbouring foreign antigens, to target unwanted cells in conditions such as cancer. The concept requires the presentation of marker antigens on unwanted cells such that they become a target for immune cells.
WO 95/17212 describes conjugates consisting of peptidic T cell antigens and cell binding partners and their use in re-directed immunotherapy. The conjugates comprise a binding partner with selectivity for target cells and a T cell antigen, and are said to induce specific cytotoxicity of T cells in the treatment of cancer, autoimmune diseases, diabetes or allergic diseases. The conjugates are said to be internalised into target cells following binding of the binding partner to surface receptors, and the T cell antigen is processed from the conjugate and expressed on the cell surface in the form of a complex with MHC molecules. Cytotoxicity of T cells for the target cells is thereby induced.
However, which binding partners enable internalisation and hence subsequent presentation of the T cell antigen, and which do not, is difficult to predict from WO 95/17212. Further, the conjugates described in WO 95/17212 do not efficiently target the MHC Class-I antigen processing pathway. An advantage of the MHC Class-I pathway is that, unlike MHC Class-II molecules, MHC Class-I molecules are present on all cell types.
Smith et al (J Immunol 169: 99-107, 2002) describe the use of ricin to deliver cytotoxic T cell epitopes into the MHC Class I pathway of tumour cells, such that they are subsequently lysed. However, ricin is highly toxic and since it can bind to most cell types, it is not selective for tumour cells.
The agents of the present invention aim to circumvent all of the above problems whilst improving specificity, and exploit the fact that T cell antigens can be presented without first being internalised into a cell and being engaged in the classical antigen processing pathways. In addition to the classical MHC Class-I processing pathway, which continuously feeds peptides from the intracellular compartment via targeted intracellular proteolysis by the proteosome, peptide transport through the TAP and MHC Class-I peptide loading within the ER, antigens can also be presented without internalisation. This less directed mechanism relies on a short half-life of some MHC Class-I associated peptides due to low affinity of some MHC bound peptides to the MHC molecule. Peptide dissociation provides empty MHC Class-I molecules which are able to bind T cell antigens (e.g. peptides) at the membrane. In the same way, T cell antigens can bind to MHC Class-II molecules and the present invention also circumvents the Class-II antigen processing pathway to directly load antigens at the cell membrane. Further, Group I CD1 molecules (CD1a, CD1b and CD1c) have been shown to present lipids to both cytotoxic alpha beta T cells as well as cytotoxic gamma delta T cells (Porcelli et al (1989) Nature, 341, 447-450).
The inventors have found that by introducing a cleavage site in close proximity to the T cell antigen, which cleavage site is selectively cleaved in the vicinity of the unwanted cells, the T cell antigen can be liberated from a targeting moiety in the vicinity of the unwanted cells and can become bound by, for example, empty MHC molecules or Group I CD1 molecules, and elicit a T cell response. In this way, internalisation of the agent into the cell and direction of the antigen into the classical processing pathways is not necessary; the agent can target cells expressing MHC Class-I molecules compared to only MHC Class-II expressing cells as in WO 95/17212; and specificity is increased by virtue of the cleavage site only being cleaved in the vicinity of the unwanted cells. For example, tumour cells secrete proteases that are required by tumours for invasion of local tissues and metastasis, and so by including a tumour-specific protease cleavage site in the agent, the specificity of the agent for the tumour is increased.
It follows that the use of a cleavage site to bypass the requirement for internalisation and classical processing in order for T cell antigens to be efficiently presented to T cells is a key advantage of the invention. The presence of the cleavage site means that all cells become amenable to re-directed immunotherapy, and not just the relatively small population of antigen presenting cells that express MHC Class II molecules. This is especially important for tumours where most tumour cells do not express MHC Class II molecules. The cleavage site also circumvents the challenges involved in ensuring that T cell antigens are not only successfully internalised, but that they correctly enter the appropriate cellular processing pathway to be presented on the cell surface. By by-passing the need for internalisation, the cleavage site further provides the ability to target neighbouring tumour cells and stromal non-malignant tissue such as tumour-fibroblasts of blood vessels. It also circumvents tumour-evasion mechanisms that operate in classical antigen processing. All in all therefore, the cleavage site provides for a simpler and more effective method of re-directing immunotherapy to more cell types.
It is important to note the distinction between the present invention and cross-presentation. In the present invention, the targeting moiety of the agent functions to bring a T cell antigen directly into the vicinity of an unwanted cell. The unwanted cell may then present the T cell antigen, once cleaved from the targeting moiety, on its surface such that the unwanted cell becomes a target for an existing T cell response.
This allows for the redirection of an existing immune response to the unwanted cell directly, and so no co-stimulation by antigen presenting cells (APCs) is necessary. Cross-presentation, on the other hand, refers to the mechanism by which an antigen is transferred to a professional APC which, in turn, presents it on an MHC Class I molecule to a naïve T cell so as to generate a primary cytotoxic T cell response specific for that antigen. The process is important in the activation of naïve T cells which must first recognise class I-associated peptide antigens and also encounter costimulators on APCs, or signals provided by helper T cells. Thus, with cross-presentation, APCs as opposed to unwanted cells are targeted so that APCs may co-stimulate cytotoxic T cells and thereby generate a new immune response.
Improving the efficiency of the cross-presentation of exogenous antigens is a key challenge in the development of vaccines that generate effective cellular immune responses. WO 2008/019366, EP 1 948 802, US 2004/0001853, WO 2005/087813, EP 1 664 270, Kawamura et al (J Immunol 168: 5709, 2002), and Howland et al (J Immunother 31(7): 607, 2008) describe methods to improve cross-presentation of exogenous antigens by targeting antigens to APCs where they are internalised and presented to naïve T cells. For example, WO 2008/019366 discusses attaching antigens to a particle that can be phagocytosed by APCs such that the antigen can be released in the phagosome of the APC and thereby be cross-presented onto MHC Class I molecules. Similarly, EP 1 948 802 describes attaching an antigen to an antibody Fc fragment so as to promote internalisation of the antigen into the APC. However, none of the above documents mention targeting of antigens to unwanted cells; rather, the antigen is targeted to a specialised subset of APCs which, in turn, activate cytotoxic T cells to kill unwanted cells. Likewise, none of the documents describe the use and redirection of an existing immune response nor do they disclose that the T cell antigen can be presented on the surface of a cell without the need for internalisation.
A first aspect of the invention provides an agent for preventing or treating a condition characterised by the presence of unwanted cells, the agent comprising (i) a targeting moiety that is capable of targeting to the unwanted cells; and (ii) a T cell antigen, wherein the T cell antigen can be released from the targeting moiety by selective cleavage of a cleavage site in the agent in the vicinity of the unwanted cells.
Targeting Moiety
By ‘targeting moiety’, we include the meaning of any moiety that is capable of targeting to the unwanted cells. Preferably, the targeting moiety is capable of targeting selectively to the unwanted cells. For example, it is preferred if the targeting moiety targets unwanted cells to a greater extent than it does normal cells, and most preferably targets only unwanted cells.
It will be appreciated that binding of the targeting moiety to normal cells may be tolerated if they can be functionally replaced by other therapeutic means or if they are not essential to life. Thus, a targeting moiety that targets to a cancer cell as well as, for example, an endocrine tissue or organ is not precluded. In this case, the targeting moiety acts to redirect an immune response to both unwanted cells and to other cells that can be functionally replaced by therapeutic means. In a life-saving situation for example, the tissue or organ may be sacrificed provided its function was either not essential to life, for instance in the case of the testes, prostate or pancreas, or could be supplied by hormone replacement therapy. Such considerations would apply to the thyroid gland, parathyroids, adrenal cortex and ovaries, for example.
It follows that the targeting moiety may be a moiety that is capable of targeting selectively to unwanted cells as opposed to wanted cells, wherein the unwanted cells may include cells whose presence in a host is undesired and optionally cells whose presence in the host is desired but whose presence can be functionally replaced by therapeutic means.
It is also appreciated that since the cleavage site in the agent confers specificity on where the T cell antigen is released, binding of the targeting moiety to normal cells, in the vicinity of which the cleavage site is not cleaved, may also be tolerated.
Most preferably, however, the targeting moiety targets selectively to unwanted cells as opposed to any other cells.
In one embodiment, the targeting moiety is a specific binding partner of an entity expressed by or associated with the unwanted cell. Typically, the expressed entity is expressed selectively on the unwanted cell. For example, the abundance of the expressed entity is typically 10 or 100 or 500 or 1000 or 5000 or 10000 higher on the unwanted cell than on other cells within the body to be treated. However, as mentioned above, the cleavage site provides additional specificity on where the T cell antigen is released and so the binding partner may bind an entity that is similarly or even underexpressed on unwanted cells relative to other cells within the body.
By “binding partner” we include the meaning of a molecule that binds to an entity expressed by a particular cell. Preferably, the binding partner binds selectively to that entity. For example, it is preferred if the binding partner has a Kd value (dissociation constant) which is at least five or ten times lower (i.e. higher affinity) than for at least one other entity expressed by another cell (e.g. a normal cell type), and preferably more than 100 or 500 times lower. More preferably, the binding partner of that entity has a Kd value more than 1000 or 5000 times lower than for at least one other entity expressed by another cell (e.g. normal cell type). Kd values can be determined readily using methods well known in the art. However, as discussed above, it is appreciated that the binding partner may bind selectively to an entity expressed by an unwanted cell and by a normal cell provided that the normal cell may be functionally replaced or else is not essential to life. For example, in lymphoma, anti-CD20 (which targets all B cells) is very effective and kills all B cells, healthy and malignant. However, this can be tolerated as B cells are not critical for health. Further, in the case of melanoma, lymphoma, prostate cancer, thyroid, testicular or ovarian cancer, targeting healthy counterpart tissue would also be tolerated.
Typically, the binding partner is one that binds to an entity that is present or accessible to the binding partner in significantly greater concentrations in or on unwanted cells than in any normal cells of the host. Thus, the binding partner may bind to a surface molecule or antigen on the unwanted cell that is expressed in considerably higher amounts than on normal cells. Similarly, the binding partner may bind to an entity that has been secreted into the extracellular fluid by the unwanted cells to a greater extent than by normal cells. For example, the binding partner may bind to a tumour associated antigen which is expressed on the cell membrane or which has been secreted into tumour extracellular fluid.
The targeting moiety may be any of a polypeptide, a peptide, a small molecule or a peptidomimetic.
In a preferred embodiment, the targeting moiety is an antibody that binds to an antigen expressed by the unwanted cell. Preferred antibody targets (with examples of unwanted cell types in parentheses) include: Her2/Neu (Epithelial malignancies); CD22 (B cells, autoimmune or malignant); EpCAM (CD326) (Epithelial malignancies); EGFR (epithelial malignancies); PSMA (Prostate Carcinoma); CD30 (B cell malignancies); CD20 (B cells, autoimmune, allergic or malignant); CD33 (Myeloid malignancies); membrane IgE (Allergic B cells); IgE Receptor (CD23) (Mast cells or B cells in allergic disease), CD80 (B cells, autoimmune, allergic or malignant); CD86 (B cells, autoimmune, allergic or malignant); CD2 (T cell or NK cell lymphomas); CA125 (multiple cancers including Ovarian carcinoma); Carbonic Anhydrase IX (multiple cancers including Renal Cell Carcinoma); CD70 (B cells, autoimmune, allergic or malignant); CD74 (B cells, autoimmune, allergic or malignant); CD56 (T cell or NK cell lymphomas); CD40 (B cells, autoimmune, allergic or malignant); CD19 (B cells, autoimmune, allergic or malignant); c-met/HGFR (Gastrointestinal tract and hepatic malignancies; TRAIL-R1 (multiple malignancies including ovarian and colorectal carcinoma); DR5 (multiple malignancies including ovarian and colorectal carcinoma); PD-1 (B cells, autoimmune, allergic or malignant); PD1L (Multiple malignancies including epithelial adenocarcinoma); IGF-1R (Most malignancies including epithelial adenocarcinoma); VEGF-R2 (The vasculature associated with the majority of malignancies including epithelial adenocarcinomas; Prostate stem cell antigen (PSCA) (Prostate Adenocarcinoma); MUC1 (Epithelial malignancies); CanAg (tumors such as carcinomas of the colon and pancreas); Mesothelin (many tumours including mesothelioma and ovarian and pancreatic adenocarcinoma); P-cadherin (Epithelial malignancies, including breast adenocarcinoma); Myostatin (GDF8) (many tumours including sarcoma and ovarian and pancreatic adenocarcinoma); Cripto (TDGF1) (Epithelial malignancies including colon, breast, lung, ovarian, and pancreatic cancers); ACVRL1/ALK1 (multiple malignancies including leukaemias and lymphomas); MUC5AC (Epithelial malignancies, including breast adenocarcinoma); CEACAM (Epithelial malignancies, including breast adenocarcinoma); CD137 (B cells or T cells, autoimmune, allergic or malignant); CXCR4 (B cells or T cells, autoimmune, allergic or malignant); Neuropilin 1 (Epithelial malignancies, including lung cancer); Glypicans (multiple cancers including liver, brain and breast cancers); HER3/EGFR (Epithelial malignancies); PDGFRa (Epithelial malignancies); EphA2 (multiple cancers including neuroblastoma, melanoma, breast cancer, and small cell lung carcinoma); and CD138 (Myeloma).
Particularly preferred antibodies include an anti-epidermal growth factor receptor antibody such as Cetuximab, an anti-Her2 antibody, an anti-CD20 antibody such as Rituximab, an anti-CD22 antibody such as Inotuzumab, an anti-CD70 antibody, an anti-CD33 antibody such as hp67.6 or Gemtuzumab, an anti-MUC1 antibody such as GP1.4 and SM3, an anti-CD40 antibody, an anti-CD74 antibody, an anti-P-cadherin antibody, an anti-EpCAM antibody, an anti-CD138 antibody, an anti-E-cadherin antibody, an anti-CEA antibody, and an anti-FGFR3 antibody.
Examples of tumour-associated, immune cell-associated and infection reagent-related antigens which may be targeted by the targeting moiety are given in Table 1.
1Hellström et al (1986) Cancer Res. 46, 3917-3923
2Clarke et al (1985) Proc. Natl. Acad. Sci. USA 82, 1766-1770
Alternatively, the targeting moiety may be any compound or part thereof that specifically binds, in a non-immune sense, to an entity expressed by unwanted cells or otherwise becomes associated with the unwanted cells. Thus, the specific binding partner may be any of a hormone, a growth factor, a cytokine, or a receptor ligand (e.g. agonist or antagonist).
For example, cytokines have previously been used to target toxins to invading bacterial. Using genetic engineering, recombinant proteins have been produced which contain for example IL-2 and a binding domain-deleted Pseudomonas exotoxin protein (Lorderboum-Galski et al, 1988 (62)). This immunotoxin was effective in experimental animal models (Kozak et al, 1990 (63)). Fusion proteins have also been produced with IL-4, IL-6, alpha-MSH, EGF and TNF-alpha (reviewed in Waldmann 1992 (35)), all of which are appropriate for use as targeting moieties in the present invention.
Particularly useful targeting moieties include cytokines such as IL-2, EGF, VEGF, Flt3L, HGF, IGF, IL-6, or IL-4. IL-2 and IL-4 can target to adult T cell leukaemia/lymphoma cells which express the high affinity IL-2 receptor whereas normal resting T-cells do not, or to T-cells expressing the IL-4 receptor. It has previously been shown that the monoclonal antibody MR6, which binds to the human IL-4 receptor, can inhibit the IL-4 induced proliferation of cloned helper T cells and the production of IgE by polyclonal B cells (Larche et al, 1988 (36)). Such targeting moieties may be used to eliminate a lymphoid cell subpopulation in autoimmune disease or allergy.
Insulin like growth factors (IGF-1 and IGF-11) are preferentially taken up by malignant cells and so may be used to target tumour cells. Similarly EGF can be used to target malignant cells which upregulate the EGF receptor. Also, tumour associated blood vessels overexpress VEGF receptor and so can be targeted by the family of VEGF growth factors.
Flt3 receptor is overexpressed in leukaemias and may be a therapeutic target for acute and chronic leukaemias and myeloproliferative disorders.
Myeloma cells express IL-6 receptor and also secrete IL-6 which acts in an autocrine fashion to stimulate cell proliferation. Thus IL-6 may be used as a targeting moiety for myeloma.
In another example, the targeting moiety is melanoma stimulating hormone (MSH) which binds to the MSH receptor which is expressed in high numbers in melanoma cells.
It is appreciated that a person skilled in the art can readily select suitable binding partners for any given unwanted cell, for example by identifying surface antigens or molecules specific for that unwanted cell and finding a binding partner for that antigen or molecule. Considerable research has already been carried out on antibodies and fragments thereof to tumour-associated antigens, immune cell antigens and infectious agents, as described above. Thus, conveniently, selecting an appropriate targeting moiety for a given cell type typically involves searching the literature. Alternatively, an unwanted cell is taken from a patient (e.g. by biopsy), and antibodies directed against the cell prepared. Such ‘tailor-made’ antibodies are already known. It has been demonstrated that antibodies confer binding to tumour cells not only from the patient they have been obtained from but also for a large number of other patients. Thus, a plurality of such antibodies has become commercially available. Other methods of identifying suitable binding partners for a given unwanted cell include genetic approaches (eg microarray), proteomic approaches (eg differential Mass spectrometry), immunological approaches (eg immunising animals with tumour cells and identifying antibody-secreting clones which specifically target malignant cells) and in silico approaches wherein targets are identified using a systems biology approach.
Further selective targets and suitable binding partners are shown in Table 2.
Further targets useful in preventing or treating various cancers are provided below.
Yet further selective targets useful for preventing or treating various conditions characterised by the presence of unwanted cells are provided below. For all of the examples below, therapeutic antibodies are already available or can be readily prepared by the skilled person.
Staphylococcus epidermidis lipoteichoic acid
Staphylococcus infected tissue.
As used herein, the term “antibody” includes but is not limited to polyclonal, monoclonal, chimeric, single chain, Fab fragments, fragments produced by a Fab expression library and bispecific antibodies. Such fragments include fragments of whole antibodies which retain their binding activity for a target substance, Fv, F(ab′) and F(ab′)2 fragments, as well as single chain antibodies (scFv), fusion proteins and other synthetic proteins which comprise the antigen-binding site of the antibody. A targeting moiety comprising only part of an antibody may be advantageous by virtue of optimising the rate of clearance from the blood and may be less likely to undergo non-specific binding due to the Fc part. Also included are domain antibodies (dAbs), diabodies, camelid antibodies and engineered camelid antibodies. Furthermore, for administration to humans, the antibodies and fragments thereof may be humanised antibodies, which are now well known in the art (Janeway et al (2001) Immunobiology, 5th ed., Garland Publishing); An et al (2009) Therapeutic Monoclonal Antibodies: From Bench to Clinic, ISBN: 978-0-470-11791-0).
Also included are asymmetric IgG-like antibodies (eg triomab/quadroma, Trion Pharma/Fresenius Biotech; knobs-into-holes, Genentech; Cross MAbs, Roche; electrostatically matched antibodies, AMGEN; LUZ-Y, Genentech; strand exchange engineered domain (SEED) body, EMD Serono; biolonic, Merus; and Fab-exchanged antibodies, Genmab), symmetric IgG-like antibodies (eg dual targeting (DT)-Ig, GSK/Domantis; two-in-one antibody, Genentech; crosslinked MAbs, karmanos cancer center; mAb2, F-star; and Coy X-body, Coy X/Pfizer), IgG fusions (eg dual variable domain (DVD)-Ig, Abbott; IgG-like bispecific antibodies, Eli Lilly; Ts2Ab, Medimmune/AZ; BsAb, ZymoGenetics; HERCULES, Biogen Idec; TvAb, Roche) Fc fusions (eg ScFv/Fc fusions, Academic Institution; SCORPION, Emergent BioSolutions/Trubion, ZymoGenetics/BMS; dual affinity retargeting technology (Fc-DART), MacroGenics; dual (ScFv)2-Fab, National Research Center for Antibody Medicine) Fab fusions (eg F(ab)2, Medarex/AMGEN; dual-action or Bis-Fab, Genentech; Dock-and-Lock (DNL), ImmunoMedics; bivalent bispecific, Biotechnol; and Fab-Fv, UCB-Celltech), ScFv- and diabody-based antibodies (eg bispecific T cell engagers (BiTEs), Micromet; tandem diabodies (Tandab), Affimed; DARTs, MacroGenics; Single-chain diabody, Academic; TCR-like antibodies, AIT, Receptor Logics; human serum albumin ScFv fusion, Merrimack; and COMBODIES, Epigen Biotech), IgG/non-IgG fusions (eg immunocytokins, EMDSerono, Philogen, ImmunGene, ImmunoMedics; superantigen fusion protein, Active Biotech; and immune mobilising mTCR Against Cancer, ImmTAC) and oligoclonal antibodies (eg Symphogen and Merus).
The antibody may possess any of the antibody-like scaffolds described by Carter (2006) “Potent antibody therapeutics by design”, Nat Rev Immunol. 6(5): 343-57, and Carter (2011) “Introduction to current and future protein therapeutics: a protein engineering perspective”, Exp Cell Res. 317(9): 1261-9. incorporated herein by reference, together with the specificity determining regions described herein. Thus, the term “antibody” also includes affibodies and non-immunoglobulin based frameworks. Examples include adnectins, anticalins, affilins, trans-bodies, darpins, trimerX, microproteins, fynomers, avimers, centgrins and kalbitor (ecallantide).
The advantages of using antibody fragments, rather than whole antibodies, are several-fold. The smaller size of the fragments may lead to improved pharmacological properties, such as better penetration of solid tissue. Moreover, antigen-binding fragments such as Fab, Fv, ScFv and dAb antibody fragments can be expressed in and secreted from E. coli or yeast, thus allowing convenient production in the laboratory and economical production on a commercial scale.
The antibody may be of any of the IgG, IgE, IgA, IgM and IgD classes and may be derived from any species. If the antibody is an IgG, it may be any of IgG1, IgG2, IgG3 or IgG4. It is preferred, however, that when the agent is for administration to a particular host, that the antibody, or at least the constant regions thereof, are derived from that host. For example, when the agent is to be administered to a human, the antibody is preferably a human antibody or a humanized antibody, and so on.
Suitable antibodies that bind to particular antigens expressed by unwanted cells can be made by the skilled person using technology long-established in the art. Methods of preparation of monoclonal antibodies and antibody fragments are well known in the art and include hybridoma technology (Kohler & Milstein (1975) “Continuous cultures of fused cells secreting antibody of predefined specificity. Nature 256: 495-497); antibody phage display (Winter et al (1994) “Making antibodies by phage display technology.” Annu. Rev. Immunol. 12: 433-455); ribosome display (Schaffitzel et al (1999) “Ribosome display: an in vitro method for selection and evolution of antibodies from libraries.” J. Immunol. Methods 231: 119-135); and iterative colony filter screening (Giovannoni et al (2001) “Isolation of anti-angiogenesis antibodies from a large combinatorial repertoire by colony filter screening.” Nucleic Acids Res. 29: E27). Further, antibodies and antibody fragments suitable for use in the present invention are described, for example, in the following publications: “Monoclonal Hybridoma Antibodies: Techniques and Application”, Hurrell (CRC Press, 1982); “Monoclonal Antibodies: A Manual of Techniques”, H. Zola, CRC Press, 1987, ISBN: 0-84936-476-0; “Antibodies: A Laboratory Manual” 1st Edition, Harlow & Lane, Eds, Cold Spring Harbor Laboratory Press, New York, 1988. ISBN 0-87969-314-2; “Using Antibodies: A Laboratory Manual” 2nd Edition, Harlow & Lane, Eds, Cold Spring Harbor Laboratory Press, New York, 1999. ISBN 0-87969-543-9; and “Handbook of Therapeutic Antibodies” Stefan Dübel, Ed., 1st Edition,—Wiley-VCH, Weinheim, 2007. ISBN: 3-527-31453-9.
As an alternative to the targeting moiety being a specific binding partner, the targeting moiety may be a non-specific molecule that is capable, following administration to a subject, of accumulating in the vicinity of the unwanted cells. For example, it is known that macromolecules accumulate non-specifically in tumours. Macromolecules known to accumulate in tumours non-specifically include albumin, immunoglobulins, transferrin, liposomes, nanoparticles (eg colloidal nanoparticles) and biodegradable polymers including dextrans, polyethylene glycol, polylysine and hydroxypropylmethylacrylamide. Macromolecules accumulate in human xenografted tumours in nude mice up to about 2.0% of administered dose per gram of tumour. Macromolecules such as polyethylene glycol and dextrans have been found to modify the clearance rate of substances to which they are attached and modify their concentration in tumours (Melton et al, 1987; Eno-Ammoquaye et al, 1996). In exceptional tumours, a non-specific macromolecule may accumulate in greater concentration than an antibody directed at the secreted antigen (Searle et al, 1981).
The discovery that such macromolecules accumulate in tumours has been called the Enhanced Permeability and Retention (EPR) effect, and has been attributed to the leakiness of tumour capillaries and deficient lymphatic drainage (Matsumura & Macda, 1986).
Thus, when the unwanted cells are tumour cells, the targeting moiety may be any of these macromolecules which accumulate in tumours. Preferably, the macromolecule used in the invention is hydrophilic and is characterised by being soluble in body fluids and in conventional fluids for parenteral administration. Suitably, the macromolecule is biodegradable so that systemic accumulation during repeated administration is avoided. Clearly, however, it must not be degraded so fast as to fail to accumulate at the site of the unwanted cells (e.g. tumour). Preferably, the molecular weight and size of the agent comprising such a macromolecule targeting moiety exceeds that of the renal threshold for urinary excretion (MW 60 000), as this helps the blood concentration to be sufficient to provide an effective blood:tumour concentration gradient. A molecular weight of up to at least 800 000 is generally suitable, for example up to 160 000. The macromolecule is preferably one which is not readily captured by the reticuloendothelial system. The molecular weights given exclude any water of hydration.
Macromolecules that are available as sub-units and are not biodegradable may be linked by biodegradable linking units so that the non-biodegradable components are filtered through the kidneys and excreted in the urine.
Alternatively, it is preferred if the polymer used to make the macromolecule is not biodegradable such that the molecular weight of any non-biodegradable portion of the conjugate should be less than the renal threshold (circa 70000) so that after degradation of the biodegradable portion the residual non-biodegradeable portion is excreted through the kidneys.
Conveniently, the macromolecule may be any of a dextran; a polyamino acid; a nanoparticle (eg colloidal nanoparticle), or a non-tumour-specific protein such as an immunoglobulin, an albumin or a transferrin. Suitably, it may be a copolymer of styrene and maleic anhydride, or may be polyaspartic acid, poly-L-lysine, polyethyleneimine or polyethylene glycol.
It is appreciated that such macromolecules are used in melanocyte-directed enzyme prodrug therapy (MDEPT), as described in WO 1998/024478.
Unwanted Cell
The unwanted cell may be any cell whose presence in a host is undesired. Thus, the cell may be a tumour cell (benign or malignant), a cell from a tumour microenvironment such as tumour fibroblasts or tumour blood vessels, a virally infected cell, a cell introduced as part of gene therapy, or a normal cell which one wishes to destroy for a particular reason. For instance, it may be desirable to eliminate a subpopulation of immune cells such as T lymphocytes in autoimmune disease or such as B lymphocytes in allergic disease.
By a ‘condition characterised by the presence of unwanted cells’ we include any biological or medical condition or disorder in which at least part of the pathology is mediated by the presence of unwanted cells. The condition may be caused by the presence of the unwanted cells or else the presence of the unwanted cells may be an effect of the condition. Examples of particular conditions include tumours (benign or malignant), autoimmune conditions, cardiovascular diseases, degenerative diseases, diabetes, allergic disease (eg asthma), neurodegenerative diseases such as Alzheimer's, transplantation patients and infectious diseases. It will be appreciated that the agent also has utility in regenerative medicine (eg laboratory grown organs or tissues). It is particularly preferred if the condition is a tumour (eg a malignant disease) and the unwanted cells are tumour cells or tumour associated tissue.
For autoimmune disease, the unwanted cells may represent cells of the adaptive or innate immune response, preferably T cells, but more preferably B cells. For cardiovascular disease, the unwanted cells may represent cells within atheromatous lesions such as macrophages. For degenerative diseases, the unwanted cells may represent cells which induce the neurodegenerative changes, for instance in Alzheimer's disease they may be microglia or astrocytes. For other degenerative diseases any cell which facilitates the process of degeneration or apoptosis may be considered a target. For processes such as aging where unwanted tissue builds up, for example in benign prostatic hyperplasis, non-malignant prostatic tissue would be a preferred target. For allergic disease, cells which participate in the allergic reaction such as tissue mast cells may be considered an ideal target, but also IgE secreting cells such as plasma cells or B cells. In transplantation, alloreactive lymphocytes would represent a preferred target cell. In the context of infectious disease, any cell harbouring a virus, bacteria or fungal pathogen may be considered a preferred target cell for example an HIV infected cell.
In an embodiment the unwanted cell is not an antigen presenting cell such as a professional antigen presenting cell with cross-presentation capability.
T Cell Antigen
By a ‘T cell antigen’ we include the meaning of any antigen which can be presented to a T cell so as to elicit a T cell response. For example, the T cell antigen may be presented to a T cell by an MHC molecule or by a Group I CD1 molecule. Once the antigen is presented on the surface of the cell, the cell is recognised as foreign and becomes the target of T cells, some of which have the natural function of eliminating foreign cells either infected by foreign organisms such as viruses, fungi, bacteria, mycobacteria or protozoa, or which have become cancerous (eg malignant). Thus, it will be appreciated that the T cell antigen may be one that is capable of being presented by a molecule on an unwanted cell. It is possible, however, that the T cell antigen may be presented on a cell other than an unwanted cell but still in the vicinity of an unwanted cell, and by virtue of subsequent T cell activation, an unwanted cell is killed, for example by local production of cytokines by activated T cells. Such indirect killing may be desirable, for example to target tumour blood vessels and/or stromal cells which support tumour growth.
It will be appreciated that the T cell antigen is one that can elicit an existing T cell response in the subject to which the agent of the invention is administered. Typically, the T cell antigen is not one which generates a new primary T cell response for that antigen via cross-presentation in APCs. To put it another way, the T cell antigen is one to which a number of T cells in the subject are already sensitised to. Determining whether a subject's cells are sensitised to a given antigen can be done by contacting isolated peripheral mononuclear blood cells from the subject with the antigen and using standard assays for cell proliferation, as described further below and in the Examples.
In an embodiment, the agent of the invention is not one which generates a new T cell response specific for the T cell antigen contained in it. Accordingly, the invention includes an agent for preventing or treating a condition characterised by the presence of unwanted cells, the agent comprising (i) a targeting moiety that is capable of targeting to the unwanted cells; and (ii) a T cell antigen, wherein the T cell antigen can be released from the targeting moiety by selective cleavage of a cleavage site in the agent in the vicinity of the unwanted cells, and wherein the T cell antigen is capable of eliciting an existing T cell response in a subject.
By ‘T cell’, we include all types of T cell including CD4+, CD8+, γδ T cells, and NK-T cells. Preferably, the T cell is a cytotoxic T cell such that a cytotoxic T cell response is elicited.
As is known in the art, the mechanism of antigen presentation will depend upon the type of T cell. Generally, CD4+ T cells recognise peptide antigens bound to MHC Class II molecules, CD8+ T cells recognise peptide antigens bound to MHC Class I molecules, γδ T cells recognise small phosphorylated molecules, alkyl amines or lipids bound to group I CD1 molecules, and NK-T cells recognise lipid antigens bound to group I CD1 molecules. It is understood that any presentation route may be used provided that the antigen elicits a T cell response. Thus, the T cell antigen may be one that is capable of binding to an MHC Class I or MHC Class II molecule, or one that is capable of binding to a group I CD1 molecule.
Preferably, the T cell antigen is an immunodominant antigen (eg an antigen that elicits an existing immunodominant response). By ‘Immunodominant’ we include the meaning that the antigen elicits a T cell response with high magnitude, sensitivity, tissue homing characteristics and efficiency in killing antigen bearing cells. Generally, an immunodominant response comprises more than 0.1% of a subject's CD8+ or CD4+ T cells. Determining the extent of a T cell response for a given antigen can be done for example by contacting isolated peripheral mononuclear blood cells from the subject with the antigen and using standard assays for cell proliferation known in the art. Suitable assays for determining the extent of an immune response include ELISpot, intracellular cytokine staining, HLA-peptide tetramer staining, proliferation assay, activation assays (eg CD69), CD107 mobilisation assays or metabolic assays (eg MTT).
Examples of suitable T cell antigens include any of a peptide, a polypeptide, a phosphopeptide or a lipid such as a phospholipid or a sphingolipid, and further examples of each of these are provided below.
When the T cell antigen is a peptide or polypeptide, typically it is one that is capable of being recognised by a T cell receptor when bound to an MHC molecule. The T cell antigen may be an MHC Class I restricted antigen that binds only to MHC Class I molecules, or it may be an MHC Class II restricted antigen that binds only to MHC Class II molecules. It is appreciated that the antigen may bind only to particular variant MHC Class I and/or MHC Class II molecules (e.g. natural variants found in particular subjects), or that the antigen may be capable of binding to any MHC Class I and/or MHC Class II molecule (i.e. the antigen is promiscuous).
In one embodiment, the T cell antigen is capable of binding to a MHC Class I molecule such as any of HLA-A, HLA-B and HLA-C. Since MHC Class I molecules are expressed on all cell types, this allows to agent of the invention to redirect an immune response to any unwanted cell. Most preferably, the peptide is capable of binding to HLA types A1, A2.1, A3.2, A11, A24, B7, B8, B35, B44, Cwt, Cw2, Cw3, Cw4 and Cw6 or mixtures thereof, which are believed to cover more than 90% of the Caucasian and Asian populations.
In another embodiment, the T cell antigen is capable of binding to a MHC Class II molecule such as any of HLA-DP, HLA-DQ or HLA-DR. Common MHC Class II types include DR1, DR3, DR4, DR7, DR52, DQ1, DQ2, DQ4, DQ8 and DP1. MHC Class II molecules are expressed on immune cells including antigen presenting cells such as dendritic cells, B cells and macrophages. Thus, when the T cell antigen is MHC Class II restricted, the agent of the invention may be used to treat conditions such as lymphomas or autoimmune diseases.
An example of a promiscuous peptide that may be used is the PADRE MHC Class-II epitope defined in Alexander et al (2000) The Journal of Immunology 164: 1625-1633; aKXVAAWTLKAAaZC (a=d-Alanine, X=L-cyclohexylalanine, Z=aminocaproic acid)) (SEQ ID No: 1). Since this epitope is artificial, it would first need to be introduced to the patient in a vaccine to generate an immune response prior to administering the agent of the invention. Another promiscuous peptide that may be used is the tetanus fragment C peptide.
Conveniently, the T cell antigen is an immunogenic peptide that is recognised by an MHC molecule. Such peptides usually have a length of 9 to 22 amino acids (for recognition in the MHC Class II complex) or of 8 to 13 amino acids (for recognition in the MHC Class I complex). Preferably, the peptide is an immunodominant peptide.
Examples of immunodominant peptides include viral derived peptides that elicit endogenous anti-viral responses. Thus, the peptide may be derived from an endogenous virus such as Varicella-Zoster virus, Herpes simplex virus, cytomegalovirus, Epstein Barr virus, or influenza. Particularly preferred examples include peptides derived from human cytomegalovirus (CMV or Human herpesvirus 5/HHV5) or Epstein-Barr Virus (EBV or HHV4); herpesviruses such as HHV1, HHV2 and HHV3; influenza virus A; influenza virus B; rhinovirus; adenovirus; and Hepadnaviridae.
For human cytomegalovirus (HHV5) the immunodominant antigens are well characterised (see Sylwester A W et al J Exp Med. 2005 Sep. 5; 202(5):673-85, incorporated herein by reference), and any such antigen described in Sylwester et al may be used in the present invention. In particular, Sylester et al synthesised consecutive 15mer peptides, overlapping by 10 amino acids, for 213 predicted human CMV proteins. This generated 13,687 peptides that were arranged in ORF or sub-ORF specific mixes. Peptides derived from ORFs UL55 (gB), UL 83 (pp65), UL 86, UL 99 (pp28), UL 122 (1E2), UL 36, UL 48, UL32 (pp150), UL 113, IRS-1, UL 123 (IE1), UL25, UL 141, UL 52 and UL 82 (pp71) were found to elicit the most CD 4+ T cell responses, and so it is particularly preferred if the peptide is derived from one of these ORFs. Alternatively, peptides derived from ORFs UL48, UL83 (pp66), UL 123 (IE1), UL 123 (1E2), US 32, UL 28, US 29, US3, UL 32 (pp150), UL 55 (gB), UL 94, UL 69, UL 105, UL 82 (pp71) and UL 99 (pp28) were found to elicit the most CD 8+ T cell responses, and so it is particularly preferred if the peptide is derived from one of these ORFs.
Particular cytomegalovirus T cell antigens are listed below.
CD8+ T cell epitopes for cytomegalovirus antigens such as IE1 include YILEETSVM (SEQ ID No: 2), YVLEETSVM (SEQ ID No: 3), VLEETSVML (SEQ ID No: 4), VLAELVKQI (SEQ ID No: 5), ATTFLQTMLR (SEQ ID No: 6), EVISVMKRR (SEQ ID No: 7), CRVLCCYVL (SEQ ID No: 8), ELRRKMMYM (SEQ ID No: 9), ELKRKMIYM (SEQ ID No: 10), QIKVRVDMV (SEQ ID No: 11), CVETMCNEY (SEQ ID No: 12), RRKMMYMCY (SEQ ID No: 13), KRKMIYMCY (SEQ ID No: 14), RRIEEICMK (SEQ ID No: 15), DELRRKMMY (SEQ ID No: 16), KEVNSQLSL (SEQ ID No: 17), EEAIVAYTL (SEQ ID No: 18) and FPKTTNGCSQA (SEQ ID No: 19); for pp65 they include YSEHPTFTSQY (SEQ ID No: 20), NLVPMVATV (SEQ ID No: 21), MLNIPSINV (SEQ ID No: 22), RIFAELEGV (SEQ ID No: 23), QYDVPAALF (SEQ ID No: 24), FTSQYRIQGKL (SEQ ID No: 25), VYALPLKML (SEQ ID No: 26), QYVKVYLESF (SEQ ID No: 27), FVFPTKDVALR (SEQ ID No: 28), YTPDSTPCHR (SEQ ID No: 29), DTPVLPHETR (SEQ ID No: 30), TPRVTGGGAM (SEQ ID No: 31), RPHERNGFTVL (SEQ ID No: 32), IPSINVHHY (SEQ ID No: 33), FPTKDVAL (SEQ ID No: 34), CPSQEPMSIYVY (SEQ ID No: 35), QPSLILVSQY (SEQ ID No: 36), SEHPTFTSQY (SEQ ID No: 37), EFFDANDIY (SEQ ID No: 38); for pp150 they include TTVYPPSSTAK (SEQ ID No: 39), QTVTSTPVQGR (SEQ ID No: 40), NVRRSWEEL (SEQ ID No: 41), KARDHLAVL (SEQ ID No: 42); for gB they include RIWCLVVCV (SEQ ID No: 43); and for pp50 they include VTEHDTLLY (SEQ ID No: 44), RGDPFDKNY (SEQ ID No: 45), TVRSHCVSK (SEQ ID No: 46).
CD4+ T cell epitopes for cytomegalovirus antigens such as pp65 include PQYSEHPTFTSQYRIQ (SEQ ID No: 47), FTSQYRIQGKLEYRHT (SEQ ID No: 48), LLQTGIHVRVSQPSL (SEQ ID No: 49), NPQPFMRPHERNGFT (SEQ ID No: 50), EPDVYYTSAFVFPTK (SEQ ID No: 51), IIKPGKISHIMLDVA (SEQ ID No: 52), AGILARNLVPMVATV (SEQ ID No: 53), KYQEFFWDANDIYRI (SEQ ID No: 54); for gB they include DYSNTHSTRYV (SEQ ID No: 55), CMLTITTARSKYPYH (SEQ ID No: 56), and VFETSGGLVVFWQGI (SEQ ID No: 57); for 1E1 they include VRVDMVRHRIKEHMLKKYTQ (SEQ ID No: 58) and NYIVPEDKREMWMACIKELH (SEQ ID No: 59); and for gH they include HELLVLVKKAQL (SEQ ID No: 60).
For Epstein Barr Virus (EBV or HHV4), immunodominant proteins are also well characterised and are provided in Hislop A D et al Annu Rev Immunol. 2007; 25:587-617 (incorporated herein by reference). A list of T cell epitopes, adapted from Hislop et al is provided below.
Further examples of immunodominant peptides include HLA-A*0201-restricted epitopes (HCMV pp65 495-504—NLVPMVATV (SEQ ID No: 21), HCMV IE1 VLEETSVML (SEQ ID No: 4), EBV LMP-2 356-364 FLYALALLL (SEQ ID No: 127), EBV BMLF-1 259-267 GLCTLVAML (SEQ ID No: 155)); HLA-A*0101-restricted epitopes (HCMV pp50 245-253—VTEHDTLLY (SEQ ID No: 44); HCMV pp65 363-373—YSEHPTFTSQY) (SEQ ID No: 20); HLA-A*0301-restricted epitopes (HCMV pp50—TVRSHCVSK (SEQ ID No: 46); HLA-B*0702-restricted epitopes (HCMV pp65 417-426 TPRVTGGGAM (SEQ ID No: 31), pp65 265-275 RPHERNGFTVL (SEQ ID No: 32)); and HLA-B*0801-restricted epitopes (HCMV IE1 88-96—ELKRKMMYM (SEQ ID N:o 253), IE1 88-96 QIKVRVDMV (SEQ ID No: 11), EBV BZLF-1 190-197 RAKFKQLL (SEQ ID No: 152), any of which may be used in the context of the invention.
It is appreciated that the T cell antigen (e.g. peptide) may be one derived from a live vaccine such as Measles, Mumps, Rubella (MMR) or HHV3; or one derived from intracellular bacteria such as mycobacteria, particularly those evoked through immunization with BCG. Such peptides are well known in the art. Similarly, the T cell antigen (e.g. peptide) may be derived from the tetanus toxoid such as P2, P4 or P30. Thus, it will be understood that the T cell antigen (e.g. peptide) may be one that elicits an existing immune response in a subject that has been generated by prior vaccination against an infectious agent. It follows that in order to increase the number of T cells sensitised to a T cell antigen, it may be desirable to vaccinate or boost a subject with a vaccine that comprises the T cell antigen. For example, the subject may be vaccinated with a tetanus toxin, before being administered the agent of the invention comprising the relevant T cell antigen.
It will be appreciated that because many people are vaccinated in childhood with these vaccines, they are likely to contain T cells which are sensitized to these T cell antigens. Thus, in one embodiment the T cell antigen is one which is found in a childhood vaccine.
Although not preferred, the T cell antigen (eg peptide) may also be one that elicits an existing immune response in a subject that has been generated by exposing that subject's T cells to the antigen in vitro.
Peptides can be produced by well known chemical procedures, such as solution or solid-phase synthesis, or semi-synthesis in solution beginning with protein fragments coupled through conventional solution methods as is known in the art. Alternatively, the peptide can be synthesised by established methods including recombinant methods.
Although it is preferred that the T cell antigen is a polypeptide or peptide, it is known that other antigens are also capable of eliciting immune responses and so have utility in the present invention. For example, γδ T cells do not recognise MHC-associated peptide antigens and are not MHC restricted. Some γδ T cell clones recognise small phosphorylated molecules, pyrophosphorylated compounds (eg HMBPP (E-4-hydroxy-3-methyl-but-2-enyl-pyrophosphate) and IPP (isopentenyl pyrophosphate)), alkyl amines or lipids (e.g. phosphorylated lipids) that may be presented by ‘non-classical’ class I MHC-like molecules called CD1 molecules. Similarly, NK-T cells (e.g. Vα24Vβ11 cells) recognise lipids (e.g. ceramides such as α-gal-ceramide) bound to CD1 molecules. Thus, the T cell antigen may be any of these molecules that are known to elicit a T cell response.
When the agent is for treating autoimmune or allergic diseases, it will be appreciated that the T cell antigen may be an autoantigen or allergen respectively. In this way the immune response that is contributing to the disorder is redirected to unwanted cells so as to combat the disorder.
It is appreciated that the T cell antigen may be chemically modified provided that it is still capable of eliciting a T cell response. Such chemical modification may include, for instance, the addition of a metal such as nickel, since it has been shown that in certain allergic patients there are T cells which recognise a peptide with a bound nickel atom (Romagnoli et al 1991, EMBO J 10: 1303-1306). The T cell antigen can also be modified by an organic molecule which enhances the immunogenicity (Romero et al 1993, J Immunol 150: 3825-3831). Other modifications include phosphorylation, acetylation, alkylation, acylation, citrulination, nitration, sulphation and hydroxylation, forming salts with acids or bases, forming an ester or amide of a terminal carboxyl group, and attaching amino acid protecting groups such as N-t-butoxycarbonal.
When the T cell antigen is a peptide, it is appreciated that it may comprise naturally occurring amino acids encoded by DNA, and/or one or more non-natural amino acids, including amino acids in the “D” isomeric form, provided that it is recognised by the corresponding T cell. Thus, the peptide may be a peptide ‘mimetic’ ie peptidomimetic which mimics the structural features of any of the peptides mentioned above. For example, the T cell antigen may be a retro-inverso peptide.
Similarly, the T cell antigen, when a peptide, may be a mimotope, ie a peptide composed of natural or non-natural amino acids that mimics the structure of the natural epitope. Mimotopes often stimulate T cells more potently.
Preferably, the T cell antigens are substantially non-toxic in the absence of T lymphocytes. By ‘substantially non-toxic’ we mean that the antigens have considerably lower or preferably no detectable toxicity, compared to toxins such as Pseudomonas exotoxin.
The skilled person will be able to identify further T cell antigens that may be used in the invention using the database available at www.immuneepitope.org (Vita R, Zarebski L, Greenbaum J A, Emami H, Hoof I, Salimi N, Damle R, Sette A, Peters B. The immune epitope database 2.0. Nucleic Acids Res. 2010 January; 38(Database issue):D854-62. Epub 2009 Nov. 11).
Selective Cleavage
By “released from the targeting moiety by selective cleavage of a cleavage site in the agent in the vicinity of the unwanted cells” we include the meaning that the T cell antigen is released from the targeting moiety by means of a cleavage site between the T cell antigen and targeting moiety being cleaved selectively in the vicinity of the unwanted cells.
By “cleavage site that is cleavable selectively in the vicinity of the unwanted cells” we include the meaning of a site that can only be cleaved by a molecule which resides selectively in the vicinity of the unwanted cells, so as to release the T cell antigen from the targeting moiety. Preferably, the molecule that cleaves the cleavage site resides in the vicinity of the unwanted cells at a concentration at least five times or ten times higher than the concentration of the molecule outside the vicinity of the unwanted cells, and more preferably at a concentration at least 100 or 500 or 1000 times higher. Most preferably, the molecule that cleaves the cleavage site is found only in the vicinity of the unwanted cells. For example, when the unwanted cells are particular tumour cells (e.g. breast tumour cells), the cleavage site may be one that is cleaved by a molecule which resides selectively in the particular tumour (e.g. breast tumour) but which molecule does not reside outside the vicinity of the particular tumour (e.g. breast tumour).
By ‘in the vicinity of cells’, we include the meaning of either at or near to the surface of the cells, or both, or in the environment that immediately surrounds the cells e.g. blood, lymph, and other body fluids. In a particularly preferred embodiment, the cleavage site is selectively cleaved outside of the unwanted cell, at or near its surface, so that the T cell antigen can be presented by the unwanted cell to T cells without needing to be internalised.
The cleavage site is selectively cleaved in the vicinity of the unwanted cells so that the T cell antigen is preferentially presented by unwanted cells rather than by wanted cells. Thus, it is preferred that the cleavage site is one that is selectively cleaved such that the T cell antigen is released in the vicinity of (e.g. at or near to the cell surface) the unwanted cells at least five times or ten times more than the extent to which it is released in the vicinity of wanted cells, and more preferably at least 100 or 500 or 1000 times more. Most preferably, the T cell antigen is not released in the vicinity of wanted cells, and therefore not presented by wanted cells.
For a given unwanted cell, the skilled person will be able to identify an appropriate cleavage site that is selectively cleavable in the vicinity of the unwanted cell, using established methods in the art. For example, which proteases cleave which peptides can be assessed by consulting peptide libraries and studying an MS analysis of the fragmentation profile following cleavage. Also, published literature of protease cleavage motifs and peptide cleavage data can be searched as described further below. Gene expression and proteomic data may also be analysed to identify which proteases are expressed by particular unwanted cells.
By virtue of the cleavage site being selectively cleavable in the vicinity of the unwanted cells, the T cell antigen is selectively released in the vicinity of the unwanted cells. The inventors believe that this allows the unwanted cells to present the T cell antigen to T cells, thereby redirecting an existing immune response to the unwanted cells.
In a preferred embodiment, the cleavage site is one that is cleaved in the vicinity of the unwanted cells and outside the unwanted cells, for example at the cell surface. In this way, the T cell antigen can be released in the vicinity of the external surface of the cell and presented to a T cell directly, without the need to be internalised and engage the appropriate processing pathways. Accordingly, the invention includes an agent for preventing or treating a condition characterised by the presence of unwanted cells, the agent comprising (i) a targeting moiety that is capable of targeting to the unwanted cells; and (ii) a T cell antigen, wherein the T cell antigen can be released from the targeting moiety by selective cleavage of a cleavage site in the agent in the vicinity of and outside of the unwanted cells. Preferably, the T cell antigen is one which does not generate a new primary T cell response for that antigen, but rather elicits an existing T cell response in a subject.
The inventors also believe, however, that the T cell antigen may be released inside the cell, without the need to undergo classical antigen processing, and still be presented to a T cell. Thus, it will be understood that the cleavage site need not be cleaved at the surface of the cell but may be cleaved within the cell, for example via a receptor cycling pathway or in near-membrane compartments such as vesicles (e.g. pinocytic vesicles).
The cleavage site may be one that is cleavable by an enzyme such as any of a protease, a nuclease, a lipase, a lyase, a phosphatase or a carbohydrase, which may or may not be membrane bound.
Generally, the cleavage site is a protease cleavage site. Thus, when the unwanted cells are tumour cells, the cleavage site may be cleavable selectively by proteases that reside in the vicinity of the tumour cells. In other words, the protease cleavage site may be one that is cleavable by a tumour associated protease. It is well known that during tumour development, tumours aberrantly express proteases which allow them to invade local tissues and eventually metastasise.
The protease may include any of a cysteine protease (including the Cathepsin family B, L, S etc), an aspartyl protease (including Cathepsin D and E) and a serine protease (including Cathepsin A and G, Thrombin, Plasmin, Urokinase, Tissue Plasminogen Activator). The protease may be a metalloproteinase (MMP1-28) including both membrane bound (MMP14-17 and MMP24-25) and secreted forms (MMP1-13 and MMP18-23 and MMP26-28). The protease may belong to the A Disintegrin and Metalloproteinase (ADAM) and A Disintegrin, or Metalloproteinase with Thrombospondin Motifs (ADAMTS) families of proteases. Other examples include CD10 (CALLA) and prostate specific antigen (PSA). It is appreciated that the proteases may or may not be membrane bound.
Protease cleavage sites are well known in the scientific literature, and linker sequences comprising such cleavage sites can be readily constructed using established genetic engineering techniques, or by synthetic synthesis techniques known in the art.
The protease cleavage site may be one that is cleavable by any of the proteases listed in Table 4 below, which indicates the expression of selected proteases in various tumour types. Candidate substrates for the proteases are provided. Thus, in order to treat a particular tumour type, the skilled person will typically select a protease cleavage site that is selectively cleaved by a protease known to be highly expressed in that tumour type, as seen from the table. For example, to treat breast cancer, it is preferred to use a protease cleavage site cleavable by any of uPA, tPA, matriptase, matriptase 2, Cathepsin K, Cathepsin 0, MMP1, MMP2, MMP3, MMP11, MMP12, MMP17, ADAM9, ADAM12, ADAM15, ADAM17, ADAM28 or ADAMTS15, and so on.
Similarly, Table 5 lists tumour sites in which ADAM protease overexpression has been reported, and so in an embodiment, the cleavage site is selectively cleavable by one of the ADAM proteases listed in Table 5. Accordingly, the agent may be used to prevent or treat the corresponding tumour type.
The cleavage site may be selectively cleavable by any of the following human proteases (MEROPS peptidase database number provided in parentheses; Rawlings N.D., Morton F. R., Kok, C. Y., Kong, J. & Barrett A. J. (2008) MEROPS: the peptidase database. Nucleic Acids Res. 36 Database issue, D320-325): pepsin A (MER000885), gastricsin (MER000894), memapsin-2 (MER005870), renin (MER000917), cathepsin D (MER000911), cathepsin E (MER000944), memapsin-1 (MER005534), napsin A (MER004981), Mername-AA034 peptidase (MER014038), pepsin A4 (MER037290), pepsin A5 (Homo sapiens) (MER037291), hCG1733572 (Homo sapiens)-type putative peptidase (MER107386), napsin B pseudogene (MER004982), CYMP g.p. (Homo sapiens) (MER002929), subfamily A1A unassigned peptidases (MER181559), mouse mammary tumor virus retropepsin (MER048030), rabbit endogenous retrovirus endopeptidase (MER043650), S71-related human endogenous retropepsin (MER001812), RTVL-H-type putative peptidase (MER047117), RTVL-H-type putative peptidase (MER047133), RTVL-H-type putative peptidase (MER047160), RTVL-H-type putative peptidase (MER047206), RTVL-H-type putative peptidase (MER047253), RTVL-H-type putative peptidase (MER047260), RTVL-H-type putative peptidase (MER047291), RTVL-H-type putative peptidase (MER047418), RTVL-H-type putative peptidase (MER047440), RTVL-H-type putative peptidase (MER047479), RTVL-H-type putative peptidase (MER047559), RTVL-H-type putative peptidase (MER047583), RTVL-H-type putative peptidase (MER015446), human endogenous retrovirus retropepsin homologue 1 (MER015479), human endogenous retrovirus retropepsin homologue 2 (MER015481), endogenous retrovirus retropepsin pseudogene 1 (Homo sapiens chromosome 14) (MER029977), endogenous retrovirus retropepsin pseudogene 2 (Homo sapiens chromosome 8) (MER029665), endogenous retrovirus retropepsin pseudogene 3 (Homo sapiens chromosome 17) (MER002660), endogenous retrovirus retropepsin pseudogene 3 (Homo sapiens chromosome 17) (MER030286), endogenous retrovirus retropepsin pseudogene 3 (Homo sapiens chromosome 17) (MER047144), endogenous retrovirus retropepsin pseudogene 5 (Homo sapiens chromosome 12) (MER029664), endogenous retrovirus retropepsin pseudogene 6 (Homo sapiens chromosome 7) (MER002094), endogenous retrovirus retropepsin pseudogene 7 (Homo sapiens chromosome 6) (MER029776), endogenous retrovirus retropepsin pseudogene 8 (Homo sapiens chromosome Y) (MER030291), endogenous retrovirus retropepsin pseudogene 9 (Homo sapiens chromosome 19) (MER029680), endogenous retrovirus retropepsin pseudogene 10 (Homo sapiens chromosome 12) (MER002848), endogenous retrovirus retropepsin pseudogene 11 (Homo sapiens chromosome 17) (MER004378), endogenous retrovirus retropepsin pseudogene 12 (Homo sapiens chromosome 11) (MER003344), endogenous retrovirus retropepsin pseudogene 13 (Homo sapiens chromosome 2 and similar) (MER029779), endogenous retrovirus retropepsin pseudogene 14 (Homo sapiens chromosome 2) (MER029778), endogenous retrovirus retropepsin pseudogene 15 (Homo sapiens chromosome 4) (MER047158), endogenous retrovirus retropepsin pseudogene 15 (Homo sapiens chromosome 4) (MER047332), endogenous retrovirus retropepsin pseudogene 15 (Homo sapiens chromosome 4) (MER003182), endogenous retrovirus retropepsin pseudogene 16 (MER047165), endogenous retrovirus retropepsin pseudogene 16 (MER047178), endogenous retrovirus retropepsin pseudogene 16 (MER047200), endogenous retrovirus retropepsin pseudogene 16 (MER047315), endogenous retrovirus retropepsin pseudogene 16 (MER047405), endogenous retrovirus retropepsin pseudogene 16 (MER030292), endogenous retrovirus retropepsin pseudogene 17 (Homo sapiens chromosome 8) (MER005305), endogenous retrovirus retropepsin pseudogene 18 (Homo sapiens chromosome 4) (MER030288), endogenous retrovirus retropepsin pseudogene 19 (Homo sapiens chromosome 16) (MER001740), endogenous retrovirus retropepsin pseudogene 21 (Homo sapiens) (MER047222), endogenous retrovirus retropepsin pseudogene 21 (Homo sapiens) (MER047454), endogenous retrovirus retropepsin pseudogene 21 (Homo sapiens) (MER047477), endogenous retrovirus retropepsin pseudogene 21 (Homo sapiens) (MER004403), endogenous retrovirus retropepsin pseudogene 22 (Homo sapiens chromosome X) (MER030287), subfamily A2A non-peptidase homologues (MER047046), subfamily A2A non-peptidase homologues (MER047052), subfamily A2A non-peptidase homologues (MER047076), subfamily A2A non-peptidase homologues (MER047080), subfamily A2A non-peptidase homologues (MER047088), subfamily A2A non-peptidase homologues (MER047089), subfamily A2A non-peptidase homologues (MER047091), subfamily A2A non-peptidase homologues (MER047092), subfamily A2A non-peptidase homologues (MER047093), subfamily A2A non-peptidase homologues (MER047094), subfamily A2A non-peptidase homologues (MER047097), subfamily A2A non-peptidase homologues (MER047099), subfamily A2A non-peptidase homologues (MER047101), subfamily A2A non-peptidase homologues (MER047102), subfamily A2A non-peptidase homologues (MER047107), subfamily A2A non-peptidase homologues (MER047108), subfamily A2A non-peptidase homologues (MER047109), subfamily A2A non-peptidase homologues (MER047110), subfamily A2A non-peptidase homologues (MER047111), subfamily A2A non-peptidase homologues (MER047114), subfamily A2A non-peptidase homologues (MER047118), subfamily A2A non-peptidase homologues (MER047121), subfamily A2A non-peptidase homologues (MER047122), subfamily A2A non-peptidase homologues (MER047126), subfamily A2A non-peptidase homologues (MER047129), subfamily A2A non-peptidase homologues (MER047130), subfamily A2A non-peptidase homologues (MER047134), subfamily A2A non-peptidase homologues (MER047135), subfamily A2A non-peptidase homologues (MER047137), subfamily A2A non-peptidase homologues (MER047140), subfamily A2A non-peptidase homologues (MER047141), subfamily A2A non-peptidase homologues (MER047142), subfamily A2A non-peptidase homologues (MER047148), subfamily A2A non-peptidase homologues (MER047149), subfamily A2A non-peptidase homologues (MER047151), subfamily A2A non-peptidase homologues (MER047154), subfamily A2A non-peptidase homologues (MER047155), subfamily A2A non-peptidase homologues (MER047156), subfamily A2A non-peptidase homologues (MER047157), subfamily A2A non-peptidase homologues (MER047159), subfamily A2A non-peptidase homologues (MER047161), subfamily A2A non-peptidase homologues (MER047163), subfamily A2A non-peptidase homologues (MER047166), subfamily A2A non-peptidase homologues (MER047171), subfamily A2A non-peptidase homologues (MER047173), subfamily A2A non-peptidase homologues (MER047174), subfamily A2A non-peptidase homologues (MER047179), subfamily A2A non-peptidase homologues (MER047183), subfamily A2A non-peptidase homologues (MER047186), subfamily A2A non-peptidase homologues (MER047190), subfamily A2A non-peptidase homologues (MER047191), subfamily A2A non-peptidase homologues (MER047196), subfamily A2A non-peptidase homologues (MER047198), subfamily A2A non-peptidase homologues (MER047199), subfamily A2A non-peptidase homologues (MER047201), subfamily A2A non-peptidase homologues (MER047202), subfamily A2A non-peptidase homologues (MER047203), subfamily A2A non-peptidase homologues (MER047204), subfamily A2A non-peptidase homologues (MER047205), subfamily A2A non-peptidase homologues (MER047207), subfamily A2A non-peptidase homologues (MER047208), subfamily A2A non-peptidase homologues (MER047210), subfamily A2A non-peptidase homologues (MER047211), subfamily A2A non-peptidase homologues (MER047212), subfamily A2A non-peptidase homologues (MER047213), subfamily A2A non-peptidase homologues (MER047215), subfamily A2A non-peptidase homologues (MER047216), subfamily A2A non-peptidase homologues (MER047218), subfamily A2A non-peptidase homologues (MER047219), subfamily A2A non-peptidase homologues (MER047221), subfamily A2A non-peptidase homologues (MER047224), subfamily A2A non-peptidase homologues (MER047225), subfamily A2A non-peptidase homologues (MER047226), subfamily A2A non-peptidase homologues (MER047227), subfamily A2A non-peptidase homologues (MER047230), subfamily A2A non-peptidase homologues (MER047232), subfamily A2A non-peptidase homologues (MER047233), subfamily A2A non-peptidase homologues (MER047234), subfamily A2A non-peptidase homologues (MER047236), subfamily A2A non-peptidase homologues (MER047238), subfamily A2A non-peptidase homologues (MER047239), subfamily A2A non-peptidase homologues (MER047240), subfamily A2A non-peptidase homologues (MER047242), subfamily A2A non-peptidase homologues (MER047243), subfamily A2A non-peptidase homologues (MER047249), subfamily A2A non-peptidase homologues (MER047251), subfamily A2A non-peptidase homologues (MER047252), subfamily A2A non-peptidase homologues (MER047254), subfamily A2A non-peptidase homologues (MER047255), subfamily A2A non-peptidase homologues (MER047263), subfamily A2A non-peptidase homologues (MER047265), subfamily A2A non-peptidase homologues (MER047266), subfamily A2A non-peptidase homologues (MER047267), subfamily A2A non-peptidase homologues (MER047268), subfamily A2A non-peptidase homologues (MER047269), subfamily A2A non-peptidase homologues (MER047272), subfamily A2A non-peptidase homologues (MER047273), subfamily A2A non-peptidase homologues (MER047274), subfamily A2A non-peptidase homologues (MER047275), subfamily A2A non-peptidase homologues (MER047276), subfamily A2A non-peptidase homologues (MER047279), subfamily A2A non-peptidase homologues (MER047280), subfamily A2A non-peptidase homologues (MER047281), subfamily A2A non-peptidase homologues (MER047282), subfamily A2A non-peptidase homologues (MER047284), subfamily A2A non-peptidase homologues (MER047285), subfamily A2A non-peptidase homologues (MER047289), subfamily A2A non-peptidase homologues (MER047290), subfamily A2A non-peptidase homologues (MER047294), subfamily A2A non-peptidase homologues (MER047295), subfamily A2A non-peptidase homologues (MER047298), subfamily A2A non-peptidase homologues (MER047300), subfamily A2A non-peptidase homologues (MER047302), subfamily A2A non-peptidase homologues (MER047304), subfamily A2A non-peptidase homologues (MER047305), subfamily A2A non-peptidase homologues (MER047306), subfamily A2A non-peptidase homologues (MER047307), subfamily A2A non-peptidase homologues (MER047310), subfamily A2A non-peptidase homologues (MER047311), subfamily A2A non-peptidase homologues (MER047314), subfamily A2A non-peptidase homologues (MER047318), subfamily A2A non-peptidase homologues (MER047320), subfamily A2A non-peptidase homologues (MER047321),subfamily A2A non-peptidase homologues (MER047322), subfamily A2A non-peptidase homologues (MER047326), subfamily A2A non-peptidase homologues (MER047327), subfamily A2A non-peptidase homologues (MER047330), subfamily A2A non-peptidase homologues (MER047333), subfamily A2A non-peptidase homologues (MER047362), subfamily A2A non-peptidase homologues (MER047366), subfamily A2A non-peptidase homologues (MER047369), subfamily A2A non-peptidase homologues (MER047370), subfamily A2A non-peptidase homologues (MER047371), subfamily A2A non-peptidase homologues (MER047375), subfamily A2A non-peptidase homologues (MER047376), subfamily A2A non-peptidase homologues (MER047381), subfamily A2A non-peptidase homologues (MER047383), subfamily A2A non-peptidase homologues (MER047384), subfamily A2A non-peptidase homologues (MER047385), subfamily A2A non-peptidase homologues (MER047388), subfamily A2A non-peptidase homologues (MER047389), subfamily A2A non-peptidase homologues (MER047391), subfamily A2A non-peptidase homologues (MER047394), subfamily A2A non-peptidase homologues (MER047396), subfamily A2A non-peptidase homologues (MER047400), subfamily A2A non-peptidase homologues (MER047401), subfamily A2A non-peptidase homologues (MER047403), subfamily A2A non-peptidase homologues (MER047406), subfamily A2A non-peptidase homologues (MER047407), subfamily A2A non-peptidase homologues (MER047410), subfamily A2A non-peptidase homologues (MER047411), subfamily A2A non-peptidase homologues (MER047413), subfamily A2A non-peptidase homologues (MER047414), subfamily A2A non-peptidase homologues (MER047416), subfamily A2A non-peptidase homologues (MER047417), subfamily A2A non-peptidase homologues (MER047420), subfamily A2A non-peptidase homologues (MER047423), subfamily A2A non-peptidase homologues (MER047424), subfamily A2A non-peptidase homologues (MER047428), subfamily A2A non-peptidase homologues (MER047429), subfamily A2A non-peptidase homologues (MER047431), subfamily A2A non-peptidase homologues (MER047434), subfamily A2A non-peptidase homologues (MER047439), subfamily A2A non-peptidase homologues (MER047442), subfamily A2A non-peptidase homologues (MER047445), subfamily A2A non-peptidase homologues (MER047449), subfamily A2A non-peptidase homologues (MER047450), subfamily A2A non-peptidase homologues (MER047452), subfamily A2A non-peptidase homologues (MER047455), subfamily A2A non-peptidase homologues (MER047457), subfamily A2A non-peptidase homologues (MER047458), subfamily A2A non-peptidase homologues (MER047459), subfamily A2A non-peptidase homologues (MER047463), subfamily A2A non-peptidase homologues (MER047468), subfamily A2A non-peptidase homologues (MER047469), subfamily A2A non-peptidase homologues (MER047470), subfamily A2A non-peptidase homologues (MER047476), subfamily A2A non-peptidase homologues (MER047478), subfamily A2A non-peptidase homologues (MER047483), subfamily A2A non-peptidase homologues (MER047488), subfamily A2A non-peptidase homologues (MER047489), subfamily A2A non-peptidase homologues (MER047490), subfamily A2A non-peptidase homologues (MER047493), subfamily A2A non-peptidase homologues (MER047494), subfamily A2A non-peptidase homologues (MER047495), subfamily A2A non-peptidase homologues (MER047496), subfamily A2A non-peptidase homologues (MER047497), subfamily A2A non-peptidase homologues (MER047499), subfamily A2A non-peptidase homologues (MER047502), subfamily A2A non-peptidase homologues (MER047504), subfamily A2A non-peptidase homologues (MER047511), subfamily A2A non-peptidase homologues (MER047513), subfamily A2A non-peptidase homologues (MER047514), subfamily A2A non-peptidase homologues (MER047515), subfamily A2A non-peptidase homologues (MER047516), subfamily A2A non-peptidase homologues (MER047520), subfamily A2A non-peptidase homologues (MER047533), subfamily A2A non-peptidase homologues (MER047537), subfamily A2A non-peptidase homologues (MER047569), subfamily A2A non-peptidase homologues (MER047570), subfamily A2A non-peptidase homologues (MER047584), subfamily A2A non-peptidase homologues (MER047603), subfamily A2A non-peptidase homologues (MER047604), subfamily A2A non-peptidase homologues (MER047606), subfamily A2A non-peptidase homologues (MER047609), subfamily A2A non-peptidase homologues (MER047616), subfamily A2A non-peptidase homologues (MER047619), subfamily A2A non-peptidase homologues (MER047648), subfamily A2A non-peptidase homologues (MER047649), subfamily A2A non-peptidase homologues (MER047662), subfamily A2A non-peptidase homologues (MER048004), subfamily A2A non-peptidase homologues (MER048018), subfamily A2A non-peptidase homologues (MER048019), subfamily A2A non-peptidase homologues (MER048023), subfamily A2A non-peptidase homologues (MER048037), subfamily A2A unassigned peptidases (MER047164), subfamily A2A unassigned peptidases (MER047231), subfamily A2A unassigned peptidases (MER047386), skin aspartic protease (MER057097), presenilin 1 (MER005221), presenilin 2 (MER005223), impas 1 peptidase (MER019701), impas 1 peptidase (MER184722), impas 4 peptidase (MER019715), impas 2 peptidase (MER019708), impas 5 peptidase (MER019712), impas 3 peptidase (MER019711), possible family A22 pseudogene (Homo sapiens chromosome 18) (MER029974), possible family A22 pseudogene (Homo sapiens chromosome 11) (MER023159), cathepsin V (MER004437), cathepsin X (MER004508), cathepsin F (MER004980), cathepsin L (MER000622), cathepsin S (MER000633), cathepsin 0 (MER001690), cathepsin K (MER000644), cathepsin W (MER003756), cathepsin H (MER000629), cathepsin B (MER000686), dipeptidyl-peptidase I (MER001937), bleomycin hydrolase (animal) (MER002481), tubulointerstitial nephritis antigen (MER016137), tubulointerstitial nephritis antigen-related protein (MER021799), cathepsin L-like pseudogene 1 (Homo sapiens) (MER002789), cathepsin B-like pseudogene (chromosome 4, Homo sapiens) (MER029469), cathepsin B-like pseudogene (chromosome 1, Homo sapiens) (MER029457), CTSLL2 g.p. (Homo sapiens) (MER005210), CTSLL3 g.p. (Homo sapiens) (MER005209), calpain-1 (MER000770), calpain-2 (MER000964), calpain-3 (MER001446), calpain-9 (MER004042), calpain-8 (MER021474), calpain-15 (MER004745), calpain-5 (MER002939), calpain-11 (MER005844), calpain-12 (MER029889), calpain-10 (MER013510), calpain-13 (MER020139), calpain-14 (MER029744), Mername-AA253 peptidase (MER005537), calpamodulin (MER000718), hypothetical protein 940251 (MER003201), ubiquitinyl hydrolase-L1 (MER000832), ubiquitinyl hydrolase-L3 (MER000836), ubiquitinyl hydrolase-BAP1 (MER003989), ubiquitinyl hydrolase-UCH37 (MER005539), ubiquitin-specific peptidase 5 (MER002066), ubiquitin-specific peptidase 6 (MER000863), ubiquitin-specific peptidase 4 (MER001795), ubiquitin-specific peptidase 8 (MER001884), ubiquitin-specific peptidase 13 (MER002627), ubiquitin-specific peptidase 2 (MER004834), ubiquitin-specific peptidase 11 (MER002693), ubiquitin-specific peptidase 14 (MER002667), ubiquitin-specific peptidase 7 (MER002896), ubiquitin-specific peptidase 9X (MER005877), ubiquitin-specific peptidase 10 (MER004439), ubiquitin-specific peptidase 1 (MER004978), ubiquitin-specific peptidase 12 (MER005454), ubiquitin-specific peptidase 16 (MER005493), ubiquitin-specific peptidase 15 (MER005427), ubiquitin-specific peptidase 17 (MER002900), ubiquitin-specific peptidase 19 (MER005428), ubiquitin-specific peptidase 20 (MER005494), ubiquitin-specific peptidase 3 (MER005513), ubiquitin-specific peptidase 9Y (MER004314), ubiquitin-specific peptidase 18 (MER005641), ubiquitin-specific peptidase 21 (MER006258), ubiquitin-specific peptidase 22 (MER012130), ubiquitin-specific peptidase 33 (MER014335), ubiquitin-specific peptidase 29 (MER012093), ubiquitin-specific peptidase 25 (MER011115), ubiquitin-specific peptidase 36 (MER014033), ubiquitin-specific peptidase 32 (MER014290), ubiquitin-specific peptidase 26 (Homo sapiens-type) (MER014292), ubiquitin-specific peptidase 24 (MER005706), ubiquitin-specific peptidase 42 (MER011852), ubiquitin-specific peptidase 46 (MER014629), ubiquitin-specific peptidase 37 (MER014633), ubiquitin-specific peptidase 28 (MER014634), ubiquitin-specific peptidase 47 (MER014636), ubiquitin-specific peptidase 38 (MER014637), ubiquitin-specific peptidase 44 (MER014638), ubiquitin-specific peptidase 50 (MER030315), ubiquitin-specific peptidase 35 (MER014646), ubiquitin-specific peptidase 30 (MER014649), Mername-AA091 peptidase (MER014743), ubiquitin-specific peptidase 45 (MER030314), ubiquitin-specific peptidase 51 (MER014769), ubiquitin-specific peptidase 34 (MER014780), ubiquitin-specific peptidase 48 (MER064620), ubiquitin-specific peptidase 40 (MER015483), ubiquitin-specific peptidase 41 (MER045268), ubiquitin-specific peptidase 31 (MER015493), Mername-AA129 peptidase (MER016485), ubiquitin-specific peptidase 49 (MER016486), Mername-AA187 peptidase (MER052579), USP17-like peptidase (MER030192), ubiquitin-specific peptidase 54 (MER028714), ubiquitin-specific peptidase 53 (MER027329), ubiquitin-specific endopeptidase 39 [misleading] (MER064621), Mername-AA090 non-peptidase homologue (MER014739), ubiquitin-specific peptidase 43 [misleading] (MER030140), ubiquitin-specific peptidase 52 [misleading] (MER030317), NEK2 pseudogene (MER014736), C19 pseudogene (Homo sapiens: chromosome 5) (MER029972), Mername-AA088 peptidase (MER014750), autophagin-2 (MER013564), autophagin-1 (MER013561), autophagin-3 (MER014316), autophagin-4 (MER064622), Cezanne deubiquitinylating peptidase (MER029042), Cezanne-2 peptidase (MER029044), tumor necrosis factor alpha-induced protein 3 (MER029050), trabid peptidase (MER029052), VCIP135 deubiquitinating peptidase (MER152304), otubain-1 (MER029056), otubain-2 (MER029061), CyID protein (MER030104), UfSP1 peptidase (MER042724), UfSP2 peptidase (MER060306), DUBA deubiquitinylating enzyme (MER086098), KIAA0459 (Homo sapiens)-like protein (MER122467), Otud1 protein (MER125457), glycosyltransferase 28 domain containing 1, isoform CRA_c (Homo sapiens)-like (MER123606), hin1L g.p. (Homo sapiens) (MER139816), ataxin-3 (MER099998), ATXN3L putative peptidase (MER115261), Josephin domain containing 1 (Homo sapiens) (MER125334), Josephin domain containing 2 (Homo sapiens) (MER124068), YOD1 peptidase (MER116559), legumain (plant alpha form) (MER044591), legumain (MER001800), glycosylphosphatidylinositol:protein transamidase (MER002479), legumain pseudogene (Homo sapiens) (MER029741), family C13 unassigned peptidases (MER175813), caspase-1 (MER000850), caspase-3 (MER000853), caspase-7 (MER002705), caspase-6 (MER002708), caspase-2 (MER001644), caspase-4 (MER001938), caspase-5 (MER002240), caspase-8 (MER002849), caspase-9 (MER002707), caspase-10 (MER002579), caspase-14 (MER012083), paracaspase (MER019325), Mername-AA143 peptidase (MER021304), Mername-AA186 peptidase (MER020516), putative caspase (Homo sapiens) (MER021463), FLIP protein (MER003026), Mername-AA142 protein (MER021316), caspase-12 pseudogene (Homo sapiens) (MER019698), Mername-AA093 caspase pseudogene (MER014766), subfamily C14A non-peptidase homologues (MER185329), subfamily C14A non-peptidase homologues (MER179956), separase (Homo sapiens-type) (MER011775), separase-like pseudogene (MER014797), SENP1 peptidase (MER011012), SENP3 peptidase (MER011019), SENP6 peptidase (MER011109), SENP2 peptidase (MER012183), SENP5 peptidase (MER014032), SENP7 peptidase (MER014095), SENP8 peptidase (MER016161), SENP4 peptidase (MER005557), pyroglutamyl-peptidase I (chordate) (MER011032), Mername-AA073 peptidase (MER029978), Sonic hedgehog protein (MER002539), Indian hedgehog protein (MER002538), Desert hedgehog protein (MER012170), dipeptidyl-peptidase III (MER004252), Mername-AA164 protein (MER020410), LOC138971 g.p. (Homo sapiens) (MER020074), Atp23 peptidase (MER060642), prenyl peptidase 1 (MER004246), aminopeptidase N (MER000997), aminopeptidase A (MER001012), leukotriene A4 hydrolase (MER001013), pyroglutamyl-peptidase II (MER012221), cytosol alanyl aminopeptidase (MER002746), cystinyl aminopeptidase (MER002060), aminopeptidase B (MER001494), aminopeptidase PILS (MER005331), arginyl aminopeptidase-like 1 (MER012271), leukocyte-derived arginine aminopeptidase (MER002968), aminopeptidase Q (MER052595), aminopeptidase 0 (MER019730), Tata binding protein associated factor (MER026493), angiotensin-converting enzyme peptidase unit 1 (MER004967), angiotensin-converting enzyme peptidase unit 2 (MER001019), angiotensin-converting enzyme-2 (MER011061), Mername-AA153 protein (MER020514), thimet oligopeptidase (MER001737), neurolysin (MER010991), mitochondrial intermediate peptidase (MER003665), Mername-AA154 protein (MER021317), leishmanolysin-2 (MER014492), leishmanolysin-3 (MER180031), matrix metallopeptidase-1 (MER001063), matrix metallopeptidase-8 (MER001084), matrix metallopeptidase-2 (MER001080), matrix metallopeptidase-9 (MER001085), matrix metallopeptidase-3 (MER001068), matrix metallopeptidase-10 (Homo sapiens-type) (MER001072), matrix metallopeptidase-11 (MER001075), matrix metallopeptidase-7 (MER001092), matrix metallopeptidase-12 (MER001089), matrix metallopeptidase-13 (MER001411), membrane-type matrix metallopeptidase-1 (MER001077), membrane-type matrix metallopeptidase-2 (MER002383), membrane-type matrix metallopeptidase-3 (MER002384), membrane-type matrix metallopeptidase-4 (MER002595), matrix metallopeptidase-20 (MER003021), matrix metallopeptidase-19 (MER002076), matrix metallopeptidase-23B (MER004766), membrane-type matrix metallopeptidase-5 (MER005638), membrane-type matrix metallopeptidase-6 (MER012071), matrix metallopeptidase-21 (MER006101), matrix metallopeptidase-22 (MER014098), matrix metallopeptidase-26 (MER012072), matrix metallopeptidase-28 (MER013587), matrix metallopeptidase-23A (MER037217), macrophage elastase homologue (chromosome 8, Homo sapiens) (MER030035), Mername-AA156 protein (MER021309), matrix metallopeptidase-like 1 (MER045280), subfamily M10A non-peptidase homologues (MER175912), subfamily M10A non-peptidase homologues (MER187997), subfamily M10A non-peptidase homologues (MER187998), subfamily M10A non-peptidase homologues (MER180000), meprin alpha subunit (MER001111), meprin beta subunit (MER005213), procollagen C-peptidase (MER001113), mammalian tolloid-like 1 protein (MER005124), mammalian-type tolloid-like 2 protein (MER005866), ADAMTS9 peptidase (MER012092), ADAMTS14 peptidase (MER016700), ADAMTS15 peptidase (MER017029), ADAMTS16 peptidase (MER015689), ADAMTS17 peptidase (MER016302), ADAMTS18 peptidase (MER016090), ADAMTS19 peptidase (MER015663), ADAM8 peptidase (MER003902), ADAM9 peptidase (MER001140), ADAM10 peptidase (MER002382), ADAM12 peptidase (MER005107), ADAM19 peptidase (MER012241), ADAM15 peptidase (MER002386), ADAM17 peptidase (MER003094), ADAM20 peptidase (MER004725), ADAMDEC1 peptidase (MER000743), ADAMTS3 peptidase (MER005100), ADAMTS4 peptidase (MER005101), ADAMTS1 peptidase (MER005546), ADAM28 peptidase (Homo sapiens-type) (MER005495), ADAMTS5 peptidase (MER005548), ADAMTS8 peptidase (MER005545), ADAMTS6 peptidase (MER005893),
ADAMTS7 peptidase (MER005894), ADAM30 peptidase (MER006268), ADAM21 peptidase (Homo sapiens-type) (MER004726), ADAMTS10 peptidase (MER014331), ADAMTS12 peptidase (MER014337), ADAMTS13 peptidase (MER015450), ADAM33 peptidase (MER015143), ovastacin (MER029996), ADAMTS20 peptidase (Homo sapiens-type) (MER026906), procollagen I N-peptidase (MER004985), ADAM2 protein (MER003090), ADAM6 protein (MER047044), ADAM7 protein (MER005109), ADAM18 protein (MER012230), ADAM32 protein (MER026938), non-peptidase homologue (Homo sapiens chromosome 4) (MER029973), family M12 non-peptidase homologue (Homo sapiens chromosome 16) (MER047654), family M12 non-peptidase homologue (Homo sapiens chromosome 15) (MER047250), ADAM3B protein (Homo sapiens-type) (MER005199), ADAM11 protein (MER001146), ADAM22 protein (MER005102), ADAM23 protein (MER005103), ADAM29 protein (MER006267), protein similar to ADAM21 peptidase preproprotein (Homo sapiens) (MER026944), Mername-AA225 peptidase homologue (Homo sapiens) (MER047474), putative ADAM pseudogene (chromosome 4, Homo sapiens) (MER029975), ADAM3A g.p. (Homo sapiens) (MER005200), ADAM1 g.p. (Homo sapiens) (MER003912), subfamily M12B non-peptidase homologues (MER188210), subfamily M12B non-peptidase homologues (MER188211), subfamily M12B non-peptidase homologues (MER188212), subfamily M12B non-peptidase homologues (MER188220), neprilysin (MER001050), endothelin-converting enzyme 1 (MER001057), endothelin-converting enzyme 2 (MER004776), DINE peptidase (MER005197), neprilysin-2 (MER013406), Kell blood-group protein (MER001054), PHEX peptidase (MER002062), i-AAA peptidase (MER001246), i-AAA peptidase (MER005755), paraplegin (MER004454), Afg3-like protein 2 (MER005496), Afg3-like protein 1A (MER014306), pappalysin-1 (MER002217), pappalysin-2 (MER014521), farnesylated-protein converting enzyme 1 (MER002646), metalloprotease-related protein-1 (MER030873), aminopeptidase AMZ2 (MER011907), aminopeptidase AMZ1 (MER058242), carboxypeptidase A1 (MER001190), carboxypeptidase A2 (MER001608), carboxypeptidase B (MER001194), carboxypeptidase N (MER001198), carboxypeptidase E (MER001199), carboxypeptidase M (MER001205), carboxypeptidase U (MER001193), carboxypeptidase A3 (MER001187), metallocarboxypeptidase D peptidase unit 1 (MER003781), metallocarboxypeptidase Z (MER003428), metallocarboxypeptidase D peptidase unit 2 (MER004963), carboxypeptidase A4 (MER013421), carboxypeptidase A6 (MER013456), carboxypeptidase A5 (MER017121), metallocarboxypeptidase 0 (MER016044), cytosolic carboxypeptidase-like protein 5 (MER033174), cytosolic carboxypeptidase 3 (MER033176), cytosolic carboxypeptidase 6 (MER033178), cytosolic carboxypeptidase 1 (MER033179), cytosolic carboxypeptidase 2 (MER037713), metallocarboxypeptidase D non-peptidase unit (MER004964), adipocyte-enhancer binding protein 1 (MER003889), carboxypeptidase-like protein X1 (MER013404), carboxypeptidase-like protein X2 (MER078764), cytosolic carboxypeptidase (MER026952), family M14 non-peptidase homologues (MER199530), insulysin (MER001214), mitochondrial processing peptidase beta-subunit (MER004497), nardilysin (MER003883), eupitrilysin (MER004877), mitochondrial processing peptidase non-peptidase alpha subunit (MER001413), ubiquinol-cytochrome c reductase core protein I (MER003543), ubiquinol-cytochrome c reductase core protein II (MER003544), ubiquinol-cytochrome c reductase core protein domain 2 (MER043998), insulysin unit 2 (MER046821), nardilysin unit 2 (MER046874), insulysin unit 3 (MER078753), mitochondrial processing peptidase subunit alpha unit 2 (MER124489), nardilysin unit 3 (MER142856), LOC133083 g.p. (Homo sapiens) (MER021876), subfamily M16B non-peptidase homologues (MER188757), leucyl aminopeptidase (animal) (MER003100), Mername-AA040 peptidase (MER003919), leucyl aminopeptidase-1 (Caenorhabditis-type) (MER013416), methionyl aminopeptidase 1 (MER001342), methionyl aminopeptidase 2 (MER001728), aminopeptidase P2 (MER004498), Xaa-Pro dipeptidase (eukaryote) (MER001248), aminopeptidase P1 (MER004321), mitochondrial intermediate cleaving peptidase 55 kDa (MER013463), mitochondrial methionyl aminopeptidase (MER014055), Mername-AA020 peptidase homologue (MER010972), proliferation-association protein 1 (MER005497), chromatin-specific transcription elongation factor 140 kDa subunit (MER026495), proliferation-associated protein 1-like (Homo sapiens chromosome X) (MER029983), Mername-AA226 peptidase homologue (Homo sapiens) (MER056262), Mername-AA227 peptidase homologue (Homo sapiens) (MER047299), subfamily M24A non-peptidase homologues (MER179893), aspartyl aminopeptidase (MER003373), Gly-Xaa carboxypeptidase (MER033182), carnosine dipeptidase II (MER014551), carnosine dipeptidase I (MER015142), Mername-AA161 protein (MER021873), aminoacylase (MER001271), glutamate carboxypeptidase II (MER002104), NAALADASE L peptidase (MER005239), glutamate carboxypeptidase III (MER005238), plasma glutamate carboxypeptidase (MER005244), Mername-AA103 peptidase (MER015091), Fxna peptidase (MER029965), transferrin receptor protein (MER002105), transferrin receptor 2 protein (MER005152), glutaminyl cyclise (MER015095), glutamate carboxypeptidase II (Homo sapiens)-type non-peptidase homologue (MER026971), nicalin (MER044627), membrane dipeptidase (MER001260), membrane-bound dipeptidase-2 (MER013499), membrane-bound dipeptidase-3 (MER013496), dihydro-orotase (MER005767), dihydropyrimidinase (MER033266), dihydropyrimidinase related protein-1 (MER030143), dihydropyrimidinase related protein-(MER030155), dihydropyrimidinase related protein-3 (MER030151), dihydropyrimidinase related protein-4 (MER030149), dihydropyrimidinase related protein-5 (MER030136), hypothetical protein like 5730457F11RIK (MER033184), 1300019j08rik protein (MER033186)), guanine aminohydrolase (MER037714), Kae1 putative peptidase (MER001577), OSGEPL1-like protein (MER013498), S2P peptidase (MER004458), subfamily M23B non-peptidase homologues (MER199845), subfamily M23B non-peptidase homologues (MER199846), subfamily M23B non-peptidase homologues (MER199847), subfamily M23B non-peptidase homologues (MER137320), subfamily M23B non-peptidase homologues (MER201557), subfamily M23B non-peptidase homologues (MER199417), subfamily M23B non-peptidase homologues (MER199418), subfamily M23B non-peptidase homologues (MER199419), subfamily M23B non-peptidase homologues (MER199420), subfamily M23B non-peptidase homologues (MER175932), subfamily M23B non-peptidase homologues (MER199665), Poh1 peptidase (MER020382), Jab1/MPN domain metalloenzyme (MER022057), Mername-AA165 peptidase (MER021865), Brcc36 isopeptidase (MER021890), histone H2A deubiquitinase MYSM1 (MER021887), AMSH deubiquitinating peptidase (MER030146), putative peptidase (Homo sapiens chromosome 2) (MER029970), Mername-AA168 protein (MER021886), COP9 signalosome subunit 6 (MER030137), 26S proteasome non-ATPase regulatory subunit 7 (MER030134), eukaryotic translation initiation factor 3 subunit 5 (MER030133), IFP38 peptidase homologue (MER030132), subfamily M67A non-peptidase homologues (MER191181), subfamily M67A unassigned peptidases (MER191144), granzyme B (Homo sapiens-type) (MER000168), testisin (MER005212), tryptase beta (MER000136), kallikrein-related peptidase 5 (MER005544), corin (MER005881), kallikrein-related peptidase 12 (MER006038), DESC1 peptidase (MER006298), tryptase gamma 1 (MER011036), kallikrein-related peptidase 14 (MER011038), hyaluronan-binding peptidase (MER003612), transmembrane peptidase, serine 4 (MER011104), intestinal serine peptidase (rodent) (MER016130), adrenal secretory serine peptidase (MER003734), tryptase delta 1 (Homo sapiens) (MER005948), matriptase-3 (MER029902), marapsin (MER006119), tryptase-6 (MER006118), ovochymase-1 domain 1 (MER099182), transmembrane peptidase, serine 3 (MER005926), kallikrein-related peptidase 15 (MER000064), Mername-AA031 peptidase (MER014054), TMPRSS13 peptidase (MER014226), Mername-AA038 peptidase (MER062848), Mername-AA204 peptidase (MER029980), cationic trypsin (Homo sapiens-type) (MER000020), elastase-2 (MER000118), mannan-binding lectin-associated serine peptidase-3 (MER031968), cathepsin G (MER000082), myeloblastin (MER000170), granzyme A (MER001379), granzyme M (MER001541), chymase (Homo sapiens-type) (MER000123), tryptase alpha (MER000135), granzyme K (MER001936), granzyme H (MER000166), chymotrypsin B (MER000001), elastase-1 (MER003733), pancreatic endopeptidase E (MER000149), pancreatic elastase II (MER000146), enteropeptidase (MER002068), chymotrypsin C (MER000761), prostasin (MER002460), kallikrein 1 (MER000093), kallikrein-related peptidase 2 (MER000094), kallikrein-related peptidase 3 (MER000115), mesotrypsin (MER000022), complement component C1r-like peptidase (MER016352), complement factor D (MER000130), complement component activated C1r (MER000238), complement component activated C1s (MER000239), complement component C2a (MER000231), complement factor B (MER000229), mannan-binding lectin-associated serine peptidase 1 (MER000244), complement factor I (MER000228), pancreatic endopeptidase E form B (MER000150), pancreatic elastase IIB (MER000147), coagulation factor XIIa (MER000187), plasma kallikrein (MER000203) coagulation factor Xia (MER000210), coagulation factor IXa (MER000216), coagulation factor Vila (MER000215), coagulation factor Xa (MER000212), thrombin (MER000188), protein C (activated) (MER000222), acrosin (MER000078), hepsin (MER000156), hepatocyte growth factor activator (MER000186), mannan-binding lectin-associated serine peptidase 2 (MER002758), u-plasminogen activator (MER000195), t-plasminogen activator (MER000192), plasmin (MER000175), kallikrein-related peptidase 6 (MER002580), neurotrypsin (MER004171), kallikrein-related peptidase 8 (MER005400), kallikrein-related peptidase 10 (MER003645), epitheliasin (MER003736), kallikrein-related peptidase 4 (MER005266), prosemin (MER004214), chymopasin (MER001503), kallikrein-related peptidase 11 (MER004861), kallikrein-related peptidase 11 (MER216142), trypsin-2 type A (MER000021), HtrA1 peptidase (Homo sapiens-type) (MER002577), HtrA2 peptidase (MER208413), HtrA2 peptidase (MER004093), HtrA3 peptidase (MER014795), HtrA4 peptidase (MER016351), Tysndl peptidase (MER050461), TMPRSS12 peptidase (MER017085), HAT-like putative peptidase 2 (MER021884), trypsin C (MER021898), kallikrein-related peptidase 7 (MER002001), matriptase (MER003735), kallikrein-related peptidase 13 (MER005269), kallikrein-related peptidase 9 (MER005270), matriptase-2 (MER005278), umbelical vein peptidase (MER005421), LCLP peptidase (MER001900), spinesin (MER014385), marapsin-2 (MER021929), complement factor D-like putative peptidase (MER056164), ovochymase-2 (MER022410), HAT-like 4 peptidase (MER044589), ovochymase 1 domain 1 (MER022412), epidermis-specific SP-like putative peptidase (MER029900), testis serine peptidase 5 (MER029901), Mername-AA258 peptidase (MER000285), polyserase-IA unit 1 (MER030879), polyserase-IA unit 2 (MER030880), testis serine peptidase 2 (human-type) (MER033187), hypothetical acrosin-like peptidase (Homo sapiens) (MER033253), HAT-like 5 peptidase (MER028215), polyserase-3 unit 1 (MER061763), polyserase-3 unit 2 (MER061748), peptidase similar to tryptophan/serine protease (MER056263), polyserase-2 unit 1 (MER061777), Mername-AA123 peptidase (MER021930), HAT-like 2 peptidase (MER099184), hCG2041452-like protein (MER099172), hCG22067 (Homo sapiens) (MER099169), brain-rescue-factor-1 (Homo sapiens) (MER098873), hCG2041108 (Homo sapiens) (MER099173), polyserase-2 unit 2 (MER061760), polyserase-2 unit 3 (MER065694), Mername-AA201 (peptidase homologue) MER099175, secreted trypsin-like serine peptidase homologue (MER030000), polyserase-1A unit 3 (MER029880), azurocidin (MER000119), haptoglobin-1 (MER000233), haptoglobin-related protein (MER000235), macrophage-stimulating protein (MER001546), hepatocyte growth factor (MER000185), protein Z (MER000227), TESP1 protein (MER047214), LOC136242 protein (MER016132), plasma kallikrein-like protein 4 (MER016346), PRSS35 protein (MER016350), DKFZp586H2123-like protein (MER066474), apolipoprotein (MER000183), psi-KLK1 pseudogene (Homo sapiens) (MER033287), tryptase pseudogene I (MER015077), tryptase pseudogene II (MER015078), tryptase pseudogene III (MER015079), subfamily S1A unassigned peptidases (MER216982), subfamily S1A unassigned peptidases (MER216148), amidophosphoribosyltransferase precursor (MER003314), glutamine-fructose-6-phosphate transaminase 1 (MER003322), glutamine:fructose-6-phosphate amidotransferase (MER012158), Mername-AA144 protein (MER021319), asparagine synthetase (MER033254), family C44 non-peptidase homologues (MER159286), family C44 unassigned peptidases (MER185625) family C44 unassigned peptidases (MER185626), secernin 1 (MER045376), secernin 2 (MER064573), secernin 3 (MER064582), acid ceramidase precursor (MER100794), N-acylethanolamine acid amidase precursor (MER141667), proteasome catalytic subunit 1 (MER000556), proteasome catalytic subunit 2 (MER002625), proteasome catalytic subunit 3 (MER002149), proteasome catalytic subunit 1i (MER000552), proteasome catalytic subunit 2i (MER001515), proteasome catalytic subunit 3i (MER000555), proteasome catalytic subunit 5t (MER026203), protein serine kinase c17 (MER026497), proteasome subunit alpha 6 (MER000557), proteasome subunit alpha 2 (MER000550), proteasome subunit alpha 4 (MER000554), proteasome subunit alpha 7 (MER033250), proteasome subunit alpha 5 (MER000558), proteasome subunit alpha 1 (MER000549), proteasome subunit alpha 3 (MER000553), proteasome subunit XAPC7 (MER004372), proteasome subunit beta 3 (MER001710), proteasome subunit beta 2 (MER002676), proteasome subunit beta 1 (MER000551), proteasome subunit beta 4 (MER001711), Mername-AA230 peptidase homologue (Homo sapiens) (MER047329), Mername-AA231 pseudogene (Homo sapiens) (MER047172), Mername-AA232 pseudogene (Homo sapiens) (MER047316), glycosylasparaginase precursor (MER003299), isoaspartyl dipeptidase (threonine type) (MER031622), taspase-1 (MER016969), gamma-glutamyltransferase 5 (mammalian-type) (MER001977), gamma-glutamyltransferase 1 (mammalian-type) (MER001629), gamma-glutamyltransferase 2 (Homo sapiens) (MER001976), gamma-glutamyltransferase-like protein 4 (MER002721), gamma-glutamyltransferase-like protein 3 (MER016970), similar to gamma-glutamyltransferase 1 precursor (Homo sapiens) (MER026204), similar to gamma-glutamyltransferase 1 precursor (Homo sapiens) (MER026205), Mername-AA211 putative peptidase (MER026207), gamma-glutamyltransferase 6 (MER159283), gamma-glutamyl transpeptidase homologue (chromosome 2, Homo sapiens) (MER037241), polycystin-1 (MER126824), KIAA1879 protein (MER159329), polycystic kidney disease 1-like 3 (MER172554), gamma-glutamyl hydrolase (MER002963), guanine 5″-monophosphate synthetase (MER043387), carbamoyl-phosphate synthase (Homo sapiens-type) (MER078640), dihydro-orotase (N-terminal unit) (Homo sapiens-type) (MER060647), DJ-1 putative peptidase (MER003390), Mername-AA100 putative peptidase (MER014802), Mername-AA101 non-peptidase homologue (MER014803), KIAA0361 protein (Homo sapiens-type) (MER042827), FLJ34283 protein (Homo sapiens) (MER044553), non-peptidase homologue chromosome 21 open reading frame 33 (Homo sapiens) (MER160094), family C56 non-peptidase homologues (MER177016), family C56 non-peptidase homologues (MER176613), family C56 non-peptidase homologues (MER176918), EGF-like module containing mucin-like hormone receptor-like 2 (MER037230), CD97 antigen (human type) (MER037286), EGF-like module containing mucin-like hormone receptor-like 3 (MER037288), EGF-like module containing mucin-like hormone receptor-like 1 (MER037278), EGF-like module containing mucin-like hormone receptor-like 4 (MER037294), cadherin EGF LAG seven-pass G-type receptor 2 precursor (Homo sapiens) (MER045397), Gpr64 (Mus musculus)-type protein (MER123205), GPR56 (Homo sapiens)-type protein (MER122057), latrophilin 2 (MER122199), latrophilin-1 (MER126380), latrophilin 3 (MER124612), protocadherin Flamingo 2 (MER124239), ETL protein (MER126267), G protein-coupled receptor 112 (MER126114), seven transmembrane helix receptor (MER125448), Gpr114 protein (MER159320), GPR126 vascular inducible G protein-coupled receptor (MER140015), GPR125 (Homo sapiens)-type protein (MER159279), GPR116 (Homo sapiens)-type G-protein coupled receptor (MER159280), GPR128 (Homo sapiens)-type G-protein coupled receptor (MER162015), GPR133 (Homo sapiens)-type protein (MER159334), GPR110 G-protein coupled receptor (MER159277), GPR97 protein (MER159322), KPG_006 protein (MER161773), KPG_008 protein (MER161835), KPG_009 protein (MER159335), unassigned homologue (MER166269), GPR113 protein (MER159352), brain-specific angiogenesis inhibitor 2 (MER159746), PIDD auto-processing protein unit 1 (MER020001), PIDD auto-processing protein unit 2 (MER063690), MUC1 self-cleaving mucin (MER074260), dystroglycan (MER054741), proprotein convertase 9 (MER022416), site-1 peptidase (MER001948), furin (MER000375), proprotein convertase 1 (MER000376), proprotein convertase 2 (MER000377), proprotein convertase 4 (MER028255), PACE4 proprotein convertase (MER000383), proprotein convertase 5 (MER002578), proprotein convertase 7 (MER002984), tripeptidyl-peptidase II (MER000355), subfamily S8A non-peptidase homologues (MER201339), subfamily S8A non-peptidase homologues (MER191613), subfamily S8A unassigned peptidases (MER191611), subfamily S8A unassigned peptidases (MER191612), subfamily S8A unassigned peptidases (MER191614), tripeptidyl-peptidase I (MER003575), prolyl oligopeptidase (MER000393), dipeptidyl-peptidase IV (eukaryote) (MER000401), acylaminoacyl-peptidase (MER000408), fibroblast activation protein alpha subunit (MER000399), PREPL A protein (MER004227), dipeptidyl-peptidase 8 (MER013484), dipeptidyl-peptidase 9 (MER004923), FLJ1 putative peptidase (MER017240), Mername-AA194 putative peptidase (MER017353), Mername-AA195 putative peptidase (MER017367), Mername-AA196 putative peptidase (MER017368), Mername-AA197 putative peptidase (MER017371), C14orf29 protein (MER033244), hypothetical protein (MER033245), hypothetical esterase/lipase/thioesterase (MER047309), protein bat5 (MER037840), hypothetical protein f1j40219 (MER033212), hypothetical protein 937464 (MER033240), hypothetical protein f1j33678 (MER033241), dipeptidylpeptidase homologue DPP6 (MER000403), dipeptidylpeptidase homologue DPP10 (MER005988), protein similar to Mus musculus chromosome 20 open reading frame 135 (MER037845), kynurenine formamidase (MER046020), thyroglobulin precursor (MER011604), acetylcholinesterase (MER033188), cholinesterase (MER033198), carboxylesterase D1 (MER033213), liver carboxylesterase (MER033220), carboxylesterase 3 (MER033224), carboxylesterase 2 (MER033226), bile salt-dependent lipase (MER033227), carboxylesterase-related protein (MER033231), neuroligin 3 (MER033232), neuroligin 4, X-linked (MER033235), neuroligin 4, Y-linked (MER033236), esterase D (MER043126), arylacetamide deacetylase (MER033237), KIAA1363-like protein (MER033242), hormone-sensitive lipase (MER033274), neuroligin 1 (MER033280), neuroligin 2 (MER033283), family S9 non-peptidase homologues (MER212939), family S9 non-peptidase homologues (MER211490), subfamily S9C unassigned peptidases (MER192341), family S9 unassigned peptidases (MER209181), family S9 unassigned peptidases (MER200434), family S9 unassigned peptidases (MER209507), family S9 unassigned peptidases (MER209142), serine carboxypeptidase A (MER000430), vitellogenic carboxypeptidase-like protein (MER005492), RISC peptidase (MER010960), family S15 unassigned peptidases (MER199442), family S15 unassigned peptidases (MER200437), family S15 unassigned peptidases (MER212825), lysosomal Pro-Xaa carboxypeptidase (MER000446), dipeptidyl-peptidase II (MER004952), thymus-specific serine peptidase (MER005538), epoxide hydrolase-like putative peptidase (MER031614), Loc328574-like protein (MER033246), abhydrolase domain-containing protein 4 (MER031616), epoxide hydrolase (MER000432), mesoderm specific transcript protein (MER199890), mesoderm specific transcript protein (MER017123), cytosolic epoxide hydrolase (MER029997), cytosolic epoxide hydrolase (MER213866), similar to hypothetical protein F1122408 (MER031608), CGI-58 putative peptidase (MER030163), Williams-Beuren syndrome critical region protein 21 epoxide hydrolase (MER031610), epoxide hydrolase (MER031612), hypothetical protein 922408 (epoxide hydrolase) (MER031617), monoglyceride lipase (MER033247), hypothetical protein (MER033249), valacyclovir hydrolase (MER033259), Ccg1-interacting factor b (MER210738),glycosylasparaginase precursor (MER003299), isoaspartyl dipeptidase (threonine type) (MER031622). taspase-1 (MER016969), gamma-glutamyltransferase 5 (mammalian-type) (MER001977), gamma-glutamyltransferase 1 (mammalian-type) (MER001629), gamma-glutamyltransferase 2 (Homo sapiens) (MER001976), gamma-glutamyltransferase-like protein 4 (MER002721). gamma-glutamyltransferase-like protein 3 (MER016970). similar to gamma-glutamyltransferase 1 precursor (Homo sapiens) (MER026204). similar to gamma-glutamyltransferase 1 precursor (Homo sapiens) (MER026205). Mername-AA211 putative peptidase (MER026207). gamma-glutamyltransferase 6 (MER159283). gamma-glutamyl transpeptidase homologue (chromosome 2, Homo sapiens) (MER037241). polycystin-1 (MER126824), KIAA1879 protein (MER159329). polycystic kidney disease 1-like 3 (MER172554). gamma-glutamyl hydrolase (MER002963). guanine 5″-monophosphate synthetase (MER043387). carbamoyl-phosphate synthase (Homo sapiens-type) (MER078640). dihydro-orotase (N-terminal unit) (Homo sapiens-type) (MER060647). DJ-1 putative peptidase (MER003390). Mername-AA100 putative peptidase (MER014802). Mername-AA101 non-peptidase homologue (MER014803). KIAA0361 protein (Homo sapiens-type) (MER042827). F1134283 protein (Homo sapiens) (MER044553). non-peptidase homologue chromosome 21 open reading frame 33 (Homo sapiens) (MER160094). family C56 non-peptidase homologues (MER177016), family C56 non-peptidase homologues (MER176613). family C56 non-peptidase homologues (MER176918). EGF-like module containing mucin-like hormone receptor-like 2 (MER037230). CD97 antigen (human type) (MER037286). EGF-like module containing mucin-like hormone receptor-like 3 (MER037288). EGF-like module containing mucin-like hormone receptor-like 1 (MER037278). EGF-like module containing mucin-like hormone receptor-like 4 (MER037294). cadherin EGF LAG seven-pass G-type receptor 2 precursor (Homo sapiens) (MER045397), Gpr64 (Mus musculus)-type protein (MER123205). GPR56 (Homo sapiens)-type protein (MER122057). latrophilin 2 (MER122199). latrophilin-1 (MER126380). latrophilin 3 (MER124612). protocadherin Flamingo 2 (MER124239). ETL protein (MER126267). G protein-coupled receptor 112 (MER126114). seven transmembrane helix receptor (MER125448). Gpr114 protein (MER159320). GPR126 vascular inducible G protein-coupled receptor (MER140015). GPR125 (Homo sapiens)-type protein (MER159279). GPR116 (Homo sapiens)-type G-protein coupled receptor (MER159280). GPR128 (Homo sapiens)-type G-protein coupled receptor (MER162015). GPR133 (Homo sapiens)-type protein (MER159334) GPR110 G-protein coupled receptor (MER159277), GPR97 protein (MER159322),KPG_006 protein (MER161773) KPG_008 protein (MER161835), KPG_009 protein (MER159335), unassigned homologue (MER166269), GPR113 protein (MER159352), brain-specific angiogenesis inhibitor 2 (MER159746), PIDD auto-processing protein unit 1 (MER020001), PIDD auto-processing protein unit 2 (MER063690), MUC1 self-cleaving mucin (MER074260), dystroglycan (MER054741), proprotein convertase 9 (MER022416), site-1 peptidase (MER001948), furin (MER000375), proprotein convertase 1 (MER000376), proprotein convertase 2 (MER000377), proprotein convertase 4 (MER028255), PACE4 proprotein convertase (MER000383), proprotein convertase 5 (MER002578), proprotein convertase 7 (MER002984), tripeptidyl-peptidase II (MER000355), subfamily S8A non-peptidase homologues (MER201339), subfamily S8A non-peptidase homologues (MER191613), subfamily S8A unassigned peptidases (MER191611), subfamily S8A unassigned peptidases (MER191612), subfamily S8A unassigned peptidases (MER191614), tripeptidyl-peptidase I (MER003575), prolyl oligopeptidase (MER000393), dipeptidyl-peptidase IV (eukaryote) (MER000401), acylaminoacyl-peptidase (MER000408), fibroblast activation protein alpha subunit (MER000399), PREPL A protein (MER004227), dipeptidyl-peptidase 8 (MER013484), dipeptidyl-peptidase 9 (MER004923), FLJ1 putative peptidase (MER017240), Mername-AA194 putative peptidase (MER017353), Mername-AA195 putative peptidase (MER017367), Mername-AA196 putative peptidase (MER017368), Mername-AA197 putative peptidase (MER017371), C14orf29 protein (MER033244), hypothetical protein (MER033245), hypothetical esterase/lipase/thioesterase (MER047309), protein bat5 (MER037840), hypothetical protein f1j40219 (MER033212), hypothetical protein f1j37464 (MER033240), hypothetical protein f1j33678 (MER033241), dipeptidylpeptidase homologue DPP6 (MER000403), dipeptidylpeptidase homologue DPP10 (MER005988), protein similar to Mus musculus chromosome 20 open reading frame 135 (MER037845), kynurenine formamidase (MER046020), thyroglobulin precursor (MER011604), acetylcholinesterase (MER033188), cholinesterase (MER033198), carboxylesterase D1 (MER033213), liver carboxylesterase (MER033220), carboxylesterase 3 (MER033224), carboxylesterase 2 (MER033226), bile salt-dependent lipase (MER033227), carboxylesterase-related protein (MER033231), neuroligin 3 (MER033232), neuroligin 4, X-linked (MER033235), neuroligin 4, Y-linked (MER033236), esterase D (MER043126), arylacetamide deacetylase (MER033237), KIAA1363-like protein (MER033242), hormone-sensitive lipase (MER033274), neuroligin 1 (MER033280), neuroligin 2 (MER033283), family S9 non-peptidase homologues (MER212939), family S9 non-peptidase homologues (MER211490), subfamily S9C unassigned peptidases (MER192341), family S9 unassigned peptidases (MER209181), family S9 unassigned peptidases (MER200434), family S9 unassigned peptidases (MER209507), family S9 unassigned peptidases (MER209142), serine carboxypeptidase A (MER000430), vitellogenic carboxypeptidase-like protein (MER005492), RISC peptidase (MER010960), family S15 unassigned peptidases (MER199442), family S15 unassigned peptidases (MER200437), family S15 unassigned peptidases (MER212825), lysosomal Pro-Xaa carboxypeptidase (MER000446), dipeptidyl-peptidase II (MER004952), thymus-specific serine peptidase (MER005538), epoxide hydrolase-like putative peptidase (MER031614), Loc328574-like protein (MER033246), abhydrolase domain-containing protein 4 (MER031616), epoxide hydrolase (MER000432), mesoderm specific transcript protein (MER199890), mesoderm specific transcript protein (MER017123), cytosolic epoxide hydrolase (MER029997), cytosolic epoxide hydrolase (MER213866), similar to hypothetical protein FLJ22408 (MER031608), CGI-58 putative peptidase (MER030163), Williams-Beuren syndrome critical region protein 21 epoxide hydrolase (MER031610), epoxide hydrolase (MER031612), hypothetical protein f1j22408 (epoxide hydrolase) (MER031617), monoglyceride lipase (MER033247), hypothetical protein (MER033249), valacyclovir hydrolase (MER033259), Ccg1-interacting factor b (MER210738).
It will be appreciated that for a given unwanted cell type, the skilled person can readily determine an appropriate protease cleavage site to use, for example by consulting scientific literature to determine which proteases are overexpressed by that cell type. Oncomine (www.oncomine.org) is an online cancer gene expression database, and so when the agent of the invention is for treating cancer, the skilled person may search the Oncomine database to identify a particular protease cleavage site that will be appropriate for treating a given cancer type. Alternative databases include European Bioinformatic Institute (//www.ebi.ac.uk) in particular (www.ebi.ac.uk/gxa). Protease databases include PMAP (www.proteolysis.org), ExPASy Peptide Cutter (ca.expasy.org/tools/peptide cutter) and PMAP.Cut DB (cutdb.burnham.org).
It is noted that it may be desirable to screen a library of peptides incorporating multiple potential cleavage sites and evaluating the optimal cleavage site for a given unwanted cell (eg tumour). Such peptides may be useful as linkers to join the T cell antigen to the targeting moiety as discussed below.
In one embodiment, the protease may be an esterase.
Other cleavage sites include linkages which are labile under certain conditions in the vicinity of unwanted cells (eg tumour microenvironment). For example, the cleavage site may comprise disulphide bonds, which can be reduced in the hypoxic tumour microenvironment, or may comprise pH sensitive moieties that break in acidic conditions. It will be understood, however, that the cleavage site must be selectively cleavable in the vicinity of the unwanted cells and so such linkages must be more labile and preferably only labile in the vicinity of unwanted cells compared to in the vicinity of wanted cells.
Alternatively, the cleavage site may comprise nucleic acid (eg DNA or RNA) that is selectively cleavable in the vicinity of unwanted cells (eg by nucleases). Other cleavage sites include phosphate, lipid or disulphide containing moieties that may be cleavable by appropriate enzymes.
Conveniently, the T cell antigen is joined to the targeting moiety by a linker. By ‘linker’ we include the meaning of a chemical moiety that attaches the targeting moiety to the T cell antigen, and which comprises a cleavage site that is cleavable selectively in the vicinity of the unwanted cells as described herein.
It is appreciated that the T cell antigen may either be bound covalently or non-covalently to the targeting moiety.
Preferably, the T cell antigen is covalently attached to the targeting moiety.
In one embodiment, the T cell antigen and targeting moiety are covalently attached by a linker.
Thus, the T cell antigen (e.g. peptide) and targeting moiety may be conveniently linked by any of the conventional ways of cross-linking molecules, such as those generally described in O'Sullivan et al Anal. Biochem. (1979) 100, 100-108, and as described in Example 2. For example, one of the T cell antigen (e.g. peptide) or targeting moiety may be enriched with thiol groups and the other reacted with a bifunctional agent capable of reacting with those thiol groups, for example the N-hydroxysuccinimide ester of iodoacetic acid (NHIA) or N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), a heterobifunctional cross-linking agent which incorporates a disulphide bridge between the conjugated species. Amide and thioether bonds, for example achieved with m-maleimidobenzoyl-N-hydroxysuccinimide ester, are generally more stable in vivo than disulphide bonds.
It is known that bis-maleimide reagents allow the attachment of a thiol group (e.g. thiol group of a cysteine residue of an antibody) to another thiol-containing moiety (e.g. thiol group of a T cell antigen or a linker intermediate), in a sequential or concurrent fashion. Other functional groups besides maleimide, which are reactive with a thiol group include iodoacetamide, bromoacetamide, vinyl pyridine, disulfide, pyridyl disulfide, isocyanate, and isothiocyanate.
Further useful cross-linking agents include S-acetylthioglycolic acid N-hydroxysuccinimide ester (SATA) which is a thiolating reagent for primary amines which allows deprotection of the sulphydryl group under mild conditions (Julian et al (1983) Anal. Biochem. 132, 68), dimethylsuberimidate dihydrochloride and N,N′-o-phenylenedimaleimide.
Particularly preferred crosslinking agents include sulfosuccinimidyl 4-[N-maleimidomethyl]cyclohexane-1-carboxylate (Sulfo-SMCC), sulfosuccinimidyl 6-(3′-[2-pyridyldithio]-propionamido) hexanoate (Sulfo-LC-SPDP) and N-[β-Maleimidopropionic acid] hydrazide, trifluoroacetic acid salt (BMPH).
It will be understood that a large number of homobifunctional and heterobifunctional crosslinking chemistries would be appropriate to join the targeting moiety to the T cell antigen, and any such chemistry may be used. For example, Click Chemistry using Staudinger Ligation Chemistry (phosphine-azido chemistry) may be used.
It is appreciated that the T cell antigen and targeting moiety do not need to be cross-linked directly to each other, but may be attached via one or more spacer moieties. For example, the T cell antigen may be crosslinked to a chemical moiety which in turn is crosslinked to the targeting moiety. In one embodiment, such a spacer moiety may comprise a cleavage site that is cleavable selectively in the vicinity of the unwanted cells, as discussed below. It will be appreciated that the spacer moiety may serve to prevent steric hindrance and facilitate protease cleavage.
Tables 6 and 7 provide examples of suitable T cell antigen peptides and how they may be incorporated into the agent of the invention. For example, the T cell antigen peptide may be joined to a protease cleavage site via a first spacer moiety, and the protease cleavage site in turn joined to a linker moiety via a second spacer moiety. The linker may be used to attach the final peptide to the targeting moiety. Tables 6 and 7 also list the proteases that cleave the corresponding protease cleavage sites.
Further examples of peptides containing a T cell antigen and protease cleavage site, that may be incorporated into the agent of the invention (e.g. by attachment to an appropriate targeting moiety such as an antibody) are listed in the table below.
In a particularly preferred embodiment when the T cell antigen is a peptide, the T cell antigen peptide is attached to the targeting moiety, either directly or indirectly through a spacer moiety, at its N-terminus. This is illustrated in
In view of the above, it is appreciated that the invention provides an agent for preventing or treating a condition characterised by the presence of unwanted cells, the agent comprising (i) a targeting moiety that is capable of targeting to the unwanted cells; (ii) a T cell antigen; and (iii) a cleavable site between the targeting moiety and T cell antigen, wherein the cleavable site can be selectively cleaved in the vicinity of the unwanted cells.
In a specific embodiment where the T cell antigen and targeting moiety are covalently attached and where both the antigen and targeting moiety are peptides or polypeptides, it is appreciated that the two components may be part of a fusion polypeptide that may be encoded by a nucleic acid molecule. The invention includes such a nucleic acid molecule and host cells containing them. For example, an antibody targeting moiety may be genetically engineered to contain the T cell antigen using genetic engineering techniques well established in the art. Thus, it will be appreciated that the T cell antigen may be embedded within the polypeptide sequence of the targeting moiety, provided that it can be released so as to be capable of being presented on an unwanted cell to elicit a T cell response. For example, the T cell antigen may reside within the polypeptide of the targeting moiety and be flanked by two cleavage sites which each may be selectively cleaved in the vicinity of the unwanted cell. Alternatively, the T cell antigen may reside at one terminus of the targeting moiety and be released by virtue of one cleavage site being cleaved. Suitably, the T cell antigen and the targeting moiety are joined so that both portions retain their respective activities such that the agent may be targeted to an unwanted cell and the T cell antigen may be presented by the unwanted cell so as to elicit an immune response. The T cell antigen and targeting moiety portions are typically joined by a linker peptide which comprises a cleavage site that is cleavable selectively in the vicinity of the unwanted cells as described below. Suitable linker peptides are those that typically adopt a random coil conformation, for example the polypeptide may contain alanine or proline or a mixture of alanine plus proline residues. Preferably, the linker contains between 2 and 100 amino acid residues, more preferably between 2 and 50 and still more preferably between 4 and 20. A particular example of having both the targeting moiety and T cell antigen as part of the same polypeptide is illustrated in
Polynucleotides which encode suitable targeting moieties are known in the art or can be readily designed from known sequences such as from sequences of proteins known to interact with surface markers expressed on unwanted cells or contained in nucleotide sequence databases such as the GenBank, EMBL and dbEST databases.
Polynucleotides which encode suitable T cell antigens are known in the art or can readily be designed from known sequences and made.
Polynucleotides which encode suitable linker peptides can readily be designed from linker peptide sequences and made.
Thus, polynucleotides which encode the agents used in the invention can readily be constructed using well known genetic engineering techniques.
The nucleic acid is then expressed in a suitable host to produce an agent of the invention. Thus, the nucleic acid encoding the agent of the invention may be used in accordance with known techniques, appropriately modified in view of the teachings contained herein, to construct an expression vector, which is then used to transform an appropriate host cell for the expression and production of the agent of the invention of the invention.
It is appreciated that the nucleic acid encoding the agent of the invention may be joined to a wide variety of other nucleic acid sequences for introduction into an appropriate host. The companion nucleic acid will depend upon the nature of the host, the manner of the introduction of the nucleic acid into the host, and whether episomal maintenance or integration is desired, as is well known in the art.
In an alternative embodiment, the T cell antigen and targeting moiety are non-covalently attached. For non-covalent bindings, immunological bindings or such binding as via biotin/avidin or streptavidin, respectively, are preferred. For example, the targeting moiety may be a bispecific antibody, one specificity of which is directed to an entity expressed by the unwanted cell and one specificity of which is directed to the T cell antigen or part thereof. Also, it is possible to couple the T cell antigen to another substance against which, in turn, the specificity of the bispecific antibody will be directed to. For instance, the T cell antigen may contain further peptidic sequences which are recognised by the bispecific antibody. Another possibility involves coupling the targeting moiety, for example to streptavidin whilst the T cell antigen is coupled to biotin, and vice versa. Other means by which non-covalent interactions can be formed include leucine zipper sequences or affinity bonds. In any event, between the T cell antigen and targeting moiety there must be a cleavage site that is cleavable selectively in the vicinity of the unwanted cells, such that the T cell antigen can be released from the targeting moiety.
Amino acid residues described herein are generally in the natural “L” isomeric form. However, residues in the “D” isomeric form can be substituted for L-amino acid residues in certain situations, provided that the agent of the invention still retains its function, namely to prevent or treat a condition characterised by the presence of unwanted cells. The definition also includes, unless otherwise specifically indicated, chemically-modified amino acids, including amino acid analogues (such as penicillamine, 3-mercapto-D-valine), naturally-occurring non-proteogenic amino acids (such as norleucine), beta-amino acids, azapeptides, N-methylated amino acids and chemically-synthesised compounds that have properties known in the art to be characteristic of an amino acid. The term “proteogenic” indicates that the amino acid can be incorporated into a protein in a cell through well-known metabolic pathways. The definition also includes amino acids in which the functional side group has been chemically derivatised. Such derivatised molecules include, for example, those molecules in which free amino groups have been derivatised to form amine hydrochlorides, p-toluene sulfonyl groups, carbobenzoxy groups, t-butyloxycarbonyl groups, chloroacetyl groups or formyl groups. Free carboxyl groups may be derivatised to form salts, methyl and ethyl esters or other types of esters or hydrazides. Free hydroxyl groups may be derivatised to form O-acyl or O-alkyl derivatives. Also included as derivatives are those peptide portions that contain one or more naturally occurring amino acid derivatives of the twenty standard amino acids.
Accordingly, it is appreciated that the peptide portions of the agent of the invention can be peptide “mimetics”, i.e. peptidomimetics which mimic the structural features of peptides comprising or consisting of the amino acid sequence as described herein. Peptidomimetics can be even more advantageous in therapeutic use, in the resistance to degradation, in permeability or in possible oral administration.
A primary goal in the design of peptide mimetics has been to reduce the susceptibility of mimetics to cleavage and inactivation by peptidases. In one approach, such as disclosed by Sherman et al (1990), one or more amide bonds have been replaced in an essentially isosteric manner by a variety of chemical functional groups. This stepwise approach has met with some success in that active analogues have been obtained. In some instances, these analogues have been shown to possess longer biological half-lives than their naturally-occurring counterparts. In another approach, a variety of uncoded or modified amino acids such as D-amino acids and N-methyl amino acids have been used to modify mammalian peptides. Alternatively, a presumed bioactive conformation has been stabilised by a covalent modification, such as cyclization or by incorporation of γ-lactam or other types of bridges (Veber et al, 1978) and Thorsett et al, 1983). Another approach, disclosed by Rich (1986) has been to design peptide mimics through the application of the transition state analogue concept in enzyme inhibitor design. For example, it is known that the secondary alcohol of statine mimics the tetrahedral transition state of the sessile amide bond of the pepsin substrate. Other approaches include the use of azapeptides and beta-amino acids.
Also included in the definition of ‘peptidomimetics’, are retro-inverso peptides. By retro-inverso peptides (also known as all-D-retro or retro-enantio peptides) we include the meaning of a peptide in which all of the L-amino acids are replaced with D-amino acids and the peptide bonds are reversed. Thus, the peptides are composed of D-amino acids assembled in the reverse order from that of the parent L-sequence. Retro-inverso peptides can be synthesised by methods known in the art, for example such as those described in Meziere et al (1997) J. Immunol. 159 3230-3237. This approach involves making pseudopeptides containing changes involving the backbone, and not the orientation of side chains which remain very similar to the parent peptide. Retro-inverse peptides are much more resistant to proteolysis.
Therefore, it will be appreciated that when any of the targeting moiety, T cell antigen, cleavage site, spacer moieties and targeting moiety as described herein are peptides or polypeptides, any one or more of those peptides or polypeptides may be substituted for a corresponding peptidomimetic that retains the respective activity of the parent peptide or polypeptide. This may help to confer protease resistance on the agent of the invention and thereby improve its stability. Thus, for example, when a T cell antigen is attached to a targeting moiety via one or more peptide spacer moieties, it may be desirable for one or more of those spacer moieties to be peptidomimetics, e.g. wherein one or more of the naturally occurring amino acids of the spacer moieties are replaced or modified, for example, to improve stability.
Another approach to increase stability of peptide portions of the agent of the invention is to have stabilising groups at one or both termini. Typical stabilising groups include amido, acetyl, benzyl, phenyl, tosyl, alkoxycarbonyl, alkyl carbonyl, benzyloxycarbonyl and the like end group modifications. Additional modifications include using a “D” amino acid in place of a “L” amino acid at the termini, and amide rather than amino or carboxy termini or acetyl rather than amino termini, to inhibit exopeptidase activity. Thus, it is appreciated that whenever the agent of the invention has an exposed peptide terminus, that terminus may have a capping moiety, preferably a moiety that is less than 200 Da in molecular weight. Further capping moieties include a naftyl group or a polyethylene glycol group. It is appreciated that retro-inverso peptides are already relatively stable and so may not require additional capping moieties.
Preferably, the agent of the invention has a half-life in plasma of at least 24 hours at 37° C.
It may be desirable to modify the agent of the invention so that it can be more easily detected, for example by biotinylating it or by incorporating any detectable label known in the art such as radiolabels, fluorescent labels or enzymatic labels.
A particular preferred embodiment of the invention provides an agent for preventing or treating cancer, the agent comprising:
i) a targeting moiety that is capable of targeting to the cancer; and
ii) an immunogenic T cell peptide,
wherein the T cell peptide can be released from the targeting moiety by selective cleavage in the vicinity of the cancer.
The cancer may be any cancer such as breast cancer, ovarian cancer, endometrial cancer, cervical cancer, bladder cancer, renal cancer, melanoma, lung cancer, prostate cancer, testicular cancer, thyroid cancer, brain cancer, oesophageal cancer, gastric cancer, pancreatic cancer, colorectal cancer, liver cancer, leukaemia, myeloma, non-Hodgkin's lymphoma, Hodgkin's lymphoma, acute myeloid leukaemia, acute lymphoblastic leukaemia, chronic lymphoblastic leukaemia, lymphoproliferative disorder, myelodysplastic disorder, myeloproliferative disease and premalignant disease.
As described above, the inventors have shown that agents of the invention may be used to redirect existing immune responses to kill particular unwanted cells in a specific manner. Since any unwanted cell may be targeted in this way, the agents of the invention offer significant therapeutic potential.
Accordingly, a second aspect of the invention provides a method of preventing or treating a condition characterised by the presence of unwanted cells, the method comprising administering an agent according to the first aspect of the invention to a subject.
Thus, the method may involve identifying a subject who has a condition or who is at risk of developing a condition characterised by unwanted cells (eg cancer), administering the agent according to the first aspect of the invention to the subject, and monitoring the levels of the unwanted cells in the subject either by conducting tests to determine the number of unwanted cells or by monitoring the clinical symptoms of the subject. Depending on the results of the monitoring step, it may be necessary to administer more of the agent.
Similarly, the invention includes an agent according to the first aspect of the invention for use in preventing or treating a condition characterised by the presence of unwanted cells.
The invention also includes the use of an agent according to the first aspect of the invention in the manufacture of a medicament for preventing or treating a condition characterised by the presence of unwanted cells.
Preferences for the condition and unwanted cells, are as described above with respect to the first aspect of the invention. Preferably, the unwanted cells are tumour cells and the condition is a tumour.
By preventing or treating a condition we include the meaning of reducing or alleviating symptoms in a patient (i.e. palliative use), preventing symptoms from worsening or progressing, treating the disorder (e.g. by inhibition or elimination of the causative agent), or prevention of the condition or disorder in a subject who is free therefrom.
It will be appreciated that the agents of the invention lend themselves to personalised medicine in the clinic whereby the most appropriate agent to be administered to the patient is determined, and either selected or prepared in the clinic. For example, before the step of administering the agent to the subject, any one of the following may be determined: (i) the MHC alleles of the subject, (ii) the cytotoxic T cell response of the subject to a T cell antigen and (iii) the expression profile of the unwanted cell with regards to a molecule which may be the target of the targeting moiety and/or an enzyme which is able to cleave the cleavage site in the agent of the invention. The MHC alleles of a subject can be assessed by serological assays at the antigen level or by using DNA assays at the genetic level. Determining whether a given antigen stimulates a specific cytotoxic T cell response in a subject can be done by contacting isolated peripheral mononuclear blood cells from the subject with the antigen and using standard assays for cell proliferation. Assessing the expression profile of the unwanted cell may be carried out on a biopsy sample using routine assays for measuring nucleic acid (e.g. DNA or RNA transcripts) or protein levels. For example, transcriptomic or proteomic techniques may be used. In this way, it will be possible to identify tailored targeting moieties that bind specifically to, for example, surface markers expressed by the unwanted cell. It may also be possible to identify appropriate protease cleavage sites that may be selectively cleaved in the vicinity of the unwanted cells.
Thus the method of the second aspect of the invention may include the steps of (i) identifying a subject who has a condition, or who is at risk of developing a condition characterised by the presence of unwanted cells (eg cancer), (ii) taking a sample from the subject, (iii) analysing the sample to identify the optimum targeting moiety, T cell antigen and/or cleavage site for preventing or treating the condition in that subject, (iii) preparing the agent of the invention, (iv) administering the agent to the subject, and (v) monitoring the levels of unwanted cells in the subject either by conducting tests to determine the number of unwanted cells or by monitoring the clinical symptoms of the subject.
It is appreciated that an apparatus may be used to select and optionally prepare the most appropriate agent to be used for a particular patient. For example, the apparatus may perform an automated analysis of one or more samples from the subject, and based on this analysis select and optionally prepare a tailor-made agent for that subject. Thus the apparatus may perform serological assays on the sample to determine a subject's MHC alleles and based on this test various peptides for their efficiency in eliciting cytotoxic T cell response, so as to identify the best T cell antigen for use in that patient. Similarly, the apparatus may carry out an expression profile of unwanted cells from the subject (eg from a biopsy sample) so as to determine a suitable targeting moiety that will bind to the unwanted cell and/or determine a suitable cleavage site that will be selectively cleaved in the vicinity of the unwanted cell.
By performing any one or more of these steps in the clinic an agent tailored for a particular subject can be prepared. For example, the agent can contain a T cell antigen that is known to bind to patient's MHC molecules and elicit a strong T cell response, a targeting moiety that is known to bind selectively to surface markers expressed by the unwanted cell, and a protease cleavage site that allows the release of the T cell antigen in the vicinity of the unwanted cells.
In one embodiment, the subject is administered a further therapeutic agent in addition to the agent according to the first aspect of the invention. For example, when administering the agent to prevent or treat a particular condition, a further therapeutic agent known to be useful for combating that condition may be administered. As an example, when the agent is for treating cancer, a further anti-cancer agent (eg anti-neoplastic chemotherapy) may be administered to the subject alongside the agent of the invention. Similarly, the further therapeutic agent may be one that is known to have therapeutic application in allergic disease, inflammatory disease, regenerative medicine and neuroregenerative disease.
It is appreciated that the further therapeutic agent may be administered at the same time as the agent of the invention (i.e. simultaneous administration optionally in a co-formulation) or at a different time to the agent of the invention (i.e. sequential administration).
The further therapeutic agent may be any one or more of a vaccine; an immuno stimulatory drug; an anti-cancer agent; an agent inhibiting an antibody response against the agent of the invention; and/or a protease inhibitor.
For example, in order to boost the effector immune response against the particular T cell antigen used, it may be desirable to vaccinate the subject with the T cell antigen; and/or administer immunostimulating agents such as IL-2, IL-7, IFNα, GM-CSF, metformin, lenalidomide; and/or administer anti-immunoregulatory agents such as Ipilimumab; all of which may be considered as further therapeutic agents.
It is also appreciated that if the subject is one to whom is administered immunosuppressive agents, that these immunosuppressive agents are withdrawn from the subject (e.g. by suspending treatment) when or before being administered the agent of the invention.
Similarly, it may be desirable to employ methods aimed at circumventing any immunogenicity issues relating to the agent of the invention whereby an adverse antibody response is elicited in vivo. For example, the subject may also be administered one or more agents that are known to inhibit the activity of B cells, such as any of Rituximab, cyclophosphamide, Syk inhibitors, an anti-BAFF antibody (eg Belimumab), an anti-CD22 antibody, an anti-CD20 antibody and an anti-CD19 antibody, all of which may be considered as further therapeutic agents. In this case, it is particularly preferred if the inhibitor of B cells is administered to the subject prior to the agent of the invention, eg as a pre-treatment to ablate B cells.
In another embodiment, it may be appropriate to administer a particular protease inhibitor so as to improve the target selectivity of the agent of the invention. For example, if a targeting moiety is known to bind cells in both the heart and breast tissue, but only those in the breast are to be targeted, it may be desirable to administer an agent that selectively inhibits the protease responsible for releasing the T cell antigen, in the heart but not the breast. In other words, an agent is administered to inhibit a protease that is capable of releasing the T cell antigen but which protease resides in the vicinity (eg at or near the surface of) of wanted cells but not in the vicinity (eg at or near the surface of) of unwanted cells. This is particularly useful in the event that a protease cleavage site of the agent of the invention is cleavable by multiple proteases, some of which reside in the vicinity of unwanted cells and some of which reside in the vicinity of wanted cells. In this case, targeting specificity may be improved by administering a protease inhibitor that inhibits a protease that resides in the vicinity of wanted cells but nevertheless is capable of cleaving the cleavage site and therefore releasing the T cell antigen from the agent of the invention. The effect of administering the inhibitor would be to ensure that the T cell antigen is preferentially released in the vicinity of the unwanted cells. For instance, if a subject with cancer also has active rheumatoid arthritis where MMP2 and other proteases are active, and the one or more cleavage sites in the agent of the invention are cleavable by multiple proteases including MMP2, it may be beneficial to inhibit MMP2 to prevent cleavage of the agent at the arthritic joint but retain cleavage at the cancer site by another protease.
The invention thus includes a composition comprising (i) an agent according to the first aspect of the invention and (ii) a further therapeutic agent, for use in preventing or treating a condition characterised by the presence of unwanted cells. Given that the agent of the invention and the further therapeutic agent may be administered simultaneously or sequentially, it will be appreciated that the invention includes an agent according to the first aspect of the invention for use in preventing or treating a condition characterised by the presence of unwanted cells in a subject who is administered a further therapeutic agent. It also follows that the invention includes a therapeutic agent for use in preventing or treating a condition characterised by the presence of unwanted cells in a subject who is administered an agent according to the first aspect of the invention.
Similarly, the invention includes a use of a composition comprising (i) an agent according to the first aspect of the invention and (ii) a further therapeutic agent, in the manufacture of a medicament for preventing or treating a condition characterised by the presence of unwanted cells. Again, given that the agent of the invention and the further therapeutic agent may be administered simultaneously or sequentially, it will be appreciated that the invention includes the use of a composition comprising an agent according to the first aspect of the invention in the manufacture of a medicament for preventing or treating a condition characterised by the presence of unwanted cells in a subject who is administered a further therapeutic agent. It also follows that the invention includes the use of a therapeutic agent in the manufacture of a medicament for preventing or treating a condition characterised by the presence of unwanted cells in a subject who is administered an agent according to the first aspect of the invention.
The invention also provides a composition comprising (i) an agent according to the first aspect of the invention and (ii) a further therapeutic agent suitable for preventing or treating the same condition characterised by the presence of unwanted cells. It is appreciated that the therapeutic agent mentioned in the immediately preceding two paragraphs may be agents suitable for treating the same condition characterised by the presence of unwanted cells, as treatable by the agents of the invention.
A third aspect of the invention provides an agent according to the first aspect of the invention for use in medicine.
A fourth aspect of the invention a pharmaceutical composition comprising an agent according to the first aspect of the invention, and a pharmaceutically acceptable carrier, diluent or excipient.
Whilst it is possible for the agent of the invention to be administered alone, it is preferable to present it as a pharmaceutical formulation, together with one or more acceptable carriers. The carrier(s) must be “acceptable” in the sense of being compatible with the therapeutic agent and not deleterious to the recipients thereof. Typically, the carriers will be water or saline which will be sterile and pyrogen free.
Where appropriate, the formulations may conveniently be presented in unit dosage form and may be prepared by any of the methods well known in the art of pharmacy. Such methods include the step of bringing into association the active ingredient (agent for treating or preventing a condition characterised by unwanted cells) with the carrier which constitutes one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing into association the active ingredient with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product.
Formulations in accordance with the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets or tablets, each containing a predetermined amount of the active ingredient; as a powder or granules; as a solution or a suspension in an aqueous liquid or a non-aqueous liquid; or as an oil-in-water liquid emulsion or a water-in-oil liquid emulsion. The active ingredient may also be presented as a bolus, electuary or paste.
A tablet may be made by compression or moulding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder (e.g. povidone, gelatin, hydroxypropylmethyl cellulose), lubricant, inert diluent, preservative, disintegrant (e.g. sodium starch glycolate, cross-linked povidone, cross-linked sodium carboxymethyl cellulose), surface-active or dispersing agent. Moulded tablets may be made by moulding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent. The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active ingredient therein using, for example, hydroxypropylmethylcellulose in varying proportions to provide desired release profile.
Formulations suitable for topical administration in the mouth include lozenges comprising the active ingredient in a flavoured basis, usually sucrose and acacia or tragacanth; pastilles comprising the active ingredient in an inert basis such as gelatin and glycerin, or sucrose and acacia; and mouth-washes comprising the active ingredient in a suitable liquid carrier.
Formulations suitable for parenteral administration include aqueous and non-aqueous sterile injection solutions which may contain anti-oxidants, buffers, bacteriostats and solutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents. The formulations may be presented in unit-dose or multi-dose containers, for example sealed ampoules and vials, and may be stored in a freeze-dried (lyophilised) condition requiring only the addition of the sterile liquid carrier, for example water for injections, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described.
The agent of the invention can be administered in the form of a suppository or pessary, or they may be applied topically in the form of a lotion, solution, cream, ointment or dusting powder. The agent may also be transdermally administered, for example, by the use of a skin patch.
Preferred unit dosage formulations are those containing a daily dose or unit, daily sub-dose or an appropriate fraction thereof, of an active ingredient.
It should be understood that in addition to the ingredients particularly mentioned above the formulations of this invention may include other agents conventional in the art having regard to the type of formulation in question, for example those suitable for oral administration may include flavouring agents.
The amount of the agent which is administered to the individual is an amount effective to combat the particular individual's condition. The amount may be determined by the physician.
Preferably, in the context of any aspect of the invention described herein, the subject to be treated is a human. Alternatively, the subject may be an animal, for example a domesticated animal (for example a dog or cat), laboratory animal (for example laboratory rodent, for example mouse, rat or rabbit) or an animal important in agriculture (i.e. livestock), for example horses, cattle, sheep or goats.
The invention provides a kit of parts for preventing or treating a condition characterised by the presence of unwanted cells, the kit comprising: (i) a targeting moiety that is capable of targeting to the unwanted cells and which is attached to a first binding partner, and (ii) a T cell antigen that is attached to a second binding partner which is capable of binding to the first binding partner, wherein the T cell antigen can be released from the second binding partner by selective cleavage of a cleavage site between the second binding partner and T cell antigen in the vicinity of the unwanted cells.
Preferences for the condition, unwanted cells, targeting moiety and T cell antigen are as defined above. It is particularly preferred if the kit of parts is for preventing or treating cancer.
By the first and second binding partners, we include the meaning of any two moieties which bind to each other selectively. Most preferably, the first and second binding partners only bind to each other and not to any other moieties. Non-covalent binding such as between biotin/avidin or streptavidin, or immunological bindings are preferred. Thus, the first binding partner may be biotin and the second binding partner may be avidin, and vice versa. Alternatively, the first binding partner may be an antigen and the second binding partner may be an antibody specific for that antigen, and vice versa. However, any pair of first and second binding partners that selectively bind to each other may be used, and suitable pairs will be known to the skilled person.
It will be appreciated that the kit allows one to first administer the targeting moiety to the subject, and establish the correct localisation of the targeting moiety in the subject (for example by the targeting moiety being detectably labelled (eg radiolabelled)) before administering the T cell antigen. The T cell antigen is then targeted to the unwanted cells by virtue of the second binding partner binding to the first binding partner. Once in the vicinity of the unwanted cells, the T cell antigen will be released from the second binding partner by selective cleavage of a cleavage site between the second binding partner and T cell antigen, allowing it to be presented on the surface of the unwanted cells so as to re-direct an existing immune response to the unwanted cells.
Accordingly, the invention further provides a method of preventing or treating a condition characterised by the presence of unwanted cells, the method comprising administering (i) a targeting moiety that is capable of targeting to the unwanted cells and which is attached to a first binding partner, and (ii) a T cell antigen that is attached to a second binding partner which is capable of binding to the first binding partner, wherein the T cell antigen can be released from the second binding partner by selective cleavage of a cleavage site between the second binding partner and T cell antigen in the vicinity of the unwanted cells, to the subject. Preferably, the targeting moiety is administered before the T cell antigen, for example to allow to correct localisation of the targeting moiety at the unwanted cells to be established. However, the targeting moiety may be administered at the same time as the T cell antigen.
Similarly, the invention provides a targeting moiety that is capable of targeting to unwanted cells and which is attached to a first binding partner, and a T cell antigen that is attached to a second binding partner which is capable of binding to the first binding partner, wherein the T cell antigen can be released from the second binding partner by selective cleavage of a cleavage site between the second binding partner and T cell antigen in the vicinity of the unwanted cells, for use in preventing or treating a condition characterised by unwanted cells in a subject. Preferably, the targeting moiety is administered before the T cell antigen, for example to allow to correct localisation of the targeting moiety at the unwanted cells to be established. However, the targeting moiety may be administered at the same time as the T cell antigen. It is appreciated that the targeting moiety and T cell antigen may be attached to each other by binding of the first and second binding partners.
A further kit of parts provided by the invention comprises (i) a targeting moiety that is capable of targeting to unwanted cells, (ii) a T cell antigen, and (iii) one or more means or reagents to assess one or more of a subject's (a) MHC alleles, (b) cytotoxic T cell response to a T cell antigen and (c) expression profile of an unwanted cell in the subject.
Preferences for the targeting moiety and T cell antigen include those as described herein. It will be appreciated that this kit of parts may be useful in tailoring a particular agent as defined in the first aspect of the invention for a given patient. Suitable means or reagents that can be used to assess a subject's (a) MHC alleles, (b) cytotoxic T cell response to a T cell antigen and (c) expression profile of an unwanted cell in the subject, are well known and widely available in the art. In one embodiment, the kit of parts comprises the agent of the first aspect of the invention and the kit may be used to determine whether that agent is suitable for a particular patient.
The invention also provides a molecule comprising (i) a T cell antigen and (ii) a cleavage site; wherein the cleavage site contains a linking moiety to allow the molecule to be attached to a targeting moiety which targeting moiety is capable of targeting to unwanted cells, and wherein the cleavage site can be selectively cleaved in the vicinity of the unwanted cells.
It is appreciated that the molecule may represent the part of the agent of the first aspect of the invention, without the targeting moiety. Thus, preferences for the T cell antigen, the cleavage site, how the cleavage site is attached to the targeting moiety (e.g. via a linker moiety comprising a thiol group such a cysteine residue), the targeting moiety and unwanted cells include all of those defined above with respect to the first aspect of the invention.
In a particular embodiment, the molecule comprises those final peptides listed in Table 6 above, wherein the ‘epitope’ listed in Table 6 corresponds to the T cell antigen of the molecule, and wherein the ‘cleavage sequence’ listed in Table 6 corresponds to the cleavage site. Thus, the molecule may comprise or consist of any of the peptides:
In a particular embodiment, the molecule comprises those final peptides listed in Table 7 above, wherein the ‘epitope’ listed in Table 7 corresponds to the T cell antigen of the molecule, and wherein the ‘cleavage site’ listed in Table 7 corresponds to the cleavage site. Thus, the molecule may comprise or consist of any of the peptides:
In another embodiment, the molecule comprises or consists of any of the following peptides:
In an embodiment, the targeting moiety described herein is Cetuximab, the T cell antigen comprises NLVPMVATV (SEQ ID No: 21) and the cleavage site comprises a MMP14 cleavage sequence.
In an embodiment, the targeting moiety described herein is Rituximab, the T cell antigen comprises DYSNTHSTRYV (SEQ ID No: 55) and the cleavage site comprises a MMP2 cleavage sequence.
In an embodiment, the targeting moiety described herein is Rituximab, the T cell antigen is TPRVTGGGAM (SEQ ID No: 31) and the cleavage site comprises a MMP2 cleavage sequence.
In an embodiment, the targeting moiety described herein is hP67.6 (Gemtuzumab parent antibody), the T cell antigen is TPRVTGGGAM (SEQ ID No: 31) and the cleavage site comprises a MMP2 cleavage sequence.
In an embodiment, the targeting moiety described herein is Cetuximab, the T cell antigen comprises NLVPMVATV (SEQ ID No: 21) and the cleavage site comprises any of the following cleavage sequences: a uPa/tPa cleavage sequence (CPGR-VVGG) (SEQ ID No: 254), a Plasmin/TMPRSS2 cleavage sequence (GGR-X) (SEQ ID No: 256), a C1s cleavage (YLGR-SYKV) (SEQ ID No: 257), a MASP2 cleavage sequence (SLGR-KIQI) (SEQ ID No: 259), a thrombin cleavage sequence (LVPRGS) (SEQ ID No: 260), a trypsin cleavage sequence (XXXR-X) (SEQ ID No: 261), an elastase 2 cleavage sequence (AAPV-X) (SEQ ID No: 262), a MT-SP1/ST14 cleavage sequence (KQLR-VVNG) (SEQ ID No: 263), a PSA cleavage sequence (SSKYQ) (SEQ ID No: 265), or a Cathepsin B cleavage sequence (GGGG-F) (SEQ ID No: 267).
The invention will be described in further detail with the aid of the following Figures and Examples.
We contacted breast cancer cells with an agent comprising Cetuximab conjugated to a HLA-B7 peptide with and without a cleavage site. Subsequent exposure to T cells resulted in the generation of a T cell response when the breast cancer cells were contacted with the agent that contained the cleavage site.
MDA.MB.231 cells, often used as a model for breast cancer, were transduced with the MMP14 gene to ensure expression of the MMP14 protein within the cell. After staining the target cells (1×105) with Cetuximab either unconjugated (1) or conjugated to RPHERNGFTVL (SEQ ID No: 32), a HLA-B7 peptide (2), NLVPMVATV (SEQ ID No: 21) without the MMP14 cleavage sequence (3) or NLVPMVATV (SEQ ID No: 21) including the cleavage sequence (4), stained cells were incubated overnight. The following day, the cells were washed and NLV-specific T cells were added to the culture (1×104) and incubated overnight. Supernatant was harvested and an ELISA used to determine the presence of IFN-γ in each culture, n=3. The results are shown in
There was very little IFN-γ release from T cells cultured together with cells stained using Cetuximab alone and cetuximab conjugated with the mismatched HLA-peptide. T cells cultured with cells stained using cetuximab conjugated with the correct peptide but lacking the MMP14 cleavage site also produced very little IFN-γ whereas T cells cultured with the cells stained using cetuximab conjugated with the correct peptide containing the MMP14 cleavage site produced a large amount of IFN-γ.
We contacted B-lymphoblastoid cells (B-LCL) with an agent comprising Rituximab conjugated to a cytomegalovirus HLA Class-II restricted peptide DYSNTHSTRYV (SEQ ID No: 55) with and without a cleavage site. Subsequent exposure to CD4+ T cells resulted in the generation of a T cell response when the B-LCL cells were contacted with the agent that contained the cleavage site.
After staining the B-LCL cells with Rituximab conjugated to an irrelevant mismatched peptide RPHERNGFTVL (SEQ ID No: 32), a HLA-B7 peptide, not containing the protease cleavage sequence (1), an irrelevant, mismatched HLA class-I peptide VLEEETSVML (SEQ ID No: 316), an HLAA-A2 peptide, with the protease cleavage sequence (2), the relevant peptide DYSNTHSTRYV (SEQ ID No: 55) without the protease cleavage sequence (3), or the relevant peptide DYSNTHSTRYV (SEQ ID No: 55) including the protease cleavage sequence (4), stained cells were incubated overnight. The following day, the cells were washed and DYSN-specific CD4+ T cells were added to the culture and incubated overnight. Supernatant was harvested to determine the presence of IFN-γ in each culture, n=3. There was very little IFN-γ release from CD4+ T cells cultured together with cells stained using Rituximab conjugated with the mismatched HLA-peptide without the protease cleavage site. CD4+ T cells cultured with cells stained using Rituximab conjugated with the correct peptide but lacking the protease cleavage site also produced very little IFN-γ whereas T cells cultured with the cells stained using Rituximab conjugated with the correct peptide containing the protease cleavage site produced a large amount of IFN-γ. However, when T cells were cultured with Rituximab conjugated with the HLA-mismatched peptide containing the protease cleavage site, there was no IFN-γ produced. The results are shown in
A similar example showing stimulation of CD4+ T cells by Rituximab-TPRVTGGGAM conjugate is shown in
An agent comprising Cetuximab that is attached to a peptide T cell antigen such as NLVPMVATV (SEQ ID No: 21), derived from a cytomegalovirus, via a linker comprising a PRSA-KELR (SEQ ID No: 321) protease cleavage site (cleavable by Matrix metalloproteinase 14 (MMP14)) is prepared. The agent is formulated with a pharmaceutically acceptable excipient and administered to patient with an epithelial malignancy such as breast cancer. The agent, Cetuximab, is targeted to breast cancer cells and upon binding comes into contact with MMP14. The cleavage of the protease cleavage site releases the T cell antigen, NLVPMVATV (SEQ ID No: 21), which subsequently binds to the HLA-A*0201 molecules on the surface of the breast cancer cell. The breast cancer cells expressing the T cell antigen is targeted by the host immune system for cytolysis by the effector CD8 T cells.
An agent comprising Rituximab that is attached to a HLA class-II peptide T cell antigen such as DYSNTHSTRYV (SEQ ID No: 55), derived from a cytomegalovirus, via a linker comprising a TIPV-SLRS (SEQ ID No: 317) protease cleavage site (cleavable by Matrix metalloproteinase 2 (MMP2)) is prepared. The agent is formulated with a pharmaceutically acceptable excipient and administered to patient with B cell lymphoma (eg chronic lymphocytic leukaemia). The agent, Rituximab, is targeted to B cells and upon binding comes into contact with a protease. The subsequent cleavage of the protease cleavage site releases the T cell antigen, DYSNTHSTRYV (SEQ ID No: 55), which subsequently binds to the HLA-DR*0107 molecules on the surface of the B cell. The B cells expressing the T cell antigen would then be targeted by the host immune system for cytolysis by the effector CD4 T cells.
An agent comprising Cetuximab that is attached to a peptide T cell antigen derived from a cytomegalovirus via a linker comprising a CPGR-VVGG (SEQ ID No: 254) protease cleavage site (cleavable by uPA) is prepared. The agent is formulated with a pharmaceutically acceptable excipient and administered to a bowel cancer patient.
An agent comprising Rituximab that is attached to a peptide T cell antigen derived from a cytomegalovirus via a linker comprising a PQG-IAGQ (SEQ ID No: 269) protease cleavage site (cleavable by MMP2) is prepared. The agent is formulated with a pharmaceutically acceptable excipient and administered to a B cell lymphoma (eg CLL) cancer patient.
We contacted B-lymphoblastoid cells (B-LCL) with an agent comprising Rituximab conjugated to a cytomegalovirus peptide TPRVTGGGAM (SEQ ID No: 31) with and without a cleavage site. Subsequent exposure to T cells resulted in the generation of a T cell response when the B-LCL cells were contacted with the agent that contained the cleavage site.
After staining the cells with Rituximab conjugated to RPHERNGFTVL (SEQ ID No: 32), a HLA-B7 peptide (1), an irrelevant, mis-matched HLA class-I peptide, VLEEETSVML (SEQ ID No: 316), (a HLA-A2 peptide) containing the protease cleavage sequence (2), the relevant peptide TPRVTGGGAM (SEQ ID No: 31) with the protease cleavage sequence (3) or the relevant peptide TPRVTGGGAM (SEQ ID No: 31) without the cleavage sequence (4), stained cells were incubated overnight at 37° C. The following day, the cells were washed and TPR-specific T cells were added to the culture and incubated overnight. Supernatant was harvested to determine the presence of IFN-γ in each culture, n=3. The results are shown in
There was very little IFN-γ release from T cells cultured together with cells stained using Rituximab conjugated with the mismatched HLA-peptide with or without the protease cleavage site (1 & 2). T cells cultured with cells stained using Rituximab conjugated with the correct peptide but lacking the protease cleavage site also produced very little IFN-γ (4) whereas T cells cultured with the cells stained using Rituximab conjugated with the correct peptide containing the protease cleavage site (3) produced a large amount of IFN-γ.
An agent comprising Rituximab that is attached to a HLA class-I peptide T cell antigen such as TPRVTGGGAM (SEQ ID No: 31), derived from a cytomegalovirus, via a linker comprising a TIPV-SLRS (SEQ ID No: 317) protease cleavage site (cleavable by Matrix metalloproteinase 2 (MMP2)) is prepared. The agent is formulated with a pharmaceutically acceptable excipient and administered to patients with B cell lymphoma (eg chronic lymphocytic leukaemia). The agent, Rituximab, is targeted to B cells and upon binding comes into contact with a protease. The cleavage of the protease cleavage site releases the T cell antigen, TPRVTGGGAM (SEQ ID No: 31), which subsequently binds to the HLA-B*0702 molecules on the surface of the B cell. The B cells expressing the T cell antigen would then be targeted by the host immune system for cytolysis by the effector CD8 T cells.
We have shown that antibodies can be engineered to deliver and release viral peptides at the tumor site by exploiting a tumor-associated proteolytic environment thus allowing resident anti-viral T cells to specifically kill tumor cells. We screened 15 HLA-A2+ tumor cell lines (THP-1 (acute monocytic leukemia cell line); A498 (renal cell carcinoma); MDA-MB-231 and MCF-7 (breast cell adenocarcinomas); NCI-H522 (non-small cell lung carcinoma); Ovcar-3 (ovarian adenocarcinoma); Colo205 and HCT-116 (colorectal carcinoma)) and showed that 100% are recognized and killed by human anti-viral T cells when pulsed with cognate viral peptides (
Antibody-peptide epitope conjugates (APEC) were generated, through covalently linking T cell epitope peptides with clinically available antibodies Cetuximab and Rituximab. Neither APEC in solution nor plate-bound were able to activate cognate T cells. Healthy CD20+ B cells bound Ritixumab-APEC (RPEC) but were unable to activate T cells in vitro. However, CD20+ lymphoma cell lines were able to be efficiently targeted by T cells when bound by RPEC in vitro through proteolytic release of bound peptide demonstrating differential tumor targeting (
Using breast cancer as a solid tumor model, EGF receptor was targeted on the malignant cell line MDA-MB-231 using Cetuximab-APEC (OPEC). Results demonstrate T cell recognition when target cells were bound by OPEC (p<0.01) (
In vivo data using a xenograft mouse model demonstrate significant efficacy in mice treated with the OPEC and T cells compared with mice treated with either T cells alone or with OPEC alone (see
Targeting tumors in this way bypasses the requirement of an intact antigen processing system in the tumor cell. We believe that the processing of the protease cleavage site and subsequent loading of peptide onto MHC class I/II molecules occurs extracellularly, without the requirement of classical antigen processing components.
Furthermore, the results demonstrate that conjugating peptides to different antibodies allows targeting of many different malignancies including breast cancer, multiple myeloma, acute myeloid leukemia and pancreatic cancer. Therefore, the immunotherapeutic potential of this mechanism is far-reaching.
Xenograft Studies
Xenograft models use NOG mice (NOD Rag2−/−γc−/−) (M. Ito et al., Blood 100, 3175 (2002)). Tumour cell lines are grown using standard laboratory tissue culture techniques and injected subcutaneously in Matrigel and left to engraft for ˜7 days. Human CD4+ and CD8+ T cells are cultured using standard techniques and cultured from healthy laboratory donors. 106 T cells are infused into each study mouse intraperitoneally. Antibody or APEC is injected into the intraperitoneal cavity. Mice are injected with 120 mg/kg luciferin weekly and growth and metastatic dissemination of the cells monitored using IVIS Spectrum (Caliper Lifesciences). Quantitation of outgrowth kinetics is determined and metastasis quantified by measuring luminescent signal from each organ at the experimental endpoint.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1104514.3 | Mar 2011 | GB | national |
| 1203434.4 | Feb 2012 | GB | national |
This application is a continuation of application Ser. No. 14/972,059, filed Dec. 16, 2015, which is a continuation of application Ser. No. 14/660,137, filed on Mar. 17, 2015, issued as U.S. Pat. No. 9,358,282, which is a continuation of application Ser. No. 14/005,452, entered the national stage on Sep. 16, 2013, issued as U.S. Pat. No. 9,402,916, which is the US National Stage of International Application No. PCT/GB2012/050577, filed Mar. 15, 2012, which designates the US, published in English, and claims priority under 35 U.S.C. §§ 119 or 365 (c) to GB Application No. 1104514.3, filed Mar. 17, 2011 and GB Application No. 1203434.4, filed Feb. 28, 2012. The entire teachings of the above applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14972059 | Dec 2015 | US |
| Child | 16366240 | US | |
| Parent | 14660137 | Mar 2015 | US |
| Child | 14972059 | US | |
| Parent | 14005452 | Sep 2013 | US |
| Child | 14660137 | US |
