Patent Application
20240180982
The invention concerns a modified low seroprevalence adenovirus; a pharmaceutical composition comprising same; and a method of treating cancer using same.
Virotherapies exploit the natural ability of a virus to infect, replicate in and lyse cells and direct this ability specifically against tumour cells. The lytic nature of this cell death is highly immunogenic, resulting in enhanced immune recruitment to the tumor microenvironment with corresponding CD8+ mediated activation and immune cell mediated cell killing. Certain viruses, such as echoviruses and reoviruses may have natural oncolytic potential, whilst other viruses require genetic manipulation to increase tumour selectivity and enhance cell killing, leading to the development of more effective cancer therapies.
Adenovirus infections are widely distributed across human and animal populations. Infection by human adenovirus (HAdV) can result in a broad array of clinical pathologies, however the majority of infections are asymptomatic or acute and self-limiting.
HAdV are non-enveloped viruses measuring 90-100 nm and are arranged in an icosahedral structure with protruding fiber proteins. The capsid is made up of 240 trimeric hexon proteins, with a pentameric penton base complex located at each vertex. Adenoviral structure has been reviewed extensively. There are 57 canonical HAdV serotypes divided into seven species (A-G) based on serological testing. Over 100 novel adenovirus serotypes have been isolated to date. Primary receptor binding is dependent on the adenoviral serotype but generally species A, C, E and F interact with coxsackievirus and adenovirus receptor (CAR), whilst species B serotypes use CD46 and/or Desmoglein 2 (DSG2). Species D is the largest of the adenovirus species, though many serotypes remain poorly understood. Several Species D serotypes including HAdV-D26 and HAdV-D37 bind sialic acid for cell entry. The extent of this receptor usage within the species is not fully understood.
Adenoviral vectors have important clinical applications ranging from vectors for gene therapy and vaccines to oncolytic viruses. A number of oncolytic HAdV virotherapies have entered clinical trials and have demonstrated safety and feasibility, although delivery and efficacy require optimization before oncolytic adenovirus can be used as an effective cancer therapy.
The most extensively evaluated HAdV, clinically and experimentally, are based on the species C type 5, HAdV-C5. However, there are limitations associated with using HAdV-C5 based vectors. HAdV-C5 binds CAR which is localized at tight junctions between cells and expressed ubiquitously throughout the body. Furthermore, CAR is reported to be downregulated in certain cancers, therefore limiting the utility of CAR as a receptor for active cancer targeting. HAdV-C5 is also known to interact with human coagulation factor X (FX) in serum, via the hexon protein, which mediates transduction to the liver and can lead to hepatotoxicity. High levels of HAdV-C5 pre-existing immunity can also reduce the clinical efficacy of potential HAdV-C5-based oncolytic virotherapies, as a substantial proportion of the population will have experienced an acute adenovirus infection, and many will have developed neutralizing antibodies against common HAdV serotypes, thus rapidly inactivate systemically delivered therapeutic vectors.
Activation of anti-tumor immunity, whilst dampening the innate host anti-viral immune response, is essential to the success of oncolytic adenovirotherapies. Previous work in our laboratory has addressed the above limitations through generation of the HAdV-C5NULL-A20 vector (27). The resulting Ad5NULL vector was retargeted to αvβ6 integrin through insertion of a 20 amino acid peptide, NAVPNLRGDLQVLAQKVART, termed A20, native to foot and mouth disease virus (FMDV). A20 modified viruses selectively infected cells expressing the αvβ6 integrin, a surface protein which is upregulated in several cancer types, including breast, ovarian, pancreatic, and colorectal.
Here, we have modified a D species adenovirus, HAdV-D10. HAdV-D10 is a rare serotype isolated from the eyes of patients with keratoconjunctivitis. Its structure and interaction with host cell receptors is poorly understood. We have optimized this virus to generate a low seroprevalence, highly tumour selective agent for optimal delivery to tumours.
Following generation of the crystal structure of HAdV-D10, we have discovered HAdV-D10 has a fiber knob protein that weakly interacts with both CAR and sialic acid and therefore requires modification to increase its transduction efficacy. It also follows that HAdV-D10 does not function via the typical host cell binding receptors, which may be advantageous given that certain cancers downregulate such typical binding proteins. We have therefore targeted HAdV-D10 to cancer cells by recombinantly expressing αvβ6 integrin using the A20 peptide native to foot and mouth disease virus (FMDV). We then demonstrated improved infectivity and selective killing of αvβ6 integrin positive cancer cell lines. Moreover, we also surprisingly discovered HAdV-D10 does not bind human coagulation factor X (FX), thus avoiding hepatotoxicity and off-site targeting that is common to more typical infectious adenovirus serotypes (such as HAdV-C5). Further still, and notably, the modified virus also evades neutralisation in human serum thus maintaining clinical efficacy.
According to a first aspect of the invention there is provided a modified D species human adenovirus of serotype 10, HAdV-D10, comprising:
a binding epitope with selective affinity for αvβ6 integrin, comprising or consisting of a 20 amino acid peptide, NAVPNLRGDLQVLAQKVART (SEQ ID NO: 1), termed A20 and native to foot and mouth disease virus (termed HAdV-D10.A20); and any one or more of the following features:
The modified HAdV-D10 virus of the invention is advantageous because it does not require multiple modifications, typically required for other serotypes, to prevent off-site adverse targeting; it exhibits remarkable organ specific targeting and experiences no loss of activity in HAdV immune reactive host serum.
As is known to those skilled in the art, in humans, there are 57 accepted human adenovirus serotypes (Ad-1 to 57) classified into seven species (Human adenovirus A to G): A—12, 18, 31; B—3, 7, 11, 14, 16, 21, 34, 35, 50, 55; C—1, 2, 5, 6, 57; D—8, 9, 10, 13, 15, 17, 19, 20, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32, 33, 36, 37, 38, 39, 42, 43, 44, 45, 46, 47, 48, 49, 51, 53, 54, 56; E—4; F—40, 41; and G—52. Accordingly, reference herein to HAdV-D10 refers to Adenovirus serotype 10 belonging to the D-subclass of adenovirus, such as that according to NCBI accession number AB724351.1 and the protein domain sequences set forth therein.
In a preferred embodiment of the invention said A20 peptide is inserted into the DG loop of HAdV-D10.A20 fiber knob protein, preferably at a position between amino acids 304-305 of the fibre knob protein, as set forth in NCBI accession number AB724351.1, specifically accession BAM66698. Unexpectedly, it has been found that when attempting to insert the A20 binding epitope, or targeting peptide, in other locations of the fiber knob protein, such as in the H1 loop (as is typically undertaken for adenovirus serotype 5, Ad5) viral particle formation was prevented. This therefore tends to indicate a preferred insertion loop for the binding epitope. In one embodiment of the invention insertion into said DG loop at position 304-305 involves the use of a short peptide sequence, or linker, such as SKKY. However, as the skilled person will appreciate, other amino acids or peptide linkers may be used with equal effect.
We show herein HAdV-D10.A20 can engage and utilise αvβ6 integrin as a tumour selective cell entry receptor and this function is mediated by the A20 peptide (SEQ ID NO: 1). A20 was originally derived from foot-and-mouth disease virus (FMDV) capsid protein VP1 and has a natively high affinity to αvβ6 integrin. αvβ6 integrin is expressed in a third of ovarian cancers and in a variety of other epithelial cancers and is non-detectable in healthy adult tissues. Therefore, as will be appreciated by those skilled in the art, through expression and incorporation of this sequence in the modified virus, the modified virus can selectively target αvβ6 integrin in cancers such as, but not limited to, lung, breast, esophageal squamous cell carcinoma, ovarian, pancreatic, cervical, head and neck cancer, oral cancer, cancer of the larynx, skin cancer, kidney cancer and colorectal cancer cells. We also show herein no cell killing by HAdV-D10.A20 in cells (e.g. A549 cells) that do not express αvβ6 integrin, thus demonstrating the selectivity of the αvβ6 integrin recombinant binding feature. In this respect, our work has shown a significant increase of HAdV-D.A20 was observed in tumour (p=<0.05) compared to levels in the liver, lung, heart, kidney, and spleen.
In a further preferred embodiment of the invention said modified D species human adenovirus, HAdV-D10.A20, has an IC50 for the coxsackievirus and adenovirus receptor (CAR) greater than 0.002 μg/105 cells, more preferably about 0.003 μg/105 cells, i.e., 0.002985 μg/105 cells, that is to say, HAdV-D10 binds CAR with an apparent 10-fold lower affinity, or a 15-fold lower affinity, or a 16.5-fold lower affinity than HAdV-C5 which possesses a binding partner for coxsackievirus and adenovirus receptor (CAR) that facilitates cell transduction. This means HAdV-D10.A20 will preferentially work through αvβ6 integrin binding.
In a further preferred embodiment of the invention said modified D species human adenovirus, HAdV-D10.A20, lacks key binding residues for FX interactions and so is unable to engage and utilize FX as a means of cell entry nor is it susceptible to eliciting hepatotoxicity. This means HAdV-D10.A20 is a safer therapeutic.
A major obstacle contributing to the reduced efficacy of many adenovirus based therapies is the proportion of patients presenting with pre-existing immunity against such adenoviruses.
Use of an alternative, rarely isolated serotypes, HAdV-D10.A20 provides for therapies that are effective for a broader population but also offers a valuable second line of treatment in the case where patients have developed immunity against HAdV therapies, such as HAdV-C5 based virotherapies, over the course of their disease treatment regimen.
In yet a further preferred embodiment still, said adenovirus is further modified to include a molecule which is a transgene encoding an agent such as, but not limited to, a therapeutic agent. This embodiment therefore concerns the delivery of an agent, intracellularly, to exert a therapeutic action on the targeted cancer cell. Examples of an agent may include an agent that directly stimulates an immune responses, for example GM-CSF, IL-12; an agent to indirectly stimulate the immune system, e.g. an antibody (or fragments of an antibody), an immune checkpoint inhibitor to inhibit a co-repressor such as CTLA-4, PD-L1, PD1, or Lag3; a Bi-specific T cell Engaging (BiTE) antibody construct; a Bi-specific natural killer cell engaging (BIKE) antibody construct; an agent that sensitises tumours to a cell based immunotherapy e.g. encoding CD19; an agent that depletes regulatory T cells within the tumour microenvironments, anti-CD25 antibodies; an agent that sensitises a tumour to radiotherapy or for imaging e.g. by encoding sodium/iodide symporter (NIS) or somatostatin receptor type 2 (SSTR2)). Alternatively, the transgene may encode a therapeutic agent that is directly toxic to a tumour cell, e.g. by encoding the transgene Reduced Expression in Immortalized Cells (REIC/DKK3), or an enzyme that sensitises a cancer cell via conversion of a non-toxic prodrug into a toxic drug e.g. cytosine deaminase, nitroreductase, thymidine kinase. Other transgenes known in the art and useful in the treatment of cancer may be used in the working of the invention.
Accordingly, in a preferred embodiment of the invention said modified adenovirus comprises a molecule encoding at least one transgene as herein described, ideally said molecule is cDNA.
In yet a further preferred embodiment still, said adenovirus is further modified to include an 8 amino acid deletion at position 103-110 (LRCYEEGF; SEQ ID NO: 2) in the E1A gene as set forth in accession number AB724351.1 to restrict viral replication. This deletion is best shown having regard to
Yet more preferably still, alternatively said adenovirus is further modified to delete one or more of the E1 and/or E3 genes, to render the virus replication deficient. However, as will be appreciated, for the purpose of a cancer lytic virotherapy it is preferred that the virus is replication competent.
In yet a further preferred embodiment still, said adenovirus is further modified to include a 24-base pair deletion dl922-947 (Δ24 mutation) in the E1A gene to restrict viral replication to pRB-defective cells.
Yet more preferably still, said adenovirus is further modified to include a single adenine base addition at position 445 within the endoplasmic reticulum (ER) retention domain in E3/19K (T1 mutation) for enhanced oncolytic potency.
In a yet further preferred embodiment, said adenovirus is further modified to include an adenovirus death protein (ADP). As is known to those skilled in the art, ADP is a type III membrane glycoprotein that ultimately localizes to the nuclear membrane, endoplasmic reticulum and Golgi of an infected cell and is encoded in the E3 transcription unit of several Adenovirus serotypes, including Ad1 (Uniprot Accession number AAQ10560.1), Ad2 (Uniprot Accession number AAA92222.1), Ad5 (Uniprot accession number AP_000221.2), Ad6 (Uniprot accession number ACN88121.1), and Ad57 (Uniprot accession number ADM46163.1). ADP is natively expressed from the E3 promoter at low levels early in infection, when viral proteins affecting cell cycle regulation, inhibition of apoptosis, immune evasion and viral DNA replication are expressed, however, later in the viral replication cycle, when progeny virions are assembled, ADP is expressed at high levels from the major late promoter (MLP) and is thought to contribute to membrane rupture to release assembled virions. Therefore, by incorporating the ADP protein, one improves the oncolytic potential of therapeutic adenovirus, which in combination with cancer cell selectivity, promotes cancer cell death. Preferably, the ADP is selected from the group comprising: Ad1 (Uniprot Accession number AAQ10560.1), Ad2 (Uniprot Accession number AAA92222.1), Ad5 (Uniprot accession number AP_000221.2), Ad6 (Uniprot accession number ACN88121.1), and Ad57 (Uniprot accession number ADM46163.1), and more preferably still that of Ad2 (Uniprot Accession number AAA92222.1) or Ad5 (Uniprot accession number AP_000221.2).
In preferred embodiments, said transgenes and/or ADP is inserted in the E1 and/or E3 region, ideally under the control of native promoters for expression or alternatively using a non-native and strong expressing promoter as known in the art such as, but not limited to, the CMV promoter.
Yet more preferably still, said adenovirus is further modified wherein the E4orf6 region was replaced with the HAdV-C5 E4orf6 to improve viral propagation.
It follows form the above that the modified adenovirus of the invention has been engineered to target cancer cells and stimulate a response against cancer and specifically in a tumour environment.
Accordingly, in a further aspect the invention concerns a pharmaceutical composition comprising the modified adenovirus according to the invention and a pharmaceutically acceptable carrier, adjuvant, diluent, or excipient.
Compounds for use in medicine will generally be provided in a pharmaceutical or veterinary composition and therefore according to a yet fifth aspect of the invention there is provided a pharmaceutical composition comprising the adenovirus as defined herein and a pharmaceutically acceptable carrier, adjuvant, diluent, or excipient.
Suitable pharmaceutical excipients are well known to those of skill in the art. Pharmaceutical compositions may be formulated for administration by any suitable route, for example oral, buccal, nasal, or bronchial (inhaled), transdermal or parenteral and may be prepared by any methods well known in the art of pharmacy.
The composition may be prepared by bringing into association the above defined adenovirus with the carrier. In general, the formulations are prepared by uniformly and intimately bringing into association the adenovirus with liquid carriers or finely divided solid carriers or both, and then if necessary shaping the product. The invention extends to methods for preparing a pharmaceutical composition comprising bringing an adenovirus as defined above in conjunction or association with a pharmaceutically or veterinary acceptable carrier or vehicle.
Accordingly, in yet a further aspect the invention concerns a method of treating cancer in a subject comprising administering to a patient an effective amount of a composition comprising a modified adenovirus according to the invention.
Reference herein to an “effective amount” of the adenovirus or a composition comprising same, is to an amount that is sufficient to achieve a desired biological effect, such as cancer cell death. It is understood that the effective dosage will be dependent upon the age, sex, health, and weight of the recipient, kind of concurrent treatment, if any, frequency of treatment, and the nature of the effect desired. Typically, the effective amount is determined by those administering the treatment.
According to a further aspect of the invention there is provided the modified adenovirus as defined herein for use as a medicament.
According to a yet further aspect of the invention there is provided the modified adenovirus as defined herein for use in the treatment of cancer.
According to still a yet further aspect of the invention there is provided the use of a modified adenovirus as defined herein in the manufacture of a medicament to treat cancer.
It follows from the above that the invention concerns the use of a modified adenovirus—optimized for cancer targeting and surprisingly found to have advantageous features, such as a lack of binding to human coagulation factor X (FX) and/or transduction ability in the presence of serum neutralising antibodies, particularly anti-HAdV-C5 antibodies.
Most preferably the cancer referred to herein includes any one or more of the following cancers: nasopharyngeal cancer, synovial cancer, hepatocellular cancer, renal cancer, cancer of connective tissues, melanoma, lung cancer, bowel cancer, colon cancer, rectal cancer, colorectal cancer, brain cancer, throat cancer, oral cancer, liver cancer, bone cancer, pancreatic cancer, choriocarcinoma, gastrinoma, pheochromocytoma, prolactinoma, T-cell leukemia/lymphoma, neuroma, von Hippel-Lindau disease, Zollinger-Ellison syndrome, adrenal cancer, anal cancer, bile duct cancer, bladder cancer, ureter cancer, brain cancer, oligodendroglioma, neuroblastoma, meningioma, spinal cord tumor, bone cancer, osteochondroma, chondrosarcoma, Ewing's sarcoma, cancer of unknown primary site, carcinoid, carcinoid of gastrointestinal tract, fibrosarcoma, breast cancer, Paget's disease, cervical cancer, colorectal cancer, rectal cancer, esophagus cancer, gall bladder cancer, head cancer, eye cancer, neck cancer, kidney cancer, Wilms' tumor, liver cancer, Kaposi's sarcoma, prostate cancer, lung cancer, testicular cancer, Hodgkin's disease, non-Hodgkin's lymphoma, oral cancer, skin cancer, mesothelioma, multiple myeloma, ovarian cancer, endocrine pancreatic cancer, glucagonoma, pancreatic cancer, parathyroid cancer, penis cancer, pituitary cancer, soft tissue sarcoma, retinoblastoma, small intestine cancer, stomach cancer, thymus cancer, thyroid cancer, trophoblastic cancer, hydatidiform mole, uterine cancer, endometrial cancer, vagina cancer, vulva cancer, acoustic neuroma, mycosis fungoides, insulinoma, carcinoid syndrome, somatostatinoma, gum cancer, heart cancer, lip cancer, meninges cancer, mouth cancer, nerve cancer, palate cancer, parotid gland cancer, peritoneum cancer, pharynx cancer, pleural cancer, salivary gland cancer, tongue cancer and tonsil cancer.
More preferably, said cancer is selected from the group comprising: ovarian cancer, pancreatic cancer, oesophageal cancer, lung cancer, cervical cancer, head and neck cancer, oral cancer, cancer of the larynx, skin cancer, breast cancer, kidney cancer, and colorectal cancer.
According to a further aspect there is provided an adenovirus for use in the treatment of cancer, and a method comprising the use of same, in a subject wherein said subject exhibits pre-existing immunity against an adenovirus such as, but not limited to one or more of: HAdV-C5, HAdV-E4, HAdV-B11, HAdV-D26, HAdV-48, the chimera HAdV-5/3 and Chimp adenovirus. As will be known to those skilled in the art, pre-existing immunity can be determined by numerous means known to those skilled in the art such as detection of host serum neutralising adenoviral antibodies to the adenovirus of interest.
In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprises”, or variations such as “comprises” or “comprising” is used in an inclusive sense i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
All references, including any patent or patent application, cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. Further, no admission is made that any of the prior art constitutes part of the common general knowledge in the art.
Preferred features of each aspect of the invention may be as described in connection with any of the other aspects.
Other features of the present invention will become apparent from the following examples. Generally speaking, the invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including the accompanying claims and drawings). Thus, features, integers, characteristics, compounds, or chemical moieties described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein, unless incompatible therewith.
Moreover, unless stated otherwise, any feature disclosed herein may be replaced by an alternative feature serving the same or a similar purpose.
Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.
An embodiment of the present invention will now be described by way of example only with reference to the following wherein:
A) The crystal structure of the HAdV-D10 fiber knob protein. B) Surface plasmon resonance data demonstrates HAdV-D10k binding to CAR, CD46 and DSG2 (nm=kinetics too fast to measure, nb=no binding, Green=specific binding detected). C) Recombinant HAdV-D10k and HAdV-C5k protein binding in CHO-CAR cells using a titration of hCAR specific primary antibody and an Alexa-488 tagged secondary antibody. Data is shown as median fluorescence intensity (MFI) with SD and IC50 values are shown in table. D) Trimeric HAdV-D10 fiber knob (red) shown in complex with hCAR receptor (white). E) Predictive modelling of the hCAR (white) and DG loop interaction of HAdV-D10 (red) in comparison with hAdV-C5 (blue) and HAdV-D48 (green). F) Predictive modelling of CD46 binding sites for HAdV-D10 (cyan) and hAdV-B11 (green), a known CD46 binding adenovirus. Red dashes indicate binding potential. Structural analysis performed using Pymol.
A) Transduction of HAdV-C5/kn10 in cells expressing CAR (CHO-CAR) and CD46 (CHO-BC1). Cells were infected at a viral load of 5000 vp/cell and luciferase production was measured at 48 hours. B) Transduction of both the HAdV-C5/kn10 pseudotype in the presence of hAdV-C5 recombinant knob protein for CAR blocking and HAdV-C5K with a 477YT mutation that ablates CAR binding. C) Neuraminidase assay determines HAdV-C5 pseudotype with HAdV-D10k binding to sialic acid in A549 cells. ns, p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001; ****, p<0.0001.
A) Schematic representing modifications made during production of HAdV-D10 vector. E1 and E3 genes were deleted indicated by the red box, E4orf6 was replaced with HAdV-C5 E4orf6 as highlighted in blue and green represents insertion of the transgenes GFP and Luciferase under the HCMV IE promoter. B) Amino acid sequence alignment of hexon hypervariable regions (HVR) in HAdV-C5 and HAdV-D10 serotypes. Sites for ‘HVR7’ FX-binding mutation in HAdV-C5 shown in purple arrows (53); ‘original’ and ‘mutated’ amino acids involved in the point mutations are shown in bold black letters. C) CHO-K1 cells were transduced with HAdV-C5 and HAdV-D10 vectors at 5000 viral particles/cell for 3 h and luciferase activity measured 48 h later. D) Biodistribution of HAdV-D10 in vivo, 72 hours post intravenous injection. GFP levels were measured in 50 μg of total protein using GFP Simplestep ELISA (Abcam) and calculated from a duplicate mean and concentration was interpolated from a standard curve and transformed using GraphPad software. Log of mean (n=4) and standard deviation of the mean have been shown. Statistical significance was determined using two-tailed unpaired t tests. ns, p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001; ****, p<0.0001. E) Histogram showing proportion of CHO-DSG2 cell line positivity stained for DSG2 receptor use. F) Transduction of CHO-K1 and CHO-DSG2 cells by HAdV-C5 and HAdV-D10 GFP vectors with HAdV-C5.3k used as a positive control for DSG2 receptor use. G) Transduction of CHO-K1, CHO-BC1 and CHO-CAR cells with HadV-C5 and HAdV-D10 with GFP expression measured 72 hours post infection. Data shown as mean of triplicate values. Error bars represent standard deviation of the mean and fold change is relative to ‘virus only’ conditions for each virus. ns, p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001; ****, p<0.0001.
A) Predictive structural modelling of HAdV-D10 knob domains with an A20 targeting peptide insertion in DG structural loop. Structures were based on species D structure Ad19p (PDB ID: 1UXB). A20 amino acid sequence NAVPNLRGDLQVLAQKVART highlighted in green. B) Histogram illustrating proportion of BT20 cells positive for CAR and αvβ6 cell surface receptors determined by flow cytometry. C) BT20 cells transduction of HAdV-C5, HAdV-D10 and HAdV-C5/kn10 pseudotypes. Viral infection was measured by expression of the transgene luciferase 48 hours post infection. D) Transduction of BT20 cells in the presence of receptor blocking antibodies. BT20 cells were preincubated with antibody (IgG and anti-αvβ6) for 30 minutes prior to a 1-hour infection on ice. Unbound virus was removed by washing and luciferase levels were measured 48 hours post infection. Data is plotted as a mean of n=3 with error bars indicating standard deviation. Significance was determined using Two-way ANOVA followed by Tukey's multiple comparison test. ns, p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001; ****, p<0.0001.
A549, BT20 and Kyse 30 cells were infected at a viral load of 10 000 vp/cell with both HAdV-C5 and HAdV-D10 vectors and the A20 modified vectors. Expression of the GFP transgene was measured using flow cytometry, 72 hours post infection. The table indicates the percentage expression of the cell surface receptors, CAR and αvβ6, determined by flow cytometry. Data shown is a mean of triplicate values with error bars representing standard error of the mean. Statistical significance was determined by Two-way 702 ANOVA using Tukey's multiple comparisons test. ns, p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001; ****, p<0.0001.
A) Intracellular trafficking of Alexa Fluor 488-labeled HAdV-D10 and HAdV-D10.A20 in Kyse-30 cells. Green, Alexa Fluor 488-labeled HAdVs; blue, nuclei stained with DAPI; gray, reflection. The images are maximum projections of confocal stacks. Representative confocal images are shown. Scale bars 10 μm. B) Quantification of virus internalization efficiency, expressed as number of viral particles per cell. The horizontal bars represent means, and the error bars indicate standard deviations; the numbers of cells analyzed are indicated (N). *** P<0.001; **** P<0,0001.
A) Viruses were preincubated for 15 minutes with serum diluted in basal media at different concentrations (40%, 706 20%, 10%, 5%, 2.5% and no serum). Kyse 30 cells were infected with 5000 vp/cell in triplicate for each serum dilution. Expression of the GFP transgene was measured using flow cytometry 72 hours post infection. B) The table indicates fold change when compared to virus infection with no serum for each serum dilution. Data shown is a mean of triplicate values with error bars representing standard deviation of the mean. C) Individual graphs highlighting statistical differences. Statistical significance was determined by a One-way ANOVA using Dunnett's multiple comparisons test. D) GFP ELISA showing biodistribution of HAdV-D10 and HAdV-D10A20 in vivo. Female NSG mice were inoculated subcutaneously with BT20 cells and growth of the xenografts was monitored. GFP expressing HAdV vectors were administered intravenously through injection into the tail vein and tumour and liver were harvested 72 hours post infection. Total protein was extracted and assessed using a BCA assay (Pierce). GFP levels were measured in 50 μg of total protein using GFP Simplestep ELISA (Abcam) and calculated from a duplicate mean and concentration was interpolated from a standard curve using GraphPad software. Data is representative of a mean (n=4) and standard error of the mean. Statistics indicated where significantly different from virus only. ns, p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001; ****, p<0.0001.
A) A549 (αvβ6 low) and BT20 (αvβ6 high) cells were infected at a viral load of 5000 vp/cell with wildtype HAdV-C5 and HAdV-D10 and wildtype HAdV-D10 with the A20 modification. Cell killing was measured hours post infection using CellTiter-Glo® Luminescent Cell Viability Assay (Promega). Data shown is a mean of triplicate values with error bars representing standard deviation. Statistical significance was determined by Two-way ANOVA using Tukey's multiple comparisons test. ns, p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001; ****, p<0.0001. B) HAdV-D10 and HAdV-D10.A20 (10×10{circumflex over ( )}10 vp/flank) and PBS controls were administered via intra-tumoural (IT) injection to mice bearing BT20 xenografts. Tumour growth was measured regularly with a caliper for nine days post administration. Data is representative of a mean (n=4) and significance was determined by Mann-Whitney test.
Biodistribution of HAdV-D10 and HAdV-D10.A20 was assessed by in vivo. Female NSG mice were inoculated sub-cutaneously with BT-20 cells and growth of the xenografts were monitored. GFP expressing HAdV vectors were administered intravenously through injection into the tail vein and organs were harvested 72 hours post infection. Protein was extracted from frozen liver, tumour, lung, kidney, spleen and heart and total protein was assess using a BCA assay (Pierce) GFP levels were measured in 50 μg of total protein using GFP Simplestep ELISA (Abcam) according to manufacturer's instructions. Data is representative of a duplicate mean and concentration was interpolated from a standard curve using GraphPad software. Data that did not fall within the standard curve range has not been plotted. Statistical significance was determined by two-tailed paired t tests. ns, p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001; ****, p<0.0001.
Table 1. HAdv-D10 Fiber Knob Protein Crystal Statistics
Table 2. Primers used in generation of viral vectors
Recombinant HAdV-C5 and HAdV-D10 fiber knob proteins were generated from SG13009 Escherichia coli harbouring pREP-4 plasmid and a pQE-30 expression vector containing the relevant fiber knob encoding DNA sequence. Glycerol stocks were used to inoculate 20 mL LB broth containing 100 μg/mL ampicillin and 50 μg/mL kanamycin and cultured overnight.
The overnight culture was added to 1 L of TB (Terrific Broth, modified, Sigma-Aldrich) supplemented with 100 μg/mL ampicillin, 50 μg/mL kanamycin and 8 mLs of glycerol (0.8%).
Cultures were placed in a shaking incubator (250 rpm) at 37° ° C. until they measured OD600=0.6. Expression of recombinant fiber knob from pQE-30 was induced by addition of IPTG to a final volume of 0.5 mM prior to incubation for 4 hours at 37° C. Bacteria were harvested by centrifugation at 4000 g for 10 minutes at 4° C. Pellets were stored at −80° C. prior to purification. Thawed pellets were resuspended in lysis buffer (50 mM Tris [pH 8.0] 300 mM NaCl, 1% (v/v) NP40, 1 mg/mL Lysozyme, 1 mM ß-mercaptoethanol) and incubated at room temperature for 30 minutes, agitating to aid lysis. Lysates were clarified by a 30-minute centrifugation at 30,000 g and filtered using a 0.22 μm syringe filter (Millipore, Abingdon, UK). Purification was conducted using the AKTA FPLC. Filtered lysates were passed through a 5 mL HisTrap FF nickel affinity chromatography column (GE life sciences, 17525501) at 2.0 mL/min and washed with 5 column volumes into elution buffer A (50 mM Tris [pH 8.0], 300 mM NaCl, 1 mM β-mercaptoethanol). Protein was eluted by 30 min gradient elution from buffer A to B (buffer A+400 mM Imidazole). Fractions were analysed by reducing SDS-PAGE, and fractions containing fiber knob were pooled and further purified using a superdex 200 10/300 size exclusion chromatography column (GE 10/300 GL, GE Life Sciences) in crystallisation buffer (10 mM Tris, [pH 8.0] and 30 mM NaCl). Fractions correlating to area under the chromatogram peaks were collected and analysed by SDS-PAGE. Pure fractions were concentrated by centrifugation in Vivaspin 10,000 MWCO (Sartorius, Goettingen, Germany) proceeding crystallisation.
Crystallization experiments were set up in a 96-well sitting-drop plate. PACT Premier commercial screen from Molecular Dimensions (UK), was used to equilibrate 200 nL drops of protein against 60 mL drops of screen. The best crystals appeared in the condition 0.2 M CaCl2, 0.1 MES, 20% w/v PEG 6000, pH 6.0. Crystals were harvested into thin plastic loops, cryocooled and transferred to the Diamond Synchrotron Light Source at Harwell, UK. Data collection was conducted at DLS Beamline 104-1. Structure determination of HAdV-D10k was conducted according to previously described methods (48). Reflection data and final model were deposited in the Protein Data Bank (PDB, www.rcsb.org) as entry 6ZC5. A low-resolution form of the structure was also determined and is deposited as entry 6QPM. Full crystallographic refinement statistics and conditions are given in Table 1.
A BIAcore 3000TM was used to acquire binding analysis data. CD46, CAR and DSG2 (approximately 500RU) were amine coupled to the surface of a CM5 sensor chip using a slow flow rate of 10 μL/min. Measurements were all performed at a flow rate of 30 μL/min in PBS buffer (Sigma, UK) at 25° C. HAdV-D10 fiber knob protein was purified and concentrated to 178UM. 5×1:3 serial dilutions were prepared for each sample and injected over the relevant sensor chip. The equilibrium binding constant (KD) values were calculated assuming a 1:1 interaction by plotting specific equilibrium-binding responses against protein concentrations followed by non-linear least squares fitting of the Langmuir binding equation. For single cycle kinetic analysis, a top concentration of 200 μM HAdV-D10K was injected, followed by four injections using serial 1:3 dilutions. The KD values were calculated assuming Langmuir binding (AB=B×ABmax/(KD+B)) and the data were analysed using the kinetic titration algorithm (BIAevaluation™ 3.1). Receptor proteins were sourced commercially, as follows:
Fiber-knob proteins were modelled in complex with CAR or CD46 using the template of existing HAdV-C5K (PDB 6HCN) for CAR binding or the HAdV-B11K (PDB 308E) for CD46 binding structures. Non-protein components and hydrogens were deleted from the template model and the fiber knob protein of interest. The Ca chains of each fiber knob proteins were aligned in such a way as to achieve the lowest possible RMSD. Models containing only the HAdV-D10 fiber knob protein and the ligand were saved, and energy minimization was performed, using the YASARA self-parametrising energy minimisation algorithm via the YASARA energy minimisation server. Results were visualised and adapted for publication using PyMoL visualisation software.
CHO-CAR cells were harvested and 20,000 cells per well were transferred to a 96-well V-bottomed plate (Nunc™; 249662). Cells were washed twice with cold PBS prior to seeding and kept on ice. Serial dilutions of recombinant soluble knob protein were made up in serum-free RPMI-1640 to give a final concentration range of 0.0001-100 μg/105 cells. Recombinant fiber knob protein dilutions were added in triplicate to the cells and incubated on ice for 1 hour. Unbound fiber knob protein was removed by washing twice in cold PBS and primary CAR RmcB (Millipore; 05-644) antibody was added to bind available CAR receptors. Primary antibody was removed after 1 h incubation on ice and cells were washed twice further in PBS and incubated on ice for 30 minutes with Alexa-647 labelled goat anti-mouse F(ab′)2 (ThermoFisher; A-21237). Antibodies were diluted to a concentration of 2 μg/mL in PBS. Cells were washed and fixed using 4% paraformaldehyde and staining detected by flow cytometry on Attune N×T (ThermoFisher). Analysis was performed using FlowJo v10 (FlowJo, LLC) by sequential gating on cell population, singlets and Alexa-647 positive cells. Median fluorescence intensity (MFI) of the Alexa-647 positive single cell population in each sample was determined as previously described and IC50 curves were fitted by non-linear regression using GraphPad software to determine the IC50 concentrations.
Cells were harvested and seeded at a density of 100,000 cells per well in a 96-well V-bottomed plate (Nunc™; 249662). Cells were washed with cold FACs buffer (5% FBS in PBS) before addition of 100 μL primary antibody. Anti-CAR (RmcB, 3022487; Millipore) and anti-αvβ6 (MAB20772; Millipore) were used at a concentration of 2 μg/mL. Primary antibody was removed after 1 h incubation on ice and cells were washed twice in FACs buffer and incubated on ice for 30 minutes with 1:500 dilution of Alexa-647 labelled goat anti-mouse F(ab′)2 (ThermoFisher; A-21237). Stained cells were fixed using 4% paraformaldehyde prior to measurement by flow cytometry on Accuri C6(BD Biosciences). Analysis was performed using FlowJo v10 (FlowJo, LLC) by sequential gating on cell population, singlets and Alexa-647 positive cells.
Cell lines were sourced either from American Type Culture Collection (ATCC) or collaborators. Cells were grown at 37° C. in a humidified atmosphere with 5% CO2 in a Human Tissue Act (HTA) certified cell culture incubator (HERA Cell, Thermo Scientific). Mammalian cell lines were sub-cultured as required (80-100% confluency) in cell line-specific media and supplements. Kyse-30 and A549 were maintained in Roswell Park Memorial Institute 1640 (RPMI; Sigma, #R0883). BT20 cells were grown in Minimum Essential Medium Eagle (EMEM, a modification; Gibco, #11095080). CHO derived cells were cultured in Dulbecco's Modified Eagle Medium: Nutrient Mixture F-12 (DMEM/F-12; Gibco, #10565018). Basal media was supplemented with 10% Foetal Bovine Serum, heat inactivated (FBS; Gibco, #10500-064), 1% L-Glutamine (stock 200 mM; Gibco, #25030-024), 2% penicillin and streptomycin (Gibco, #15070-063).
Pseudotyped HAdV-C5/kn10 and HAdV-C5/kn10.A20 vectors were produced by AdZ recombineering using previously described methods (33, 49). To generate BAC DNA containing the HAdV-D10 genome HAdV-D10 virus was obtained from ATCC and passaged in A549 cells. Viral stocks were prepared by standard methods and DNA extracted using QIAamp MinElute Virus Spin Kit. A capture BAC containing 500 b.p. homology to each end of the Ad10 genome was generated and used to capture the genome by recombination in SW102 bacteria. This enabled rapid and efficient manipulation of the viral genome by further recombineering. The E1 and E3 genes were deleted to render the vector non-replicative and HAdV-D10 E4orf6 region was replaced with the HAdV-C5 E4orf6 to enhance production in 293 cells. GFP or Luciferase transgenes were inserted under the control of a CMV promoter replacing the E1 region. HAdV-D10 was retargeted to αvβ6 insertion of the A20 peptide into the DG loop of the HAdV-D10 fiber knob. The primers used are detailed in Table 2.
DNA was amplified using a maxiprep kit as described in the manufacturer's instructions (Nucleobond BAC 100, Macherey-Nagel). DNA concentration was determined using a Nanodrop ND-1000 (Thermo Scientific, UK). Virus particles were generated by lipofectamine transfection onto a T25 CELLBIND flask of T-REX cells or 29386 cells. Cells were collected when CPE was apparent, and virus was amplified using the respective cell lines. Caesium chloride (CsCl) two-step purification method was used to extract pure virus. Alexa-Fluor 488 labelled viruses were prepared using CsCl purification with dialysis into PBS. Viral particles were then incubated for two hours at RT with 20-fold excess of Alexa-Fluor488-TFP (Molecular Probes). Zeba Spin desalting columns (Pierce) were used to purify labelled viral particles. Viral titer was determined using both microBCA and NanoSight (Malvern Panalytical) technology. Viruses were maintained at −80° C. for long term storage.
Cells were seeded at the appropriate density on a sterile 96-microwell Nunc tissue culture plate (Thermo Scientific, #163320) 24 hours prior to infection. Cells were washed with PBS and viruses diluted to the stated concentration in serum free media were added in triplicate. Plates were incubated for 3 hours at 37° C. then virus dilution was replaced with complete growth media. Viral transduction was measured at either 48 or 72 hours post infection. Luciferase expression was detected using Luciferase Assay System kit, according to the manufacturers protocol (#E1501; Promega UK Ltd, Southampton, UK). Protein concentration (mg/mL) determined using a Pierce™ BCA Protein Assay Kit (#23227; Thermo Scientific, Loughborough, UK) and absorbance was measured at A570 nm on an iMark™ Microplate Absorbance Reader (BioRad, Hertfordshire, UK). GFP expression was measured by flow cytometry using Attune N×T (ThermoFisher). Cells were trypsinised, resuspended in FACs buffer (5% FBS in PBS) and transferred to a 96-well V-bottomed plate (Nunc™; 249662).
Cells were washed with cold PBS and fixed using 4% paraformaldehyde for 10 minutes at 4° C. GFP was detected in the BL-1 channel and raw data was analysed using FlowJo v10 (FlowJo, LLC) by gating sequentially on cell population, singlets and GFP positive cells. GFP expression was quantified by percentage of cells positive for GFP compared to an uninfected control.
A549 cells were seeded at a density of 20,000 cells per well and allowed to adhere overnight. Cells were washed twice with PBS before addition of 50 μL of neuraminidase enzyme from Vibrio Choleraa (11080725001, Roche) used at 50 mU/mL. Cells were incubated at 37° C. for 1 hour prior to washing with cold PBS. Viral transduction was carried out as previously described on ice to ensure cleaved sialic acid is not replenished.
For assessment of the impact of physiological concentrations of human coagulation FX on transduction efficiency, viral transduction was performed as described for the luciferase assay above. Virus dilutions were prepared in serum-free medium that was supplemented with 10 μg/mL of FX (#HCX0050, Haematologic Technologies, Cambridge Bioscience, Cambridge, UK) for 3 h.
Kyse-30 cells were seeded on a coverslip in 24-well plates at a density of 20000 cells per well. The following day cells were infected with Alexa-Fluor 488 labelled viruses at a concentration of 25000 or 50000 vp/cell and transferred to 37° C. for 3 hours. Virus was removed and plates returned to 37° C. for 72 hours after which cells were fixed with 4% paraformaldehyde in PBS for 10 minutes at RT. Coverslips were mounted onto slides using a single drop of VECTASHIELD Antifade Mounting Media (H-100-10) containing DAPI to stain nuclei. Confocal microscopy was carried out using a Leica TC SP2 AOBS scanning microscope and images processed using the Leica Application Suite X (LASX).
To determine the effect of neutralising antibodies on viral transduction, serum was collected from the blood of a healthy donor. Serum was serially diluted by half in basal media from 80% to 5%. Serum dilutions were added at a 1:1 ratio with basal media containing 5000 vp/cell giving a final well serum concentration range of 40% to 2.5%. GFP expression was measured by flow cytometry as described.
Cells were seeded at a density of 10,000 cells per well in triplicate in a white, opaque bottom 96 well plate (Corning™ 3915). Cells were seeded 24 hours prior to viral infection. Wildtype HAdV-C5, HAdV-D10 and HAdV-D10.A20 were added to cells at a concentration of 5000 vp/cell. The plates were incubated at 37° C. and the viability was measured using CellTiter-Glo® Luminescent Cell Viability Assay (Promega). CellTiter-Glo reagents were prepared according to the manual and 50 μL of the reagent was added to the cells. The plates were protected from light and shaken to fully lyse cells before luminescence was read using a multimode plate reader (FLUOstar Omega, BMG Labtech, Aylesbury, UK).
Female NSG mice were sub-cutaneously implanted with 6×10{circumflex over ( )}6 BT-20 cells/flank and xenograft growth was monitored. When tumours were established, a total of 1×10{circumflex over ( )}11 replication deficient virus particles was administered through intravenous tail vein injection to each mouse (n=5). Liver, lung, kidneys, spleen, heart, and tumour were harvested 72 hours post infection. Tissue was stored at −80 degrees. Tissue was homogenized using the TissueRuptor (Qiagen). Protein was extracted from frozen tissue as recommended for the GFP SimpleSTEP ELISA (Abcam, ab171581) and GFP was measured according to the kit protocol. Total protein was determined using a BCA assay (Pierce) and all samples were diluted to 50 μg prior to the ELISA. Absorbance was measured at OD450 using a Cytation 5 microplate reader (Biotek). For replication competent wildtype analysis, 10 days after injection of the cells, HAdV-D10 and HAdV-D10.A20 (10×10{circumflex over ( )}10 vp/flank) and PBS controls were administered via intra-tumoural (IT) injection. Tumour growth was measured regularly with a caliper ensuring no more than 15% weight loss was observed. Mice were harvested nine days post administration. For All animal experiments were approved by the Animal Ethics Committee, Cardiff University.
Analysis of raw data was performed using GraphPad unless stated otherwise. Data is shown as a mean of triplicates with standard error (SEM) or standard deviation of the mean (SD). Statistical analysis was carried out as indicated and statistical significance is shown as follows; ns=p>0.05; *=p<0.05; ** 287=p<0.01; ***=p<0.001; ****=p<0.0001.
HAdV-D10 Knob Binds with Weak Affinity to Known Adenoviral Receptors
We determined the crystal structure of HAdV-D10 fiber knob (HAdV-D10k;
We investigated whether the predicted weak interaction between HAdV-D10k and CD46 was sufficient to result in cell attachment and infection. We firstly modelled the interaction between CD46 and HAdV-D10k using predictive homology modelling (
We next assessed the use of these receptors in viral transduction assays. CHO-K1 cells (expressing no known HAdV receptor), CHO-CAR and CHO-BC1 cells (expressing CAR and CD46 respectively) were infected with the pseudotyped HAdV-C5/kn10 vector (
After establishing HAdV-D10 is able to bind and use CAR as an entry receptor, we investigated whether HAdV-C5 expressing the HAdV-D10 fiber knob (HAdV-C5/kn10 pseudotype) could use CAR to infect cells (
As HAdV-D10 formed weak interactions with CAR, CD46 and DSG2 it is unlikely they are used as a primary receptor. Several species D adenoviruses have been reported as binding and using sialic acid. To investigate whether HAdV-D10k utilizes sialic acid, we infected neuraminidase-treated A549 cells with HAdV-C5/kn10 (
HAdV-D10 does not Interact with Coagulation Factor X (FX)
To generate a HAdV-D10 vector, genomic DNA was captured within a BAC to enable rapid and efficient manipulation of the viral genome (
HAdV-D10 Vector does not Use DSG2 or CD46 for Cell Entry
We assessed the ability of HAdV-D10 vector to use DSG2 and CD46 receptors. A newly generated CHO cell line, referred to as CHO-DSG2, was developed in house. Flow cytometry analysis showed 93% of the population was positive for DSG2 expression compared to an IgG control (
A recent study suggests several species D viruses can interact with CD46 via direct engagement of the hexon. Using the whole serotype, we investigated whether Ad10 can engage CD46 as an entry receptor (
Vectorised HAdV-D10 and the HAdV-C5/kn10 pseudotype were then evaluated as potential vectors for cancer virotherapy applications. We incorporated the A20 peptide into the previously described HAdV-C5 NULL vector to engineer selective tumour targeting (27). A20 (NAVPNLRGDLQVLAQKVART; SEQ ID NO: 1) is a 20aa long peptide from foot and mouth disease virus (FMDV) that has high selectivity and affinity for αvβ6 integrin, which is not expressed on normal epithelial cells, but commonly expressed on the surface of aggressively transformed epithelial cells, in particular malignancies of pancreatic, breast, oesophageal and ovarian origins. Incorporation of the A20 peptide into the adenovirus fiber knob has been shown to retarget the virus to these cancer cells. We inserted this peptide into the DG loop of HAdV-D10 fiber knob. SWISS-MODEL homology modelling was used to predict structure and compare HAdV-D10 fiber knob expressing the A20 peptide (
HAdV-D10.DG.A20 Infects Multiple Cancer Cell Lines Via αvβ6 Integrin
In addition to generating a pseudotyped αvβ6 targeted HAdV-C5/kn10.DG.A20 vector, we generated whole HAdV-D10 serotype targeting αvβ6 through insertion of A20 into HAdV-D10 vector in the same position as the HAdV-C5/kn10.DG.A20 vector. To determine the cancer selectivity of these vectors we evaluated transduction in several cancer cell lines expressing varying levels of αvβ6 integrin and CAR (
HAdV-C5.RGE.KO1.A20 refers to an HAdV-C5 vector modified to present the A20 peptide in the HI loop of the fiber knob domain, that also possesses a RGD/E mutation in the penton base to prevent binding to cellular integrins and mutations in the fiber knob domain (KO1) to ablate CAR binding—therefore this virus is ablated for native cellular receptors and can only infect cells expressing αvβ6 integrin. As expected, αvβ6 integrin engaging viruses were unable to infect A549 cells due to lack of the αvβ6 receptor. HAdV-C5.RGE.KO1.A20 readily infects both αvβ6 expressing BT20 and Kyse 30 cell lines. Interestingly, HAdV-D10 exhibits a limited infectivity in all three cell lines. Introduction of the A20 peptide significantly increased the ability of HAdV-D10.A20 to infect both BT20 and Kyse 30 cell lines (p=<0.0001) via αvβ6 integrin.
HAdV-D10 and HAdV-D10.A20 labelled with Alexa Flour 488 were used to compare intracellular trafficking of these viruses. Kyse-30 cells were seeded on a coverslip prior to infection at 25000 vp/cell and 50000 vp/cell. Cells were fixed and mounted 72 hours post infection. A confocal microscope was used to evaluate the differences in viral transduction (
A major obstacle contributing to reduced efficacy of HAdV-C5 based oncolytics are the proportion of patients presenting with pre-existing immunity to HAdV-C5. Use of alternative, rarely serotypes such as HAdV-D10 may provide therapies that are effective for a broader population but also offer a valuable second line of treatment in the case patients develop immunity to HAdV-C5 based virotherapies over the course of their disease. We investigated the effect of preincubation of HAdV-C5 and HAdV-D10 vectors with patient serum known to be highly neutralising against HAdV-C5 (
HAdV-C5 was effectively neutralised even at the lowest concentration of serum (2.5%). HAdV-C5.RGE.KO1.A20 required higher concentrations of serum but could be effectively neutralised by the presence of >20% serum. It was not possible to detect any effect of neutralising serum in the case of HAdV-D10 due to the low level of infectivity at all concentrations. HAdV-D10.A20 however was able to infect the Kyse 30 cells and resist neutralization even at the highest concentration of serum tested (40%). When quantified as fold change (
We assessed αvβ6 targeting in vivo. Female NSG mice bearing sub-cutaneous BT20 xenografts were inoculated systemically with GFP expressing HAdV vectors via intravenous injection. Liver and tumour were harvested 72 hours post infection (
Enhanced αvβ6 Dependent Tumour Cell Killing Using a Wild Type Replication Competent HAdV-D10.A20 Virotherapy
We investigated the tumour cell killing of wildtype replication competent HAdV-D10.A20 as a virotherapy. Two cell lines were infected with 5000 vp/cell of HAdV-C5, HAdV-D10 and HAdV-D10.A20 wild types (
Based on the in vitro efficacy, we then determined whether this could be effective in vivo. Nude mice bearing BT20 xenografts were injected intratumorally with replication competent virotherapies, and the effects on tumour growth was monitored (
Finally, we assessed the biodistribution of HAdV-D10 and HAdV-D10.A20 in vivo. Female NSG mice bearing sub-cutaneous BT-20 xenografts were inoculated with GFP expressing HAdV vectors. Liver, lung, spleen, heart, kidney, and tumours were harvested 72 hours post infection. Protein was extracted according to GFP SimpleSTEP ELISA kit (Abcam) and GFP levels measured in 50μ total protein (
We have evaluated the suitability of a novel species D adenovirus, HAdV-D10 for use as virotherapy. Literature surrounding HAdV-D10 is extremely limited and mainly focus on its pathology. Therefore, we aimed to further our understanding of the receptor interactions by studying the fiber knob structure and its binding capabilities including binding with CAR, CD46 and DSG2. DSG2 binding is of particular interest, despite having the weakest interaction since this has only been described as a receptor for species BII adenoviruses previously. HAdV-B3, a well described DSG2 user, also binds DSG2 with low affinity. On further investigation, we demonstrated HAdV-D10 was not able to infect CHO-DSG2 cells and therefore consider that like other species D adenoviruses HAdV-D10 does not use DSG2 as a cellular receptor. The highest HAdV-D10 affinity interaction observed was with CAR. Using recombinant HAdV-D10k protein we confirmed that it binds CAR in vitro with a 16.5-fold lower affinity than HAdV-C5k as indicated by the IC50 values. We concluded that although the binding is weak, HAdV-D10 can bind and use CAR as an entry receptor. In addition, we determined HAdV-D10 only forms weak interactions with CD46 and that it is not sufficient to infect cells. Preliminary experiments suggest HAdV-D10 may be capable of utilizing sialic acid as a mechanism for cell entry.
Alignment of HAdV-C5 and HAdV-D10 hypervariable regions identified that the key FX binding regions present in HAdV-C5 HVR7 were not present in HAdV-D10 hexon. HAdV-D10 does not interact with FX, and therefore that HAdV-D10-based virotherapies may bypass the “off target” sequestration in the liver observed using HAdV-C5-based therapies.
The A20 peptide was inserted into the DG loop of the fiber knob of HAdV-D10. A20 has previously been used to retarget HAdV-C5 to αvβ6 integrin which is upregulated in a number of cancer types including ovarian, pancreatic, breast and oesophageal cancer.
We also investigated the effect of neutralising antibodies found in patient serum on viral transduction. HAdV-D10.A20 was not neutralised even in the presence of 40% serum suggesting HAdV-D10 may provide an attractive alternative to the currently used HAdV-C5-based virotherapies to avoid pre-existing immunity.
We investigated tumour specific cell killing using wildtype and HAdV-D10.A20. HAdV-D10.A20 was able to infect BT20 cells through engagement of the αvβ6 integrin resulting in significant cell death.
We compared the tumour and liver uptake of GFP expressing vectors in vivo following systemic application and demonstrated increased tumour selective transduction through incorporation of A20 peptides, whilst transduction of other of targeted tissue was not enhanced, indicating successful targeting of HAdV-D10.A20 to αvβ6 positive tumours following systemic administration.
Finally, we investigated the tumoricidal activity of HAdV-D10.A20 in αvβ6low/CARhigh A549 and αvβ6high/CARlow BT20 cells. HAdV-C5 killed A549 cells via CAR but not BT20 cells. HAdV-D10 demonstrated consistently low levels of activity in both cell lines. HAdV-D10.A20 infected BT20 cells through engagement of αvβ6 integrin, resulting in significant cell death. We administered HAdV-D10 and HAdV-D10.A20 to mice bearing BT20 xenografts via IT injection and observed a significant decrease in tumour volume nine days post administration of HAdV-D10.A20 when compared to PBS and HAdV-D10. We have therefore developed a highly tumour selective version of HAdV-D10 that is capable of cancer specific cell killing and has shown efficacy in vivo without the need for additional de-targeting modifications.
We have therefore developed a highly targeted version of HAdV-D10 that is capable of cancer specific cell killing and has shown efficacy in vivo without the need for additional de-targeting modifications.
We have generated the first reported structure of the HAdV-D10 fiber knob and demonstrated HAdV-D10k is capable of forming weak interactions with several known adenoviral receptors including CAR, CD46, DSG2 and sialic acid. We demonstrated that HAdV-D10 does not bind FX—a feature that may improve the pharmacokinetics of HAdV-D10 based virotherapies when delivered systemically, reducing “off target” uptake in the liver. We have identified that HAdV-D10 has a limited level of infectivity across cell lines. Using this as a platform we have engineered in tumour selectivity; we successfully generated a HAdV-D10.A20 virus which infects and kills cancer cells with upregulated αvβ6 integrin expression, even in the presence of highly neutralising serum. Our findings therefore highlight that retargeted HAdV-D10 based vectors may offer significant therapeutic potential, combining reduced off target interactions with native receptors providing a platform to engineer tropism towards high affinity “on target” tumour associated receptors, with a capacity to circumvent pre-existing anti-HAdV-C5 immunity in the population. HAdV-D10 may provide therapies that are effective for a broader population but also offer a valuable second line of treatment in the case of patients who acquire treatment related immunity to HAdV-C5 based virotherapies.
Such virotherapies therefore hold significant promise as platforms for successful systemic delivery of immunovirotherapies.
1Twin Law 1/Fraction 1
1Twin Law 2/Fraction 2
1Twin Law 3/Fraction 3
1Twin Law 4/Fraction 4
2rms deviations
3Coordinate error
1Twin laws determined and fractions estimated automatically by REFMAC5
2Figures in brackets are rms targets
3Coordinate Estimated Standard Uncertainty in (Å), calculated based on maximum likelihood statistics.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2104409.4 | Mar 2021 | GB | national |
| 2115496.8 | Oct 2021 | GB | national |
| 2200186.1 | Jan 2022 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2022/050745 | 3/24/2022 | WO |
