Patent Application
20210338811
This invention is related to the area of immunotherapy. In particular, it relates to combination regimens for treating tumors and kits and medicaments for accomplishing them.
Glioblastoma is the most dismal malignant brain tumor among all primary brain and central nervous system tumors. The median survival time for glioblastoma patients with the current standard treatment or even newly developed agents is less than 15 months. Thus, there is an urgent need to develop advanced and efficient therapeutic approaches to improve the poor survival outlook of glioblastoma patients as well as other tumors expressing EGFR receptors.
According to one aspect of the invention a method is provided for treating a tumor in a patient. An immunotoxin and an immune checkpoint inhibitor are administered to the patient. The immunotoxin comprises a single chain variable region antibody fused to a PE38 truncated Pseudomonas exotoxin. The single chain variable region antibody has CDR1, CDR2, and CDR3 regions as shown in SEQ ID NO: 6-11.
According to another aspect of the invention a kit is provided for treating a tumor. The kit comprises an immunotoxin and an immune checkpoint inhibitor. The immunotoxin comprises a single chain variable region antibody fused to a PE38 truncated Pseudomonas exotoxin, wherein the single chain variable region antibody has CDR1, CDR2, and CDR3 regions as shown in SEQ ID NO: 6-11;
These and other embodiments which will be apparent to those of skill in the art upon reading the specification provide the art with treatment methods, regimens, kits, and agents for treating glioblastomas and other tumors expressing epidermal growth factor (EGF) receptors i.e., EGFR and its mutants, e.g., EGFR variant III.
The inventors have developed targeted immunotoxins (IT), D2C7-(scdsFv)-PE38KDEL (D2C7-IT), by fusing the single chain variable fragment (scFv) from the D2C7 monoclonal antibody (mAb) with the Pseudomonas exotoxin A (PE), optionally fused to KDEL peptide. D2C7-IT reacts with both the wild-type epidermal growth factor receptor (EGFRwt) and the EGFR variant III (EGFRvIII), two proteins that are overexpressed in glioblastoma. The robust antitumor efficacy of D2C7-IT is mediated through PE in orthotopic glioma xenograft models in immunocompromised mice. In addition to direct tumor cell killing, the immunotoxin monotherapy induces a secondary antitumor immune response through the engagement of T cells. When the immunotoxin is administered in a combination regimen with an immune checkpoint inhibitor, improved and synergistic results are observed.
Other moieties which can be attached to the antibodies include those which provide additional beneficial properties. For example, a KDEL (lys-asp-glu-leu) tetra-peptide can be added at the carboxy-terminus of the protein to provide retention in the endoplasmic reticulum. Variants such as DKEL, RDEL, and KNEL which function similarly can also be used.
Tumors which can be treated are any that react with the D2C7 antibody. These include but are not limited to those in which at least one EGFRvIII allele is present. These may be found in breast, head and neck, brain, glioblastoma multiforme, astrocytoma, lung, or other tumors. It may be desirable to determine the presence of such an allele prior to therapy. This can be done using an oligonucleotide-based technique, such as PCR, or using an immunological technique, such as immunohistochemistry. It may be desirable to determine the amount, fraction, ratio, or percentage of cells in the tumor which express EGFR and/or EGFRvIII. The more cells which express EGFR on their surfaces, the more beneficial such antibody therapy is likely to be. Even tumors that express little to no EGFRvIII may be treated due to the ability of the antibody to bind to wild-type EGFR. Optionally, tumors may be tested prior to treatment for reactivity with D2C7 antibody. The immunotoxin itself could be used as an immunohistochemistry agent, before treatment, during treatment, or after treatment. A secondary reagent could be used with the immunotoxin for detection. It could, for example, recognize the Pseudomonas component of the immunotoxin.
Immunotoxins can be administered by any technique known in the art. Compartmental delivery may be desirable to avoid cytotoxicity for normal tissues that express EGFR. Suitable compartmental delivery methods include, but are not limited to delivery to the brain, delivery to a surgically created tumor resection cavity, delivery to a natural tumor cyst, and delivery to tumor parenchyma.
Tumors which can be treated by the method of the present invention are any which express epidermal growth factor receptor (EGFR), whether wild type, EGFRvIII, or other variants. Preferably the tumor expresses the receptor in amounts far exceeding expression by normal tissues. The mechanism of high level expression may be by genetic amplification, other alterations, whether genetic or epigenetic or post translational modifications. Exemplary tumors which can be treated include without limitation: malignant gliomas, breast cancer, head and neck squamous cell carcinoma, lung cancer.
Blockade of T cell immune checkpoint receptors, can be performed against any such targets, including but not limited to PD-1, PD-L1, TIM-3, LAG-3, CTLA-4, and CSF-1R and combinations of such checkpoint inhibitors. The immune checkpoint receptors may be on tumor cells or immune cells such as T cells, monocytes, microglia, and macrophages, without limitation. The agents which assert immune checkpoint blockade may be small chemical entities or polymers, antibodies, antibody fragments, single chain antibodies or other antibody constructs, including but not limited to bispecific antibodies and diabodies.
Immune checkpoint inhibitors which may be used according to the invention include any that disrupt the inhibitory interaction of cytotoxic T cells and tumor cells. These include but are not limited to anti-PD-1 antibody, anti-PD-L1 antibody, anti-CTLA4 antibody, anti-LAG-3 antibody, anti-TIM-3 antibody. The inhibitor need not be an antibody, but can be a small molecule or other polymer. If the inhibitor is an antibody it can be a polyclonal, monoclonal, fragment, single chain, or other antibody variant construct. Inhibitors may target any immune checkpoint known in the art, including but not limited to, CTLA-4, PDL1, PDL2, PD1, B7-H3, B7-H4, BTLA, HVEM, TIM3, GAL9, LAG3, CSF-1R, VISTA, KIR, 2B4, CD160, CGEN-15049, CHK 1, CHK2, IDO, A2aR, and the B-7 family of ligands. Combinations of inhibitors for a single target immune checkpoint or different inhibitors for different immune checkpoints may be used.
Examples of inhibitors of CSF-1R which may be used in the combination therapy with the immunotoxin include, without limitation, the following agents which are in clinical development: PLX3397, PLX486, RG7155, AMG820, ARRY-382, FPA008, IMC-CS4, JNJ-40346527, and MCS110.
The immune checkpoint inhibitor may be administered at the same time, before, or after the immunotoxin. Typically the two agents will be administered within 30, 28, 21, 14, 7, 4, 2, or 1 day(s) of each other. The agents may be given repeatedly, either serially or in a cycle of first and second agents. It may be advantageous but not necessary for the vaccine to be administered prior to the checkpoint inhibitor. But the reverse order may also be used. Priming of a cytotoxic T lymphocyte response by the immunotoxin may take from about 5 to about 14 days. Administration of the checkpoint inhibitor may beneficially be commenced during or after the priming period.
Immune checkpoint inhibitors may be administered by any appropriate means known in the art for the particular inhibitor. These include intravenous, oral, intraperitoneal, sublingual, intrathecal, intracavitary, intramuscularly, and subcutaneously.
Treatment regimens may include, in addition to delivery of the immunotoxin and immune checkpoint inhibitor(s), surgical removal of the tumor, surgical reduction of the tumor, chemotherapy, biological therapy, radiotherapy. These modalities are standard of care in many disease states, and the patient need not be denied the standard of care. The immunotoxin and immune checkpoint inhibitor(s) may be administered before, during, or after the standard of care. The immunotoxin and immune checkpoint inhibitor(s) may be administered after failure of the standard of care.
Kits may comprise, in a single divided or undivided container, the immunotoxin or its components or its encoding DNA and the immune checkpoint inhibitor or combination of immune checkpoint inhibitors. Storage stability may vary between the two agents so separate vessels may be used. Optionally one or both agents may be lyophilized or frozen.
Immunotoxins can directly kill cancer cells that express high levels of the targeted tumor antigen. Immunotoxin monotherapy can efficiently and directly destroy tumor cells expressing targeted epitopes, such as EGFRwt and/or its truncated variant, EGFRvIII, in malignant brain tumor xenograft models in immunocompromised mice. Immunotoxin therapy can induce a secondary anti-tumor immune response in a mouse model, which is different from the direct killing mechanism and needs the cooperation of the immune system. Since malignant brain tumors are always a heterogeneous mass, it is possible that some tumor cells can escape from the direct targeted attack of the immunotoxin therapy due to the lack of epitopes. For this reason, the secondary anti-tumor immune response stimulated by the immunotoxin may play an important role in eliminating those tumor cells not directly targeted.
Recently, several studies successfully demonstrated that tumor regression and significantly improved survival were achieved in murine glioma models by suppressing co-inhibitory molecules, such as CTLA4, CSF-1R, IDO, and PD1. Based on the promising preclinical data, several clinical trials have started to investigate the utilization of immune checkpoint inhibitors to treat malignant brain tumors, either as monotherapy or combinatorial therapy with other anti-tumor agents.
However, malignant gliomas, including glioblastomas, have relatively low mutation rates, which may generate fewer and subtle tumor antigens, leading to relatively poor basal immunogenicity compared to other tumor types that respond well to immunotherapies, for example, melanoma and NSCLC. Therefore, a combination of targeted cytotoxic immunotherapy and immune checkpoint inhibitors may provide a synergistic anti-tumor effect.
The ideal combinatorial therapy may have a lower dose of targeted cytotoxic immunotherapy to limit its side effects, and achieve long-term anti-tumor immunity. Immunotoxin therapy can efficiently and directly kill cancer cells that express high levels of the targeted antigen through its unique cytotoxic mechanism. Cancer cells destroyed by localized immunotoxin therapy release tumor antigens and/or other neoantigens. These antigens can then be presented by the APCs to host T cells in the local draining lymph nodes, which activate CTLs to migrate and eliminate the remaining or recurrent tumor cells expressing specific tumor antigens at the tumor site. Throughout this process, various co-inhibitory checkpoint pathways between T cells and APCs and/or between T cells and tumor cells can trigger different mechanisms to de-activate T cells, and to adjust the continuation and intensity of the anti-tumor immunity. Immune checkpoint inhibitors, such as anti-CTLA4 and anti-PD1 mAbs, can block these immunosuppressive pathways and therefore augment tumor cell death caused by lymphocytes activated by the targeted immunotoxin therapy.
We established a subcutaneous mouse CT2A-mD2C7 glioma model in C57BL/6 immunocompetent mice with six groups, in which the mice were treated by the control immunotoxin P588-IT or D2C7-IT, combined with αCTLA4 or αPD1 inhibitors after the tumor grew to a certain size. In this in vivo subcutaneous CT2A-mD2C7 glioma model, four doses of the low-dose D2C7-IT but not αCTLA4 or αPD1 monotherapy, and D2C7-IT+αCTLA-4 or αPD-1 combinatorial therapy generated a significant delay in tumor growth compared to the control immunotoxin P588-IT treatment groups (
Subsequently, we established a bilateral subcutaneous mouse glioma model to investigate whether a localized high-dose immunotoxin treatment can provide a systemic anti-tumor effect on the tumors in the distal region, and whether the combination of immune checkpoint inhibitors can enhance this systemic anti-tumor immunity induced by the localized immunotoxin therapy. The D2C7-IT monotherapy, D2C7-IT+αCTLA4, and D2C7-IT+αPD1 combinatorial therapy led to significant growth delay of the right tumors (P<0.01), and cured 4/10, 6/10, and 5/10 right tumors, respectively (
We have demonstrated that the intratumoral delivery of D2C7-IT induces secondary anti-tumor immunity, which destroys not only mD2C7-expressing tumor cells, but also tumor cells not expressing mD2C7 at the systemic level. A combination of D2C7 immunotoxin with immune checkpoint inhibitors can enhance this immunotoxin-induced anti-tumor immunity to achieve a synergistic long-term anti-tumor effect.
The above disclosure generally describes the present invention. All references disclosed herein are expressly incorporated by reference. A more complete understanding can be obtained by reference to the following specific examples which are provided herein for purposes of illustration only, and are not intended to limit the scope of the invention.
We established a mouse glioma line, CT-2A-mD2C7, overexpressing the D2C7-IT antigen mouse EGFRvIII (mEGFRvIII). The reactivity and therapeutic efficacy of D2C7-IT against CT-2A-mD2C7 cells was determined by flow cytometry and in vitro cytotoxicity assays (WST1), respectively. CT-2A-mD2C7 cells were further analyzed for MHC class I and PD-L1 expression by flow cytometry. In vivo efficacy of D2C7-IT or αCTLA-4 or αPD-1 monotherapy or D2C7-IT+αCTLA-4 or D2C7-IT+αPD-1 combination therapy was evaluated in subcutaneous CT-2A-mD2C7 glioma-bearing C57BL/6 immunocompetent mice.
WST-1 is a reagent for measuring cell proliferation. It is used for the nonradioactive, spectrophotometric quantification of cell proliferation and viability in cell populations. The assay is based on the cleavage of the tetrazolium salt WST-1 to formazan by cellular mitochondrial dehydrogenases. Expansion in the number of viable cells results in an increase in the activity of the mitochondrial dehydrogenases, which in turn leads to increase in the amount of formazan dye formed. The formazan dye produced by viable cells can be quantified by measuring the absorbance at λ=440 nm.
Flow cytometry analysis confirmed the specific binding ability of D2C7 monoclonal antibody to the CT-2A-mD2C7 cells (
Construction, expression, and purification of D2C7-(scdsFv)-PE38KDEL immunotoxin. The carboxyl terminus of the D2C7 VH domain was connected to the amino terminus of the VL domain by a 15-amino-acid peptide (Gly4Ser)3 linker. In order to obtain a stable IT, it is essential to ensure that during renaturation VH is positioned near VL. This was achieved by mutating a single key residue in each chain to cysteine, for the stabilizing disulfide bond to form. On the basis of predictions using molecular modeling and empirical data with other dsFv-recombinant ITs, we chose one amino acid in each chain to mutate to cysteine. These are residues 44 in the framework region 2 (FR2) of VH and 100 in the FR4 of VL (according to the Kabat numbering). Thus, we prepared an Fv that contains both a peptide linker and a disulfide bond generated by cysteine residues that replace Ser44 of VH and Gly100 of VL. The D2C7 (scdsFv) PCR fragment was then fused to DNA for domains II and III of Pseudomonas exotoxin A. The version of Pseudomonas exotoxin A used here, PE38KDEL, has a modified C terminus which increases its intracellular retention, in turn enhancing its cytotoxicity. The D2C7-(scdsFv)-PE38KDEL was expressed in E. coli under the control of T7 promoter and harvested as inclusion bodies.
Targeting tumor and tumor-associated macrophages for glioblastoma therapy: We evaluated the ability of D2C7-IT and BLZ945 combination treatment to function synergistically and produce an effective antitumor response in immunocompetent glioblastoma mouse models.
Intracranial growth curve for CT2A-mD2C7 in C57BL/6 mice: To determine the time course of CT2A-mD2C7 intracranial tumor growth, 3×105 cells/3 μl were implanted into 9 female C57BL/6 mice, and a survival curve was plotted (
Phenotypic profile of the immune cells populating the CT2A-mD2C7 brain tumor microenvironment: To characterize the immune cell phenotype of intracranial CT2A-mD2C7 tumors, C57BL/6 immunocompetent mice were implanted with 3×105 tumor cells. The mice were followed to assess tumor development and were euthanized when they became moribund. Upon euthanization, the brains were harvested and the tumors were analyzed for infiltrating immune cells by flow cytometry. Cells isolated from naïve C57BL/6 mice were used as the control. The primary cell types in the normal brain were microglia (80%), macrophages (F480lo+F480int+F480hi=11%), and T cells (5%) (
Anti-tumor efficacy of D2C7-IT and BLZ945 combination therapy against the intracranial CT2A-mD2C7 glioma model: The experimental outline for D2C7-IT+BLZ945 combination therapy against the CT2A-mD2C7 cell line is shown in
In previous pilot studies, we observed that the subcutaneous rechallenged mouse glioma allografts were rejected in those immunocompetent mice bearing SC mouse glioma allografts cured by the intratumoral (i.t.) immunotoxin therapy, suggesting that there can be a memory anti-tumor immune response following the SC immunotoxin therapy. This phenomenon was also reported in the SC melanoma mouse model treated by an immunotoxin targeting IL-13, in which CTLs played a major role in mediating this immunotoxin-induced anti-tumor response, although melanoma is a dramatically different type of tumor compared to malignant gliomas in the CNS. Therefore, it is necessary to establish appropriate mouse glioma models to investigate the secondary immune response, induced by immunotoxins, against glioblastomas, and to determine how to enhance this response by the combinatorial therapy of immune checkpoint inhibitors, such as anti-CTLA4 or anti-PD1 antibodies (αCTLA4 or αPD1), in order to achieve a long-lasting remission.
We established a subcutaneous mouse CT2A-mD2C7 glioma model in C57BL/6 immunocompetent mice with six groups, in which the mice were treated by the control immunotoxin P588-IT or D2C7-IT, combined with αCTLA4 or αPD1 inhibitors. In this in vivo subcutaneous CT2A-mD2C7 glioma model, four doses (every 3 days) of the D2C7-IT (low dose, 1.5 μg per mouse per dose, i.t.) but not αCTLA4 (100 μg per mouse per dose, intraperitoneal [i.p]) or αPD1 (250 μg per mouse per dose, i.p.) monotherapy and D2C7-IT+αCTLA-4 or αPD-1 combinatorial therapy (immune checkpoint inhibitors administered on the next day after IT therapy) generated a significant delay in tumor growth compared to the control immunotoxin P588-IT treatment groups (P<0.01,
Tumor Rechallenging Studies on the Cured Mice from the D2C7-IT and Immune Checkpoint Inhibitors Combinatorial Treatment Groups
To determine whether those cured mice from D2C7-IT and immune checkpoint inhibitors combinatorial treatment groups can recall a protective anti-tumor memory immune response, on Day 72 after the initial tumor challenge, all nine cured mice were then first subcutaneously rechallenged (1° SCR) with a dose of 106 CT2A parental cells in the left flank. All these mice rejected the mD2C7-negative tumors, whereas tumors grew in all untreated naïve mice, suggesting that the combinatorial treatment provided long lasting anti-tumor immunity that extended to mD2C7-negative parental cells as well (
To determine whether this protective anti-tumor immunity can protect the mice from the tumor rechallenging in a remote immune-privileged region, for example, the brain, all nine cured mice were then intracranially (IC) rechallenged (2° ICR) for a second time on Day 126 (after the initial subcutaneous tumor challenge) with a dose of 3×105 CT2A-mD2C7 cells in the brain. At the end of this study, all surviving mice were euthanized for brain histopathologic examination, which did not show tumors in the brains (data not shown). All these mice rejected the CT2A-mD2C7 intracranial (IC) rechallenge (2° ICR), whereas tumors grew in all untreated naïve mice, suggesting that the combinatorial treatment also provided long lasting anti-tumor immunity that extended to the remote immune-privileged CNS as well (
In an in vivo bilateral subcutaneous CT2A-mD2C7 glioma model, tumor cells were inoculated in both sides of the flank simultaneously in C57BL/6 mice, with a high density (3×106 cells) on the right side and a low density (106 cells) on the left side. The larger tumors (on the right) were treated with four doses (every two days) of D2C7-IT or αCTLA4 or αPD1 monotherapy or D2C7-IT+αCTLA4 or D2C7-IT+αPD1 combination therapy (immune checkpoint inhibitors administered on the same day of immunotoxin therapy), while the left tumors were untreated. The D2C7-IT monotherapy (high dose, 4.5 μg per mouse per dose, intratumoral), D2C7-IT+αCTLA4 (100 μg per mouse per dose, intraperitoneal), and D2C7-IT+αPD1 (250 μg per mouse per dose, intraperitoneal.) combinatorial therapies led to significant growth delays of the right tumor (P<0.01), which cured 4/10, 6/10, and 5/10 right tumors, respectively (
Interestingly, in the groups where the right tumors were treated with D2C7-IT or αCTLA-4 or αPD-1 monotherapy or D2C7-IT+(αCTLA-4 or αPD-1) combinatorial therapy, the left untreated tumors also grew much slower compared to the control group (
This invention was made with government support under CA197264 and CA-154291 awarded by the National Institutes of Health. The government has certain rights in the invention.
| Number | Date | Country | |
|---|---|---|---|
| 62250749 | Nov 2015 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15773418 | May 2018 | US |
| Child | 17376319 | US |
