Abstract 3244: Improved Fc-mediated effector functions by an anti-CTLA-4 multivalent Fc agent

Numerous therapeutic monoclonal antibodies (mAbs) rely on antibody-dependent cell cytotoxicity (ADCC), antibody-dependent cell phagocytosis (ADCP) and complement-dependent cytotoxicity (CDC) Fc effector functions to deplete target cells and achieve clinical efficacy. It has been previously shown that adding multiple Fc domains to Abs or afucosylating the Fc domain increases Fc effector functions. We have leveraged a proprietary Fc multimerization technology (SIF; selective immunomodulator of Fc receptors) to identify potential novel products designed to improve the immune system’s elimination of tumor and other pathogenic cells. These agents utilize the valency effect of Fc multimerization to increase the binding to Fc receptors and complement, enhancing immune-mediated cytotoxicity mechanisms. CTLA-4 is a clinically validated immune checkpoint inhibitor exemplified by the human IgG1 therapeutic mAb ipilimumab. CTLA-4 is induced upon activation on T cells and constitutively expressed on T regulatory cells (Tregs). Based on data from mouse models of cancer and clinical studies, the proposed mechanisms of action of anti-CTLA-4 mAbs, including ipilimumab, are to block the interaction of CTLA-4 with its ligands CD80 and CD86 resulting in T cell activation and to induce Fc-mediated ADCC of CTLA-4+ cells, mainly intratumoral Tregs. Therefore, we have produced an anti-CTLA-4 multivalent IgG1 Fc agent termed anti-CTLA-4 SIFbody with the purpose of enhancing binding to Fc gamma receptors (FcγRs) and complement and increasing Fc-mediated elimination of intratumoral Tregs. Data from avidity binding to low affinity FcγRs showed more than 100-fold increase with anti-CTLA-4 SIFbody as compared to ipilimumab. In in vitro functional assays using CTLA-4 transfected target cells and primary human effector cells, anti-CTLA-4 SIFbody showed more than 10-fold increase in potency in ADCC and more than 5-fold increase in ADCP as compared to ipilimumab. Anti-CTLA-4 SIFbody induced 80% cell lysis by CDC, whereas ipilimumab failed to show any activity. More importantly, we generated in vitro expanded Tregs with suppressive function and showed that anti-CTLA-4 SIFbody induced significant enhanced ADCC on these cells as compared to ipilimumab and to an afucosylated anti-CTLA-4 mAb. ADCP was also significantly increased on Tregs. Unexpectedly, Tregs were resistant to anti-CTLA-4 SIFbody induced CDC. Notably, the blocking activity of the SIFbody F(ab)s was not altered by the multivalent Fc structure as shown by similar CTLA-4/CD80 and CD86 blockade and induction of IL-2 production upon antigen stimulation of PBMC. In conclusion, these data demonstrate that our Fc multimerization technology applied to an anti-CTLA-4 mAb significantly improves Fc-dependent immune-mediated cytotoxicity and suggest that anti-CTLA-4 SIFbody may represent an optimized novel product to deplete intratumoral Tregs and enhance anti-tumor activity.

Citation Format: Laura Rutitzky, Daniel F. Ortiz, Jonathan C. Lansing, Julia Brown, Joseph Paquette, Kevin Garofalo, Josephine D'Alessandro, Naveen Bhatnagar, Maurice Hains, Abhinav Gupta, Stan Lee, Radouane Zouaoui, Jason Wang, John Schaeck, Salvatore Marchese, Robin Meccariello, Nathaniel Washburn, Kimberly Holte, Carlos J. Bosques, Anthony M. Manning. Improved Fc-mediated effector functions by an anti-CTLA-4 multivalent Fc agent [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3244.

Abstract 2336: M402, a heparan sulfate mimetic, inhibits tumor revascularization and invasiveness after high-dose taxane treatment in a mouse breast cancer model

Treatment with certain anti-cancer agents, particularly taxanes and sunitinib, can lead to mobilization of pro-angiogenic factors and an acute mobilization of endothelial progenitor cells (EPCs) and other stromal cells, which migrate to the viable tumor rim where they can enhance tumor vascularization, invasion and metastasis. This phenomenon has been linked to rapid tumor regrowth following chemotherapy or treatment with specific angiogenesis inhibitors and may thus diminish the long-term efficacy of the treatment. Stromal cells like EPCs are mobilized in response to circulating growth factors and chemokines (VEGFR, FGF, G-CSF, IL-6, SDF1α, etc.) that are induced by the drug or the progressing tumor. Many of these factors contain heparin binding domains for their anchorage to proteoglycans on cell surfaces or the extracellular matrix. We tested a novel heparan sulfate mimetic, M402, for its ability to inhibit EPC mobilization as well as tumor vascularization and invasion. Mice bearing orthotopic 4T1 breast carcinoma and treated with a single high dose of docetaxel (40 mg/kg) showed highly vascularized tumor rims by histology and Microfil perfusion followed by microCT (vessel volume of 5.8 ± 4.6 mm3 vs. 0.6 ± 0.3 mm3; vessel surface area of 153.9 ± 65.5 mm2 vs. 21.1 ± 6.7 mm2, respectively) as compared to the saline control group. The tumors also showed a higher rate of invasion through the peritoneal wall as compared to vehicle treated mice (5 of 16 mice vs. 2 of 16 mice, respectively). The effect correlated with mobilization of EPCs and other bone marrow derived stromal cells. Treatment with M402 did not show such a response but rather inhibited the effects of docetaxel when dosed concomitantly for 3-5 days, starting with the docetaxel administration. Analysis of the blood, tumor and bone marrow indicated that M402 prevented the mobilization of progenitor cells from the bone marrow and their recruitment into the tumor microenvironment, likely through disruption of the SDF-1α/CXCR4 axis. Furthermore, we observed synergistic anti-tumor and anti-metastatic activity of M402 with docetaxel in this 4T1 model. In conclusion, the experiments provide a rationale for the clinical investigation of M402 in combination with docetaxel or other agents that induce similar effects.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2336. doi:1538-7445.AM2012-2336

Abstract 1524: M402, a novel heparan sulfate mimetic, inhibits pancreatic tumor growth and desmoplasia potentially via sonic hedgehog signaling in an orthotopic mouse model

One of the hallmarks of pancreatic ductal adenocarcinoma (PDAC) is extensive desmoplasia in the surrounding tumor microenvironment that prevents delivery of chemotherapeutics (such as gemcitabine). Dysregulation of sonic hedgehog (SHH, a heparin-binding morphogen), has been implicated in pancreatic cancer tumorigenesis. We have rationally designed a heparan sulfate mimetic, M402, that has previously been shown in animal studies to reduce metastatic seeding through disruption of several key heparin-binding growth factors (including FGF2, VEGF, SDF-1α and P-Selectin). We hypothesized that M402, alone or in combination with gemcitabine, could potentially modulate tumor-stroma interactions in an orthotopic pancreatic cancer model (Capan-2 cell line) which secretes SHH and displays a desmoplastic response in vivo. Capan-2 human adenocarcinoma cells (∼1x106 cells) were injected into the pancreata of immunodeficient mice (Nu/Nu CD-1). M402 (10-40 mg/kg/day) or saline treatment commenced on Day 4 or 32. Gemcitabine (30-60 mg/kg, twice weekly, IP) treatment commenced between Weeks 3-6. At the termination of each study (Week 8), gross anatomical observations were made of the primary pancreatic tumor and metastatic lesions in the surrounding tissues including the spleen, intestines and liver. Gemcitabine was increasingly less effective when started at later time points, but still reduced the primary tumor weight by 60-70% (at 30-45 mg/kg) when treatment was started at week 5. While the addition of M402 to gemcitabine showed some additive effect on primary tumor burden, metastasis, invasion, and surrounding fibrotic lesions appeared particularly impacted by the combination treatment. M402 was also effective as monotherapy showing a dose-dependent reduction in primary tumor weight and fibrotic lesions. Immunohistochemical and qPCR analyses showed reduced fibrosis and SHH signaling with M402 and gemcitabine combination treatment. These results demonstrate that M402 can modulate tumor-stroma interactions involved in the desmoplastic response in a murine model of pancreatic cancer and provide a rationale for the clinical investigation of M402 as a potential anti-desmoplastic agent in pancreatic cancer therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1524. doi:1538-7445.AM2012-1524

Abstract 3113: M402, a novel heparan sulfate mimetic, modulates the desmoplastic response in an orthotopic pancreatic cancer model in mice

Pancreatic ductal adenocarcinoma (PDAC), currently the fourth leading cause of cancer-related deaths in the US, is one of the most lethal cancers due in part to its resistance to or poor delivery of existing chemotherapeutics (such as gemcitabine). One of the hallmarks of this deadly disease is extensive desmoplasia in the surrounding tumor microenvironment. Recent advances in pancreatic cancer research implicate the involvement of several heparin-binding growth factors that control tumor-stroma interactions (including sonic hedgehog (shh), HB-EGF, TGFs, PDGF and HGF). We have rationally designed a heparan sulfate mimetic, M402, that has previously been shown in animal studies to reduce metastatic seeding through disruption of multiple heparin-binding growth factor-mediated pathways. We hypothesized that M402, alone or in combination with gemcitabine, could potentially modulate tumor-stroma interactions in an orthotopic pancreatic cancer model (Capan-2 cell line) which displays moderate desmoplasia in vivo. Capan-2 human adenocarcinoma cells (∼1×106 cells) were injected into the pancreases of immunodeficient mice (Nu/Nu CD-1, female, 8 weeks old). M402 (40 mg/kg/day) or saline treatment commenced on day 4 (via osmotic pump). Gemcitabine (30-60 mg/kg, twice weekly, IP) treatment commenced between weeks 3-6. At the termination of each study (week 8), gross anatomical observations were made of the primary pancreatic tumor and metastatic lesions in the surrounding tissues including the spleen, intestines and liver. The primary pancreatic tumor was weighed and further processed for immunohistochemistry and mRNA expression of fibrotic matrix markers (fibronectin and COLI) and shh signaling (shh and Gli1). Gemcitabine was increasingly less effective when started at later time points, but still reduced the primary tumor weight by 60-70% (30-45 mg/kg) when treatment was started at week 5. M402 was also effective as monotherapy. The addition of M402 to gemcitabine showed only marginally more activity on primary tumor burden; however, metastasis, invasion, and surrounding fibrotic lesions appeared more impacted by the combination treatment than either agent alone. Immunohistochemical and qPCR analyses showed reduced shh and Gli1 with M402 and gemcitabine combination treatment. These results show that M402 can modulate tumor-stroma interactions involved in the desmoplastic response in a murine model of pancreatic cancer. These results provide a rationale for the clinical investigation of M402 as a potential anti-desmoplastic agent in pancreatic cancer patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3113. doi:10.1158/1538-7445.AM2011-3113