Emil Michelotti

A Monoclonal Antibody to ADAM17 Inhibits Tumor Growth by Inhibiting EGFR and Non–EGFR-Mediated Pathways

ADAM17 is the primary sheddase for HER pathway ligands. We report the discovery of a potent and specific ADAM17 inhibitory antibody, MEDI3622, which induces tumor regression or stasis in many EGFR-dependent tumor models. The inhibitory activity of MEDI3622 correlated with EGFR activity both in a series of tumor models across several indications as well in as a focused set of head and neck patient–derived xenograft models. The antitumor activity of MEDI3622 was superior to that of EGFR/HER pathway inhibitors in the OE21 esophageal model and the COLO205 colorectal model suggesting additional activity outside of the EGFR pathway. Combination of MEDI3622 and cetuximab in the OE21 model was additive and eradicated tumors. Proteomics analysis revealed novel ADAM17 substrates that function outside of the HER pathways and may contribute toward the antitumor activity of the monoclonal antibody. Mol Cancer Ther; 14(7); 1637–49. ©2015 AACR.

Antibody-drug conjugates bearing pyrrolobenzodiazepine or tubulysin payloads are immunomodulatory and synergize with multiple immunotherapies

Immunogenic cell death (ICD) is the process by which certain cytotoxic drugs induce apoptosis of tumor cells in a manner that stimulates the immune system. In this study, we investigated whether antibody-drug conjugates (ADCS) conjugated with pyrrolobenzodiazepine dimer (PBD) or tubulysin payloads induce ICD, modulate the immune microenvironment, and could combine with immuno-oncology drugs to enhance antitumor activity. We show that these payloads on their own induced an immune response that prevented the growth of tumors following subsequent tumor cell challenge. ADCs had greater antitumor activity in immunocompetent versus immunodeficient mice, demonstrating a contribution of the immune system to the antitumor activity of these ADCs. ADCs also induced immunologic memory. In the CT26 model, depletion of CD8+ T cells abrogated the activity of ADCs when used alone or in combination with a PD-L1 antibody, confirming a role for T cells in antitumor activity. Combinations of ADCs with immuno-oncology drugs, including PD-1 or PD-L1 antibodies, OX40 ligand, or GITR ligand fusion proteins, produced synergistic antitumor responses. Importantly, synergy was observed in some cases with suboptimal doses of ADCs, potentially providing an approach to achieve potent antitumor responses while minimizing ADC-induced toxicity. Immunophenotyping studies in different tumor models revealed broad immunomodulation of lymphoid and myeloid cells by ADC and ADC/immuno-oncology combinations. These results suggest that it may be possible to develop novel combinatorial therapies with PBD- and tubulysin-based ADC and immuno-oncology drugs that may increase clinical responses. Cancer Res; 77(10); 2686-98. ©2017 AACR.

In Vivo Loss of Function Screening Reveals Carbonic Anhydrase IX as a Key Modulator of Tumor Initiating Potential in Primary Pancreatic Tumors

Reprogramming of energy metabolism is one of the emerging hallmarks of cancer. Up-regulation of energy metabolism pathways fuels cell growth and division, a key characteristic of neoplastic disease, and can lead to dependency on specific metabolic pathways. Thus, targeting energy metabolism pathways might offer the opportunity for novel therapeutics. Here, we describe the application of a novel in vivo screening approach for the identification of genes involved in cancer metabolism using a patient-derived pancreatic xenograft model. Lentiviruses expressing short hairpin RNAs (shRNAs) targeting 12 different cell surface protein transporters were separately transduced into the primary pancreatic tumor cells. Transduced cells were pooled and implanted into mice. Tumors were harvested at different times, and the frequency of each shRNA was determined as a measure of which ones prevented tumor growth. Several targets including carbonic anhydrase IX (CAIX), monocarboxylate transporter 4, and anionic amino acid transporter light chain, xc- system (xCT) were identified in these studies and shown to be required for tumor initiation and growth. Interestingly, CAIX was overexpressed in the tumor initiating cell population. CAIX expression alone correlated with a highly tumorigenic subpopulation of cells. Furthermore, CAIX expression was essential for tumor initiation because shRNA knockdown eliminated the ability of cells to grow in vivo. To the best of our knowledge, this is the first parallel in vivo assessment of multiple novel oncology target genes using a patient-derived pancreatic tumor model.

Anti-ADAM17 monoclonal antibody MEDI3622 increases IFNγ production by human NK cells in the presence of antibody-bound tumor cells

Several clinically successful tumor-targeting mAbs induce NK cell effector functions. Human NK cells exclusively recognize tumor-bound IgG by the FcR CD16A (FcγRIIIA). Unlike other NK cell activating receptors, the cell surface density of CD16A can be rapidly downregulated in a cis manner by the metalloproteinase ADAM17 following NK cell stimulation in various manners. CD16A downregulation takes place in cancer patients and this may affect the efficacy of tumor-targeting mAbs. We examined the effects of MEDI3622, a human mAb and potent ADAM17 inhibitor, on NK cell activation by antibody-bound tumor cells. MEDI3622 effectively blocked ADAM17 function in NK cells and caused a marked increase in their production of IFNγ. This was observed for NK cells exposed to different tumor cell lines and therapeutic antibodies, and over a range of effector/target ratios. The augmented release of IFNγ by NK cells was reversed by a function-blocking CD16A mAb. In addition, NK92 cells, a human NK cell line that lacks endogenous FcγRs, expressing a recombinant non-cleavable version of CD16A released significantly higher levels of IFNγ than NK92 cells expressing equivalent levels of wildtype CD16A. Taken together, our data show that MEDI3622 enhances the release of IFNγ by NK cells engaging antibody-bound tumor cells by blocking the shedding of CD16A. These findings support ADAM17 as a dynamic inhibitory checkpoint of the potent activating receptor CD16A, which can be targeted by MEDI3622 to potentially increase the efficacy of anti-tumor therapeutic antibodies.

Abstract 1166: ASCT2: A novel metabolic target for cancer therapy

Uncontrolled proliferation of cancer cells is often fueled by the deregulation of various cellular signaling pathways. Such deregulation also frequently rewires the metabolism of cancer cells in order to meet their increased need for energy and nutrients required for growth and proliferation. In the process, tumor cells produce high levels of anabolic intermediates required for biosynthesis of macromolecules and redox homeostasis. Many of these building blocks are derived from tri-carboxylic acid cycle (TCA) intermediates that need to be replenished in a process called anapleurosis. Glutaminolysis, the process in which glutamine (Gln) is converted into TCA intermediates by glutaminase is one of the key pathways that feeds anapleurosis in cancers. Many tumor cell lines fail to grow in the absence of glutamine and are therefore addicted to this nutrient. Glutamine is a preferred substrate for ASCT2, a member of ASC family of amino acid transporters, and thus this transporter may play a role in this addiction. We screened a variety of cancer cells for their dependence on Gln and determined that a significant subset of cell lines require this important nutrient. Biochemical experiments indicated that the ASCT2 family of proteins is the main driver of Gln transport. In agreement with these findings, shRNA-mediated knock down of ASCT2 significantly inhibited 14C-Gln uptake and tumor cell proliferation. Expression of an shRNA-resistant ASCT2 gene rescued both the inhibition of cell proliferation and transport of Gln. Furthermore, stable knockdown of ASCT2 induced autophagy and significantly slowed growth in vivo of various tumor types such as colon carcinoma, prostate carcinoma, and in neuroblastoma. The above findings identify ASCT2 as an attractive target for therapeutic intervention. Note: This abstract was not presented at the meeting. Citation Format: Nabendu Pore, Wanda King, Kristen Lekstrom, Susan Wilson, Robert Hollingsworth, David A. Tice, Emil Michelotti. ASCT2: A novel metabolic target for cancer therapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1166. doi:10.1158/1538-7445.AM2015-1166

Abstract 1109:In vivoloss of function screening reveals carbonic anhydrase IX (CAIX) as a key modulator of tumor initiating potential in primary pancreatic tumors

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Re-programming of energy metabolism is one of the emerging hallmarks of cancer. Upregulation of energy metabolism pathways fuels cell growth and division, a key characteristic of neoplastic disease, and can lead to dependency on specific metabolic pathways. Thus targeting energy metabolism pathways might offer the opportunity for novel therapeutics. Here we describe the application of a novel in vivo screening approach for the identification of genes involved in cancer metabolism using a patient derived pancreatic xenograft model. Lenti-viruses expressing shRNAs targeting twelve different cell surface protein transporters were separately transduced into the primary pancreatic tumor cells. Transduced cells were pooled and implanted into mice. Tumors were harvested at different times and the frequency of each shRNA was determined as a measure of which ones prevented tumor growth. Several targets including CAIX, MCT4, and xCT were identified in these studies and shown to be required for tumor initiation and growth. Interestingly, CAIX was overexpressed in the tumor initiating cell population. CAIX expression alone correlated with a highly tumorigenic subpopulation of cells. Furthermore, CAIX expression was essential for tumor initiation since shRNA knockdown eliminated the ability of cells to grow in vivo. To the best of our knowledge, this is the first parallel in vivo assessment of multiple novel oncology target genes using a patient derived pancreatic tumor model. Citation Format: Nabendu Pore, Sanjoo Jalla, Brandon Higgs, Roger Liu, David A. Tice, Robert Hollingsworrth, Emil Michelotti, Claudio Sorio, Aldo Scarpa. In vivo loss of function screening reveals carbonic anhydrase IX (CAIX) as a key modulator of tumor initiating potential in primary pancreatic tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1109. doi:10.1158/1538-7445.AM2015-1109

Abstract 30: Medi3622, a monoclonal antibody to ADAM17, inhibits tumor growth by inhibiting EGFR- and non-EGFR-mediated pathways

ADAM17 is the primary sheddase for HER pathway ligands. We report the discovery of a potent and specific ADAM17 inhibitory antibody, MEDI3622, which induces tumor regression or stasis in many EGFR-dependent tumor models. The inhibitory activity of MEDI3622 correlated with EGFR activity both in a series of tumor models across several indications as well as in a focused set of head and neck patient derived xenograft models. Cynomolgus monkey and rat PK/PD assays showed MEDI3622 inhibited TNFα shedding. Toxicity observed in cynomolgus monkey and rat was similar to EGFR inhibitor-induced rash. However, the antitumor activity of MEDI3622 was superior to that of EGFR/HER pathway inhibitors in OE21 head and neck and COLO205 colorectal xenograft models suggesting additional activity outside of the EGFR pathway. Combination of MEDI3622 and cetuximab in the OE21 model was additive and eradicated tumors. Proteomics analysis revealed novel ADAM17 substrates which function outside of the HER pathways and may contribute towards the antitumor activity of the monoclonal antibody. Citation Format: Darrin Sabol, Jonathan RiosDoria, Jon Chesebrough, David Stewart, Kevin Schifferli, Raymond Rothstein, Ching Ching Leow, Jenny Heidbrink-Thompson, Li Cheng, Qun Du, Linda Xu, Xiaofang Jin, Ravinder Tammali, Chanshou Gao, Jay Friedman, Brandy Wilkinson, Melissa Damschroder, Andrew Pierce, MunMun Patnaik, Rong Zeng, Yuling Wu, Susan Spitz, Gabriel Robbie, Lorin Roskos, Robert Hollingsworth, David Tice, Emil Michelotti. Medi3622, a monoclonal antibody to ADAM17, inhibits tumor growth by inhibiting EGFR- and non-EGFR-mediated pathways. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 30. doi:10.1158/1538-7445.AM2015-30