Jon Chesebrough

Dual IGF-I/II-neutralizing antibody MEDI-573 potently inhibits IGF signaling and tumor growth.

Insulin-like growth factors (IGF), IGF-I and IGF-II, are small polypeptides involved in regulating cell proliferation, survival, differentiation, and transformation. IGF activities are mediated through binding and activation of IGF-1R or insulin receptor isoform A (IR-A). The role of the IGF-1R pathway in promoting tumor growth and survival is well documented. Overexpression of IGF-II and IR-A is reported in multiple types of cancer and is proposed as a potential mechanism for cancer cells to develop resistance to IGF-1R-targeting therapy. MEDI-573 is a fully human antibody that neutralizes both IGF-I and IGF-II and inhibits IGF signaling through both the IGF-1R and IR-A pathways. Here, we show that MEDI-573 blocks the binding of IGF-I and IGF-II to IGF-1R or IR-A, leading to the inhibition of IGF-induced signaling pathways and cell proliferation. MEDI-573 significantly inhibited the in vivo growth of IGF-I- or IGF-II-driven tumors. Pharmacodynamic analysis demonstrated inhibition of IGF-1R phosphorylation in tumors in mice dosed with MEDI-573, indicating that the antitumor activity is mediated via inhibition of IGF-1R signaling pathways. Finally, MEDI-573 significantly decreased (18)F-fluorodeoxyglucose ((18)F-FDG) uptake in IGF-driven tumor models, highlighting the potential utility of (18)F-FDG-PET as a noninvasive pharmacodynamic readout for evaluating the use of MEDI-573 in the clinic. Taken together, these results demonstrate that the inhibition of IGF-I and IGF-II ligands by MEDI-573 results in potent antitumor activity and offers an effective approach to selectively target both the IGF-1R and IR-A signaling pathways.

Antitumor efficacy of IPI-504, a selective heat shock protein 90 inhibitor against human epidermal growth factor receptor 2–positive human xenograft models as a single agent and in combination with trastuzumab or lapatinib

IPI-504 is a novel, highly soluble small-molecule inhibitor of heat shock protein 90 (Hsp90), a protein chaperone essential for regulating homeostasis of oncoproteins and cell signaling proteins. Human epidermal growth factor receptor 2 (HER2; ErbB2) oncoprotein, expressed in a subset of metastatic breast cancers, is a Hsp90 client protein. In this study, we investigated the antitumor activity and the mechanism of action of IPI-504 in HER2+, trastuzumab-sensitive and trastuzumab-refractory cell lines in vitro and in vivo. IPI-504 exhibited potent antiproliferative activities (range of IC50, 10-40 nmol/L) against several tumor cell lines examined, whereby mechanism of action was mediated through HER2 and Akt degradation. Both intravenous and oral administration of IPI-504 assessed in multiple schedules showed potent tumor growth inhibition in vivo with corresponding degradation of HER2. The tolerability and efficacy of IPI-504 combined with either trastuzumab or lapatinib were also investigated in HER2+ tumor xenograft models. Combination of IPI-504 with trastuzumab significantly enhanced tumor growth delay and induced greater responses when compared with either agent alone. Although, as expected, trastuzumab alone did not exhibit any significant antitumor activity in the trastuzumab-resistant JIMT-1 model, IPI-504 administered in combination with trastuzumab yielded greater antitumor efficacy than either agent alone. Finally, combination of IPI-504 and lapatinib was well tolerated up to 50 mg/kg IPI-504 and 100 mg/kg lapatinib and resulted in significant delay in tumor growth, including partial and complete tumor responses. These lines of evidence support the development of IPI-504 in HER2-positive breast cancers as a single agent and in combination with either trastuzumab or lapatinib.[Mol Cancer Ther 2009;8(8):2131–41]

Doxil Synergizes with Cancer Immunotherapies to Enhance Antitumor Responses in Syngeneic Mouse Models

Based on the previously described roles of doxorubicin in immunogenic cell death, both doxorubicin and liposomal doxorubicin (Doxil) were evaluated for their ability to boost the antitumor response of different cancer immunotherapies including checkpoint blockers (anti–PD-L1, PD-1, and CTLA-4 mAbs) and TNF receptor agonists (OX40 and GITR ligand fusion proteins) in syngeneic mouse models. In a preventative CT26 mouse tumor model, both doxorubicin and Doxil synergized with anti–PD-1 and CTLA-4 mAbs. Doxil was active when CT26 tumors were grown in immunocompetent mice but not immunocompromised mice, demonstrating that Doxil activity is increased in the presence of a functional immune system. Using established tumors and maximally efficacious doses of Doxil and cancer immunotherapies in either CT26 or MCA205 tumor models, combination groups produced strong synergistic antitumor effects, a larger percentage of complete responders, and increased survival. In vivo pharmacodynamic studies showed that Doxil treatment decreased the percentage of tumor-infiltrating regulatory T cells and, in combination with anti–PD-L1, increased the percentage of tumor-infiltrating CD8+ T cells. In the tumor, Doxil administration increased CD80 expression on mature dendritic cells. CD80 expression was also increased on both monocytic and granulocytic myeloid cells, suggesting that Doxil may induce these tumor-infiltrating cells to elicit a costimulatory phenotype capable of activating an antitumor T-cell response. These results uncover a novel role for Doxil in immunomodulation and support the use of Doxil in combination with checkpoint blockade or TNFR agonists to increase response rates and antitumor activity.

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.

Novel Neutralizing Hedgehog Antibody MEDI-5304 Exhibits Antitumor Activity by Inhibiting Paracrine Hedgehog Signaling

The hedgehog pathway has been implicated in the tumorigenesis, tumor progression, and metastasis of numerous human cancers. We generated the first fully human hedgehog antibody MEDI-5304 and characterized its antitumor activity and preclinical toxicology. MEDI-5304 bound sonic hedgehog (SHH) and Indian hedgehog (IHH) with low picomolar affinity and neutralized SHH and IHH activity in cellular mGLI1 reporter assays. The antibody inhibited transcription of hedgehog target genes and osteoblast differentiation of C3H10T1/2 cells. We evaluated the activity of MEDI-5304 in vivo in model systems that allowed us to evaluate two primary hypotheses of hedgehog function in human cancer, paracrine signaling between tumor and stromal cells and cancer stem cell (CSC) self-renewal. MEDI-5304 displayed robust pharmacodynamic effects in stromal cells that translated to antitumor efficacy as a single agent in an HT-29/MEF coimplantation model of paracrine hedgehog signaling. MEDI-5304 also improved responses to carboplatin in the HT-29/MEF model. The antibody, however, had no effect as a single agent or in combination with gemcitabine on the CSC frequency or growth of several primary pancreatic cancer explant models. These findings support the conclusion that hedgehog contributes to tumor biology via paracrine tumor-stromal signaling but not via CSC maintenance or propagation. Finally, the only safety study finding associated with MEDI-5304 was ondontodysplasia in rats. Thus, MEDI-5304 represents a potent dual hedgehog inhibitor suitable for continued development to evaluate efficacy and safety in human patients with tumors harboring elevated levels of SHH or IHH. Mol Cancer Ther; 13(2); 386–98. ©2013 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.

Abstract A49: Anti-DLL4 antibodies inhibit cancer stem cells in small cell lung cancer.

Small cell lung cancer (SCLC) is a very aggressive lung cancer with features suggesting enrichment in cancer stem cells (CSCs). Delta-like ligand 4 (DLL4) is a membrane bound ligand for Notch receptors critical for functional angiogenesis. Blocking DLL4 signaling increases the density of nonfunctional blood vessels and hypoxia of tumors, and thereby inhibits growth of tumor xenografts in mice. In addition, growing evidence implicates DLL4 Notch signaling pathway in the maintenance of CSCs. Here we investigated the anti-CSC activity of anti-DLL4 mAbs using in vitro and in vivo models of SCLC. Biochemical and flow cytometry analyses revealed that multiple SCLC cell lines express DLL4, and notably, SCLC spheres cultured under CSC-enriching conditions express higher levels of DLL4. Prior to determining the ability of anti-DLL4 mAb in inhibiting CSC in vivo, we first characterized the phenotype of CSCs in the SCLC cell line NCI-H69. NCI-H69 cells enriched for high CD133 expression were more tumorigenic and expressed higher levels of Nanog, Oct 3/4, and EZH2, which are genes crucial for maintenance of CSCs, than cells with low or negative levels of CD133. Moreover, RNA level of DLL4 was found to be three fold higher in CD133 high cells compared to CD133 low cells, suggesting that expression of DLL4 correlates with the CSC phenotype. In vivo, an anti-DLL4 antibody leads to inhibition of NCI-H69 tumor growth when the antibody is administered as a single agent, or in combination with cisplatin+etoposide or topotecan, chemotherapy agents commonly used in treatment of SCLC. To determine if blockade of DLL4 inhibits CSCs in vivo, NCI-H69 tumor xenografts treated with anti-DLL4 mAb were analyzed by flow cytometry. A subset of dissociated tumor cells expressed CD133 and DLL4, and a reduction of these populations of cells was observed in the anti-DLL4 antibody treated groups. In summary, these studies highlight that, in addition to vascular expression, (1) DLL4 is frequently expressed in SCLC cells, (2) DLL4 expression correlates with a CSC phenotype, and (3) that DLL4 blockade using an anti-DLL4 mAb results in inhibition of CSCs. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A49. Citation Format: Patrick Strout, Martin Korade, Ching Ching Leow, Ivan Inigo, Suneetha Thomas, Elaine Hurt, Jon Chesebrough, Adeela Kamal, Song Cho. Anti-DLL4 antibodies inhibit cancer stem cells in small cell lung cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A49.

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

Abstract 5098: A mouse DLL4 cross-reactive variant of MEDI0639 disrupts functional vessel formation and inhibits tumor growth in preclinical models.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Delta-like ligand 4 (DLL4) is a membrane bound ligand for Notch receptors essential for functional vessel formation during development and angiogenesis. We have shown previously that MEDI0639, a human anti-DLL4 antibody, has potent in vitro and in vivo activity in blocking DLL4-Notch interaction. However, because MEDI0639 has low binding affinity to mouse DLL4, to enable in vivo pharmacology studies using xenograft tumor models in mice, MEDI0639 was engineered to bind more strongly to mouse DLL4. The resulting affinity-optimized variant antibody (anti-mDLL4 mAb) bound with high affinity to both human and mouse DLL4 and maintained binding specificity to DLL4. In a number of human cancer xenograft models in nude mice, the MEDI0639 variant antibody markedly inhibited the growth of tumors. qRT-PCR analysis using the Fluidigm platform showed decreases in mouse genes downstream of the Notch signaling pathway at efficacious doses, indicating on-target antibody effect on tumor vasculature. In addition, IHC and imaging analysis of xenograft tumors from the anti-DLL4 mAb dosed animals showed a dose-dependent increase in microvessel density and decrease in tumor perfusion compared to the control groups. In summary, we describe here the generation of mouse and human DLL4 cross-reactive antibody and the utilization of this antibody in demonstrating a positive correlation between the anticipated mechanism of action of DLL4 blockade on vasculature and inhibition of tumor growth. Citation Format: Song H. Cho, David W. Jenkins, Patrick Strout, Martin Korade, Haihong Zhong, Ching Ching Leow, Shannon Breen, Jon Chesebrough, Nicholas Holoweckyj, Ivan Inigo, Gennady Gololobov, Ping Tsui, Kimberly Cook, Melissa Damschroder, Meggan Czapiga, Philip Brohawn, Jiaqi Huang, Sally-Ann Ricketts, Juliana Maynard, Adeela Kamal. A mouse DLL4 cross-reactive variant of MEDI0639 disrupts functional vessel formation and inhibits tumor growth in preclinical models. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5098. doi:10.1158/1538-7445.AM2013-5098

Abstract 1757: MEDI-573, an IGF-I/II neutralizing human antibody inhibits both IGF-1R and IR-A signaling pathways

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Insulin-like growth factors (IGF), IGF-I and IGF-II, are small polypeptides involved in regulating cell proliferation, survival, differentiation and transformation. IGF activities are mediated through binding and activation of IGF-1R or insulin receptor isoform A (IR-A). Overexpression of IGF-II and IR-A has been reported in multiple types of cancer, and has also been proposed as a potential mechanism for cancer cells to develop resistance to IGF-1R targeting therapy. MEDI-573 is a dual targeting human antibody that neutralizes both IGF-I and IGF-II. We have shown previously that this antibody inhibits IGF-1R activation by IGF and demonstrated potent in vivo tumor growth inhibition activity in IGF driven xenograft models. Here we show that MEDI-573 inhibits IGF-II activated IR-A signal pathways without cross reactivity to insulin, and therefore has minimum impact on glucose metabolism, which is mediated mainly by insulin/IR interaction. MEDI-573 blocks the binding of IGF-II to, and inhibits the subsequent phosphorylation of IR-A and IRS-1. MEDI-573 inhibited IGF-II-induced in vitro growth of IR-A overexpressing cells with or without the presence of up to 10uIU of insulin in the medium. In addition, MEDI-573 inhibited IGF-II-induced proliferation of IR-A-overexpressing cells as effectively as it inhibited the IGF-1R-overexpressing cells. The anti-proliferative activity of MEDI-573 is not changed across heterogeneous mixed cell populations with various ratios of IR-A- versus IGF-1R-expressing cells. In contrast, an IGF-1R specific antibody was most active at inhibiting the proliferation of a pure IGF-1R expressing homogenous population, but lost activity when the heterogeneous cell population contained increasing percentages (25-50%) of IR-A-expressing cells. We also examined the relative abundance of IR-A versus IR-B (insulin receptor isoform B) mRNA in multiple cancer cell lines using a previously published quantitative RT-PCR method. The results show that IR-A is frequently the dominant isoform overexpressed in these cancer cells. Taken together, these results demonstrate that by neutralizing IGF-I and IGF-II ligands, MEDI-573 is a dual targeting antibody that offers an effective approach to selectively target both the IGF-1R and IR-A signaling pathways and potentially overcome IGF-1R targeting resistance. 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 1757. doi:10.1158/1538-7445.AM2011-1757