Lin Nie

Therapeutically Targeting ErbB3: A Key Node in Ligand-Induced Activation of the ErbB Receptor–PI3K Axis

Computational modeling of the ErbB signaling network affirms ErbB3 as a therapeutic target. Zooming In on ErbB3 Aberrant signaling involving the ErbB family of receptors, which can signal as homo- or heterodimers to activate the phosphatidylinositol 3-kinase (PI3K) signaling pathway, has been implicated as contributing to various cancers. Using a systems approach, Schoeberl et al. implicated ErbB3—a member of the ErbB family that is catalytically inactive—as critical to signaling stimulated by ligands that bind either ErbB1 or ErbB3. Computational analysis suggested that inhibiting ligand binding to ErbB3 might represent a more successful approach to treating cancers associated with ligand-induced stimulation of ErbB-PI3K signaling mediated by combinatorial receptor activation than do current therapies that target overexpressed or mutationally activated ErbB-family receptors. Moreover, experimental analysis revealed that a monoclonal antibody developed on the basis of this strategy could stop the growth of tumors grafted into immunodeficient mice. The signaling network downstream of the ErbB family of receptors has been extensively targeted by cancer therapeutics; however, understanding the relative importance of the different components of the ErbB network is nontrivial. To explore the optimal way to therapeutically inhibit combinatorial, ligand-induced activation of the ErbB–phosphatidylinositol 3-kinase (PI3K) axis, we built a computational model of the ErbB signaling network that describes the most effective ErbB ligands, as well as known and previously unidentified ErbB inhibitors. Sensitivity analysis identified ErbB3 as the key node in response to ligands that can bind either ErbB3 or EGFR (epidermal growth factor receptor). We describe MM-121, a human monoclonal antibody that halts the growth of tumor xenografts in mice and, consistent with model-simulated inhibitor data, potently inhibits ErbB3 phosphorylation in a manner distinct from that of other ErbB-targeted therapies. MM-121, a previously unidentified anticancer therapeutic designed using a systems approach, promises to benefit patients with combinatorial, ligand-induced activation of the ErbB signaling network that are not effectively treated by current therapies targeting overexpressed or mutated oncogenes.

An ErbB3 Antibody, MM-121, Is Active in Cancers with Ligand-Dependent Activation

ErbB3 is a critical activator of phosphoinositide 3-kinase (PI3K) signaling in epidermal growth factor receptor (EGFR; ErbB1), ErbB2 [human epidermal growth factor receptor 2 (HER2)], and [hepatocyte growth factor receptor (MET)] addicted cancers, and reactivation of ErbB3 is a prominent method for cancers to become resistant to ErbB inhibitors. In this study, we evaluated the in vivo efficacy of a therapeutic anti-ErbB3 antibody, MM-121. We found that MM-121 effectively blocked ligand-dependent activation of ErbB3 induced by either EGFR, HER2, or MET. Assessment of several cancer cell lines revealed that MM-121 reduced basal ErbB3 phosphorylation most effectively in cancers possessing ligand-dependent activation of ErbB3. In those cancers, MM-121 treatment led to decreased ErbB3 phosphorylation and, in some instances, decreased ErbB3 expression. The efficacy of single-agent MM-121 was also examined in xenograft models. A machine learning algorithm found that MM-121 was most effective against xenografts with evidence of ligand-dependent activation of ErbB3. We subsequently investigated whether MM-121 treatment could abrogate resistance to anti-EGFR therapies by preventing reactivation of ErbB3. We observed that an EGFR mutant lung cancer cell line (HCC827), made resistant to gefitinib by exogenous heregulin, was resensitized by MM-121. In addition, we found that a de novo lung cancer mouse model induced by EGFR T790M-L858R rapidly became resistant to cetuximab. Resistance was associated with an increase in heregulin expression and ErbB3 activation. However, concomitant cetuximab treatment with MM-121 blocked reactivation of ErbB3 and resulted in a sustained and durable response. Thus, these results suggest that targeting ErbB3 with MM-121 can be an effective therapeutic strategy for cancers with ligand-dependent activation of ErbB3.

Abstract CT237: Preclinical characterization and first-in-human study of MM-141, a dual antibody inhibitor of IGF-1R and ErbB3

Background: MM-141 is a tetravalent bi-specific monoclonal antibody that binds IGF-1R and ErbB3, oncogenic receptors commonly co-expressed in solid tumors. In preclinical models, MM-141 blocks both ligand-dependent and -independent PI3K/AKT/mTOR signaling initiated through IGF-1R and ErbB3 complexes and potentiates the activity of gemcitabine, paclitaxel, nab-paclitaxel, docetaxel, irinotecan, tamoxifen, and everolimus. A multi-arm phase I study is ongoing, with continuing patient enrollment in Arm B (MM-141 in combination with everolimus). Monotherapy Arm A and combination Arm C (MM-141 with nab-paclitaxel and gemcitabine) are completed. Methods: Tumor expression of IGF-1R and ErbB3 was measured by immunohistochemistry. In vitro expression and degradation of IGF-1R and ErbB3 in pancreatic cell line models post-treatment were measured by immunoblotting and ubiquitination, respectively. The phase I dose-escalation study evaluated safety, tolerability, pharmacokinetic (PK), and pharmacodynamic (PD) properties of MM-141 as monotherapy (Arm A, n = 15) and in combination with everolimus (Arm B) or with nab-paclitaxel and gemcitabine (Arm C, n = 11). Pre- and post-treatment biopsies were acquired where mandated. Patients in the monotherapy Arm A received MM-141 at 6, 12, 20 mg/kg weekly or 40 mg/kg biweekly. Patients in the dose-escalation portion of Arm C received MM-141 at a weekly dose of 12 or 20 mg/kg in combination with weekly nab-paclitaxel (125 mg/m2) and gemcitabine (1000 mg/m2) on a schedule of 3 weeks on, 1 week off. Enrollment in Arm B (MM-141 in combination with everolimus) is ongoing. Patient serum free IGF-1 levels were detected using an in-house developed CLIA validated ELISA-based assay. Results: Here we report common co-expression of IGF-1R and ErbB3 in solid tumors. In stage IV metastatic pancreatic cancer, co-expression of IGF-1R and ErbB3 was associated with decreased patient survival. In preclinical models, increased expression of IGF-1R and ErbB3 desensitized tumors to gemcitabine and paclitaxel. However, co-treatment with MM-141 reversed this acquired resistance through blockade of growth factor binding and induction of IGF-1R and ErbB3 degradation. In the monotherapy arm of a phase I study, no dose-limiting toxicities were observed at any of the studied dose levels. The safety, tolerability, PK and PD profile of MM-141 support 2.8g bi-weekly MM-141 phase II recommended dose. The analysis of pre- and post-treatment biopsies confirmed that levels of IGF-1R and ErbB3 were decreased following MM-141 administration. In Arm C, the observed safety profile of MM-141 in combination with nab-paclitaxel and gemcitabine was comparable to expected toxicities reported with the chemotherapy combination when used alone. Retrospective analysis of serum free IGF-1 levels in breast cancer patients (Arm B) demonstrated that patients with elevated levels of this potential biomarker remained on study longer and received a greater number of doses of MM-141. Conclusion: These data support continued development of MM-141 in biomarker-selected patient populations and the upcoming phase II study of MM-141 in combination with nab-paclitaxel and gemcitabine in front-line metastatic pancreatic cancer patients with detectable free IGF-1 serum levels. Citation Format: Alexey A. Lugovskoy, Michel Curley, Jason Baum, Sharlene Adams, Sergio Iadevaia, Victoria Rimkunas, Adam Camblin, Lin Nie, Gege Tan, Bryan Johnson, Sara Mathews, Kerry Horgan, Chrystal U. Louis, Akos G. Czibere, Monica Arnedos, Jean-Charles Soria, Rastilav Bahleda, Anthony Shields, Patricia M. LoRusso, Mansoor Saleh, Steven J. Isakoff. Preclinical characterization and first-in-human study of MM-141, a dual antibody inhibitor of IGF-1R and ErbB3. [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 CT237. doi:10.1158/1538-7445.AM2015-CT237

Dual Inhibition of IGF-1R and ErbB3 Enhances the Activity of Gemcitabine and Nab-Paclitaxel in Preclinical Models of Pancreatic Cancer

Purpose: Insulin-like growth factor receptor 1 (IGF-1R) is critically involved in pancreatic cancer pathophysiology, promoting cancer cell survival and therapeutic resistance. Assessment of IGF-1R inhibitors in combination with standard-of-care chemotherapy, however, failed to demonstrate significant clinical benefit. The aim of this work is to unravel mechanisms of resistance to IGF-1R inhibition in pancreatic cancer and develop novel strategies to improve the activity of standard-of-care therapies. Experimental Design: Growth factor screening in pancreatic cancer cell lines was performed to identify activators of prosurvival PI3K/AKT signaling. The prevalence of activating growth factors and their receptors was assessed in pancreatic cancer patient samples. Effects of a bispecific IGF-1R and ErbB3 targeting antibody on receptor expression, signaling, cancer cell viability and apoptosis, spheroid growth, and in vivo chemotherapy activity in pancreatic cancer xenograft models were determined. Results: Growth factor screening in pancreatic cancer cells revealed insulin-like growth factor 1 (IGF-1) and heregulin (HRG) as the most potent AKT activators. Both growth factors reduced pancreatic cancer cell sensitivity to gemcitabine or paclitaxel in spheroid growth assays. Istiratumab (MM-141), a novel bispecific antibody that blocks IGF-1R and ErbB3, restored the activity of paclitaxel and gemcitabine in the presence of IGF-1 and HRG in vitro. Dual IGF-1R/ErbB3 blocking enhanced chemosensitivity through inhibition of AKT phosphorylation and promotion of IGF-1R and ErbB3 degradation. Addition of istiratumab to gemcitabine and nab-paclitaxel improved chemotherapy activity in vivo. Conclusions: Our findings suggest a critical role for the HRG/ErbB3 axis and support the clinical exploration of dual IGF-1R/ErbB3 blocking in pancreatic cancer. Clin Cancer Res; 24(12); 2873–85. ©2018 AACR.

Abstract 3756: Prediction of xenograft response to MM-121, an anti-ErbB3 inhibitor, using computational modeling and measurements of five biomarkers

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC One of the challenges faced by targeted therapeutics currently in the clinic is the relatively small population of patients who derive significant benefit from their use. We report the development of a preclinical classifier which can correctly predict xenograft response to MM-121, an anti-ErbB3 antibody, based on the measurement of a few key biomarkers in cell lysates. Deregulation of the ErbB family receptors is common in many cancers. Using a combination of computational modeling and quantitative experiments we identified ErbB3 as a key mediator of mitogenic signaling downstream of the ErbB receptors. Based on these results, we developed MM-121, a first in class anti-ErbB3 monoclonal antibody that blocks heregulin-induced signaling and inhibits tumor growth in multiple xenograft models of human cancer. Here we present our efforts to derive a predictive biomarker signature that identifies tumors that are responsive to MM-121. Using our computational model of the ErbB signaling pathway we identified the five most critical proteins for predicting activation of phospho-AKT - a key mediator of cell survival and apoptosis. These proteins include MM-121s target, ErbB3, and its ligand, heregulin. We profiled these biomarkers in a large panel of cancer cell lines, and using the measured effect of MM-121 on inhibiting tumor growth in eight xenograft tumor models, we determined a classification rule for predicting xenograft response. We subsequently used this classification rule to correctly predict a priori MM-121 response in 11 xenograft models. These results suggest that our computationally-derived biomarker signature is sufficient for predicting response to MM-121 in xenografts, and could offer significant clinical benefit by helping select patients for MM-121 treatment. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3756.

Abstract 1806: Efficacy of MM121 in ER+ and triple negative breast cancer studies

In women, breast cancer is among the most common cancers and the fifth most common cause of cancer deaths. Due to the heterogeneity of the disease, 10-year progression free survival can vary widely with stage and type from 98% to 10%. We present data showing that MM-121, a fully human monoclonal anti-ErbB3 antibody, is efficacious in studies of both hormone dependent (ER+) and triple negative (ER-,PR-, Low Erb2) breast cancer lines that express the molecular profile consistent with MM-121 response (co-expression of ErbB3 and HRG). Using a combination of computational and experimental approaches, ErbB3 was identified as a critical transducer of oncogenic signaling leading to the development of MM-121, a first in class anti-ErbB3 antibody. We have previously demonstrated that MM-121, when used as a single agent, inhibits heregulin-induced signaling events in human cancer cell lines. Moreover, MM-121 caused dose-dependent inhibition of tumor growth in multiple xenograft models of human cancer, including ovarian, renal cell, pancreatic, lung, and prostate cancer. Estrogen dependent, or ER+ breast cancers, make up about 80% of breast cancers. A standard treatment for ER+ breast cancer includes hormone therapy; however a substantial number of ER+ breast cancers eventually develop resistance requiring additional treatments. Here we show that in ER+ breast cancer cells, MM-121 can block HRG induced ErbB3 activation and VEGF secretion as well as HGF induced pErbB3 in vitro. Additionally, in ER+ breast cancer xenograft models, MM121 is effective in combination with both chemotherapy agents and targeted therapies and may be effective in ER+ breast cancers that are refractory to hormone treatment. The triple negative breast cancers are characterized by poor prognosis, aggressiveness, and reduced responsiveness to standard treatments. MM-121 used as a single agent therapy was able to suppress tumor growth in triple negative primary human tumors, when grown as xenografts suggesting that MM-121 monotherapy may be clinically efficacious in triple negative breast cancers. Together, these data suggest that MM-121, when used as a single agent or in combination with other therapies, could offer significant clinical benefit to both ER+ and triple negative breast cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1806.