Beck, Thaddeus

Abstract Despite progress of immune checkpoint therapies, many cases of non-small cell lung cancer (NSCLC) are refractory or acquire resistance to current therapies. Antibody blockade of semaphorin 4D (SEMA4D, CD100) can overcome resistance mechanisms of immune exclusion and myeloid suppression. Importantly, combinations of anti-SEMA4D with various immunotherapies enhanced T cell infiltration and activity, leading to durable tumor regression in preclinical models. Pepinemab (VX15/2503) is a first-in-class humanized monoclonal antibody targeting SEMA4D. The CLASSICAL-Lung clinical trial tests the combination of pepinemab with avelumab to couple immune activation via checkpoint inhibition with beneficial modifications of the tumor immune microenvironment via pepinemab. Here, we present interim results of the Phase 2 portion of the CLASSICAL-Lung study. This phase 1b/2, open label, single arm, first-in-human combination study is designed to evaluate the safety, tolerability and efficacy of pepinemab in combination with avelumab in 62 subjects with advanced stage (IIIB/IV) NSCLC, including immunotherapy-naïve (ION) patients and patients whose tumors progressed during or following immunotherapy (IOF). Dose escalation was successfully completed, presented previously, and no concerning safety signals have been identified to date. Among 29 evaluable IOF patients, 2 experienced confirmed partial response (PR) with 66% and 52% tumor reduction following acquired resistance to prior treatment with pembrolizumab, 15 additional patients experienced stable disease (SD), and at least 7 patients had durable clinical benefit of ≥ 23 weeks. Among 21 evaluable ION patients, 5 experienced PR, and 3 patients had clinical benefit ≥ 1 year. The disease control rate was 81%. Analysis of pre- and on-treatment biopsies demonstrated increased CD8+ T cell density correlating with response, with reduction or elimination of tumor in 10/11 biopsies from subjects with PR or SD. It was notable that 79% of patients who experienced PR or SD were reported to have tumors with negative or low PD-L1 expression. Enrollment is complete and this interim analysis suggest the combination of pepinemab plus avelumab is well tolerated and shows initial clinical signals of antitumor activity. Updated clinical response data, as well as additional immunophenotyping of both inflammatory and suppressive myeloid cells will be presented. Citation Format: Jonathan W. Goldman, Terrence L. Fisher, Elizabeth Evans, John E. Leonard, Desa Rae Pastore, Crystal Mallow, Ernest Smith, Andreas Schröeder, Kevin Chin, Michael Shafique, Thaddeus Beck, Megan A. Baumgart, Ramaswamy Govindan, Nashat Gabrail, Rachel E. Sanborn, Alexander I. Spira, Nagashree Seetharamu, Yanyan Lou, Aaron S. Mansfield, Maurice Zauderer. Interim results from CLASSICAL-Lung, phase 1b/2 study of pepinemab (VX15/2503) in combination with avelumab in advanced NSCLC [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT191.

Abstract Background: Abemaciclib, a small molecule inhibitor of CDK4 and CDK6, induces G1 cell cycle arrest in Rb-proficient human cancers.1 The clinical safety profile of abemaciclib enables continuous oral dosing to achieve sustained target inhibition, resulting in single-agent antitumor activity against multiple human cancers. The drug also reaches relevant concentrations in the central nervous system and, in patients taking the drug orally, can be detected in the cerebrospinal fluid.2 For women with previously treated hormone receptor positive (HR+) metastatic breast cancer (MBC), abemaciclib as a single agent achieved a six-month clinical benefit rate of 61.1% and an objective response rate of 33.3%.3 Clinical trials investigating abemaciclib combined with fulvestrant4 or aromatase inhibitors5 have led to randomized Phase 3 studies for women with HR+ breast cancer.6,7 Methods: This Phase 1b study (NCT02057133) with multiple cohorts evaluates safety and tolerability of abemaciclib combined with endocrine or HER2-targeted therapies for MBC. Secondary objectives include pharmacokinetics (PK) and antitumor activity of abemaciclib when given in combination with other therapies. Cohorts were opened to enrollment sequentially. Patients with HR+ HER2 negative MBC received abemaciclib orally every 12 hours (Q12H) in combination with the following standard therapies daily until progression: letrozole (Part A), anastrozole (Part B), tamoxifen (Part C), exemestane (Part D), or exemestane plus everolimus (Part E). Patients with HER2 positive MBC received abemaciclib orally Q12H in combination with trastuzumab every 21 days until progression (Part F). Adverse events (AEs) were graded by NCI CTCAE v4.0 and tumor response was assessed radiographically using RECIST v1.1. Results: Abemaciclib has been combined with multiple targeted therapies for the treatment of women with MBC. We previously reported safety and early efficacy results for the combinations of abemaciclib with letrozole, anastrozole, tamoxifen, exemestane, and exemestane plus everolimus.5 Due to limited follow-up at that time, the efficacy results were not mature. Safety, PK, and efficacy results with approximately 6 months of additional follow-up will be reported across all parts of the study. The most common treatment-emergent AEs include effects on the gastrointestinal and hematopoietic systems. Consistent with previously reported results for both single-agent abemaciclib and the combination of abemaciclib with fulvestrant, tumor responses have been observed among women receiving abemaciclib in combination with targeted therapies for MBC. Conclusions: This study for women with MBC demonstrates the potential for abemaciclib to be combined with therapies targeting specific signaling pathways. References: 1Gelbert et al. Invest New Drugs. 2014;32(5):825-37. 2Shapiro et al. J Clin Oncol 31, 2013 (suppl; abstr 2500). 3Tolaney et al. SABCS 2014: Abstract 763. 4Patnaik et al. J Clin Oncol 32:5s, 2014 (suppl; abstr 534). 5Tolaney et al. J Clin Oncol 33, 2015 (suppl; abstr 522). 6Llombart et al. SABCS 2014: OT1-1-07 (MONARCH 2, NCT02107703). 7Goetz et al. J Clin Oncol 33, 2015 (suppl; abstr TPS624) (MONARCH 3, NCT02246621). Citation Format: Goetz MP, Beeram M, Beck T, Conlin AK, Dees EC, Dickler MN, Helsten TL, Conkling PR, Edenfield WJ, Richards DA, Turner PK, Cai N, Chan EM, Pant S, Becerra CH, Kalinsky K, Puhalla SL, Rexer BN, Burris HA, Tolaney SM. Abemaciclib, an inhibitor of CDK4 and CDK6, combined with endocrine and HER2-targeted therapies for women with metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-13-25.