Preliminary Results From Classical-Lung, A Phase 1b/2 Study Of Pepinemab (Vx15/2503) In Combination With Avelumab In Advanced Nsclc.

2601 Background: Rational combination therapies are needed to overcome resistance mechanisms in NSCLC. Pepinemab is an IgG4 humanized monoclonal antibody targeting semaphorin 4D (SEMA4D, CD100). In vivo preclinical models demonstrated antibody blockade of SEMA4D promoted immune infiltration and reduced function and recruitment of immunosuppressive myeloid cells within the tumor. Importantly, preclinical combinations of anti-SEMA4D with various immunotherapies enhanced T cell activity and tumor regression. The CLASSICAL-Lung clinical trial tests the combination of pepinemab with avelumab to couple immune activation via checkpoint inhibition with beneficial modifications of the immune microenvironment via pepinemab. Methods: This ongoing 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 patients (pts) with advanced (stage IIIB/IV) NSCLC (NCT03268057). The trial is split into dose escalation (n = 12) and dose expansion (n = 50) phases and includes 2 cohorts; 1) pts who are immunotherapy naïve, and 2) pts whose tumors progressed during or following immunotherapy (IO failure). Pts in the dose escalation cohorts received ascending doses of pepinemab i.v. (5, 10, 20 mg/kg, Q2W) in combination with avelumab i.v. (10mg/kg, Q2W). Results: Dose escalation is complete and the RP2D was selected as 10mg/kg pepinemab, Q2W. No pts experienced a TRAE leading to study discontinuation or death. The most frequent related AEs were grades 1 or 2 fatigue, pyrexia, or chills; no grade 3 AEs occurred in more than one subject. One DLT, a grade 3 pulmonary embolism occurred in the 10mg/kg pepinemab cohort, and resolved without reoccurrence. The disease control rate for pts treated > 2 months is 90% (19/21), and, at this early stage, a PR with a 49% reduction in target lesion was observed in at least 1 of 8 pts in the IO failure cohort. Updated data from the dose expansion phase will be presented. Conclusions: Preliminary data suggest the combination is well tolerated and shows initial signals of antitumor activity. Dose escalation is complete and the expansion phase is ongoing. Clinical trial information: NCT03268057.