Vaccinex, Inc. reported that it has enrolled 36 subjects in the open-label, Phase 1b/2 KEYNOTE-B84 study (NCT04815720) to evaluate first line therapy of pepinemab in combination with KEYTRUDA®, Merck's anti-PD-1 therapy, in immunotherapy naïve patients with recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC). Based on this milestone, the Company expects to conduct a planned interim analysis and disclose the results in mid-2023. The KEYNOTE-B84 study was designed to evaluate the use of pepinemab, in combination with anti-PD-1 therapy, KEYTRUDA (pembrolizumab), as first line treatment for patients with R/M HSNCC who are immunotherapy naïve.

Patients in the Phase 2 dose-expansion segment receive pepinemab, dosed intravenously (IV) at 20 mg/kg, with pembrolizumab, dosed at 200 mg IV, every three weeks. The ongoing Phase 2 study plans to enroll approximately 62 patients in total. With enrollment of the first 36 study subjects completed, Vaccinex will conduct a planned interim analysis on all study subjects who have received at least one cycle of pepinemab/pembrolizumab treatment and completed a tumor evaluation at or before 9-weeks of treatment.

Primary outcome measures include an assessment of safety (defined as treatment emergent adverse events (TEAE's) and efficacy, determined by the Objective Response Rate (ORR), defined as complete response (CR) or partial response (PR). Secondary outcome measures will assess disease response and survival across standard parameters including duration of response (DOR), overall survival (OS) and progression free survival (PFS). The study will also include assessments of biomarkers in blood and tumor to evaluate tumor-directed immune responses.