Phase 2, multicenter, safety and efficacy study of pidilizumab in patients with metastatic melanoma.

9001 Background: Pidilizumab (CT-011), a humanized anti PD-1 IgG1k, was studied in two Phase 2 studies in aggressive and indolent lymphomas showing clinical activity correlated with PD-1/PD-L1+ lymphocytes. Thus, we initiated a Phase 2 multicenter, randomized, open-label, study to evaluate the safety and efficacy of pidilizumab in patients (pts) with metastatic melanoma (MM). Methods: Eligibility criteria: measurable disease; Stage IV clearly progressive; ECOG 0-1; ≤ 3 prior systemic therapies for MM; stabilized brain mets allowed; 6 weeks from prior ipilimumab (Ipi), no prior PD-1/PD-L1/PD-L2 blockade. Pts were randomized to 2 dose levels (1.5 or 6 mg/kg IV q2 wk X 27), each with 50 pts and each balance stratified by prior Ipi (yes/no). Results: 103 pts were randomized; 75% M1c, 15.5% brain mets, 30% elevated LDH, 33% disease spread to ≥ 3 organs. 77% received prior systemic therapy for MM; 51% prior Ipi, 7.8% prior Braf inhibitor, 44% prior biologics (cytokines). 45% did not respond to most recent thera...