Redirected T Cell Lysis In Patients With Metastatic Uveal Melanoma With Gp100-Directed Tcr Imcgp100: Overall Survival Findings

9521Background: IMCgp100 is a bispecific biologic comprised of a soluble T cell receptor recognizing the gp100 antigen fused to a scFV anti-CD3 and redirects T cell lysis of melanoma cells expressing gp100. Safety and preliminary efficacy of IMCgp100 were assessed in a Ph 1/2 study in metastatic UM (mUM). Methods: HLA-A*0201+ pts with mUM were treated with QW dosing of IMCgp100 iv at Cycle 1, Day 1 (C1D1, 20 mcg) and C1D8 (30 mcg), followed by the escalated dose administered at C1D15 and beyond. Results: Pts with mUM (n = 19), elevated LDH (87%), liver metastases (100%), and median of 4 prior therapies (0 – 8) were treated across 4 doses (54 to 73 mcg) in Ph 1; 23 pts were treated in the Ph 2 RP2D (68 mcg) expansion cohort. Related AE included pruritus (90%), pyrexia and fatigue (84%), and hypotension (74%). Gr 3/4 related AE include AST elevation, erythema and hypotension (all, 16%). Ten of the 19 pts in Ph 1 were treated at or above the RP2D. Objective PR by RECIST in Ph 1 were observed in 2 pts and min...