Atezolizumab (A) + cobimetinib (C) + vemurafenib (V) in BRAFV600-mutant metastatic melanoma (mel): Updated safety and clinical activity.

3063Background: Targeted inhibition of MEK with C and BRAF with V in BRAFV600-mutant mel can lead to both anticancer immune activation and direct tumor cell death. A, an anti–PD-L1 monoclonal antibody, inhibits PD-L1/PD-1 signaling. Combining C + V with A may enhance antitumor activity, potentially leading to improved clinical responses and durability. Preliminary data from this phase Ib study (NCT01656642) showed that A + C + V had a manageable safety profile and promising antitumor activity in patients (pts) with untreated BRAFV600-mutant unresectable/metastatic mel, with increases in CD8-positive T-cell infiltration observed after C + V (Sullivan et al SMR 2016). We present updated safety and efficacy data. Methods: Pts received A + C + V after a 28-day run-in with C + V. A was given at 800 mg q2w, C at 60 mg qd for the first 21 days of each 28-day cycle, and V at 960 mg bid during day 1–21 of run-in and 720 mg thereafter. Safety was evaluated in pts who had ≥1 dose of A; efficacy, in pts who had ≥1 do...