18-month efficacy and safety update from JAVELIN Merkel 200 part A: A phase II study of avelumab in metastatic Merkel cell carcinoma progressed on chemotherapy.

192Background: Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer. Avelumab, a human anti–PD-L1 monoclonal antibody, is FDA and EMA approved for the treatment of metastatic MCC (mMCC). Here, we report efficacy and safety data for avelumab in patients (pts) with mMCC at ≥18-mo of follow-up. Methods: Pts with mMCC and progression on prior chemotherapy received avelumab 10 mg/kg IV Q2W. Objective response rate (ORR), duration of response (DOR), and progression-free survival (PFS) were evaluated by independent review committee (RECIST v1.1) with tumor assessment every 6 wks; overall survival (OS) and adverse events (AEs; NCI CTCAE v4.0) were also evaluated. Results: As of Mar 24, 2017, 88 pts were treated and followed for a median of 23.0 mo (range 18.7–32.0). Median treatment duration was 17 wks (range 2–132; mean 35 wks ±37). Treatment was ongoing in 15 pts (17%); 7 pts (8%) voluntarily discontinued with continuing responses (5 complete responses [CR] and 2 partial responses). Other reasons for d...