Second-line avelumab treatment of patients (pts) with metastatic Merkel cell carcinoma (mMCC): Experience from a global expanded access program (EAP).

9537 Background: Avelumab is a human anti–PD-L1 IgG1 antibody that showed a favorable efficacy and toxicity profile in pts with mMCC and progressive disease (PD) on or after chemotherapy (CT) in the phase 2 JAVELIN Merkel 200 trial (JM 200; NCT02155647), leading to accelerated approval in the US and Europe. We describe real-world experience with avelumab in a global EAP for pts with mMCC. Methods: Pts participating in the EAP (NCT03089658) had stage IV mMCC and PD on or after CT or were ineligible for CT. In contrast to JM 200, pts in the EAP could have ECOG performance status of 2, treated brain metastases, or immunosuppressive conditions with sponsor medical approval. Pts received avelumab 10 mg/kg IV Q2W until PD or unacceptable toxicity. A 3-mo supply of avelumab for approved pts was provided to treating physicians; additional re-supply was allowed for pts who had complete response (CR), partial response (PR), stable disease (SD), or clinical benefit per treating physician assessment. No central imaging was obtained. Results: Between Jan 2016 and Jan 2018, 460 requests for avelumab were received from 37 countries: 395 were approved, 45 were medically rejected for various reasons (eg, incorrect diagnosis, lack of appropriate prior therapy, incomplete information), and 37 were withdrawn. Most requests were from France (n = 97), Italy (n = 69), and Australia (n = 46). Median age was 74 y (range, 28-95), and 65.7% of pts were male. Among 131 response-evaluable pts, the objective response rate was 51.1%, including CR in 22.1% (n = 29) and PR in 29.0% (n = 38; including 1 pt with HIV); 19.1% (n = 25) had SD and 29.8% (n = 39) had PD. Durable responses were observed in immune-competent and immunosuppressed pts. Updated data will be presented. The safety profile was similar to that of JM 200. The EAP is ongoing but will close in 2018 (US closed in April 2017) with regulatory approval in multiple countries. Conclusions: The avelumab EAP rapidly enrolled many pts with mMCC and answered an unmet, urgent medical need for pts ineligible for clinical trials or for whom no approved alternative treatments were available. In a real-world setting, avelumab demonstrated safety and efficacy consistent with JM 200. Clinical trial information: NCT03089658.