On 23 March 2017, the US Food and Drug Administration (FDA) granted accelerated approval to the programmed death receptor 1 ligand (PD-L1) inhibitor avelumab (Bavencio®, EMD Serono, Inc.) for the treatment of adult and pediatric patients (12 years and older) with metastatic Merkel cell carcinoma (MCC), including those patients who have not received prior treatment with chemotherapy. Avelumab is the first approved treatment option for Merkel cell carcinoma.
Approval is based on results from the open-label phase II JAVELIN Merkel 200 trial (n = 88), in which treatment with avelumab demonstrated clinically meaningful and durable responses in patients with previously treated metastatic MCC. The updated overall response rate (ORR) was 33%, including a 11.4% complete response. The duration of response was ≥6 months in 86% of patients and ≥12 months in 45% of patients. Expression of the PD-L1 biomarker was associated with higher ORR (34.5% vs 18.8%). Median progression-free survival (PFS) was 2.7 months and median overall survival was 11.3 months.
Most patients experienced adverse events (AEs) of grade 1 or 2, with the most common being fatigue (23.9%), infusion reaction (17%), diarrhea (9.1%), nausea (9.1%), asthenia (8%), rash (6.8%), decreased appetite (5.7%), and maculopapular rash (5.7%). Only 4.5% of patients experienced grade 3 AEs and there were no grade 4 or 5 AEs.