Discussion:
Avelumab, a human IgG1 monoclonal antibody against PD-L1, is the first approved drug for metastatic MCC. Approval for avelumab in metastatic MCC was based on single-arm, phase II trial, JAVELIN Merkel 200. The study, confirmed objective responses were observed in 32% of patients with chemotherapy-refractory metastatic MCC treated with avelumab. The responses appeared to be durable, with an estimated 74% of responses having a duration ≥ 12 months. Furthermore, interim results from a separate cohort of patients indicated an objective response rate for avelumab of > 60% in patients who were chemotherapy-naïve in the metastatic disease setting. Avelumab is associated with a risk of immune-related adverse events, however, they are acceptable and manageable.
Short-course radiation therapy is not appropriate treatment for metastatic MCC.
Infliximab is a chimeric monoclonal antibody that inhibits TNF-alpha and has no role in the treatment of metastatic MCC. Cetuximab is an epidermal growth factor receptor (EGFR) inhibitor indicated for the treatment of metastatic colorectal cancer, and head and neck squamous cell carcinoma. Cemiplimab is a programmed cell death receptor-1 (PD-1) blocking antibody indicated for the treatment of patients with metastatic cutaneous squamous cell carcinoma (CSCC) or locally advanced CSCC who are not candidates for curative surgery or curative radiation.
Suggested Reading:
- D’Angelo S., Hunger M. et al. Early objective response to avelumab treatment is associated with improved overall survival in patients with metastatic Merkel cell carcinoma. Cancer Immunol Immunotherapy. 2019 Apr; 68(4):609-618.
- Shirley M., Avelumab: A Review in Metastatic Merkel Cell Carcinoma. Target Oncol. 2018 Jun;13(3):409-416
- Kaufman H., Russell J., et al. Avelumab in patients with chemotherapy – refractory metastatic Merkel cell carcinoma: a multicenter, single-group, open-label, phase 2 trial. Lancet Oncol. 2016 Oct; 17(10):1374-1385.
