New perspectives in Merkel cell carcinoma.

PURPOSE OF REVIEW: Merkel cell carcinoma (MCC), a rapidly progressing skin cancer, has poor prognosis. We reviewed the epidemiology, pathogenesis, diagnosis and treatment of MCC, with a focus on recent therapeutic advancements.

RECENT FINDINGS: Risk factors for MCC, such as old age, immunosuppression, polyomavirus infection and exposure to UV radiation have already been identified, but the underlying mechanisms leading to carcinogenesis still need clarification. On the basis of recent advances, immunotherapy - in particular, inhibition targeting the programmed cell death protein 1/programmed death-ligand 1 (PD1)/PDL1) immune checkpoint blockade - is currently being investigated in the treatment of metastatic MCC. Avelumab, an anti-PDL1 antibody, was the first drug to be approved internationally as second-line monotherapy for patients with advanced MCC, based on results from the JAVELIN Merkel 200 clinical trial. Avelumab has also recently been approved as first-line treatment for advanced MCC in Europe. Pembrolizumab (anti-PD1) in first-line and nivolumab (anti-PD1) in first-line and second-line treatments are two other checkpoint inhibitors that are under investigation, and showing promising results. New innovative therapies are also in development.

SUMMARY: New insights concerning advances in MCC diagnosis and treatment have been highlighted. Immunotherapy for metastatic MCC constitutes a recent breakthrough in an unmet medical need, but alternative therapies should continue to be investigated.