US regulators have agreed to undertake a priority review EMD Serono's avelumab as a potential treatment for metastatic Merkel cell carcinoma (MCC), a rare and aggressive disease in which cancer cells form in the top layer of the skin, close to nerve endings.

If approved, the investigational immunotherapy could be the first treatment indicated for patients with the condition, according to the company, the biopharmaceutical business of Merck KGaA, and Pfizer.

The submission is based on data from JAVELIN Merkel 200, a multicenter, single-arm, open-label, Phase II study of 88 patients with metastatic MCC, whose disease had progressed after at least one chemotherapy treatment.

The data, recently published in the Lancet Oncology, showed durable responses to drug; the proportion of patients who achieved an objective response was 28 (31·8 percent) of 88 patients, including eight complete responses and 20 partial responses.

"Metastatic Merkel cell carcinoma is an aggressive disease, and patients face a very poor prognosis, with less than 20 percent surviving beyond five years," said Chris Boshoff, head of Immuno-oncology, Early Development and Translational Oncology at Pfizer Global Product Development. 

"We are encouraged by the results of our Phase II trial and believe avelumab may have potential to be an important treatment option for patients living with this hard-to-treat skin cancer."

The drug has already picked up FDA Breakthrough Therapy and Fast Track Designations for metastatic MCC, as well as orphan status. It is also currently under review in Europe.

Avelumab, a fully human anti-PD-L1 IgG1 monoclonal antibody, has not yet been approved anywhere in the world. The clinical development programme for the drug, known as JAVELIN, is evaluating its potential across more than 15 different tumour types, including breast, gastric/gastro-esophageal junction, head and neck, Hodgkin's lymphoma and urothelial (primarily bladder).