Avelumab, also known as MSB0010718C, inhibits PD-L1 interactions to potentially allow the activation of T-cells and the adaptive immune system.
It is believed to engage the innate immune system and induce antibody-dependent cell-mediated cytotoxicity by retaining a native Fc-region.
The data supporting the designation was generated in the phase II JAVELIN Merkel 200 study. The companies plan to present the trial’s results at upcoming scientific congresses in 2016.
The study’s primary objective is overall response rate. Duration of response, progression-free survival, overall survival and safety are secondary endpoints.
Merck and Pfizer are carrying out the study in 88 patients in sites across Asia Pacific, Australia, Europe and North America.
Merck global head of research & development of the biopharma business Luciano Rossetti said: "Metastatic Merkel cell carcinoma is a devastating disease with limited treatment options currently available for patients.
"With this Breakthrough Therapy designation, we are one step closer to our goal of making a significant difference to patients living with difficult-to-treat cancers, such as metastatic Merkel cell carcinoma, by researching and developing potential new treatment options."
The clinical development program for avelumab now includes over 1,400 patients who have been treated across more than 15 tumor types.
Avelumab is being developed and commercialized jointly by Merck and Pfizer under an alliance formed in November 2014.
Image: If approved, avelumab could potentially become the first immunotherapy to treat metastatic MCC. Photo: courtesy of Merck KGaA, Darmstadt, Germany.