Merck (NYSE:MRK), known as MSD outside the United States and Canada, said today it has started a rolling submission to the U.S. Food and Drug Administration (FDA) of a Biologics License Application for MK-3475, the company’s investigational anti-PD-1 immunotherapy, for patients with advanced melanoma who have been previously treated with ipilimumab. A rolling submission allows completed portions of the application to be submitted and reviewed by the FDA on an ongoing basis. The company expects to complete the application in the first half of 2014. “Our MK-3475 is a novel immunomodulatory molecule that holds promise for patients with advanced malignancy who now have limited treatment options,” said Roger M. Perlmutter, M.D., Ph.D., president, Merck Research Laboratories. “Initiation of this rolling submission represents an important milestone in the MK-3475 clinical development program for patients suffering from malignant melanoma.” Clinical Development of MK-3475 in Advanced Melanoma MK-3475 is currently being studied in three clinical trials for advanced melanoma including a Phase III trial of MK-3475 versus ipilimumab in ipilimumab-naïve advanced melanoma patients (PN 006). Enrollment is complete in the advanced melanoma cohorts in the company’s Phase IB trial (PN 001) and the Phase II trial (PN 002) comparing two doses of MK-3475 versus chemotherapy in patients with advanced melanoma who have progressed after prior therapy. In April 2013, Merck announced that MK-3475 received a Breakthrough Therapy designation for advanced melanoma from the FDA. About MK-3475 Many tumors are able to evade the immune system through a mechanism that exploits the PD-1 inhibitory checkpoint protein. MK-3475 is an investigational, highly selective anti-PD-1 immunotherapy designed to restore the natural ability of the immune system to recognize and target cancer cells by selectively achieving dual ligand blockade (PD-L1 and PD-L2) of the PD-1 protein. By blocking PD-1, MK-3475 enables activation of the immune system’s T-cells that target cancer by essentially releasing a brake on the immune system.