Onconova Therapeutics, Inc. announced that it has submitted a Special Protocol Assessment request to the U.S. Food and Drug Administration (FDA) for a Phase 3 study of oral rigosertib combination therapy with azacitidine (Vidaza®) for the treatment of adult patients with treatment-naïve higher-risk MDS. The request is part of the Company’s ongoing interaction with the FDA, following an End-of-Phase 2 Meeting with FDA guidance for the proposed Phase 3 study and Scientific Advice from the European Health Authorities, consistent with the Company’s strategy to study rigosertib in an earlier higher-risk MDS patient population with a more convenient mode of oral rigosertib administration. The End-of-Phase 2 Meeting also outlined that the primary endpoint of the proposed pivotal trial will be overall response rate (ORR), a composite of complete remission (CR), and partial remission (PR) based on the IWG Response Criteria. The FDA’s SPA process fosters dialogue between the FDA and clinical trial sponsors before studies commence, in an attempt to reach potential agreement with the agency on the design and size of clinical trials, to determine if they adequately address the scientific and regulatory requirements for a study to ultimately support marketing approval. The Company expects its dialogue with the FDA on this SPA submission to conclude in first half of 2019.