Onconova Presents Patient Selection Criteria and Intermediate Clinical Endpoints for Rigosertib in Higher-Risk Myelodysplastic Syndromes (HR-MDS) at EHA Annual Meeting

Onconova Therapeutics, Inc.

, a clinical-stage biopharmaceutical company focused on discovering and developing novel products to treat cancer, today announced the presentation of clinical data on rigosertib in HR-MDS at the 20th Congress of the European Hematology Association (EHA) in Vienna, Austria, June 11 – 14, 2015. Onconova collaborators from the United States and Europe presented multiple posters analyzing subgroup data, key clinical endpoints and eligibility criteria from the completed Phase 3 ONTIME trial of IV rigosertib in patients with HR-MDS previously treated with hypomethylating agents (HMAs). These data are being utilized in the design of a new global Phase 3 trial for IV rigosertib in HR-MDS, which Onconova expects to initiate in 2015, pending receipt of appropriate financing. Electronic versions of the posters can be accessed by visiting "Posters" under the Investors and Media section of the Onconova website at www.onconova.com. Abstract number: P616 Title: Overall Survival (OS) and Baseline Disease Characteristics in MDS Patients with Primary HMA Failure in a Randomized, Controlled, Phase III Study of Rigosertib Primary Author: Guillermo Garcia-Manero, MD, MD Anderson Cancer Center, Houston, TX Abstract number: P625 Title: Correlation of Overall Survival (OS) with Bone Marrow Blast (BMBL) Response in Patients (Pts)