Onconova advances rigosertib into new Phase II study for refractory MDS

Onconova Therapeutics, Inc., announced today the advancement of the oral formulation of rigosertib (Estybon^®, ON 01910.Na), an anti-cancer agent with demonstrated activity in solid tumors and hematologic malignancies, into a new Phase II study. The intravenous (IV) formulation of rigosertib is currently in a pivotal Phase III trial for refractory myelodysplastic syndromes (MDS) in the U.S. and EU.

"A randomized Phase II evaluation of oral rigosertib will be conducted in patients with Low or Intermediate-1 risk transfusion-dependent myelodysplastic syndromes at Columbia University Medical Center," said Siddhartha Mukherjee, MD, DPhil, Principal Investigator of the study, Assistant Professor of Medicine at Columbia University and staff physician at Herbert Irving Comprehensive Cancer Center of Columbia University Medical Center/New York-Presbyterian Hospital in New York. "This is a significant step forward in the development of this new medicine. The objective of the study is to determine if oral rigosertib will reduce the need for blood transfusions in transfusion-dependent MDS patients. The need for blood transfusions and the complications from receiving transfusions are serious medical issues for these patients."

This Phase II study follows the positive findings of a Phase I dose escalation study in MDS patients treated with orally-administered rigosertib. These findings were presented at the December 2011 American Society of Hematology Annual Meeting (Blood 118: Abstract 3797, 2011).

• In the Phase I study, orally delivered rigosertib was well tolerated and bioavailable. Clinical activity observed included favorable bone marrow responses in high-risk patients who were refractory to hypomethylating agents, a reduction in need for red blood cell (RBC) transfusions in transfusion-dependent patients, and a transition to transfusion independence. Rami Komrokji, M.D. and colleagues, and Azra Raza, M.D., conducted the trial at the H. Lee Moffitt Cancer Center and Columbia University Medical Center, respectively.

The final analysis of the Phase I clinical trial, along with results from a separate study of oral rigosertib in patients with solid tumors, will be reported in two presentations at the 2012 American Society of Clinical Oncology (ASCO) Annual Meeting, in Chicago, June 1-5.

"The reduction in RBC transfusions observed in this study was a breakthrough," said Dr. Raza. "Confirmation of these findings in the Phase II study will be a significant step forward, potentially leading to a safe and effective treatment for patients with low-risk MDS."