The study enrolled 270 patients with myelodysplastic syndromes (MDS) who had failed prior therapy with hypomethylating agents, such as azacitidine and decitabine.
Onconova chief executive officer Ramesh Kumar said at present very limited treatment options are available for high-risk MDS patients who fail hypomethylating agents.
"We are developing rigosertib as a second-line therapy for this patient population," Kumar said.
"We are grateful for the support that we have received from patients, investigators and the Leukemia and Lymphoma Society for the ONTIME trial.
"We expect to present top-line survival results from this study either in the fourth quarter of 2013 or the first quarter of 2014."
The randomised, controlled study of rigosertib is being conducted in the US and five EU countries under a Special Protocol Assessment from the US FDA and Scientific Advice from the European Medicines Agency.
Both groups of patients in the ONTIME trial will receive best supportive care and the active treatment group will also receive rigosertib.
The overall survival is the primary objective of the ONTIME trial.
Secondary objectives include evaluation of bone marrow, cytogenetic and blood profiles, quality of life scores and time to transition to acute myelogenous leukemia.
Rigosertib works by inhibiting two important cellular signaling pathways, phosphoinositide 3-kinase (PI3K) and polo-like kinase (PLK), which are frequently activated in cancer cells.