Rigosertib falls short for high-risk myelodysplastic syndromes after failure on azacitidine or decitabine


Rigosertib failed to extend overall survival beyond that seen with best supportive care in a trial of patients who had myelodysplastic syndrome with excess blasts after failure of azacitidine or decitabine treatment.

A randomized phase III trial of rigosertib (NCT 02562443) is now underway in specific subgroups of high-risk patients, including patients with very high risk on the basis of the Revised International Prognostic Scoring System criteria, to determine whether the drug may benefit specific patient subgroups, according to Dr. Guillermo Garcia-Manero of the University of Texas MD Anderson Cancer Center, Houston, and his colleagues.

The ONTIME study (NCT01241500) was an open-label, randomized controlled trial at 74 medical centers in the US and Europe. Patients with refractory anemia with excess blasts ([RAEB]-1, RAEB-2, RAEB-t, or chronic myelomonocytic leukemia) were enrolled based on local site assessment and treatment failure with a hypomethylating drug in the past 2 years.

Patients were randomly assigned on a 2:1 basis to receive rigosertib or best supportive care with or without low-dose cytarabine. Randomization was stratified by pretreatment bone marrow blast percentage. The 199 patients given rigosertib received 1,800 mg per 24 hours via a 72-hour continuous intravenous infusion administered every other week. Another 100 patients were assigned to best supportive care.

Median follow-up was 19.5 months. Median overall survival was 8.2 months (95% confidence interval, 6.1-10.1) in the rigosertib group and 5.9 months (95% CI, 4.1-9.3) in the best supportive care group (hazard ratio, 0.87; 95% CI, 0.67-1.14; P = 0.33), the researchers reported (Lancet Oncol. 2016;17(4):496-508. doi: 10.1016/S1470-2045(16)00009-7).

The most common grade 3 or higher adverse events were anemia (18% of 184 patients in the rigosertib group and 8% of 91 patients in the best supportive care group), thrombocytopenia (19% vs 7%), neutropenia (17% vs. 8%), febrile neutropenia (12% vs 11%], and pneumonia (12% vs 11%). Adverse events led to death in 22% of 184 patients in the rigosertib group and 33% of 91 patients in the best supportive care group; three deaths were attributed to rigosertib treatment.

The study was funded by Onconova Therapeutics and the Leukemia and Lymphoma Society.


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