The Food and Drug Administration on Wednesday approved a new drug to treat patients with multiple myeloma, overruling a panel of outside cancer experts who expressed concerns about its toxicity.

The new multiple myeloma drug, called selinexor, will be marketed by Karyopharm Therapeutics under the brand name Xpovio.

The FDA cleared Xpovio under an accelerated, or conditional, approval based on a single-arm clinical trial showing a 25% tumor response rate. The patients enrolled in the clinical trial had advanced multiple myeloma no longer responsive to at least four prior therapies. 

The same clinical trial also raised concerns about Xpovio’s safety, including reductions in platelets and white blood cell counts that caused serious, potentially fatal bleeding and infections. 

Last February, a panel of outside cancer experts convened by the FDA recommended against Xpovio’s approval, concluding the drug’s benefits did not outweigh its safety risks. The vote was 8-5 against the drug. Some experts on the panel, however, believed the drug should be approved given the need for new medicines to treat multiple myeloma patients who have run out of other treatment options. 

The Xpovio label approved by the FDA discusses the drug’s toxicity and advises doctors to reduce dosing when certain side effects are observed. The label also states that Xpovio’s “continued approval” is dependent on “verification and description of clinical benefit in a confirmatory trial.”

Karyopharm, based in Newton, Mass., is conducting a randomized, controlled Phase 3 study of Xpovio in multiple myeloma patients, with a readout expected by the end of 2019 or early 2020. The primary goal of this study is to determine if Xpovio can delay tumor progression and improve overall survival compared to current standard of care. 

Karyopharm share rose 36% to $8.90 in Wednesday trading.

About the Author

Adam Feuerstein

Senior Writer, Biotech

Adam is STAT’s national biotech columnist, reporting on the intersection of biotech and Wall [email protected]@adamfeuerstein