Karyopharm Therapeutics Inc. said the U.S. Food and Drug Administration has extended the decision date for its new drug application for Selinexor to treat a type of blood cancer by three months.

The agency had granted priority review to the company's application for Selinexor to treat recurring or unresponsive multiple myeloma. Multiple myeloma is an incurable blood cancer that forms in plasma cells, a type of white blood cell responsible for producing antibodies. It is characterized by a recurring pattern of remission and relapse.

In February, the FDA's Oncologic Drugs Advisory Committee recommended that the U.S. regulator wait for results from Boston, a late-stage study evaluating Selinexor in combination with Takeda Pharmaceutical Co. Ltd.'s Velcade in patients with relapsed refractory multiple myeloma, before approving the drug.

Since then, the Newton, Mass.-based biotechnology company has submitted, on the FDA's request, additional clinical information. The agency has moved the Prescription Drug User Fee Act action date from April 6 to July 6.

The European Medicines Agency's Committee for Medicinal Products for Human Use granted accelerated assessment to Selinexor in January, which could reduce the review time of the marketing authorization application to 150 days from the standard 210 days.

Karyopharm's stock rose 7.05% to close at $4.71 on March 15.