FDA Approves Xpovio (Selinexor) for Multiple Myeloma

July 3, 2019

Nuclear export inhibitor indicated in combination with dexamethasone.

The FDA granted accelerated approval to Karyopharm Therapeutic’s Xpovio (selinexor), a nuclear export inhibitor indicated in combination with dexamethasone for treatment of adult patients with relapsed or refractory multiple myeloma (RRMM) that have undergone at least four prior therapies and whose disease is refractory to at least two proteasome inhibitors, two immunomodulatory agents, and an anti-CD38 monoclonal antibody. 

According to an FDA release, the accelerated approval was based on the results of Part 2 of STORM (Selinexor Treatment of Refractory Myeloma) (KCP-330-012 and NCT-02336815), a multicenter single-arm open-label study of 122 patients with RRMM who had previously received at least three or more antimyeloma treatments. Patients participating in the study had a disease that was refractory to glucocorticoids, a proteasome inhibitor, an immunomodulatory agent, an anti-CD38 monoclonal antibody, and the last line of therapy received. 

Efficacy and safety evaluations in a prespecified subgroup analysis of 83 patients resulted in an overall response rate of 25.3%. Results included one patient that achieved a stringent complete response, no complete responses, four patients achieved very good partial responses, and 16 patients achieved partial responses. Efficacy evaluation, according to the FDA, was supported by additional information from an ongoing, randomized trial in patients with multiple myeloma. 

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“Despite recent advances in the treatment of multiple myeloma, almost all our patients will develop disease that is resistant to the five most commonly used anti-myeloma drugs we currently have available, and the prognosis for this patient population is particularly poor.  The accelerated approval of oral XPOVIO marks an important advance in the treatment paradigm for patients with relapsed refractory multiple myeloma, and in my view, is an important addition to our therapeutic armamentarium,” said Dr. Paul Richardson, MD, Clinical Program Leader and Director of Clinical Research at the Jerome Lipper Multiple Myeloma Center at the Dana-Farber Cancer Institute, in a statement.

Starting dosage for selinexor is 80 mg in combination with 20 mg of dexamethasone, taken orally on days one and three of each week. Selinexor tablets are available in 20 mg tablets. 

Prescribing information for selinexor warns of thrombocytopenia, neutropenia, gastrointestinal toxicity, hyponatremia, neurological toxicity, embryo-fetal toxicity, and various infections that may develop in patients as a result of taking the medication. 

Adverse reactions reported in at least 20% of patients in all clinical studies of selinexor include thrombocytopenia, fatigue, nausea, anemia, decreased appetite, decreased weight, diarrhea, vomiting, hyponatremia, neutropenia, leukopenia, constipation, dyspnea, and upper respiratory tract infection

Full Prescribing Information