Xpovio Approved to Treat Multiple Myeloma
July 3, 2019 – The U.S. FDA has approved Xpovio™ (selinexor), manufactured by Karyopharm Therapeutics, for use in combination with dexamethasone (a corticosteroid) to treat relapsed refractory multiple myeloma (RRMM) in adult patients who have received at least four prior therapies and whose disease is resistant to several other forms of treatment. These forms of treatment include at least two proteasome inhibitors, at least two immunomodulatory agents, and an anti-CD38 monoclonal antibody.
According to the American Cancer Society, an estimated 32,110 new cases of multiple myeloma will be diagnosed in the United States in 2019, and 12,960 individuals will die of the disease. Multiple myeloma occurs when abnormal plasma cells build up in the bone marrow and form tumors.
Xpovio is the first in a new class of drugs called nuclear export inhibitors. It works by selectively binding to and inhibiting the nuclear export protein exportin 1 (XPO1 or CRM1). This causes certain anti-cancer proteins to accumulate in the nucleus of cancer cells, which reduces the cells’ ability to grow and multiply.
In a clinical study, Xpovio taken with dexamethasone produced an overall response rate of 25.3%, with a median time to first response of four weeks and median duration of response of 3.8 months. Recommended dosing is 80mg (four 20mg tablets) of Xpovio taken by mouth with 20mg of dexamethasone on the first and third day of each week. Dosage modification may be required if the patient experiences an adverse reaction. The exact modification is based on the type of adverse reaction.
Because the FDA granted Xpovio accelerated approval, continued approval may require verification and description of clinical benefit in a confirmatory trial. Karyopharm has launched the product at a wholesale acquisition cost (WAC) of $22,000 per month.