- Cancer biotech Karyopharm Therapeutics will soon ask the Food and Drug Administration to broaden the approval for its multiple myeloma therapy Xpovio, following positive results announced Monday from a crucial clinical trial of the drug.
- In a study known as BOSTON, adding Xpovio to a common myeloma treatment regimen reduced the risk of disease progression or death by 30% versus using the regimen without Karyopharm's drug. Patients enrolled in the trial had previously received one to three previous lines of therapy for their cancers.
- Success in the BOSTON study is a key milestone for Karyopharm, which aims to expand use of Xpovio into earlier treatment. If the drug is approved for the population studied, thousands more U.S. patients with multiple myeloma would be eligible to receive Xpovio, currently approved for use after four or more other therapies.
Xpovio, Karyopharm's first drug, won U.S. approval last July, becoming the newest treatment for multiple myeloma since four therapies were cleared by the FDA in 2015.
Notably, Xpovio was the first of its type, working in a different way than immunomodulatory drugs like Revlimid or monoclonal antibodies like Darzalex.
The FDA's approval was narrow, however. Only patients who had received at least four previous drugs, and whose cancer proved resistant to other types of treatment, are eligible for Xpovio. By Karyopharm's reckoning, roughly 6,000 Americans were treated with fourth-line or higher drug regimens last year.
BOSTON is the company's first major step toward expanding Xpovio's use into earlier settings, where competition with older drug types is likely to be fiercer. Some 32,000 people in the U.S. were treated in the second- and third-line setting last year, Karyopharm claims.
The Phase 3 trial, which enrolled 402 patients, found combining Xpovio with Takeda's Velcade and low-dose dexamethasone extended progression-free survival times by roughly four and a half months over Velcade plus dexamethasone alone. That translated into a 30% relative risk reduction between the two treatment arms.
Karyopharm did not disclose detailed information on the drug's safety, although it said no new side effects were observed. In the trial which led to Xpovio's approval, side effects like low platelet counts and fatigue were common. Roughly half of Xpovio-treated patients reduced their dosage, and two-thirds had dosing interrupted.
Karyopharm said it would submit data from the BOSTON study to the FDA in the second quarter of this year, seeking an approval in second-line, relapsed or refractory multiple myeloma. No data on overall survival were available.
Should the agency accept and approve the company's application, BOSTON would also serve as the confirmatory study for Xpovio's initial approval, which was granted on an accelerated basis for overall response rate to treatment.
Karyopharm is testing Xpovio in combination with other myeloma drugs, and also expects the FDA to soon decide on whether the therapy can be used in a certain type of lymphoma.
Shares in Karyopharm rose by 45% early Monday in response to news of the data from BOSTON.