Karyopharm Therapeutics Inc. (Nasdaq: KPTI), an oncology-focused pharmaceutical company, today announced positive top-line results from the randomized Phase 3 BOSTON study evaluating once-weekly XPOVIO® (selinexor) in combination with once-weekly Velcade® (bortezomib) and low-dose dexamethasone (SVd) compared to standard twice-weekly Velcade plus low-dose dexamethasone (Vd) in patients with multiple myeloma who have received one to three prior lines of therapy. The BOSTON study met its primary endpoint of a statistically significant increase in progression-free survival (PFS). The median PFS in the SVd arm was 13.93 months compared to 9.46 months in the Vd arm, representing a 4.47 month (47%) increase in median PFS (hazard ratio=0.70; p=0.0066). There were no new safety signals on the SVd arm and there was no imbalance in deaths between the two arms in the study. The full top-line data will be submitted for presentation at upcoming medical meetings.

“We are thrilled to report these highly significant top-line results from the BOSTON study, the first randomized Phase 3 trial to demonstrate clinically and statistically significant activity of once-weekly XPOVIO in combination with a current standard of care treatment in patients with myeloma after one to three prior therapies,” said Sharon Shacham, PhD, MBA, President and Chief Scientific Officer of Karyopharm. “In the study, patients on the SVd regimen lived 47% longer without their disease worsening, which we believe represents an important improvement in the treatment of patients with relapsed or refractory multiple myeloma. We plan to submit the full data set for presentations at upcoming medical meetings to share the results with the medical community. We also intend to submit these data as quickly as possible to the U.S. Food and Drug Administration (FDA) as part of a supplemental New Drug Application seeking to expand the approved indication for XPOVIO into second line treatment for patients with relapsed or refractory multiple myeloma. If approved, the SVd regimen would be the first and only FDA-approved combination drug regimen that includes once-weekly Velcade therapy for relapsed myeloma.”

XPOVIO received accelerated approval from the FDA on July 3, 2019 for the treatment of adult patients with relapsed or refractory multiple myeloma who have received at least four prior therapies and whose disease is refractory to at least two proteasome inhibitors, at least two immunomodulatory agents, and an anti-CD38 monoclonal antibody. This indication is approved under accelerated approval based on response rate. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial. Karyopharm expects to submit data from the Phase 3 BOSTON study to serve as this confirmatory trial. The full Prescribing Information for XPOVIO is available at www.XPOVIO.com.