Karyopharm Therapeutics (KPTI -39.5%) is down on a 6x surge in volume following the release of briefing materials for next Tuesday’s FDA advisory committee meeting on selinexor tablets (with dexamethasone) in relapsed/refractory multiple myeloma (RRMM). The review team does not appear to be on board with the application.
Section 2.1: The bulk of the data supporting the filing was generated in the open-label, single-arm Phase 2 STORM study, but the review team states: “Given that historical studies have shown response rates of 10-27% to high-dose dexamethasone for RRMM and selinexor did not demonstrate single agent activity in RRMM in the phase 1 trial KCP-330-001, it is difficult to isolate the treatment effect of selinexor.”
Section 2.2: Selinexor is associated with “significant toxicity” with “worse overall survival than physician’s choice” (KCP-330-008 study).
Section 2.3: The proposed starting dose was not well tolerated with the data indicating dose-limiting toxicity, adding that a “lower dose may be better tolerated.”
Feb. 22, 2019