FDA Delays Selinexor Approval By 3 Months — So Why Is Karyopharm Ripping Higher?

Karyopharm Therapeutics Inc KPTI shares, which suffered a setback in late February following the release of the FDA's briefing document and panel vote on its multiple myeloma treatment candidate Selinexor, were seeing upward momentum on double their average volume Friday.

What Happened

Karyopharm said Thursday after the close the FDA has extended the review period for its NDA for Selinexor in combination with dexamethasone by three months from the original PDUFA date of April 6 to July 6.

The Selinexor combo is being evaluated for treating patients with relapsed refractory multiple myeloma who have received at least three prior therapies.

Karyopharm attributed the delay to the FDA's request for additional — but already existing — information as an amendment to the NDA following the Adcom meeting.

"We look forward to the continued collaboration with FDA in trying to meet the needs of patients with relapsed refractory multiple myeloma," Sharon Shacham, Karyopharm's founder, president and chief scientific officer, said in a statement.

Why It's Important

The FDA briefing document made available Feb. 22 for review by the FDA's Oncologic Drugs Advisory Committee and expressed worries over both safety and efficacy.

The FDA panel voted 8-5 following its Feb. 26 meeting in favor of delaying Selinexor approval until the results of the Phase 3 BOSTON trial are out. The Boston trial readout was not expected until at least late 2019 or into 2020.

The positive stock reaction, notwithstanding the delay in approval, may be attributable to the fact that Karyopharm may not have to do further clinical trials to satisfy the regulatory agency.

The three-month delay communicated by the FDA raises a faint hope of approval coming through earlier than the timeframe expected following the Adcom meeting.

Although the exact nature of the additional clinical information provided is unclear, the FDA action is encouraging, especially as the agency previously required only the results from the Phase 2b STORM study, Wedbush analyst David Nierengarten said in a Friday note.

"Nonetheless, while this development could be a positive for KPTI and approval before BOSTON is now a higher probability event (but still clearly in question), we're maintaining our estimates and valuation at this time until further updates," the analyst said.

What's Next

The focus now shifts to the July 6 PDUFA date, when it will be determined whether Selinexor is good enough to clear the FDA hurdle. 

Citing the new PDUFA date, H.C. Wainwright analyst Edward White said he is delaying his launch expectation for Selinexor by three months and consequently lowering the price target from $30 to $29. The firm maintained a Buy rating on Karyopharm. 

Despite Friday's rebound, Karyopharm shares are still off their pre-briefing document release levels of around $9.

At last check, the shares were trading up 10.68 percent at $4.87. 

Related Links:

The Daily Biotech Pulse: KaryoPharm's Selinexor Review Delayed, FDA Accepts Adamis Opioid Overdose Drug NDA

Attention Biotech Investors: Mark Your Calendar For These March PDUFA Dates

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