KPTI Stock Slumps Pre-Market Even As Karyopharm’s Myelofibrosis Treatment Meets Primary Endpoint — Retail Doubtful About FDA Approval

• Karyopharm’s Phase 3 SENTRY trial met its primary endpoint, with 50% of patients on selinexor combined with ruxolitinib achieving significant spleen reduction versus 28% on ruxolitinib alone.
• Across secondary and exploratory endpoints, no meaningful difference was observed, the company said.
• Karyopharm also signed a private placement deal with RA Capital Management to raise about $30 million.

Shares of Karyopharm Therapeutics Inc. (KPTI) reversed initial gains to plummet 13% in pre-market trading on Tuesday, after the pharmaceutical firm reported positive topline results from its Phase 3 trial to treat myelofibrosis, a rare bone marrow cancer, and announced a $30 million private placement with RA Capital.

KPTI stock has been under pressure recently, falling for six straight sessions and dropping about 27% over that period.

Phase 3 Trial Meets Primary Endpoint

Karyopharm’s Phase 3 SENTRY trial of selinexor combined with ruxolitinib met its primary endpoint, with 50% of patients achieving significant spleen volume reduction compared to 28% with ruxolitinib alone.

Symptom improvement was similar across both groups, but the combination therapy showed a promising signal in overall survival, Karyopharm added. The safety profile was consistent with known effects of both drugs, with manageable side effects and no new safety concerns.

Across secondary and exploratory endpoints of hemoglobin stabilization and bone marrow fibrosis improvement, no meaningful difference was observed as of February 20. The company plans to further evaluate the endpoints.  

Karyopharm plans to meet with the U.S. Food and Drug Administration (FDA) to discuss next steps, including a potential supplemental new drug application (sNDA) filing.

“In totality, these data underscore selinexor's potential to meaningfully improve clinical outcomes for patients with myelofibrosis,” said Reshma Rangwala, Chief Medical Officer and Head of Research of Karyopharm.

How Did Stocktwits Users React?

While retail sentiment turned ‘extremely bullish’ on Stocktwits, from ‘neutral’ a day earlier, chatter was mixed.

One user said that while the results are good, there is uncertainty about whether the FDA will approve the drug.

Another user added that the “FDA won’t approve it since the other endpoint is missing.”

However, one user believes the market may have misread the news.

$30 Million Private Placement

Separately, Karyopharm announced a private placement with RA Capital Management to raise about $30 million upfront, with proceeds potentially rising to around $74 million if the warrants are fully exercised. The company will sell a mix of common shares, pre-funded warrants, and additional warrants.

The deal is expected to close around March 26. Karyopharm said the funds, along with existing cash, should support operations into late third-quarter (Q3) in 2026. The proceeds will mainly be used for general corporate needs, including advancing its ongoing and planned clinical trials.

Year-to-date, the stock has shed more than 10%.

Read also: EVTV Stock Gets Pre-Market Boost: AZIO Locks In Customers Before GPU Infrastructure Goes Live

For updates and corrections, email newsroom[at]stocktwits[dot]com.