Karyopharm Therapeutics Inc. 8-K

What Happened

• Karyopharm Therapeutics announced topline results from its Phase 3 SENTRY trial (selinexor 60 mg weekly + ruxolitinib vs placebo + ruxolitinib) on March 24, 2026. The trial met the co‑primary spleen endpoint: 50% of patients on the combination achieved ≥35% spleen volume reduction (SVR35) at week 24 versus 28% with ruxolitinib alone (one‑sided p<0.0001). The symptom co‑primary (Abs‑TSS at week 24) showed comparable improvement between arms and was not statistically significant. A promising overall survival (OS) signal was observed (hazard ratio 0.43; nominal one‑sided p=0.0222); Karyopharm will continue OS follow‑up and discuss the data with the FDA.
• The company also filed an 8‑K disclosing a private placement with RA Capital dated March 24, 2026: sale of common stock and pre‑funded warrants expected to yield about $30 million in gross proceeds at closing, with an additional ~ $44 million if accompanying warrants are exercised in full. Closing was expected on or about March 26, 2026. Jefferies and Piper Sandler acted as placement agents.
• Separately, Karyopharm said it will voluntarily withdraw the accelerated approval for the diffuse large B‑cell lymphoma (DLBCL) indication of XPOVIO® after an FDA request, and will cease further development in that indication; the company said this decision is not due to safety concerns and DLBCL sales are immaterial.

Key Details

• SENTRY spleen results: SVR35 at week 24 — 50% (selinexor+ruxolitinib) vs 28% (ruxolitinib); rapid and sustained effect (49% at week 12; 47% at week 36 in combo arm).
• Symptoms: mean Abs‑TSS improvement at week 24 — 9.89 points (combo) vs 10.86 points (ruxolitinib); difference not statistically significant.
• Safety: grade 3+ treatment‑emergent adverse events 70% (combo) vs 50% (placebo+ruxolitinib); most common TEAEs in combo arm included thrombocytopenia (59%), anemia (57%), nausea (57%); discontinuations 15% vs 9%.
• Financing: Private placement with RA Capital to issue 1,030,354 common shares and pre‑funded warrants for up to 3,391,164 shares, plus warrants to buy 4,421,518 shares exercisable at $10.00; pre‑funded warrant exercise price $0.0001 and includes ownership caps (default 9.99%, can be increased up to 19.99% after notice).

Why It Matters

• Clinical: Meeting the spleen reduction co‑primary endpoint is a clear positive readout for the selinexor + ruxolitinib regimen in frontline myelofibrosis; the non‑significant symptom result and higher rates of serious AEs will be key considerations for regulators, physicians and payers. The OS signal and VAF reductions are encouraging but require longer follow‑up and detailed review.
• Financial and liquidity: The near‑term private placement (~$30M at close, potential ~$74M total if warrants exercised) and recent ATM sales ($9.6M net) strengthen short‑term liquidity and, per the filing, satisfy a capital‑raise trigger tied to amendments/forbearance on existing credit agreements. This reduces near‑term financing risk but could dilute existing shareholders if warrants and pre‑funded warrants convert.
• Regulatory impact: Voluntary withdrawal of the DLBCL accelerated approval ends Karyopharm’s confirmatory effort in that indication and reduces related development spending; company states no safety issue and that other approvals are unaffected.