Current Report · Items 8.01 · 8-K

Karyopharm Therapeutics Inc.

KPTINASDAQEQUITYCurrent

Other Events

Filed Aug 31, 2026Accepted Aug 31, 2026, 8:08 AM EDTCIK 1503802Accession 0001193125-26-375495

Company context

Karyopharm Therapeutics is a commercial-stage pharmaceutical company pioneering the science of nuclear export inhibition to develop differentiated therapies for patients with cancer. The Company's lead therapy, XPOVIO® (selinexor), is a first-in-class inhibitor of exportin 1 (XPO1). XPOVIO is marketed by the Company in the U.S. for adults with relapsed or refractory multiple myeloma and is approved as XPOVIO or NEXPOVIO® in more than 50 ex-U.S. countries and territories. Building on its leadership in XPO1 biology, Karyopharm is advancing selinexor's potential in hematological cancers, including in myelofibrosis. The Company is also exploring opportunities to evaluate XPO1 inhibition across myeloproliferative neoplasms using next-generation compounds, including eltanexor. Headquartered in Newton, Massachusetts, Karyopharm has an established, efficient, and scalable commercial infrastructure to bring novel therapeutic options to patients with cancer. For more information, visit www.karyopharm.com and follow Karyopharm on LinkedIn and on X at @Karyopharm.

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Items 8.01

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Item 8.01Item 8.01 - Other Events

Item 8.01 Other Events. On August 31, 2026, Karyopharm Therapeutics Inc. (the “Company”) announced that it has submitted a supplemental New Drug Application (“sNDA”) to the U.S. Food and Drug Administration (“FDA”) seeking Accelerated Approval for XPOVIO® (selinexor) in combination with ruxolitinib for patients with myelofibrosis. The Company requested Priority Review of the application, which, if granted, could result in a six-month review process. The Company expects to receive notice of the FDA’s decision on sNDA filing acceptance and, if accepted, the anticipated review timelines in the fourth quarter of 2026, following the FDA’s 60-day filing review period. Following the topline results of the Phase 3 SENTRY trial, the Company has engaged productively with the FDA. The sNDA submitted is based, in part, on data from the SENTRY trial that the Company believes supports a positive benefit-risk profile for the combination, including a promising signal of overall survival. The Company expects approval under the Accelerated Approval pathway would require the FDA to agree that spleen volume reduction ≥ 35% (SVR35) is a reasonably likely surrogate endpoint to predict overall survival. The Company plans to use long-term overall survival data from the Phase 3 SENTRY trial to verify clinical benefit and support conversion from accelerated to traditional approval and expects to continue working with the FDA during its review of the sNDA to finalize the confirmatory evidence plan.