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Karyopharm’s drug reduces spleen size in rare blood cancer study

By Thomson Reuters Mar 24, 2026 | 6:17 AM

March 24 (Reuters) – Karyopharm Therapeutics said on Tuesday its therapy for patients with a rare blood cancer showed a reduction in spleen size in a late-stage ​trial, meeting one of the two main goals of ‌the study.

Shares of the company were up nearly 14% in premarket trade.

In the 353-patient trial, half of those given Karyopharm’s drug Xpovio in combination with Incyte’s Jakafi saw their spleen size reduced by at ‌least ​35% after 24 weeks. In comparison, only ⁠28% of patients who ⁠received only Jakafi saw a similar spleen size reduction.

However, the drug missed the other goal of showing a statically significant improvement in patients’ symptoms between those receiving the ​combination and those on Jakafi alone.

Karyopharm also said the combination may help patients live longer, with a preliminary analysis ⁠suggesting a more than 50% reduction ⁠in risk of death compared with Jakafi alone. ​It plans to continue monitoring survival outcomes.

The company said it ​will meet the U.S. Food and Drug Administration to ‌discuss the results and a potential application for approval.

Xpovio, which was first greenlit by the FDA in 2019, is approved to treat other blood cancers, such as types of myeloma ⁠and lymphoma.

The blood cancer myelofibrosis causes scarring in the bone marrow, which makes it difficult for the tissue to make healthy blood ⁠cells, and causes ‌an enlarged spleen and progressive anemia.

According to ⁠Karyopharm, myelofibrosis affects about 20,000 people in ​the United ‌States. Current treatments rely on JAK inhibitors ​such as ⁠Jakafi.

Separately, Karyopharm agreed to a $30 million private placement with RA Capital, with up to $44 million more if accompanying warrants are fully exercised.

The proceeds will support general corporate purposes, including clinical programs.

(Reporting by Puyaan Singh and Sahil Pandey in Bengaluru; Editing by ​Krishna Chandra Eluri)