Adding Sunharbo (asundexian), a first-in-class Factor XI inhibitor, to single or dual antiplatelet therapy reduces ischemic stroke risk without increasing the risk of major bleeding.
Having an ischemic stroke or an transient ischemic stroke (TIA), sometimes called a “ministroke,” markedly increases a person’s risk of having a second ischemic stroke or, in the case of those with TIAs, the first full-fledged ischemic stroke. The American Stroke Association and other groups have many secondary stroke prevention recommendations, but the risk remains.
On Monday, the FDA announced the approval of a new medication that has been shown to reduce the risk of these secondary stroke by 26% and, importantly, does not increase the risk of bleeding, an abiding concern with drugs that are often referred to as blood thinners because they work by interfering with blood coagulation.
The newly approved drug, which Bayer is selling under the brand name Sunharbo (asundexian), breaks new ground, as it is the first FDA-approved drug that blocks activated Factor XI, a coagulation factor. Other medications —collectively referred to as direct oral anticoagulants (DOACs) — such as Xarelto (rivaroxaban) and Eliquis (apixaban), also work by blocking a coagulation factor, but it is a different one, called Factor Xa.
A Bayer spokesman said in an email to Managed Healthcare Executive today that the company is setting the list price of Sunharbo at $748.50 for a 30-day supply, which works out to an annual price of nearly $9,000. The actual amount that health plans and other payers will pay for the Sunharbo will depend on discount and rebate negotiations and other pricing arrangements. For patients in the U.S. with health insurance, the cost of the new drug will depend on the many elements that go into the benefit design of pharmacy coverage, such as coinsurance and deductible amounts.
The pool of patients who might be appropriately prescribed Sunharbo is large. Sunharbo is approved to reduce the stroke risk in adults who have had a mild-to-moderate noncardioembolic stroke or a high-risk TIA. A Bayer spokesman said that approximately 80% of ischemic strokes are noncardioembolic ischemic strokes. Using that proportion, approximately 520,000 noncardioembolic ischemic strokes occur each year in the U.S.
Bristol Myers Squibb and Johnson & Johnson also have a Factor XI inhibitor, called milvexian, in development, but their plans for that drug were dealt a setback when they halted a
Sunharbo will not replace Eliquis and Xarelto as DOACs for stroke prevention among people with atrial fibrillation. The FDA news release Monday noted that Sunharbo is not approved for stroke prevention in that population. Also, notably, Sunharbo is not approved as monotherapy but is to be taken in combination with dual or single antiplatelet therapy. Aspirin and clopidogrel are the antiplatelet medications used in this circumstance.
Sunharbo’s approval “represents a meaningful advance for patients and health care providers seeking a new option for secondary stroke prevention,” Hylton V. Joffe, M.D., M.M.Sc., director of the Office of Cardiology, Hematology, Endocrinology, and Nephrology in the FDA’s Center for Drug Evaluation and Research, said in the FDA’s new release.
“For those who survive a stroke, the risk of another potentially devastating event is highest in the days and weeks after the initial event, and that risk persists over time,” Ashkan Shoamanesh, M.D., co–principal investigator of the phase 3 trial that led to Sunharbo’s approval, said in Bayer’s news release about Sunharbo’s FDA approval. “I believe asundexian introduces an important new addition to post-stroke care that can be used to help patients reduce the risk of a secondary stroke,” added Shoamanesh, who is a senior scientist at the Population Health Research Institute, a research center jointly supported by McMaster University and Hamilton Health Sciences.
Results of the pivotal phase 3 trial, called OCEANIC-STROKE, of Sunharbo were presented at the 2026 International Stroke Conference in New Orleans in early February 2026 and then published in the New England Journal of Medicine (NEJM) in April 2026. The Bayer-sponsored trial enrolled 12,327 patients at 702 sites in 27 countries. The researchers randomly assigned patients within 72 hours after an onset of a noncardioembolic ischemic stroke or a high-risk TIA to receive a 50-milligram dose of Sunharbo daily or a placebo in addition to dual or single antiplatelet therapy. Shoamanesh and his colleagues reported that after a median follow-up period of 19 months, the incidence of ischemic stroke was lower in the Sunharbo group than in the placebo group, 6.2% compared with 8.4%, a 26% difference.
In the discussion section of the NEJM paper, Shoamanesh and his colleagues noted that other attempts at combining antithrombotic therapy haven’t worked out because of lack of efficacy, bleeding risk or both. A combination low dose of Xarelto and aspirin showed some promise, with evidence that it reduced stroke risk among patients with stable atherosclerosis, but that benefit was offset by an increase in major bleeding. Against this backdrop, there was added salience to the OCEANIC-STROKE data that showed that the incidence of major bleeding was similar in the Sunharbo and placebo groups (1.9% vs. 1.7%).
