FDA approved Bayer’s Sunharbo (asundexian) on November 9, 2026, the first Factor XIa inhibitor, after it cut repeat ischemic strokes 26% in OCEANIC-STROKE.
Last updated: November 10, 2026
The FDA approved Bayer’s Sunharbo (asundexian) 50 mg tablets on November 9, 2026, as the first Factor XIa inhibitor in the US. Taken once daily with antiplatelet therapy, it lowered the risk of another ischemic stroke by 26% after a recent noncardioembolic stroke or high risk TIA.
Scope: the label, the pivotal data, the safety limits, launch and pricing signals, and what the approval means for the rest of the Factor XI class. Sources are the FDA announcement and Bayer’s releases unless attributed.
What did the FDA approve on November 9?
The FDA approved Sunharbo (asundexian), an oral Factor XIa inhibitor from Bayer HealthCare Pharmaceuticals, to reduce the risk of stroke when used with antiplatelet therapy in adults after a recent mild to moderate noncardioembolic ischemic stroke or a high risk transient ischemic attack. The dose is 50 mg once daily.
The agency called it the first Factor XIa inhibitor for this use and said Sunharbo had Fast Track and Priority Review designations. Bayer’s release, datelined Berlin, November 10, defines the population more tightly as patients with a National Institutes of Health Stroke Scale score of 15 or below. The FDA was explicit on one boundary: Sunharbo is not approved for stroke prevention in patients with atrial fibrillation. Neither release states the application type, so we refer to it simply as a US marketing application.
Hylton Joffe, director of the FDA’s Office of Cardiology, Hematology, Endocrinology, and Nephrology, called the approval a meaningful advance for patients and providers.
| Label element | What the FDA announcement says |
|---|---|
| Drug | Sunharbo (asundexian) 50 mg tablets, once daily |
| Mechanism | Factor XIa inhibitor, the first approved in the US |
| Use | With antiplatelet therapy, after recent mild to moderate noncardioembolic ischemic stroke or high risk TIA |
| Excluded | Not approved for stroke prevention in atrial fibrillation |
| Designations | Fast Track and Priority Review |
| Interactions | Use with combined P glycoprotein and strong CYP3A4 inducers, such as carbamazepine, not recommended |
| Liver | Not recommended in moderate or severe hepatic impairment |
| Procedures | Withhold at least 24 hours before elective surgery or invasive procedures, and at least 24 hours after thrombolysis for acute ischemic stroke |
How well did asundexian work in OCEANIC-STROKE?
In OCEANIC-STROKE, asundexian cut the risk of ischemic stroke by 26% against placebo, both on top of antiplatelet therapy, with a cause specific hazard ratio of 0.74 (95% CI 0.65 to 0.84; p<0.001), according to Bayer’s April 16, 2026 release on the New England Journal of Medicine publication.
The trial randomized 12,327 adults within 72 hours of a qualifying stroke or TIA. The FDA describes a median treatment duration of 14.2 months. The American College of Cardiology’s summary of the NEJM paper reports ischemic stroke in 6.2% of the asundexian group versus 8.4% on placebo, a median follow up of 567 days, and fewer events on the key secondary composite of cardiovascular death, heart attack or stroke. Those event rates come from the ACC summary rather than a company document, so treat them as attributed. On those figures, the absolute gap is 2.2 percentage points, our arithmetic.
Bayer says the effect held across age, sex, type of index event, stroke subtype, stroke severity, thrombolysis and single or dual antiplatelet therapy. The data were first presented at the International Stroke Conference 2026 in New Orleans.
| OCEANIC-STROKE measure | Asundexian 50 mg | Placebo | Source |
|---|---|---|---|
| Patients randomized (total) | 12,327 | FDA, Bayer | |
| Ischemic stroke, relative reduction | 26% (csHR 0.74; 95% CI 0.65 to 0.84) | Bayer | |
| Ischemic stroke, event rate | 6.2% | 8.4% | ACC summary of NEJM |
| Major bleeding | 1.9% | 1.7% | ACC summary (HR 1.10; 95% CI 0.85 to 1.44) |
| Any adverse event | 69.3% | 70.1% | ACC summary |
| Serious adverse event | 19.2% | 19.5% | ACC summary |
| Median treatment / follow up | 14.2 months treatment (FDA); 567 days follow up (ACC) | FDA, ACC | |
What is the bleeding risk with Sunharbo?
Overall major bleeding was similar between Sunharbo and placebo, the FDA said, but it was higher with Sunharbo in patients older than 75 and during the first 90 days of treatment. Gastrointestinal bleeding was more common on the drug, and diarrhea was the most frequent adverse reaction at 3% or more.
That nuance matters more than the headline. The Factor XI thesis has always been that blocking the intrinsic pathway can prevent clots with less bleeding than drugs that act further down the cascade. OCEANIC-STROKE supports that on average. The FDA’s language tells prescribers where to watch: older patients and the weeks right after the index event, which is exactly when stroke teams start the drug. Bayer’s release describes ISTH major bleeding as similar between arms and does not mention the age or early treatment findings.
Why does Sunharbo matter if it failed in atrial fibrillation?
Because it shows Factor XI inhibition can work, but the label now defines where. In November 2023, Bayer stopped OCEANIC-AF, its Phase 3 trial against apixaban in atrial fibrillation, after the independent data monitoring committee saw inferior efficacy of asundexian versus the control arm. The same committee recommended OCEANIC-STROKE continue.
So the first approval in the class lands in secondary prevention after noncardioembolic stroke, a setting where patients typically get antiplatelet therapy rather than an anticoagulant. Sunharbo adds to that regimen. It does not replace the direct oral anticoagulants in atrial fibrillation, and the FDA wrote that limit into its announcement.
Who else is developing Factor XI drugs?
Bristol Myers Squibb and Johnson & Johnson’s milvexian is the closest rival. BioPharma Dive reports it has had multiple clinical setbacks and that two large ongoing trials, in stroke and atrial fibrillation, could still disappoint. The same outlet cites a Leerink Partners model of $2.5 billion in risk adjusted milvexian sales in 2032.
Novartis holds an injectable Factor XI antibody from its $925 million purchase of Anthos Therapeutics in 2025, and City Therapeutics has an RNA based Factor XI medicine in early testing, both per BioPharma Dive. Sunharbo’s label, especially the bleeding language, becomes the reference point every one of these programs will be compared against.
| Program | Company | Status as reported |
|---|---|---|
| Sunharbo (asundexian), oral | Bayer | Approved US Nov 9, 2026; approved in China per Bayer; other filings under review |
| Milvexian, oral | BMS and J&J | Two large Phase 3 trials ongoing (stroke, AF), per BioPharma Dive |
| Injectable Factor XI antibody | Novartis (from Anthos) | In development; acquired for $925 million in 2025, per BioPharma Dive |
| RNA based Factor XI medicine | City Therapeutics | Early testing, per BioPharma Dive |
How much will Sunharbo cost and how will it launch?
A 30 day supply carries a list price of $748.50, a Bayer spokesperson told BioPharma Dive. Bayer has not published a launch date.
Sebastian Guth, chief operating officer of Bayer’s pharmaceuticals division and president of Bayer U.S., told the outlet that stroke neurologists will be central to the early rollout, with primary care a bigger focus over time, and described a robust patient support program. BioPharma Dive flags access as the possible limiting factor. For hospital stroke programs, the practical issue is that the drug starts in the inpatient or early discharge window and then has to survive the handoff to outpatient coverage.
Bayer says asundexian was also recently approved by China’s National Medical Products Administration and has been submitted in additional markets.
Our framework: five questions for a Factor XI launch
- Who starts it? Map which stroke units and neurologists see eligible noncardioembolic stroke and high risk TIA patients within the first days.
- Who keeps it going? Persistence depends on the primary care and payer handoff after discharge. Track prior authorization friction from week one.
- Who is excluded? Atrial fibrillation, moderate or severe hepatic impairment, and patients on strong inducers. Build these into order sets.
- Where is bleeding watched? Patients over 75 and the first 90 days. Pharmacy and stroke teams should agree on monitoring before the first prescription.
- What does the next label look like? Milvexian’s stroke and AF trials will show whether the class story is asundexian specific or broader.
What to watch next
- Bayer’s launch timing, early prescription data and payer coverage decisions
- Regulatory decisions in other markets where Bayer says applications are under review
- Milvexian Phase 3 readouts in stroke and atrial fibrillation
- Any guideline update from stroke societies on adding a Factor XIa inhibitor to antiplatelet therapy
- Postmarketing bleeding signals in patients over 75
Frequently asked questions
What is Sunharbo?
Sunharbo is Bayer’s brand name for asundexian, an oral Factor XIa inhibitor taken as a 50 mg tablet once daily with antiplatelet therapy.
When was Sunharbo approved?
The FDA announced the approval on November 9, 2026.
What is Sunharbo approved for?
Reducing the risk of stroke, with antiplatelet therapy, in adults after a recent mild to moderate noncardioembolic ischemic stroke or a high risk transient ischemic attack.
Is Sunharbo approved for atrial fibrillation?
No. The FDA stated it is not approved for stroke prevention in patients with atrial fibrillation. Bayer stopped its OCEANIC-AF trial in 2023 for inferior efficacy versus the control arm.
How much did asundexian reduce strokes?
It reduced ischemic stroke by 26% versus placebo in OCEANIC-STROKE (hazard ratio 0.74; 95% CI 0.65 to 0.84), per Bayer.
How many patients were in OCEANIC-STROKE?
The trial randomized 12,327 adults within 72 hours of their stroke or TIA.
Does Sunharbo increase bleeding?
Overall major bleeding was similar to placebo, but the FDA said it was higher in patients older than 75 and during the first 90 days, and gastrointestinal bleeding was more common.
What is a Factor XIa inhibitor?
A drug that blocks activated Factor XI, part of the intrinsic clotting pathway, aiming to prevent harmful clots while sparing more of the body’s ability to stop bleeding than older anticoagulants.
How much does Sunharbo cost?
A Bayer spokesperson told BioPharma Dive the list price is $748.50 for a 30 day supply.
Is Sunharbo approved outside the US?
Bayer says asundexian was recently approved in China and has been submitted for marketing authorization in other markets.
What are the main competitors?
Milvexian from Bristol Myers Squibb and Johnson & Johnson, Novartis’ injectable Factor XI antibody, and earlier stage programs such as City Therapeutics’ RNA based approach.
Sources
Primary
- U.S. Food and Drug Administration, “FDA Approves First Factor XIa Inhibitor to Help Prevent Stroke in Certain Adults at High Risk,” November 9, 2026
- Bayer, “Bayer’s asundexian first FXIa inhibitor approved by U.S. Food and Drug Administration for secondary stroke risk reduction,” Berlin, November 10, 2026
- Bayer, OCEANIC-STROKE NEJM publication release, Berlin, April 16, 2026
- Bayer, “OCEANIC-AF study stopped early due to lack of efficacy,” November 19, 2023
Attributed
- American College of Cardiology, OCEANIC-STROKE journal scan of Sharma et al., NEJM (doi 10.1056/NEJMoa2513880), April 22, 2026 (event rates, bleeding rates, follow up)
- BioPharma Dive, “Bayer wins FDA nod for a new kind of blood thinner,” November 9, 2026 (price, launch comments, competitor context, Leerink estimate)
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