Bayer's Sunharbo wins FDA approval after cutting repeat strokes 26%

The Food and Drug Administration on Monday approved Bayer's Sunharbo, a once-daily pill that cut the risk of another ischemic stroke by 26% in a 12,327-patient trial, making it the first approved factor XIa inhibitor in the U.S., the agency said.

The approval gives doctors a new class of drug for preventing a second stroke. About 795,000 people in the U.S. have a stroke each year, and about 23% of those strokes are repeat events, Bayer said. About one in 10 survivors has another stroke within a year. Ashkan Shoamanesh, a co-principal investigator of the trial at the Population Health Research Institute in Ontario, said the risk is highest in the days and weeks after the first event and persists over time. Many blood thinners are not used after a stroke because they raise the risk of bleeding, STAT reported, and Sunharbo is designed to stop harmful clots with less effect on normal clotting.

The drug, known by the generic name asundexian, is approved for adults who recently had a mild-to-moderate ischemic stroke not caused by a clot from the heart, or a high-risk transient ischemic attack, often called a mini-stroke. It is taken at 50 mg once a day alongside antiplatelet therapy.

The evidence came from a late-stage study called OCEANIC-STROKE. Patients were randomly assigned to Sunharbo or a placebo within 72 hours of their symptoms starting, and both groups kept taking antiplatelet drugs. The trial split 6,162 patients onto the drug and 6,165 onto placebo, with an average age of 68. Over a median of 14.2 months, 6.2% of patients on Sunharbo had an ischemic stroke, against 8.4% on placebo. The drug also lowered the rate of all strokes, including bleeding strokes, to 6.6% from 8.8%, and cut a combined measure of cardiovascular death, heart attack or stroke to 9.2% from 11.1%, Bayer said. Put another way, 53 patients need to be treated for a year to prevent one recurrent stroke, according to STAT.

Sunharbo works by blocking factor XIa, a protein that amplifies the body's production of thrombin. In preclinical models, Bayer said, blocking it hits pathological clotting harder than normal clotting. STAT described the new class as holding the promise of preventing blood clots more safely.

The bleeding data were mixed. The overall rate of major bleeding was similar between the two groups, at 1.6 events per 100 patient-years on Sunharbo against 1.5 on placebo. But major bleeding rose in patients older than 75 and during the first 90 days of treatment, when the rate was 4.5 against 3.1. Gastrointestinal bleeding was also more common on the drug. Diarrhea was the most frequently reported side effect.

The label carries other limits. Sunharbo is not approved for stroke prevention in patients with atrial fibrillation, and it is not recommended for people with moderate or severe liver impairment. Doctors should hold the pill for at least 24 hours before elective surgery and for at least 24 hours after clot-busting treatment for an acute stroke, the FDA said.

Hylton V. Joffe, director of the FDA's Office of Cardiology, Hematology, Endocrinology, and Nephrology, said in the agency's announcement that "today’s approval represents a meaningful advance for patients and health care providers seeking a new option for secondary stroke prevention." Nelson Ambrogio, president of Bayer U.S. Pharmaceuticals, said the company was proud to bring the first approved factor XIa inhibitor to the U.S. market for preventing a second stroke.

The FDA gave the drug Fast Track and Priority Review designations. The approval went to Bayer HealthCare Pharmaceuticals in Whippany, N.J. China's drug regulator approved Sunharbo on Oct. 26, and the drug is under review in Europe and Japan, Bayer said.

The decision came on a busy day for the agency, which also ordered a new vision-loss warning on Ozempic and similar drugs. Bayer expects Sunharbo to begin shipping in mid-to-late November, with hospitals and pharmacies able to order it across the U.S. shortly after. More drug coverage is in the Healthcare Sector.