Bayer’s asundexian (Sunharbo) FDA-approved as first FXIa inhibitor for secondary stroke prevention

Regulatory milestone

The U.S. Food and Drug Administration approved asundexian 50 mg tablets (Sunharbo) for use in combination with antiplatelet therapy to reduce the risk of stroke in adults with recent non‑cardioembolic ischemic stroke (NIHSS ≤15) or high‑risk transient ischemic attack. Sunharbo is the first Factor XIa (FXIa) inhibitor approved worldwide; the drug has also received approval from China’s NMPA and is under review in other markets.

Evidence base

Authorization is based on the pivotal Phase III OCEANIC‑STROKE trial, which demonstrated that asundexian 50 mg plus antiplatelet therapy reduced ischemic stroke by 26% compared with antiplatelet therapy alone. The reduction was observed with a similar rate of ISTH major bleeding between asundexian and placebo, and the treatment effect was consistent across key subgroups and planned antiplatelet regimens.

Trial design

OCEANIC‑STROKE was a multicenter, international, randomized, placebo‑controlled, double‑blind, parallel‑group, event‑driven study that randomized 12,327 participants. The primary efficacy endpoint was time to ischemic stroke and the primary safety endpoint was ISTH major bleeding. Full results were published in The New England Journal of Medicine.

Clinical context and mechanism

FXIa is implicated in pathological thrombus growth but plays a minor role in hemostatic plug formation. Asundexian selectively inhibits FXIa to reduce pathological clot formation while preserving hemostasis. The approval addresses an unmet need: about one in ten non‑cardioembolic ischemic stroke survivors have another stroke within one year and one in five within five years.