Andexanet Alfa for Life-Threatening Bleeding Following Factor Xa Inhibitor Treatment: Postmarketing Surveillance...

Andexanet alfa, a reversal agent for factor Xa inhibitors (FXaI), has demonstrated efficacy and safety for treatment of FXaI-associated major bleeding in clinical trials in a largely Western population with a limited Japanese sample size.

This postmarketing surveillance study evaluated andexanet alfa, particularly the safety profile, in Japanese patients with life-threatening or uncontrolled bleeding following FXaI therapy under real-world clinical conditions.

Enrolled patients prescribed andexanet alfa for treatment of life-threatening or uncontrolled bleeding during treatment with an FXaI were followed for up to 30 days after andexanet alfa administration. Key outcomes of interest were safety (including adverse drug reactions, rebleeding events, and thrombotic events) and effectiveness (including physician-reported treatment effectiveness).

Of 1,283 patients enrolled at 388 study sites, 365 patients (63.3% men [231 of 365]; median age 80.0 years [min-max 39-97 years]) were included in safety analyses. The median duration of the follow-up period was 34.0 days (min-max 1-396 days). A total of 86 adverse drug reactions were reported in 64 patients (17.5%), with 2 (0.5%) of 365 patients experiencing infusion reactions. Five (1.4%) of 365 patients met the physician assessment criteria for rebleeding. A total of 32 (8.8%) of 365 patients experienced 34 thrombotic events, most commonly cerebral infarction (6.6% [24 of 365]). Kaplan-Meier analysis yielded a 30-day survival rate of 83.5% (95% CI: 77.4%-88.0%) overall, and physician's assessment of andexanet alfa treatment was "effective" or "excellent" for 80.9% (157 of 194) of patients.

This study supports the safety and effectiveness of andexanet alfa in a real-world population of Japanese patients with FXaI-associated major bleeds.