Data Published Today in the New England Journal of Medicine Demonstrates Anthos Therapeutics’ Novel Factor XI inhibitor, Abelacimab 150mg, Reduced Major or Clinically Relevant Non-Major Bleeding by 62% Compared to Rivaroxaban (Xarelto) in Patients With AF

• Secondary endpoints also showed a highly significant 67% reduction in major bleeding and an 89% reduction in gastrointestinal (GI) bleeding
• The company’s AZALEA-TIMI 71 study is the longest head-to-head study of a Factor XI inhibitor vs. a direct oral anticoagulant (DOAC) 
   

Anthos Therapeutics Press Release 

CAMBRIDGE, Mass., Jan. 22, 2025--Anthos Therapeutics, Inc., a transformative, clinical-stage biopharmaceutical company developing innovative therapies for the treatment of cardiovascular metabolic diseases, founded by Blackstone Life Sciences, announced today the publication of the results of the landmark AZALEA-TIMI 71 study in the January 23 issue of New England Journal of Medicine (NEJM). 

Originally presented at a late-breaking session of the 2023 American Heart Association (AHA) meeting, the NEJM publication provides more complete clinical details of the study, which demonstrated an unprecedented reduction in bleeding events in patients taking abelacimab versus a standard of care direct-oral anticoagulant (DOAC) across all primary and secondary endpoints in patients with atrial fibrillation. 

Atrial fibrillation, also known as AFib, is an irregular heartbeat, or arrhythmia, which can increase the risk of stroke by five times and cause other heart-related complications.¹ Affecting 60 million people worldwide,²  the prevalence of AFib is expected to increase by 60% by 2050 due to an aging population and rising cardiometabolic risk factors.³  In addition, the Centers for Disease Control and Prevention (CDC) estimates that more than 12 million Americans will have AFib by 2030.⁴

Today, 40% to 60% of patients with AFib are either not prescribed anticoagulants or are undertreated.⁵ In a physician survey, the foremost barrier to patients taking oral anticoagulants was the risk of bleeding.⁶ This underuse of anticoagulants for stroke prevention has been cited as one of the greatest public health issues facing cardiovascular patients.⁷

“Many doctors are put in the unfortunate position of having to weigh the risk of stroke against the risk of bleeding for their patients with AFib,” said Christian T. Ruff, MD, MPH, director of General Cardiology at Brigham and Women’s Hospital, associate professor of Medicine at Harvard Medical School, senior investigator in the TIMI Study Group, and principal investigator of the AZALEA-TIMI 71 trial.  “This study reinforces the promise of abelacimab as a potentially safer alternative to current anticoagulants to address the risk of bleeding.” 

Study Highlights⁸
•    Median 99% inhibition of Factor XI sustained over 2 years with abelacimab 150 mg dosed once monthly
•    62% reduction in major or clinically relevant non-major bleeding with abelacimab 150 mg compared with rivaroxaban 20 mg in patients with AFib who are at moderate-to-high risk of stroke (P<0.001, HR 0.38, 95% Cl 0.24–0.60)
•    67% reduction in major bleeding alone with abelacimab 150 mg vs rivaroxaban 20 mg (P=0.001, HR 0.33, 95% CI 0.16-0.66)
•    89% reduction in gastrointestinal (GI) bleeding

With a median follow up of 21 months, the AZALEA-TIMI 71 Phase 2 study is the longest head-to-head study to date of a Factor XI inhibitor, and provides evidence of a highly significant reduction in bleeding versus a DOAC.  In September 2023, the study was stopped early by the Independent Data Monitoring Committee (IDMC) due to an overwhelming, greater-than-anticipated reduction in major and clinically relevant non-major bleeding with abelacimab and a benefit/risk profile favoring abelacimab.

Additional data from the AZALEA-TIMI 71 study comparing abelacimab to rivaroxaban, which was presented last September at the European Society of Cardiology meeting, demonstrated low levels of bleeding during surgical procedures, also referred to as periprocedural bleeding, despite patients being fully anticoagulated with abelacimab. Additional data from the study presented at the American Heart Association’s Scientific Sessions last November showed that even among patients on antiplatelet therapy, abelacimab reduced bleeding as compared with rivaroxaban.  

“Building on the overwhelmingly positive data from the AZALEA study, data on the safety of abelacimab in patients undergoing surgical procedures as well as data in patients taking antiplatelet therapy further reinforce the fundamental premise of the promise of Factor XI inhibition – the potential to prevent thrombotic events without affecting normal hemostasis,” said Dan Bloomfield, MD, Chief Medical Officer of Anthos Therapeutics. “Even when the risk of bleeding is highest, during surgery or invasive procedures or when using antiplatelet therapy, patients treated with abelacimab have a very low rate of bleeding, despite near complete inhibition of Factor XI.  The growing body of safety data on abelacimab elevates its promise for patients and, if approved, its potential to be a very attractive therapeutic option for those seeking a safer, more convenient anticoagulant.”

In September 2022, the Food and Drug Administration (FDA) granted abelacimab Fast Track status for the prevention of stroke and systemic embolism in patients with atrial fibrillation, recognizing the unmet need and the potential benefits of abelacimab.  Anthos Therapeutics’ LILAC-TIMI 76 study launched in January 2023 and was designed to determine whether abelacimab can reduce the rate of stroke in AFib patients more effectively and safely compared to placebo. Study completion is anticipated for the second half of 2026. 

About Anthos Therapeutics
Founded by Blackstone Life Sciences (BXLS) in 2019, Anthos Therapeutics is a transformative, clinical-stage biopharmaceutical company with the exclusive global rights from Novartis Pharma AG to develop, manufacture and commercialize abelacimab. For more information, visit the Company’s website or follow us on X and LinkedIn.

About Abelacimab
Abelacimab is a novel, investigational, highly selective, fully human monoclonal antibody that binds tightly to Factor XI to block its activation and prevent the generation of the activated form (Factor XIa). This mimics natural Factor XI deficiency, which is associated with protection from thromboembolic disease.

Abelacimab received a Fast Track Designation from the FDA in July 2022 for the treatment of thrombosis associated with cancer. In September 2022, abelacimab was also granted a Fast Track Designation for the prevention of stroke and systemic embolism in patients with atrial fibrillation.

1 https://www.ncbi.nlm.nih.gov/books/NBK534135/

2 Patel SM, Ruff CT. Curr Cardiol Rep. 2024 Jul 23.

3 Rahman F et al. Nat Rev Cardiol 2014;11(11):639-54

4 Colilla S, Crow A, Petkun W, Singer DE, Simon T, Liu X. Estimates of current and future incidence and prevalence of atrial fibrillation in the U.S. adult population. Am J Cardiol. 2013;112:1142–1147.

5 Hsu J et al JAMA Cardiol 2016:1 :55-62

6 Yao C et al PEC Innov 2022;1:100062 (https://www.sciencedirect.com/science/article/pii/S2772628222000474)

7 Pokorney et al. American Heart Journal, April 2019

8 Ruff C et al. Abelacimab versus Rivaroxaban in Patients with Atrial Fibrillation. N Engl J Med 2025