A little over a year after reabsorbing its anticoagulant abelacimab, Novartis has now terminated two phase 3 trials for the antibody after one of the studies failed to beat Eliquis.
The Swiss pharma had been evaluating abelacimab, a factor XI/XIa inhibitor, against Bristol Myers Squibb’s and Pfizer’s blockbuster anticoagulant Eliquis in a phase 3 study of patients with cancer-associated thrombosis (CAT). The trial kicked off in 2022 and enrolled 1,150 patients, according to the federal trials database.
But the study had been halted after a data review suggested that abelacimab would fail to beat the blockbuster, a Novartis spokesperson confirmed to Fierce. As a result, the pharma decided to end work on abelacimab for CAT—including halting a separate phase 3 trial comparing the drug to Pfizer’s anticoagulant Fragmin in patients with venous thromboembolism specifically related to gastrointestinal or genitourinary cancer.
But Novartis isn’t ready to give up on the antibody completely. Abelacimab is still chugging along in a phase 3 trial for atrial fibrillation, its lead indication. Novartis plans to file the blood thinner for approval in 2028, according to the company’s 2025 annual report (PDF).
Novartis regained abelacimab by buying Anthos Therapeutics, a biotech that Novartis originally created in 2019 to lead development of the antibody. Novartis paid $925 million upfront in February 2025 to get its hands back on abelacimab, at a time when other factor XI inhibitors had faced setbacks.
In the time between Anthos’ creation and reacquisition, Bayer found about twice as many people died of a cardiovascular event when taking its factor XIa inhibitor asundexian compared to Eliquis, while BMS and Johnson & Johnson’s milvexian failed a phase 2 trial.
But Bayer went on to link asundexian to a significant stroke reduction in a phase 3 win that set the German pharma up for an approval filing this year. Milvexian, meanwhile, flopped a phase 3 trial last fall.
