Novartis is now betting its entire $925 million abelacimab investment on one remaining trial after the factor XI/XIa inhibitor failed to beat Eliquis in cancer-associated thrombosis.
The CAT study enrolled 1,150 patients and kicked off in 2022. A data review signaled abelacimab wouldn’t beat the blockbuster, so Novartis halted it and simultaneously killed a second phase 3 comparing the drug to Pfizer’s Fragmin in venous thromboembolism patients with gastrointestinal or genitourinary cancer. Two indications, one decision.
Novartis paid $925 million upfront in February 2025 to reacquire abelacimab from Anthos Therapeutics, a spinout it created in 2019 to advance the antibody. At the time, the factor XI class looked troubled: Bayer’s asundexian had posted twice the cardiovascular death rate of Eliquis in one trial, and BMS and Johnson & Johnson’s milvexian had flopped phase 2.
Now one phase 3 remains: atrial fibrillation, abelacimab’s lead indication, with a 2028 filing target per Novartis’s 2025 annual report. If it holds, the $925 million looks defensible. If it doesn’t, Novartis will have spent nine figures to exit every front.
The factor XI class isn’t failing uniformly. Bayer’s asundexian posted a phase 3 stroke-reduction win and is targeting an approval filing this year, while milvexian flopped its own phase 3 last fall. Abelacimab can’t afford to follow milvexian.
The 2028 filing is the last chance to make the $925 million work.
— Sarah Chen