Bristol-Myers Squibb and Pfizer have suffered a setback with the news that a late-stage trial of their investigational blood-clotting treatment apixaban has been stopped to an increase in bleeding.

The drug majors have  discontinued a Phase III study of apixaban, called APPRAISE-2, in patients with recent acute coronary syndrome. It has been stopped on the recommendation of an independent data monitoring committee which noted that "there was clear evidence of a clinically important increase in bleeding among patients randomised to apixaban" and the rise "was not offset by clinically meaningful reductions in ischemic events".

APPRAISE-2, one of nine clinical trials evaluating  the drug, was expected to enrol 10,800 patients with a recent ACS. However Brian Daniels, head of global development and medical affairs at B-MS, said the partners "remain committed to the development of apixaban in other patient populations." Primarily, they are focusing on the rolling submission of data for the prevention of stroke in patients with atrial fibrillation who are unsuitable for treatment with the gold standard warfarin to the US Food and Drug Administration and the application to the European Medicines Agency for venous thromboembolism prevention.

News of the apixaban setback comes just after Bayer and Johnson & Johnson presented strong data for their rival drug Xarelto (rivaroxaban) at the American Heart Association meeting in Chicago, showing it was superior to warfarin, with less risk of bleeding, in protecting against stroke among patients with AF. Boehringer Ingelheim's Pradaxa (dabigatran) was approved by the FDA for stroke risk reduction in non-valvular AF in October.

Despite the competition, most analysts believe that discontinuing APPRAISE-2 is no great disaster for Pfizer and B-MS. Tim Anderson of Sanford Bernstein issued a research note saying that  “in this particular indication, we did not have high hopes, and we built nothing into our sales forecast". He claims that “while a setback to some degree, failing in ACS is of little real consequence” and he believes apixaban could still have sales of $1.7 billion in other indications in 2015.