Four patients experienced serious adverse events during a clinical trial of Roche's experimental hemophilia med, ACE910.
As Roche races to win a piece of the 11 billion-a-year hemophilia drug market, the four reports of blood clots in patients being treated with ACE910 (emicizumab) is a setback for the potential blockbuster.
Roche is aiming to report phase III data for emicizumab early next year in patients who have developed inhibitors to factor VIII clotting factors, putting it on track for approval in 2018.
Deutsche Bank analyst Richard Parkes told Reuters, "We view the news as the first blemish on ACE910's profile."
Read the Reuters coverage