Lilly and Daiichi hope prasugrel eventually becomes a strong rival to Bristol-Myers Squibb Co.'s $6 billion-a-year Plavix.
The 10,000-patient clinical study, called Trilogy ACS, will compare prasugrel to Plavix in patients with heart attacks, clogged coronary arteries and other severe heart problems.
The trial could be crucial for the fate of prasugrel because more than half of patients treated for severe heart problems do not receive stents. Instead, they are treated with medicines, such as ones to prevent blood clots that can trigger heart attacks and stroke.
Mixed results were announced yesterday from another Phase III trial comparing prasugrel and Plavix among patients with acute coronary syndrome who were planning to receive stents.
In that trial, called Triton, prasugrel was 19 percent more effective than Plavix in preventing cardiovascular death, nonfatal heart attacks and strokes. But prasugrel caused a significantly higher amount of serious bleeding, some of which was fatal.
Some industry analysts predict U.S. marketing approval for prasugrel, despite the mixed results. But they caution that sales of the drug could be limited unless it shows more compelling results-effectiveness without more serious bleeding-in the planned Trilogy ACS trial.
Daiichi Sankyo and Lilly are co-developing prasugrel, which works by preventing blood cells called platelets from sticking together to form clots. Daiichi Sankyo and its Japanese research partner, Ube Industries Ltd., invented the drug.