The success or failure of GlaxoSmithKline's experimental heart drug darapladib remains "an open question" and will hinge on a second pivotal clinical study, the company's chief executive said on Monday.
"There are some interesting potential signals in the secondary endpoints but an awful lot about what we've got here is going to depend on what we see on the second study," Andrew Witty told Reuters.
"I think it is still an open question as to whether we've got something (that works) or not."
Although darapladib failed the main goal of the first Phase III study, the trial's co-leader said on Sunday it still provided a glimmer of hope, after presenting a detailed report at the American College of Cardiology.
Most investors remain skeptical about the medicine's prospects and Jefferies analysts said in a note that they saw few incremental positives in the latest data.
The second Phase III study is looking at the drug's effects in less stable patients who received the medicine within 30 days of a heart attack, where it is possible it may show a bigger benefit.
Gaining full control of darapladib was one of the reasons behind GSK's $3.6 billion acquisition of Human Genome Sciences in 2012 and the company has invested heavily in the two clinical trials into the drug, which involved nearly 30,000 patients.
(Reporting by Ben Hirschler; editing by Jason Neely)