Roche (RHHBY (OTC:RHHBY)) shares dropped 5.4% on Wednesday following an update about the early-stage trial of its weight-loss pill, CT-996.
The Swiss pharmaceutical giant said in July that the experimental pill resulted in a 6.1% placebo-adjusted weight loss over four weeks in a Phase I trial, creating optimism around its potential.
However, recent details show the reported results came from a subgroup of only six participants, with the news disappointing investors, sending Roche shares lower on Wednesday.
Presentation slides published on Wednesday demonstrate that while the Phase I trial involved 25 participants in total, only six of them were given a placebo for comparison, and the 6.1% weight loss figure came from the best-performing of three treatment subgroups.
The second-best-performing subgroup had seven volunteers and is said to have achieved a lower placebo-adjusted weight loss of 4.6%.
Roche noted that larger, more rigorous trials will commence next year to gather more definitive data.
The company defended the trial's design, explaining that doses were ramped up more quickly than planned for future trials to identify any potential side effects early on.
Roche's acquisition of CT-996's developer, Carmot, for $2.7 billion in December signaled its ambition to compete in the lucrative weight-loss drug market, which analysts predict could reach $150 billion by the early 2030s.
Meanwhile, competitors Novo Nordisk and Eli Lilly saw their stocks rise by 4.3% and 2%, respectively, further benefiting from their leadership positions in the weight-loss market.