Investing.com -- Novo Nordisk shares surged more than 11% in premarket trading Thursday after Eli Lilly’s data on its oral obesity drug orforglipron underwhelmed investors, prompting concerns over both efficacy and tolerability.

Wolfe Research described the 11.5% placebo-adjusted weight loss achieved by orforglipron at 72 weeks as “modestly below investor expectations of 13–15%.”

Analysts said the study clears a key hurdle but noted that both “weight loss and tolerability came in light.”

The highest dose of orforglipron saw treatment discontinuation rates of 24.4%, while even the lower strength showed dropout rates in the mid-teens.

“We’d flag the 10.3% and 24.4% treatment discontinuation rates... We look to results at EASD, Sept. 17th, to further gauge prescriber sentiment,” Wolfe said, maintaining an Outperform rating on LLY.

Mizuho analysts echoed concerns about tolerability, calling the outcome “clearly not the ideal outcome here despite [a] good quarter.”

They pointed to a “near 25% patient drop-out rate on the highest dose” and suggested that the unusually high 29% placebo discontinuation rate “almost does not compute.”

Despite the disappointment, Mizuho believes orforglipron still has long-term potential: “11.2% weight-loss for a pill we think is solid given ease of use... maybe more of a consumer product than a drug.”

However, in the near term, the results appeared to benefit Novo Nordisk (NYSE: NVO). “NVO rallying... as investors believe gap between the two has now narrowed to some extent,” Mizuho noted.

Lilly shares are down more than 7% premarket, despite a strong quarter that included $3.38 billion in Zepbound sales and raised full-year guidance.