Roche's Obesity Drug Shows Promise But Trails GLP-1 Giants Novo Nordisk And Eli Lilly

Roche Group AG’s obesity drug push faces stiff competition after Genentech, a unit of Roche, reported Phase 2 results showing up to 10.7% weight loss—below expectations and lagging leading treatments from Novo Nordisk A/S and Eli Lilly and Co. .

Genentech on Thursday shared topline results from the Phase 2 ZUPREME-1 trial evaluating petrelintide versus placebo in 493 obese participants (mean BMI of 37 kg/m²).

In 2025, Genentech and Roche entered into an agreement with Zealand Pharma to co-develop and co-commercialize petrelintide for obesity.

Zealand Pharma received an upfront payment of $1.65 billion. It is also eligible for development milestones of $1.2 billion and sales-based milestones of $2.4 billion.

The study met its primary endpoint.

Once-weekly subcutaneous injections of petrelintide (escalated every fourth week ) showed statistically significant and clinically meaningful weight loss from baseline after 28 weeks in all five treatment arms compared to placebo.

Roche/Zealand Partnered Obesity Drug Achieves 11% Weight Loss

Petrelintide demonstrated a favorable tolerability profile comparable to placebo, and the study observed no unexpected safety signals.

In patients with the highest reduction in body weight, 98% of petrelintide-treated participants reached the maintenance dose.

Accordingly, body weight reduction using the treatment regimen estimand was largely consistent with the efficacy estimand.

Favorable Safety Profile

Petrelintide demonstrated a favorable tolerability profile comparable to placebo. No unexpected safety signals were observed.

The treatment discontinuation rate due to adverse events was 4.8% with petrelintide in the maximally effective treatment arm versus 4.9% with placebo.

Gastrointestinal-related events were the most frequently reported adverse events, mostly being mild.

Across petrelintide treatment arms, 8.4% of participants withdrew from the trial for any reason, compared with 13.6% in the placebo group. 

Coming Up Next For Roche’s Obesity Drug

Researchers will present the final ZUPREME-1 data at an upcoming medical congress. The findings will inform optimal Phase 3 designs and settings to evaluate petrelintide.

The second Phase 2 ZUPREME-2 trial of petrelintide versus placebo for obesity and type 2 diabetes is expected to deliver topline results in the second half of 2026.

The company will initiate a Phase 2 trial exploring the combination of petrelintide and CT-388 later in 2026.

In January, Roche released topline results from the CT388-103 Phase 2 trial of CT-388 for obesity.

The study found that once-weekly subcutaneous injections of CT-388 (titrated up to 24 mg) produced weight loss of 22.5% without reaching a weight-loss plateau at 48 weeks.

Price Action

Roche shares fell 6.34% to $54.19 on Thursday after investors reacted to underwhelming weight-loss trial results from partner Zealand Pharma. Shares of Zealand Pharma, which trades on the Copenhagen Stock Exchange, plunged more than 30% on Friday following the update.

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