Petrelintide: 9.8% weight loss, and vomiting no commoner than placebo

Design

phase 2, multicentre, randomised, double-blind, placebo-controlled, 42 weeks

Population

485 adults with obesity (BMI 30, or 27 with hypertension or dyslipidaemia) and without type 2 diabetes

Primary outcome

percentage change in bodyweight from baseline at 28 weeks

Effect

-9.8% on 5.0 mg vs -1.7% on placebo; difference -8.1% (95% CI -9.7 to -6.5)

ZUPREME 1 randomised 493 adults with obesity and without type 2 diabetes, 5:1, to once-weekly subcutaneous petrelintide at maintenance doses of 1.0 to 9.0 mg or to placebo, across 32 sites in Poland, Romania and the USA. Mean age was 47, mean BMI 36.7 kg/m2, and 86% were White. The primary endpoint was percentage weight change at 28 weeks.

At 28 weeks the 5.0 mg dose gave -9.8% (95% CI -10.9 to -8.6) against -1.7% (-2.8 to -0.5) on placebo, a difference of -8.1% (-9.7 to -6.5). The 7.0 mg and 9.0 mg doses gave -9.3% and -9.4%, so the curve flattens above 5.0 mg. Weight was still falling at week 42, reaching up to -10.7%. Nausea affected 20% on petrelintide against 6% on placebo, but vomiting was 3% against 6%, and diarrhoea and constipation were much the same in both arms.

That tolerability profile is the point. Amylin is a different mechanism from the incretins, and the gastrointestinal burden that drives so much GLP-1 discontinuation was largely absent here apart from mild nausea during escalation. This is phase 2, manufacturer-funded, with no cardiovascular or glycaemic outcome data and none in type 2 diabetes. It is a reason to watch the phase 3 programme, not to counsel a patient about a drug they cannot yet have.

• Petrelintide is an amylin analogue, not an incretin - a separate mechanism from semaglutide and tirzepatide.
• Doses above 5.0 mg weekly added no further weight loss at 28 weeks.
• Nausea was three times commoner than placebo; vomiting was not commoner at all.
• Trial excluded people with type 2 diabetes, so glycaemic effect is unknown.
• No approval anywhere; nothing to discuss with patients as an option yet.

Why it matters

If the gastrointestinal ceiling on incretin dosing is mechanism-specific rather than inevitable, the drugs that follow may be tolerated by people who could not stay on a GLP-1.

Don't overread it

Phase 2, in people without diabetes, with no outcome data - this is a signal to follow, not a class to plan around.

The statistics, in plain English

The treatment differences are large and their confidence intervals sit well away from zero, so the weight effect itself is not in doubt at this sample size. What phase 2 cannot tell you is whether it holds over years, whether it changes any outcome that matters, or how it behaves in people with diabetes - none of whom were enrolled. The flat dose-response above 5.0 mg is a genuine signal rather than noise, since the three top doses cluster within half a percentage point of each other.

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