Petrelintide and Amylin: How This Approach Differs From GLP-1

Most weight-management drugs in the news work through GLP-1. Petrelintide takes a different route. It copies amylin, a separate hormone with its own receptors. This article explains how the two signals differ, what petrelintide's human studies have actually shown, and what is still only a hypothesis. For the compound's full profile, see our petrelintide page. No doses, protocols, or sourcing here.

Two hormones, two different signals

Amylin

Amylin is a hormone made by the beta cells of the pancreas. It is released together with insulin after you eat. Reviews of the research describe three main jobs: it slows how fast the stomach empties, it lowers glucagon (a hormone that raises blood sugar) after meals, and it helps end a meal by acting on the brain. It works through its own amylin receptors, mostly in brain areas that sense hormones in the blood (Hay et al., Pharmacological Reviews, 2015).

There is human evidence that copying amylin changes eating. In a 6-week controlled study, the older amylin drug pramlintide reduced daily calorie intake and meal size in people with obesity (PMID 17505051). Pramlintide is the one amylin analog approved as a medicine, for diabetes alongside mealtime insulin. See our pramlintide profile.

GLP-1

GLP-1 is made in the gut, not the pancreas. It is released by cells in the intestine when food arrives. It boosts insulin release when blood sugar is high, lowers glucagon, slows stomach emptying, and reduces food intake (Drucker, Cell Metabolism, 2018). In a small placebo-controlled human study, a GLP-1 infusion increased fullness and cut calorie intake at a free-choice lunch by 12% (Flint et al., 1998). Drugs that copy it are called GLP-1 receptor agonists. Our GLP-1 peptides guide covers them in detail.

Where they overlap, and where they don't

On paper the two look similar. Both slow the stomach and both reduce eating. The differences are where they come from and which receptors they use. Amylin comes from the pancreas and acts on amylin receptors. GLP-1 comes from the gut and acts on GLP-1 receptors. Because the routes are separate, researchers are testing amylin drugs on their own and in combination with GLP-1-type drugs. Some also hope separate receptors could mean a different side-effect pattern. That last idea is a hypothesis, not a finding. A 2026 review notes that nausea with amylin drugs may depend on receptor details, drug exposure, and brain circuits that are still being worked out (Fischer and Borner, Pharmacological Research, 2026).

Where petrelintide fits

Petrelintide was formerly called ZP8396. Zealand Pharma, a Danish company, describes it as an investigational long-acting amylin analog for once-weekly injection under the skin. In March 2025 Zealand and Roche signed a collaboration and license agreement to co-develop it (Zealand pipeline page, checked September 15, 2026). Natural amylin clumps and breaks down easily. Zealand's chemists report that petrelintide was engineered to stay stable around neutral pH (J Med Chem, 2025). In the Phase 1 trials it had a half-life of about 10 days, which is what makes weekly dosing possible in trials (Diabetes, Obesity & Metabolism, 2026).

Petrelintide does not act on GLP-1 receptors. That is the point of the approach. It tests whether the amylin signal alone can produce useful weight loss. Roche is also planning to test it in combination with its own incretin drug, which is a separate question.

The approaches side by side

What the human studies actually showed

Every petrelintide trial below was sponsored by Zealand Pharma or Roche, the companies developing it. The Phase 1 results are published in a peer-reviewed journal. The Phase 2 results come from company press releases and a conference presentation.

Two cautions about the Phase 2 numbers. First, 10.7% is the best result across five dose groups, not an average across everyone treated. Second, it uses the efficacy estimand. That method estimates the effect if people stayed on treatment as planned. It usually gives a larger number than a method that counts everyone who started, whether or not they kept going. Zealand says the second method gave largely consistent results, but did not publish those figures in its releases. The nausea and vomiting percentages in the June 2026 release are not broken down by dose group, so we cannot tell which groups they describe.

The 'gentler than GLP-1' pitch is unproven

Zealand's pipeline page says current data suggest long-acting amylin analogs could deliver weight loss comparable to GLP-1 drugs with improved tolerability. That is the sponsor's framing of a goal. It has not been tested directly. We found no registered trial comparing petrelintide head-to-head with a GLP-1 drug when we checked ClinicalTrials.gov on September 15, 2026.

It is tempting to set petrelintide's Phase 2 nausea figures next to published GLP-1 trials. That comparison doesn't work. The trials enrolled different people, ran for different lengths of time, stepped up doses on different schedules, and analyzed results differently. Only a trial that randomizes people to both drugs can answer the question. Reviews also note that nausea is common when amylin drugs are started and stepped up, much as with GLP-1 drugs, and mostly settles with continued use (Bailey et al., Peptides, 2026). In ZUPREME-1 itself, nausea was about three times as common on petrelintide as on placebo.

Is petrelintide in Phase 3? What we could verify

Short answer: not confirmed. The Zealand pipeline page's graphic places petrelintide in the Phase 3 column, which can read as if Phase 3 has started. The text on the same page says something narrower. Here is what we verified on September 15, 2026:

• Sponsor page (checked Sep 15, 2026): the status text says petrelintide "will advance into Phase 3" for chronic weight management, with a planned initiation in the second half of 2026.
• Latest dated sponsor report (Aug 13, 2026): Zealand's first-half 2026 results say it plans to initiate registrational Phase 3 trials with petrelintide on its own in the second half of 2026. It does not say any Phase 3 trial has started.
• ClinicalTrials.gov (searched Sep 15, 2026): no Phase 3 record for petrelintide or ZP8396. Registered petrelintide trials are Phase 1 and Phase 2 only. Both Phase 2 monotherapy trials are listed as completed.
• Next Phase 2 trial: a Roche-sponsored Phase 2 trial of petrelintide given with enicepatide (Roche's incretin drug, also called CT-388) is registered as not yet recruiting, with an estimated start of September 30, 2026 (NCT07589686).
• Not checked: European (CTIS) and other national trial registries. A Phase 3 trial could be registered elsewhere or announced after our check.

What further trials need to establish

1. Peer-reviewed Phase 2 results. Full ZUPREME-1 data, with both analysis methods, results by dose group, and side effects by dose group.
2. Results in type 2 diabetes. ZUPREME-2 has finished, according to the registry, but no results have been reported.
3. Large, longer Phase 3 trials. Registered, randomized trials in thousands of people over a year or more, showing whether weight loss holds and whether rarer side effects appear.
4. A real tolerability comparison. If the claim is 'easier to tolerate than GLP-1 drugs', a trial needs to randomize people to both and measure side effects and dropouts directly.
5. Body composition in people. Whether the weight lost is mostly fat, measured properly, rather than inferred from animal studies.
6. Combination value. Whether adding petrelintide to an incretin drug helps enough to justify a second drug, which is what the planned Roche combination trial is for.
7. Health outcomes beyond the scale. Effects on blood sugar, blood pressure, liver fat, and heart and kidney outcomes, which weight-loss trials alone don't show.

The bottom line

Amylin and GLP-1 are two different fullness signals that happen to overlap. Petrelintide is a clean test of whether the amylin signal alone is enough. The published human evidence is early: two small Phase 1 trials. The Phase 2 results look promising but are still sponsor-reported. The idea that it is gentler than GLP-1 drugs is a hypothesis nobody has tested head to head. Phase 3 is planned, not confirmed as started. For how amylin drugs compare with each other, see cagrilintide vs pramlintide.

What this does not mean