Obesity pipeline broadens beyond GLP-1 with new phase 3 starts

By late 2026, the obesity drug pipeline had grown well beyond the GLP-1 medicines that built the market, such as Ozempic, Wegovy and Mounjaro/Zepbound. AstraZeneca advanced its oral small-molecule GLP-1 drug elecoglipron into phase 3 testing, Structure Therapeutics began dosing patients in phase 3 trials of its oral GLP-1 candidate aleniglipron, and Zealand Pharma and Roche continued moving the amylin analog petrelintide toward late-stage trials ^[1][2]. Industry trackers now count more than 150 active obesity and weight-related drug programs, spanning GLP-1, amylin, glucagon and several non-incretin mechanisms ^[1].

In earlier-stage data, elecoglipron produced an average 11.8% body-weight loss over 36 weeks, while aleniglipron produced 15.3% weight loss over 44 weeks, according to a comparison table compiled by drug-intelligence platform Ozmosi ^[1]. Both are daily oral small-molecule GLP-1 drugs, a format similar to Eli Lilly's approved pill Foundayo (orforglipron), rather than the peptide-based oral semaglutide sold as the Wegovy pill ^[1].

Petrelintide takes a different approach. It targets the amylin receptor rather than GLP-1. In Roche's phase 2 ZUPREME-1 trial, petrelintide produced up to 10.7% average weight loss at 42 weeks, and at the highest effective dose there was no vomiting and no discontinuations caused by gastrointestinal side effects, with overall tolerability described as similar to placebo ^[1]. Roche paid $1.65 billion upfront for rights to the drug, which Zealand Pharma's partner reporting describes as a bet on amylin-based mechanisms as an alternative or complement to GLP-1 drugs ^[2]. Sources differ slightly on timing: one industry estimate lists an expected phase 3 program start around April 2031 ^[1], while an earlier report said a phase 3 program was due to begin in the second half of 2026 ^[2] — a discrepancy that reflects how fluid these estimates can be before formal trial registrations.

Why it matters for patients

For patients currently using or considering GLP-1 drugs like semaglutide (Ozempic, Wegovy, Rybelsus) or tirzepatide (Mounjaro, Zepbound), this broadening pipeline does not change anything about currently approved medicines or their side effects. But it signals that future choices may not all work the same way in the body. Elecoglipron and aleniglipron are still GLP-1 drugs, meaning they would likely carry similar gastrointestinal side effects to existing options, just in pill form ^[1]. Petrelintide, by contrast, does not act on the GLP-1 receptor at all, which is why its early tolerability data — no vomiting and no GI-related discontinuations at the top dose in one trial — has drawn attention from people who have struggled with nausea or vomiting on current drugs ^[1]. None of these drugs is approved, and none should be assumed to work as well or as safely as trial data suggest until larger, longer studies are complete.

What happens next

Elecoglipron and aleniglipron are now in phase 3, the stage required before an FDA application, though specific completion dates were not detailed in available sources ^[1][2]. Petrelintide's phase 3 program is described as either not yet begun or having a 2031 completion estimate, depending on the source, underscoring that firm timelines are not yet settled ^[1][2]. Novo Nordisk's CagriSema, an injectable combination of semaglutide and the amylin drug cagrilintide, remains under FDA review after a December 2025 submission, with a decision expected later in 2026 ^[1][2]. Until these newer drugs clear phase 3 trials and regulatory review, currently approved GLP-1 medicines remain the only options available by prescription in this class.