Eli Lilly and Company (NYSE: LLY) announced results from two late-phase trials showing that participants maintained weight loss when switching from higher-dose injectable incretin therapy to either Foundayo or lower-dose Zepbound.

In the ATTAIN-MAINTAIN trial, participants who switched from Wegovy (semaglutide) maximum tolerated dose to Foundayo maintained all but 0.9 kg of their previously achieved weight loss after one year. Those switching from Zepbound maximum tolerated dose to Foundayo maintained all but 5.0 kg of their prior weight loss.

The SURMOUNT-MAINTAIN trial examined participants who continued with Zepbound at either maximum tolerated dose or reduced to 5 mg. Those remaining on maximum tolerated dose maintained all of their prior weight loss on average, while those reduced to 5 mg maintained all but 5.6 kg after one year.

Both trials met their primary and key secondary endpoints. SURMOUNT-MAINTAIN enrolled 441 participants who received open-label tirzepatide for 60 weeks before randomization to either continued maximum tolerated dose, reduced 5 mg dose, or placebo for 52 weeks. ATTAIN-MAINTAIN randomized 376 participants who had completed the SURMOUNT-5 trial.

The findings were presented at the European Congress on Obesity and published in The Lancet and Nature Medicine. Foundayo is an oral GLP-1 receptor agonist approved for adults with obesity or overweight with weight-related medical problems. Zepbound is a weekly injectable dual GIP and GLP-1 receptor agonist approved for similar indications and for moderate-to-severe obstructive sleep apnea with obesity.

Safety profiles for both medications remained consistent with previous Phase 3 studies, with gastrointestinal side effects being most common.