Expected: further retatrutide and MariTide program readouts

Two of the biggest questions in obesity medicine right now are how well Eli Lilly's retatrutide and Amgen's MariTide perform in large, late-stage trials, and neither company has finished answering them. Lilly has already reported some data, while Amgen's next major trial readouts are still ahead.

On July 23, 2026, Lilly announced results from two Phase 3 retatrutide trials, TRIUMPH-2 and TRIUMPH-3 ^[1]. In TRIUMPH-2, adults with obesity or overweight and type 2 diabetes lost an average of up to 49.6 pounds, or 20.8% of body weight, at 80 weeks on the highest dose tested ^[1]. In TRIUMPH-3, adults with severe obesity and established cardiovascular disease lost up to an average of 55.8 pounds, or 22.6%, over the same period ^[1]. Retatrutide is a once-weekly injection that activates three hormone receptors — GIP, GLP-1, and glucagon — rather than the one or two receptors targeted by currently approved drugs ^[1].

Lilly said these were its fourth and fifth positive Phase 3 studies for retatrutide, and that detailed results from TRIUMPH-2 and TRIUMPH-3 will be presented at future medical meetings and published in journals ^[1]. The company said it plans to submit a Biologics License Application to the FDA in the first quarter of 2027, seeking approval for obesity, knee osteoarthritis pain, and obstructive sleep apnea ^[1]. The TRIUMPH program began in 2023 and has enrolled more than 5,800 participants across four global trials ^[1]. Common side effects in the two trials included diarrhea, nausea, constipation, decreased appetite, and vomiting, with rates generally rising at higher doses ^[1].

Amgen's MariTide, a different investigational injectable, is further behind in its testing. In its first-quarter 2026 financial results, Amgen reported that research and development spending rose 16%, driven partly by higher investment in what it called "Later-Stage Clinical Programs, including those related to MariTide" ^[2]. That filing does not include specific results from MariTide's Phase 3 program, known as MARITIME, or a confirmed date for when those results will be released ^[2].

Why it matters for patients

Neither retatrutide nor MariTide is approved for use, so people currently managing weight or type 2 diabetes cannot get either drug yet. The retatrutide numbers released so far come from Lilly's own announcement, not from a peer-reviewed publication or independent review, so the full data — including how side effects played out over time and in different patient groups — are not yet public ^[1].

For patients weighing options today among approved drugs like Zepbound, Wegovy, Ozempic, Mounjaro, Rybelsus, or Foundayo, this news does not change what is available or reimbursable right now. It signals that more competition could eventually arrive, which over time might affect pricing or give doctors more choices, but that is not guaranteed and there is no timeline in these sources for when, or if, either drug reaches pharmacies.

It is also not yet known from these sources how retatrutide's cardiovascular findings — including mixed results on major adverse cardiovascular events in TRIUMPH-3 — will be interpreted by regulators, or how MariTide's safety and effectiveness data will ultimately compare ^[1][2].

What happens next

Lilly says it plans to submit its retatrutide application to the FDA in the first quarter of 2027, with full trial data to follow at medical meetings and in journals ^[1]. Amgen has not stated a specific date for MariTide's next major trial results in the source reviewed here, though its increased spending on late-stage MariTide programs suggests continued active development ^[2]. Any FDA decision on retatrutide would come after that submission is reviewed, a process not detailed in these sources.