Sixteen challenger programs are now in Phase 3, and none reads out before 2027

A count of recruiting Phase 3 obesity programs in the United States as of September 2026 turns up sixteen challenger candidates — drugs from companies other than Eli Lilly and Novo Nordisk. Almost none of them is scheduled to produce a primary result before 2028. That gap between a crowded pipeline and an empty near-term calendar is the single most important fact for anyone weighing their options over the next 18 months.

The list includes Structure Therapeutics' oral aleniglipron (ACCOMPLISH-1 and -2), Eli Lilly's amylin drug eloralintide across five ENLIGHTEN trials, Roche's enicepatide in three trials, AstraZeneca's oral elecoglipron in nine, AstraZeneca's AZD6234 in three SELENE trials, ribupatide in three KaiNETIC trials, Pfizer/Metsera's berobenatide, ASC30 in AURORA-1 and -2, and several Amgen MariTide outcomes and extension studies. The two industry sources reviewed here confirm parts of that picture but do not list every trial: BioSpace reports that AstraZeneca is running a Phase 3 trial of elecoglipron in obesity and type 2 diabetes plus a separate late-stage study in type 2 diabetes alone, with analysts at William Blair expecting those to read out in 2027 or 2028 ^[1]. Pfizer's berobenatide Phase 3 program was planned as ten trials starting in 2026 ^[2], and Structure was targeting a registrational Phase 3 start in the third quarter of 2026 ^[2].

Earliest primary completion dates cluster in 2028. The nearest exception is MariTide, with January 2027 dates on some studies. Amgen's monthly injection produced up to roughly 20% weight loss over 52 weeks in Phase 2 — 12.3% to 16.2% under the stricter treatment-policy analysis — and its Phase 3 MARITIME program runs 72 weeks ^[2]. Viking Therapeutics has guided its decisive VANQUISH-1 trial, about 4,650 patients over 78 weeks, to a topline readout in late 2027 ^[2]. Structure's own market-entry estimate for aleniglipron, which produced about 16.3% placebo-adjusted weight loss at 44 weeks in Phase 2, is around 2029 ^[2].

Why it matters for patients

A readout is not an approval, and an approval is not a pharmacy shelf. Even the fastest challenger timelines imply that the branded US market remains a two-company market — Lilly and Novo Nordisk — through 2027 no matter how full the pipeline looks on paper.

That has practical consequences. Price competition in branded drugs usually arrives with a third and fourth seller. Until then, the levers that move cost and access are coverage decisions and manufacturer programs, not new entrants. Lilly's tirzepatide products Mounjaro and Zepbound, its oral Foundayo (orforglipron), and Novo's semaglutide products including the Wegovy pill are the field. Novo held about 90% of weekly oral prescriptions as of July, roughly 1.5 million people, many new to GLP-1s ^[1]. Foundayo is under regulatory review in more than 40 markets ^[1].

The more immediate access change is payment, not pipeline. A temporary Medicare GLP-1 Bridge program began in July and, by William Blair's estimate, expands coverage by about 35% and reaches roughly 20 million potential patients ^[1]. Overall, obesity therapeutics reached $66 billion in sales last year and could hit $105 billion to $200 billion by 2027 and beyond, according to IQVIA ^[1].

What happens next

Near-term news will come from earlier-stage data and regulatory decisions, not Phase 3 finishes. AstraZeneca is expected to present AZD6234 amylin data at the European Association for the Study of Diabetes meeting, held September 28 to October 2 in Italy ^[1]. Roche's Pharma Day on September 28 is expected to cover enicepatide, which produced 22.5% weight loss after nearly a year in a Phase 2 obesity study ^[1]. A US decision on Novo's CagriSema, which delivered about 22.7% weight loss, was expected in the fourth quarter of 2026 ^[1][2]. Lilly has guided a regulatory submission for retatrutide — 28.3% weight loss in TRIUMPH-1 — to early 2027 ^[1][2].

Whether any challenger files before 2029 is not yet known from these sources.