Eloralintide

Eloralintide (LY3841136) is Eli Lilly's selective amylin receptor agonist now in Phase 3 for obesity. In a 48-week Phase 2 trial, the highest dose delivered ~20% body weight loss as a standalone drug - a number that puts a monotherapy on par with some combination regimens [1]. Lilly has launched four Phase 3 trials (the ENLIGHTEN program) enrolling nearly 5,000 people across obesity with and without type 2 diabetes, obstructive sleep apnea, and as add-on therapy for patients who hit a weight-loss plateau on GLP-1 drugs [4][5][6][7]. The real strategic play here is not eloralintide alone: it's eloralintide stacked on top of tirzepatide (Zepbound/Mounjaro), which Lilly is already testing in a Phase 2 combination trial expected to read out mid-2026 [8]. If that combination works, Lilly would own both halves of the amylin-plus-incretin formula - a direct counter to Novo Nordisk's CagriSema, which bundled cagrilintide with semaglutide and filed for FDA approval in December 2025 [9].

Eloralintide is a novel compound - never approved for any indication. Lilly has moved fast: Phase 1 data came in early 2024, Phase 2 results published in the Lancet in late 2025, and four Phase 3 trials are now recruiting [1][2][3]. No FDA designations (Fast Track, Breakthrough Therapy, or Priority Review) have been reported for eloralintide as of March 2026. The ENLIGHTEN Phase 3 program spans four trials: ENLIGHTEN-1 (obesity without diabetes, n=1,980) [4], ENLIGHTEN-2 (obesity with type 2 diabetes, n=1,035) [5], ENLIGHTEN-3 (obstructive sleep apnea with obesity, n=800) [6], and ENLIGHTEN-6 (persistent obesity despite incretin therapy, n=900) [7]. Primary completion dates range from January 2028 (ENLIGHTEN-2) to June 2028 (ENLIGHTEN-6), meaning the earliest top-line Phase 3 data could arrive in early-to-mid 2028, with a regulatory filing plausible by late 2028 or 2029. A Phase 1 renal impairment study (NCT07426380, n=28) is also running - standard pharmacokinetic work needed for the label [10]. Perhaps more consequential than any individual Phase 3 trial: the Phase 2 combination study of eloralintide plus tirzepatide (NCT06603571, n=350) has a primary completion date of June 2026 [8]. That dataset will be the first real signal on whether amylin plus dual incretin agonism can push weight loss into the 25-30% range.

Amylin is a hormone your pancreas secretes alongside insulin every time you eat. It acts on a brain region called the area postrema - essentially a sensor that sits outside the blood-brain barrier and monitors what's circulating - to generate satiety signals, slow gastric emptying, and suppress glucagon (a hormone that raises blood sugar) [3]. GLP-1 receptor agonists like semaglutide and tirzepatide also reduce appetite, but they work through different neurons in overlapping brain areas. Amylin targets calcitonin receptor-expressing neurons; GLP-1 targets a separate set. In preclinical models, there is virtually no overlap in the neurons activated by each pathway [3]. This is the biological basis for combining them: two independent brake lines on appetite, applied simultaneously. Eloralintide was designed to be selective for the AMY1 receptor subtype, with 12-fold selectivity over the calcitonin receptor and 11-fold selectivity over AMY3R [3]. Why does that matter? The calcitonin receptor is thought to mediate some of the nausea that plagued earlier amylin analogs like pramlintide (which had to be injected before every meal and still made people sick). In head-to-head preclinical testing against Novo's cagrilintide, eloralintide caused significantly less conditioned taste aversion at equivalent appetite-suppressing doses (p < 0.05), and it drove weight loss preferentially through fat mass rather than lean mass [3]. It's a once-weekly subcutaneous injection - a significant practical advantage over pramlintide's three-times-daily dosing.

The registrational trial referenced in the node data is ENLIGHTEN-1 (NCT07321886): a Phase 3, randomized, double-blind, placebo-controlled study in 1,980 adults with obesity (BMI ≥30) or overweight (BMI ≥27 with a weight-related comorbidity) who do not have type 2 diabetes [4]. The primary endpoint is percent change from baseline in body weight at 64 weeks. Multiple eloralintide dose levels are tested against placebo, with subcutaneous once-weekly administration. Study duration is approximately 75-80 weeks including a treatment-free follow-up period. This is a well-powered study - the enrollment target reflects Lilly's confidence and the Phase 2 effect sizes. The broader ENLIGHTEN program tests eloralintide across the standard obesity regulatory playbook: without diabetes (ENLIGHTEN-1), with type 2 diabetes (ENLIGHTEN-2, n=1,035, NCT07282600) [5], obstructive sleep apnea (ENLIGHTEN-3, n=800, NCT07369011) [6], and as add-on to incretin therapy for patients with persistent obesity (ENLIGHTEN-6, n=900, NCT07392190) [7]. ENLIGHTEN-6 is the most strategically interesting trial - it directly tests whether amylin agonism can break through the weight-loss plateau that many patients hit after 6-12 months on GLP-1 drugs. The Phase 2 data supporting this program showed dose-dependent weight loss from 9.5% (1 mg) to 20.1% (9 mg) at 48 weeks, with a placebo-subtracted effect of up to 19.7% [1]. Nausea was the main tolerability concern, reaching 64% at the 6 mg dose versus 14% on placebo, though slower titration schedules helped [1].

Our model gives this drug a 51% chance of eventually being approved. The starting point is the historical approval rate for Phase 3 drugs in this area - about 66% - which the model then adjusts using ten facts about the trial and its sponsor. The estimate is pulled up by larger-than-typical enrollment, more secondary endpoints than usual, and the sponsor's strong approval track record, but pulled down by weak or limited earlier-phase results. The remaining factors are close to average for this stage, so they leave the final number near 51%.

Eloralintide is a high-conviction watch. This is Lilly's answer to CagriSema, and the Phase 2 monotherapy data are genuinely impressive - 20% weight loss from a single-mechanism drug at 48 weeks is a strong foundation to build on [1]. The strategic logic of pairing it with tirzepatide is obvious: if amylin plus GLP-1 is the next frontier in obesity pharmacotherapy (and CagriSema's data suggest it is [9]), then amylin plus GIP/GLP-1 should be at least as good, possibly better. The catalyst to watch is the Phase 2 eloralintide-plus-tirzepatide combination readout, expected around mid-2026 [8]. That dataset will tell us whether stacking these two mechanisms produces additive weight loss or something closer to the ceiling. If the combination delivers 25%+ body weight reduction at 48 weeks with tolerable side effects, Lilly has a pipeline asset that could extend and protect its obesity franchise well beyond tirzepatide's patent life. The company generated $36.5 billion from Mounjaro and Zepbound in 2025 [11], and the entire obesity portfolio strategy depends on having next-generation options ready. Check back in Q3 2026 for the combination Phase 2 data. The Phase 3 monotherapy readouts (starting early 2028) are the next major milestones after that. The risk to track: nausea management in Phase 3. If dropout rates run high, the efficacy advantage narrows.