Weight Loss: Eloralintide (LY3841136) – Eli Lilly's Selective Amylin Agonist After Tirzepatide

Lancet Phase 2 (Dec 2025): −20% body weight at 48 weeks, once weekly, AMY1R-selective. Why this compound finally decouples the satiety axis cleanly from GLP-1 — and why it could become the third pillar of pharmacological obesity therapy.

While Semaglutide and Tirzepatide have dominated the obesity landscape over the past five years, Eli Lilly is now advancing Eloralintide (development code LY3841136), a compound that rebuilds the satiety mechanism on a new foundation: a selective, long-acting amylin receptor agonist with no meaningful cross-reactivity at calcitonin or AMY3 receptors. The Phase 2 RCT was published on 6 December 2025 in the Lancet (Billings et al., Lancet 2025 Dec 6;406:2631-2643, PMID 41207310): 263 adults with obesity, 48 weeks, six dose levels — and the result is clear: the 9 mg dose achieved a mean weight reduction of −20% versus −0.4% on placebo. With once-weekly subcutaneous injection. Without GLP-1. This is not just another pipeline candidate — this is Lilly's answer to Novo Nordisk's Cagrilintide, and it positions amylin as an independent pharmacological pillar at last.

Readers of the previous article on Cagrilintide and CagriSema will recognise the argument: GLP-1 agonists alone achieve 15–21% weight loss depending on the study, but plateau in a substantial fraction of patients. Amylin agonists act at a different node of the satiety circuit — in the brainstem, in the area postrema, via the nucleus of the solitary tract. Eloralintide makes this mechanism pharmacologically cleaner than any predecessor molecule.

Background: Amylin — the Forgotten Satiety Hormone

When you think of obesity hormones, leptin, ghrelin and insulin come to mind first — and, since 2020, GLP-1. Amylin (also IAPP – Islet Amyloid Polypeptide) is easily overlooked, although it plays an equally central physiological role in satiety regulation. The 37-amino-acid peptide is co-secreted with insulin from pancreatic beta cells in response to the same stimulus: glucose, meals, sulphonylureas.

The biological actions of amylin are particularly relevant in the context of the obesity pipeline:

• Satiety: Amylin binds AMY1R/AMY2R/AMY3R in the area postrema, a circumventricular brainstem region without a blood–brain barrier. The signal travels via the nucleus of the solitary tract to the hypothalamus — the feeling of fullness arrives during a meal and portion size decreases.
• Gastric emptying: Amylin slows gastric emptying via vagal afferents and direct central action, flattening the postprandial glucose and triglyceride peak.
• Postprandial glucagon suppression: Amylin suppresses postprandial glucagon release from alpha cells — a separate, insulin-independent pathway.
• Long-term body-weight effect: In chronic hyperglycaemia and obesity the amylin system is frequently down-regulated — similar to leptin resistance. Exogenous supply reactivates the satiety set-point.

The pioneer among therapeutic amylin analogues was Pramlintide (Symlin), approved in 2005 as an adjunct to insulin therapy in type 1 and type 2 diabetes. Pramlintide is a modified rat amylin analogue that avoids the aggregation of human amylin (which contributes to islet amyloidosis in type 2 diabetes) — but its short half-life and frequent injections (3× daily at meals) made it unattractive for obesity therapy. Only the second generation with slowed clearance — Cagrilintide, Eloralintide, Petrelintide — makes amylin pharmaceutically usable for chronic weight reduction (Bailey, Flatt & Conlon, Peptides 2026, PMID 41747885).

Sequence and Chemistry: What is Eloralintide at the Molecular Level?

Eloralintide (LY3841136) is a synthetic human amylin analogue, optimised through targeted amino-acid substitutions to address three first-generation problems: aggregation, rapid clearance and lack of receptor selectivity.

1. Aggregation: Human amylin aggregates into amyloid fibrils in type 2 diabetes. Like Pramlintide, Eloralintide carries substitutions at amyloidogenic positions 25, 28 and 29 that prevent fibril formation.
2. Clearance: Native amylin is rapidly degraded renally (half-life ≈ 50 min). Eloralintide was equipped with a fatty-acid side chain and albumin-affine modifications that enforce albumin binding in the subcutaneous depot, extending half-life to several days — consistent with once-weekly dosing (Bhattachar et al., PMID 41559929).
3. Receptor selectivity: Eloralintide was optimised for AMY1R preference. In vitro, it activates AMY1R 12-fold more strongly than CTR and 11-fold more strongly than AMY3R (Briere et al., PMID 41109426). Cagrilintide lacks this selectivity.

The exact primary sequence and acylation position are not disclosed — Lilly withholds them for patent and regulatory reasons. What is known: the molecule is 37 amino acids long, N-terminally modified, C-terminally amidated, with a fatty-acid side chain and resistance-conferring substitutions in the amyloidogenic region.

Mechanism of Action: Satiety in the Brainstem — Without the Pancreas

The mechanism of action of Eloralintide differs in one pharmacologically decisive point from Cagrilintide and Pramlintide: selectivity. While Cagrilintide is a promiscuous amylin/calcitonin receptor agonist and Pramlintide shows mixed activity, Eloralintide preferentially activates the AMY1R subtype — that is, the calcitonin receptor paired with RAMP1 (Receptor Activity-Modifying Protein 1).

The signalling cascade proceeds as follows:

• Subcutaneous injection (1×/week) → slow release from the albumin-bound depot, half-life several days
• Systemic distribution → AMY1R-expressing tissues, especially the area postrema (brainstem, circumventricular organ, no blood–brain barrier)
• AMY1R activation in the area postrema → cAMP rise in neurons that project to the nucleus of the solitary tract
• Nucleus of the solitary tract → relay station to the hypothalamus (arcuate nucleus, paraventricular nucleus) and to the ventral reward loop
• Result: satiety signal during the meal, reduced portion size, reduced postprandial glucagon release, delayed gastric emptying

Unlike GLP-1 agonists (gut–brain), the amylin pathway is evolutionarily older and more conserved. Satiety via amylin is a pre-installed safety valve against overfeeding — released physiologically whenever insulin is released. Pharmacological reactivation bypasses the GLP-1 axis entirely, making Eloralintide attractive as a Tirzepatide combination partner: two orthogonal satiety mechanisms, no pharmacological interference (Lempesis & Dalamaga, Metabol Open 2026, PMID 41948476).

Preclinical Evidence: Fat Loss with Muscle Preservation

In the preclinical studies published in Mol Metab (Briere et al., PMID 41109426), Eloralintide reduced food intake and body weight in diet-induced obese rats in a dose-dependent manner — primarily through fat-mass loss. That is an important difference from pure GLP-1 agonists, for which 25–40% of the weight loss comes from fat-free mass. If this body-recomposition benefit is confirmed in Phase 3, Eloralintide is pharmacologically complementary to Tirzepatide.

Clinical Evidence

Phase 1 — Safety, Pharmacokinetics, Dose-Finding (Bhattachar 2026, PMID 41559929)

The Phase 1 multiple-ascending-dose study ran March 2022 – January 2024 at three US centres. 100 participants with obesity (mean age 44, 29% women, BMI 32.6) were randomised into five cohorts and received Eloralintide or placebo subcutaneously once weekly for 12 weeks — without dose escalation.

• Pharmacokinetics: AUC_τ,ss and C_max were dose-proportional (ratios 1.1 and 1.0). Linear PK across the tested range.
• Weight loss at week 12: least-squares-mean reduction 2.6–11.3% across the dose groups.
• Safety: most common TEAEs: decreased appetite (19%), headache (12%), fatigue (11%). GI events low: diarrhoea 10%, nausea 8%, vomiting 4% — remarkably little for an obesity peptide. Most TEAEs were mild.
• Serious events: no deaths. One SAE in the 6 mg cohort, not study-related.

The Mol Metab publication (Briere et al., PMID 41109426) supplements a single-ascending-dose study (NCT05295940) with 48 healthy participants (BMI 27.5) and single doses of 0.04–12 mg. Favourable safety profile: 9 participants with 16 AEs, mostly mild (15/16); only 2 with 4 GI events, including one moderate nausea.

Phase 2 — Lancet Pivotal Study (Billings 2025, PMID 41207310)

The Phase 2 RCT ran from 5 February 2024 to 14 August 2025 at 46 US centres (ClinicalTrials.gov NCT06230523). Enrolled: 263 adults (18–75 years) with BMI ≥30 or ≥27 with comorbidity — without type 2 diabetes. Mean age 49 years, weight 109.1 kg, BMI 39.1 kg/m², 78% women.

Randomisation was 2:1:1:1:2:1:2 across six Eloralintide arms (1, 3, 6, 9 mg; 6→9 mg; 3→9 mg escalation) and placebo. Therapy: once-weekly subcutaneous injection over 48 weeks. Primary endpoint: percentage change in body weight from baseline.

Weight-Loss Results (Efficacy Estimand):

• Placebo: −0.4% (95% CI −2.2 to 1.4)
• 1 mg: −9% (−12.6 to −6.3)
• 3 mg: −12% (−14.9 to −9.8)
• 6 mg: −18% (−20.7 to −14.5)
• 9 mg: −20% (−22.7 to −17.5)
• 6→9 mg (escalation): −20% (−22.7 to −17.0)
• 3→9 mg (escalation): −16% (−18.6 to −14.1)

That is a dose-dependent, monotonic weight reduction. The upper end (−20%) is clinically impressive for a monotherapy without GLP-1. Tirzepatide achieved −21% in SURMOUNT-1 (72 weeks), Semaglutide −15% in STEP-1 (68 weeks), Cagrilintide alone ~−6 to −8% in Phase 2 (26 weeks). Eloralintide monotherapy therefore sits in the range of the best available therapies — on a different receptor (PMID 41207310).

Tolerability (most common adverse events):

• Nausea: 1 mg 11%, 3 mg 13%, 6 mg 64%, 9 mg 33%, 6→9 mg 54%, 3→9 mg 25% vs. placebo 14%
• Fatigue: 1 mg 0%, 3 mg 13%, 6 mg 29%, 9 mg 43%, 6→9 mg 46%, 3→9 mg 21% vs. placebo 12%

The nausea spike in the 6 mg cohort (64%) is striking — this is the least well-tolerated arm and explains why Lilly will probably pursue primarily the 9 mg group (33% nausea) and the escalation schedules (25–54%) in Phase 3. The 3→9 mg dose escalation shows the lowest nausea rate among the high-dose arms (25%) with still −16% weight loss — an attractive profile for practice.

Network Meta-Analysis — Amylin Agonists Head-to-Head (Kamrul-Hasan 2026, PMID 42175595)

A frequentist random-effects NMA published May 2026 compared all RCTs of long-acting amylin-based therapies (ABT) in adults with obesity without diabetes — Cagrilintide, Eloralintide and the fixed combination CagriSema. Endpoints: weight loss, anthropometric measures, GI safety. The NMA places Eloralintide in the upper league and highlights GI tolerability versus Cagrilintide.

Reviews — Amylin as the Third Pillar (Alhazmi & le Roux 2026, PMID 42452898; Bailey 2026, PMID 41747885)

Two narrative reviews published in 2026 summarise the state of the amylin class:

• Alhazmi & le Roux, Diabetes Obes Metab 2026 (PMID 42452898): "Amylin Analogs: The Next Major Class of Weight Loss Therapy" — the authors list Eloralintide alongside Cagrilintide, Petrelintide, MET-233i, ABBV-295 and AZD6234 as the most promising candidates. They emphasise that amylin agonists do not replace GLP-1, but act complementarily — which pharmacologically underpins the combination approach.
• Bailey, Flatt & Conlon, Peptides 2026 (PMID 41747885): "Long-acting amylin-related peptides as therapies for obesity and type 2 diabetes" — focus on the pharmacology of the second generation, including unimolecular AMYR/CTR/GLP-1R multi-agonists that are in the preclinical pipeline.

Comparison Table: The Amylin Class and Tirzepatide at a Glance

Sources: Billings et al. Lancet 2025 (PMID 41207310), Bhattachar et al. Diabetes Obes Metab 2026 (PMID 41559929), Briere et al. Mol Metab 2025 (PMID 41109426), Alhazmi & le Roux Diabetes Obes Metab 2026 (PMID 42452898).

Approval & Market: Where Does Eloralintide Stand in August 2026?

Eloralintide is investigational. Phase 2 was completed on 14 August 2025, the Lancet publication appeared on 6 December 2025. Phase 3 is in preparation; FDA/EMA approval is not expected before 2027/2028. Lilly positions Eloralintide as complementary to Tirzepatide: a fixed Tirzepatide + Eloralintide combination would be the logical next step — two orthogonal satiety mechanisms, no pharmacological interference. Novo Nordisk pursues the same concept with CagriSema (Cagrilintide + Semaglutide). The race between the two pipelines will shape the next 24 months of obesity therapy.

Alongside this, the market is watching further amylin candidates: Petrelintide (Novo Nordisk, Phase 2), MET-233i (Merck, Phase 1), ABBV-295 (AbbVie, Phase 1) and AZD6234 (AstraZeneca, Phase 1) — all listed in the review literature (Alhazmi & le Roux 2026, PMID 42452898). Eloralintide is the most advanced clinical candidate among them.

Side Effects & Safety Profile

The safety profile from Phase 1 and Phase 2 can be summarised as follows:

• Very common (>20% at high dose): nausea (dose-dependent 11–64%, placebo 14%), fatigue (0–46%, placebo 12%), decreased appetite (~19% in Phase 1). These effects are transient, peaking in the first 4–8 weeks — comparable to the titration phase of Semaglutide or Tirzepatide.
• Common (5–20%): headache, diarrhoea, vomiting, injection-site reactions, constipation. In Phase 1, remarkably moderate (diarrhoea 10%, vomiting 4%).
• Rare (<5%): severe hypoglycaemia — not reported. A theoretical risk exists only with insulin or sulphonylureas. Insulin-therapy patients should use Eloralintide only with close glucose monitoring once approved.
• Serious events: no deaths in Phase 1 or Phase 2. One serious adverse event in the 6 mg cohort of Phase 1, not study-related.
• Theoretical safety cross-check: amylin analogues are evaluated for thyroid C-cell hyperplasia / medullary thyroid carcinoma (MTC) similarly to GLP-1 agonists — a rodent-specific observation of debated clinical relevance. The published Phase 1 and Phase 2 data show no C-cell signal. In patients with a history of MTC or MEN2 syndrome, Eloralintide would be contraindicated, analogous to GLP-1 preparations.

In direct comparison to Cagrilintide and Tirzepatide, Eloralintide has a more favourable nausea profile — likely a consequence of AMY1R selectivity (less CTR activation) and clean PK without peak concentrations.

Practical Implications — Body Recomposition and Longevity

What does Eloralintide mean — beyond the sheer magnitude of weight reduction — for practice? Three aspects in the context of healthy aging and longevity:

1. Body recomposition: preclinical data from Mol Metab (Briere et al., PMID 41109426) show disproportionate fat loss with muscle preservation. If confirmed in Phase 3, Eloralintide is complementary to GLP-1 agonists, which typically lose 25–40% from fat-free mass — critical for older patients where sarcopenia increases mortality.
2. Combination with Tirzepatide: Amylin + GLP-1 = orthogonal satiety mechanisms, no interference. A Phase 2b/3 of Tirzepatide + Eloralintide is expected within 12–24 months — pharmacologically the most powerful conceivable obesity therapy.
3. Safety in long-term use: amylin agonists have a different side-effect spectrum than GLP-1 — less pancreatitis signal, no C-cell signal, no typical gastrointestinal dominance. For GLP-1-intolerant or plateaued patients, Eloralintide could be an alternative.

In the healthy-aging context, obesity is one of the most important modifiable drivers of frailty, insulin resistance and cognitive decline. A pharmacological therapy that delivers −20% weight loss with muscle preservation is essential for any serious longevity programme — provided it reaches the patient.

Outlook: What Comes After Phase 2?

Three development paths are plausible:

• Phase 3 as monotherapy: the Lancet data support a Phase 3 registration study — likely 9 mg or 3→9 mg escalation, 1×/wk s.c. Start announcement Q4 2026 / Q1 2027.
• Combination with Tirzepatide: the strategically more interesting path; Tirzepatide + Eloralintide would push satiety therapy to the next level.
• Orally available amylin agonists: Lempesis & Dalamaga (PMID 41948476) discuss the prospect of oral formulations — for GLP-1 (Orforglipron) and prospectively amylin. Oral peptide bioavailability remains the greatest pharmaceutical hurdle.

In the broader class context, pharmacological obesity therapy is becoming multimodal: GLP-1/GIP as a baseline, amylin as a satiety amplifier, glucagon agonism for energy expenditure. Eloralintide is a pioneer of the amylin pillar — and within that pillar the cleanest candidate. AMY1R selectivity is associated in animal models with less aversion and in humans with less nausea. If Phase 3 confirms this, Lilly has a pharmacological differentiator versus Cagrilintide.

Personal assessment (subjective): Eloralintide is the peptide that in 2027 could have the greatest impact on obesity therapy — not because it is the most potent monotherapy, but because it provides the first clean, combinable building block of a multimodal pharmacological obesity regimen. Tirzepatide occupies the GLP-1/GIP axis; Eloralintide the amylin axis. Together they are stronger than either alone.

Sources