Eloralintide: Selective Amylin Receptor Agonist Research, LY3841136 & AMY1R Selectivity

Written by NorthPeptide Research Team

For laboratory and research use only. Not for human consumption.

Eloralintide is an investigational long-acting amylin analog from Eli Lilly, developed under the code LY3841136. What separates it from earlier amylin peptides is not potency but selectivity — it was engineered to activate one receptor subtype preferentially rather than the whole family. That single design decision is the entire story of this compound, and it is what makes it a genuinely different object of study from cagrilintide, the amylin analog it is most often compared against.

Two things should be established before anything else. First, eloralintide is investigational and has not been approved by the FDA or any other regulatory authority, anywhere, for any indication. Second, the published human evidence base consists of phase 1 studies and one 48-week phase 2 trial. There is no phase 3 result. There is no long-term data. This guide covers the molecular design, the receptor pharmacology that motivated it, what the published trials actually reported, and — just as importantly — which parts of the popular story about this molecule the data does not yet support.

What Is Eloralintide?

Eloralintide is a synthetic analog of human amylin, the 37-amino-acid peptide hormone co-secreted with insulin from pancreatic beta cells after nutrient intake. Native amylin signals meal termination, slows gastric emptying, and suppresses postprandial glucagon release. Its usefulness as a pharmacological agent has always been constrained by two properties: a circulating half-life measured in minutes, and a strong tendency to aggregate into amyloid fibrils.

The discovery-to-proof-of-concept paper published in Molecular Metabolism in December 2025 describes eloralintide as a C-terminally amidated linear polypeptide of 37 amino acids, with two structural features doing the heavy lifting (PMID 41109426):

• A methylene thioacetal bridge between Cys2 and Cys7 — Native amylin carries a disulfide bond in this position. Replacing it with a methylene thioacetal linkage removes a chemically labile bond, a common stabilization strategy in peptide engineering.
• Acylation at Lys26 with a C20 fatty diacid — The lysine at position 26 carries a side chain built from two gamma-glutamate spacer residues terminating in a saturated, linear 20-carbon diacid. This lipid tail supports reversible, non-covalent binding to serum albumin, the most abundant carrier protein in plasma.

The albumin-binding strategy is the same general approach used across the long-acting metabolic peptide field, including cagrilintide and semaglutide. A peptide bound to albumin is shielded from renal filtration and enzymatic degradation, and is released gradually — converting a molecule with a minutes-long residence time into one that can be studied on a weekly administration schedule.

In the phase 1 multiple-ascending-dose study published in Diabetes, Obesity and Metabolism, eloralintide's terminal half-life was characterized as approximately two weeks, with a comparatively slow time to peak plasma concentration (PMID 41559929). The authors of that paper raised the possibility that slow absorption itself — not only receptor selectivity — could contribute to how the compound behaved on tolerability measures. That is a hypothesis in the paper, not a demonstrated mechanism, and it is worth holding alongside the selectivity argument rather than in place of it.

The Receptor Problem: Why "The Amylin Receptor" Is a Misnomer

To understand what eloralintide's selectivity means, it is necessary to understand a peculiarity of amylin receptor biology that has no clean analog elsewhere in metabolic pharmacology.

There is no dedicated amylin receptor gene. What the literature calls an amylin receptor is the calcitonin receptor (CTR) — a class B G-protein-coupled receptor whose primary role concerns bone and calcium handling — in complex with a small accessory protein from the receptor activity-modifying protein (RAMP) family. The RAMP binds the calcitonin receptor's extracellular region and reshapes its pharmacology:

• CTR + RAMP1 = AMY1R — The amylin 1 receptor. Densely represented in the area postrema and associated brainstem circuits.
• CTR + RAMP2 = AMY2R — The least characterized of the three subtypes.
• CTR + RAMP3 = AMY3R — The most broadly distributed subtype, present in brain and peripheral tissues.
• CTR alone — Reverts to a conventional calcitonin receptor.

The consequence for drug design is severe. An amylin-selective molecule is not aiming at a different protein than a calcitonin-selective one; it is aiming at the same protein wearing an accessory subunit. Selectivity has to be achieved through interactions with the RAMP-modified interface rather than through a distinct binding pocket. This is why amylin analogs have historically been promiscuous across the family, and why a compound that meaningfully separates AMY1R from CTR is a pharmacologically notable achievement independent of whether it turns out to be clinically superior.

Eloralintide vs Cagrilintide: Two Opposite Design Choices

Cagrilintide and eloralintide resolve the receptor problem in opposite directions, and the contrast is the clearest way to understand either one.

Cagrilintide does not attempt to separate the receptors. It activates the amylin receptor subtypes and the bare calcitonin receptor at broadly comparable potency, which is why it is frequently described in the literature as a dual amylin and calcitonin receptor agonist. Its developers treated the calcitonin receptor arm as part of the pharmacology rather than as an off-target liability.

Eloralintide was built the other way. In cell assays on human receptors reported in the Molecular Metabolism discovery paper, eloralintide preferentially activated human AMY1R by approximately 12-fold over the calcitonin receptor and approximately 11-fold over AMY3R (PMID 41109426).

One detail in that same paper deserves more attention than it usually receives: the selectivity ordering was not conserved across species. At rat receptors, both AMY1R and AMY3R were activated more potently than CTR — a different profile from the human one. Selectivity here is a property of a particular receptor sequence in a particular assay, not a fixed attribute of the molecule. Any preclinical rodent finding attributed to AMY1R selectivity has to be read with that caveat attached.

Mechanism of Action: What Amylin Signaling Does

The physiological effects associated with amylin receptor activation have been characterized across decades of research on native amylin, pramlintide, and more recently the long-acting analogs. The following pathways have been described in the research literature:

• Satiety signaling through the area postrema — The area postrema is a circumventricular organ in the brainstem that sits outside the blood-brain barrier, so circulating peptides reach its neurons directly. Amylin receptor activation in this region has been associated in preclinical models with reduced meal size and extended intervals between meals. This is mechanistically distinct from the hypothalamic route used by GLP-1 receptor agonists.
• Delayed gastric emptying — Amylin receptor signaling has been shown to slow gastric transit through vagal afferent pathways, prolonging the postprandial state. This effect is also the most plausible source of the gastrointestinal adverse events observed across the class.
• Suppression of postprandial glucagon secretion — Reduced glucagon release lowers hepatic glucose output after meals. In published research on amylin analogs this suppression has been characterized as glucose-dependent, preserving the counter-regulatory glucagon response.
• Leptin sensitivity — Preclinical work across the amylin class has explored whether amylin receptor activation restores responsiveness to leptin, a mechanism proposed as a reason amylin agonism may complement rather than duplicate incretin-based approaches.

Lilly's stated position on eloralintide's own mechanism is deliberately narrow: the company describes the compound as having the potential to decrease calorie intake, with the effects likely mediated by satiety. Note the hedging in that formulation — it is a description of a proposed mechanism, not a demonstrated one, and this guide does not upgrade it.

What the Selectivity Is Supposed to Buy

The rationale for building a selective amylin receptor agonist rests on a specific hypothesis: that activation of the calcitonin receptor and AMY3R contributes disproportionately to nausea and other gastrointestinal effects, while AMY1R activation carries most of the satiety signal. If that partition is real, a molecule that preferentially engages AMY1R should produce a better ratio of appetite effect to gastrointestinal burden.

This is a coherent hypothesis and it is the reason the compound exists. It is not, at present, an established fact. Three points bear on whether the published data supports it:

• The supporting comparison is preclinical and indirect. In the discovery paper, eloralintide induced significantly less conditioned taste avoidance in lean rats than cagrilintide (p < 0.05). Conditioned taste avoidance — where an animal learns to avoid a flavor it associates with feeling unwell — is the standard rodent proxy for nausea, but it is a proxy. A rat cannot report nausea.
• The species discrepancy undercuts the mechanistic chain. The rat receptor selectivity profile differs from the human one, which weakens the inference from a rat behavioral result to a human tolerability claim built on human receptor selectivity.
• No head-to-head human comparison exists. Eloralintide and cagrilintide have not been compared in the same trial in humans. Cross-trial comparison of adverse event rates between separately designed studies with different populations, escalation schemes and reporting conventions does not settle the question.

It is also not settled that avoiding the calcitonin receptor is desirable at all. Calcitonin receptor engagement may contribute to the efficacy of the dual agonists rather than only to their side effects. The selective and non-selective design philosophies are, at this point, competing hypotheses under test — not a solved problem with a known winner.

Preclinical Research

The preclinical package described in the Molecular Metabolism paper covered in vitro receptor pharmacology in cell lines expressing rat or human AMY1R, AMY3R, or CTR, followed by in vivo work in rats and monkeys (PMID 41109426). Reported findings included:

• In diet-induced obese rats, eloralintide reduced food intake dose-dependently and lowered body weight, with the reduction described as occurring primarily through loss of fat mass.
• In lean rats, eloralintide produced significantly less conditioned taste avoidance than cagrilintide.
• Pharmacokinetic profiles in both rats and monkeys were characterized as favorable and consistent with once-weekly administration in subsequent human study designs.

Clinical Trial Data

Published human data on eloralintide comes from phase 1 studies and one completed phase 2 trial. Everything below describes observations in enrolled trial participants under controlled research conditions.

Phase 1: Single-Dose Findings

The discovery paper reported a phase 1 evaluation in 48 healthy participants with a mean body mass index of 27.5 kg/m². Among participants who received single administrations of 4 mg and 12 mg, the mean percent change in body weight from baseline at week 4 was −2.5% and −4.4% respectively, compared with +0.6% in the placebo group. Adverse events reported in this study were predominantly mild (PMID 41109426).

Phase 1: 12-Week Multiple Ascending Dose Study

Bhattachar and colleagues published a 12-week randomized, placebo-controlled, participant- and investigator-blinded multiple ascending dose study in Diabetes, Obesity and Metabolism, enrolling 100 participants with obesity or overweight (mean age 44 years, 29% female, mean BMI 32.6 kg/m²) across five dose cohorts administered without escalation (PMID 41559929). Reported observations included:

• Least-squares mean percent reduction in body weight across the dose cohorts ranged from 2.6% to 11.3% at week 12.
• Steady-state exposure and peak concentration were dose-proportional at week 12.
• The most common treatment-emergent adverse events across the eloralintide cohorts were decreased appetite (19%), headache (12%), fatigue (11%) and COVID-19 (11%).
• Gastrointestinal events were characterized as infrequent: diarrhea 10%, nausea 8%, vomiting 4%.
• Most treatment-emergent adverse events were mild in severity. There were no deaths, and one serious adverse event was reported and assessed as unrelated to study drug.

These phase 1 gastrointestinal rates are the origin of much of the "gentle amylin" framing that has attached to this compound. They should be read against the phase 2 data below, which came from a longer trial with higher exposures and looked considerably less gentle.

Phase 2: 48-Week Trial (NCT06230523)

The pivotal published trial to date is a 48-week, multicenter, double-blind, randomized, placebo-controlled phase 2 study conducted at 46 research centers in the United States, published in The Lancet (PMID 41207310; NCT06230523). It enrolled 263 adults with obesity or overweight and at least one weight-related comorbidity, excluding those with type 2 diabetes. Mean age was 49 years and 78% of participants were female. The primary endpoint was percent change in body weight from baseline at week 48.

Participants were randomized to once-weekly subcutaneous placebo or to one of six eloralintide regimens. The table below records what each trial arm received and what was observed in that arm — it is a summary of trial history, not a protocol.

Trial arm	Participants	Mean body weight change at week 48	Nausea reported	Fatigue reported
Placebo	53	−0.4%	14%	12%
Eloralintide 1 mg	28	−9.5%	11%	0%
Eloralintide 3 mg	24	−12.4%	13%	13%
Eloralintide 6 mg	28	−17.6%	64%	29%
Eloralintide 9 mg	54	−20.1%	33%	43%
Escalating 6–9 mg	24	−19.9%	54%	46%
Escalating 3–9 mg	52	−16.4%	25%	21%

Weight change figures to one decimal place are as reported by Eli Lilly for the efficacy estimand (Lilly, November 2025); the published abstract reports the same values rounded to whole percentages. All treatment arms met the primary endpoint.

Two observations from this table are worth stating plainly:

• The dose-response for weight change is clean; the dose-response for nausea is not. Nausea was reported by 64% of the 6 mg arm and 33% of the 9 mg arm — more on the lower administered level. With arms of 28 and 54 participants, that inversion may simply reflect the sample sizes involved. It is recorded here because it is what the trial reported, and inventing a mechanism to explain it away would be worse than leaving it looking strange.
• Slower escalation was associated with lower symptom rates. The 3–9 mg escalation arm reached −16.4% with 25% nausea, while the fixed 6 mg arm reached −17.6% with 64%. The published trial reported that escalation starting from 3 mg reduced gastrointestinal symptoms and fatigue relative to starting at 6 mg or 9 mg.

Discontinuations and Overall Adverse Event Burden

Across the trial, adverse events were reported by 81% of participants receiving eloralintide compared with 71% receiving placebo. Adverse events leading to discontinuation occurred in 10% of eloralintide participants overall and in 8% of the placebo group — but in 21% of the 6 mg arm, the same arm that reported 64% nausea.

That figure is the single most important qualifier on the tolerability narrative surrounding this compound. A 21% adverse-event discontinuation rate in a trial arm is not consistent with a description of the molecule as uniformly well tolerated, and any summary of eloralintide that omits it is presenting an incomplete picture of its own source material.

Comparison Within the Amylin Class

The following table places eloralintide alongside other amylin-pathway peptides. Figures are drawn from separately conducted trials with different populations, durations, endpoints and escalation schemes; they are not head-to-head comparisons and should not be read as one.

Feature	Eloralintide	Cagrilintide	Petrelintide	Pramlintide
Developer	Eli Lilly	Novo Nordisk	Zealand Pharma / Roche	Amylin Pharmaceuticals
Receptor profile	Selective: human AMY1R ~12× over CTR, ~11× over AMY3R	Non-selective: amylin receptors and CTR at comparable potency	Long-acting amylin analog; selectivity profile not characterized in public materials	Amylin receptor agonist
Half-life extension	C20 fatty diacid at Lys26, albumin binding	C18 fatty diacid acylation, albumin binding	Albumin-binding acylation	None — short-acting
Reported half-life	~2 weeks	~7 days	Supports weekly administration	Hours
Most advanced published result	Phase 2, 48 weeks	Phase 2 monotherapy; phase 3 in combination	Phase 2, ZUPREME-1	Approved product (US)
Weight change reported	Up to −20.1% at week 48 vs −0.4% placebo	~10–11% at 26 weeks vs ~3% placebo	Up to −10.7% vs −1.7% placebo	Modest, adjunctive
Regulatory status	Investigational — not approved anywhere	Investigational — not approved anywhere	Investigational — not approved anywhere	Approved

Petrelintide figures are drawn from Zealand Pharma's phase 2 ZUPREME-1 announcement, which reported up to 10.7% mean body weight reduction versus 1.7% with placebo in 493 participants, with treatment discontinuation at the maximally effective dose of 4.8% versus 4.9% for placebo and no vomiting reported in that arm (Zealand Pharma, March 2026). Cagrilintide figures are covered in more depth in the cagrilintide research guide and the CagriSema overview.

The headline contrast is that eloralintide's phase 2 trial reported the largest weight change of any amylin monotherapy published to date, while petrelintide's phase 2 reported the most placebo-like tolerability. Those are different trials answering different questions, and no published study has yet asked both at once across compounds.

Development Status and Ongoing Trials

Eloralintide's development program has moved into phase 3, and into combination work with an incretin agent:

• ENLIGHTEN-1 (NCT07321886) — A phase 3 randomized, double-blind, placebo-controlled study of once-weekly eloralintide in adults with obesity or overweight without type 2 diabetes. Sponsored by Eli Lilly, with an estimated enrollment of 1,980 participants. The study began on 6 February 2026 with an estimated primary completion date of March 2028. The primary outcome measure is percent change from baseline in body weight.
• Combination with tirzepatide (NCT06603571) — A phase 2 study of eloralintide and tirzepatide, alone or in combination, in adults with obesity or overweight and type 2 diabetes. Enrollment of 367 participants, started September 2024, with primary completion recorded in July 2026.
• Broader ENLIGHTEN program — Lilly has registered additional phase 3 studies under the ENLIGHTEN name covering further obesity-related populations and endpoints.

Eloralintide has not been submitted for regulatory approval. Lilly's own public position is that any potential submission or resulting approval depends on the outcomes of ongoing and future clinical trials.

Limitations of the Current Evidence

An honest account of this compound has to be explicit about how early the evidence is. The following limitations apply to everything above:

• Phase 1 and phase 2 only. There is no published phase 3 result for eloralintide in any population. The first is not expected to reach primary completion before March 2028.
• No exposure data beyond 48 weeks. Nothing published addresses what happens with longer administration, including whether observed effects persist, plateau, or reverse on cessation.
• All human trials to date were sponsored and funded by the developer. This is normal for a compound at this stage and is not in itself a criticism, but no independent replication exists.
• Small arms. Individual phase 2 arms held between 24 and 54 participants. Adverse event rates from groups that size carry wide uncertainty, which is directly relevant to the nausea ordering discussed above.
• Narrow population. The phase 2 trial excluded participants with type 2 diabetes, was conducted entirely in the United States, and was 78% female and 78% White. Generalisation beyond that population is not supported by the published data.
• The selectivity thesis is unproven in humans. The tolerability advantage attributed to AMY1R selectivity rests on a receptor potency ratio measured in cell assays plus one rodent behavioral experiment, with a species discrepancy in the selectivity ordering and no head-to-head human comparison.
• Body composition data is not detailed in the public phase 2 materials. The rodent work described fat-mass-predominant loss; the published human summary materials reviewed for this guide do not report a comparable body composition breakdown.

Summary

Eloralintide is a scientifically interesting compound for a reason that has nothing to do with its headline weight numbers. It is a test of whether the amylin receptor family can be pharmacologically separated, and whether that separation matters.

• The design is genuinely novel. Achieving roughly 12-fold preference for human AMY1R over the calcitonin receptor, when the two share the same underlying receptor protein, is a non-trivial piece of peptide engineering.
• The efficacy signal in phase 2 was substantial. The 48-week trial reported mean body weight changes from −9.5% to −20.1% across arms versus −0.4% for placebo, with all arms meeting the primary endpoint.
• The tolerability story is more complicated than its reputation. Nausea reached 64% in one arm, 21% of that arm discontinued for adverse events, and the nausea rate did not order cleanly with administered amount.
• Slower escalation looked better on symptoms. The trial reported reduced gastrointestinal symptoms and fatigue when escalation began at 3 mg rather than 6 mg or 9 mg, at some cost to the week-48 weight figure.
• The central hypothesis remains open. Whether selective AMY1R agonism is meaningfully better tolerated than non-selective amylin agonism in humans has not been tested head-to-head, and it is not established that avoiding the calcitonin receptor is even desirable.

The comparison the field actually needs — eloralintide against a non-selective amylin analog, in the same trial, in the same population — has not been run. Until it is, the selectivity argument is a well-motivated hypothesis with supporting in vitro and rodent data, not a demonstrated clinical advantage. Anyone describing the selective design as proven gentler is ahead of the published evidence.

Researchers following the metabolic peptide landscape may also find these guides relevant: cagrilintide (dual amylin and calcitonin receptor agonist), retatrutide (triple GLP-1/GIP/glucagon agonist), and tirzepatide (dual GIP/GLP-1 agonist). For research-grade eloralintide, visit the product page.

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Summary of Key Research References

Study	Year	Type	Focus	Reference
Eloralintide phase 2 trial	2025	Clinical Trial	48-week phase 2, selective amylin receptor agonist in obesity	PMID 41207310
Eloralintide discovery to proof of concept	2025	Translational	Molecular design, receptor selectivity, rodent and primate data	PMID 41109426
Bhattachar et al.	2026	Clinical Trial	Phase 1 multiple ascending dose, pharmacokinetics and tolerability	PMID 41559929
NCT06230523	2024–2025	Trial Registry	Phase 2 eloralintide vs placebo, completed	ClinicalTrials.gov
NCT07321886 (ENLIGHTEN-1)	2026–2028	Trial Registry	Phase 3 eloralintide monotherapy, recruiting	ClinicalTrials.gov
NCT06603571	2024–2026	Trial Registry	Phase 2 eloralintide with tirzepatide, alone or combined	ClinicalTrials.gov
Eli Lilly phase 2 announcement	2025	Company Release	Arm-level weight change figures, efficacy estimand	lilly.com
Zealand Pharma ZUPREME-1 announcement	2026	Company Release	Petrelintide phase 2 comparator context	GlobeNewswire