Lilly reported phase 2b results for EloraTZP on 30 September 2026, and within hours people were saying retatrutide had been dethroned. The comparison being made is not a fair one.
EloraTZP is eloralintide, a selective amylin receptor agonist, given with tirzepatide, the drug in Zepbound and Mounjaro. In this trial they were two separate injections; the version Lilly intends to take into phase 3 is a single co-formulated one.1 At the top dose combination it produced 23.3% weight loss over 48 weeks in 367 adults who had obesity or overweight and type 2 diabetes.1
The retatrutide figure people are comparing it against, 28.3%, comes from a trial that excluded diabetes. The closer retatrutide comparison is TRIUMPH-2, in obesity with type 2 diabetes, which produced 20.8%.2 That is the honest matchup: 23.3% against 20.8%.
And the other half of the result is being left out. The dropout rate because of side effects ran 10.8% to 27.0% across the EloraTZP arms, against 2.9% for tirzepatide alone.1 At the top dose, more than one in four people stopped.
There is no published head-to-head EloraTZP-versus-retatrutide trial; a comparison of separate studies cannot establish which is better.
What did the EloraTZP trial test?
A phase 2b study whose design matters more than usual here.
NCT06603571 randomised 367 adults in the US and Argentina, all with obesity or overweight and type 2 diabetes, across ten arms in equal ratio: placebo, eloralintide alone, tirzepatide alone, and the combinations.1 Ten arms into 367 people leaves roughly 37 per arm, so the 23.3% headline rests on a group of about that size.
Treatment ran 48 weeks. Baseline A1C was 8.1%.
| At 48 weeks, efficacy estimand | Weight | A1C |
|---|---|---|
| Eloralintide 3 mg + tirzepatide 5 mg | -13.2% | -2.2% |
| Eloralintide 6 mg + tirzepatide 5 mg | -19.4% | -2.7% |
| Eloralintide 6 mg + tirzepatide 10 mg | -19.9% | -2.6% |
| Eloralintide 9 mg + tirzepatide 15 mg | -23.3% | -2.9% |
| Tirzepatide 15 mg alone | -14.8% | -2.4% |
| Eloralintide 3 mg alone | -8.2% | -1.1% |
| Eloralintide 6 mg alone | -12.3% | -1.4% |
| Eloralintide 9 mg alone | -11.1% | -1.3% |
| Placebo | -3.0% | -0.3% |
From Lilly's release.1 Average baseline weight was 232.4 lbs and average baseline A1C 8.1%.
One line in that table is odd and nobody is mentioning it. Eloralintide alone did worse at 9 mg than at 6 mg, 11.1% against 12.3%. A dose-response that goes backwards at the top is unusual, and in a trial with roughly 37 people per arm it may be noise. It is also the dose used in the top combination.
One detail from Lilly's own release is worth holding on to: the comparisons between EloraTZP and tirzepatide were secondary endpoints.1 The trial was designed to show the combinations worked, not primarily to beat tirzepatide.
EloraTZP vs retatrutide: why the comparison is wrong
Three mismatches. The first accounts for most of the gap.
Different populations. EloraTZP was tested in people with type 2 diabetes. Weight loss on every drug in this class is consistently smaller in that group. Retatrutide's 28.3% comes from TRIUMPH-1, which specifically excluded diabetes. Its diabetes trial, TRIUMPH-2, produced 20.8% at the top dose.2
Different phases. This is a phase 2b trial with roughly 37 people per arm. TRIUMPH-2 is a phase 3 trial. Phase 2 results in this field have a habit of shrinking when the trial gets larger.
Different durations. 48 weeks against 80. Weight loss curves in these trials were still descending at the end, so a longer trial is not a like-for-like comparison in either direction.
EloraTZP vs retatrutide vs tirzepatide, lined up as fairly as the data allows. All three figures below come from trials in adults with obesity or overweight and type 2 diabetes, on the efficacy estimand.
| Weight loss | Duration | Phase | Stopped for side effects | Published? | |
|---|---|---|---|---|---|
| EloraTZP, eloralintide 9 mg with tirzepatide 15 mg | 23.3% | 48 weeks | 2b | 27.0% | No, company release and conference |
| Retatrutide 12 mg, TRIUMPH-2 | 20.8% | 80 weeks | 3 | See primary paper | Yes, The Lancet |
| Tirzepatide 15 mg, same trial as EloraTZP | 14.8% | 48 weeks | 2b arm | 2.9% | No |
Sources as cited.12 Semaglutide is absent because we have not verified a comparable figure in this population from a primary source.
EloraTZP is ahead on weight in a smaller and shorter trial, and its discontinuation figure warrants attention. That is a real result and it is not a dethroning.
How many people stopped taking it?
Between 10.8% and 27.0%, and it is the most striking figure in the release.
Across the EloraTZP arms, 10.8% to 27.0% of participants stopped because of adverse events. Tirzepatide alone was 2.9%. Eloralintide alone ran 0% to 10.8%. Placebo was 16.7%.1
Two things stand out. The top dose combination lost more than a quarter of its participants to side effects, roughly nine times the tirzepatide rate. And the placebo arm's 16.7% is higher than several active arms, which is unusual and worth noting before anyone treats these numbers as precise.
This also matters for reading the headline figure. 23.3% is the efficacy estimand, which estimates what would have happened had everyone stayed on treatment. In a trial where up to 27% did not, the gap between that number and what a group of real patients would average is wider than usual.
Why combine amylin with an incretin at all
A different hormone. That is the whole point.
Tirzepatide acts on the GIP and GLP-1 receptors. Retatrutide adds glucagon, a third incretin pathway. Eloralintide is not an incretin at all: it is an amylin receptor agonist, and amylin is a separate hormone released alongside insulin that acts on satiety through different brain circuits.
So this is not a dose increase wearing a new name. Adding amylin to an incretin is a genuinely different combination from adding a second incretin, and it is the strategy both large manufacturers are pursuing. Our guide on stacking covers why combining two GLP-1 drugs is advised against on both approved labels while this pairing is being developed deliberately.
Has an amylin combination been tried before?
Yes, and it did not go well. Novo's has already reported.
CagriSema pairs cagrilintide, an amylin analogue, with semaglutide. In its head-to-head trial against tirzepatide alone, it missed non-inferiority. A purpose-built amylin and incretin combination, properly dosed and escalated, failed to beat a single drug, and our piece on that result covers what it did and did not show.
That does not predict anything about EloraTZP, which uses a different amylin agent and a different partner. It does mean the amylin plus incretin strategy has one prior readout at this level, and that readout disappointed.
It is also the reason the discontinuation figure deserves the weight this page gives it. The first combination in this class produced less benefit than hoped. The second is producing more weight loss and losing a quarter of its top-dose arm.
What happens next
Eloralintide alone is already in phase 3 for obesity.1 The combination is at the end of phase 2.
Lilly states in the release that it will initiate phase 3 trials of EloraTZP in the fourth quarter of 2026, using a co-formulation product and an optimised escalation schedule.1
That last phrase is worth noticing. An optimised escalation schedule is what a company changes after a quarter of its top-dose arm stopped because of side effects.
Full results have not appeared in a peer-reviewed journal. What exists is a company release and a conference presentation, which is the same standing TRIUMPH-3 and TRIUMPH-4 have, and a step below TRIUMPH-1 and TRIUMPH-2, which are published.
What this tells you about the vial being sold
Very little. The gap is wider here than usual.
Eloralintide is already on the grey market. In our October 5, 2026 capture, 11 sellers list it across 11 listings, all vials, with 10 mg the most common stated size and a median price of $17.80 per mg among in-stock single vials with a stated size.3 Several list it under abbreviations rather than the compound name.
Three things that trial does not tell you about those vials. It tested eloralintide manufactured by Lilly, at known doses, alongside tirzepatide, under supervision. A research-labelled vial is none of those things. It tested a combination, so results from the combination arms say nothing about eloralintide used alone. The tracked price is a reason to be more careful about what is in the vial rather than less.
The trial also reported a side effect profile from a setting where people were monitored and could stop. More than a quarter of them did.
Common questions
Is EloraTZP better than retatrutide?
No comparison exists. In the fairest available matchup, both in people with obesity and type 2 diabetes, EloraTZP produced 23.3% over 48 weeks in phase 2b and retatrutide produced 20.8% over 80 weeks in phase 3. EloraTZP's discontinuation rate at the top dose was 27.0%; these are separate trials, not a head-to-head comparison.
Why do people say retatrutide was beaten?
Because they are comparing EloraTZP's 23.3% in people with diabetes against retatrutide's 28.3% in people without. Those come from different populations, and weight loss runs lower in diabetes for every drug in this class.
What is EloraTZP?
Eloralintide, a selective amylin receptor agonist, given together with tirzepatide, a dual GIP and GLP-1 receptor agonist. Lilly describes it as a combination of the two.
Is EloraTZP one injection or two?
Two, in this trial. Lilly's release states that eloralintide and tirzepatide were administered as separate injections in the phase 2b study. The company plans to advance a co-formulation product, a single injection, into phase 3 by the end of 2026. So the thing tested and the thing intended for market are not the same product.
How many people were in the trial?
367 adults across ten arms, which leaves roughly 37 per arm. The 23.3% figure comes from one of those arms.
What is the EloraTZP dropout rate?
Between 10.8% and 27.0% across the EloraTZP arms, against 2.9% for tirzepatide alone, 0% to 10.8% for eloralintide alone, and 16.7% for placebo.
How is this different from stacking two GLP-1 drugs?
Eloralintide is not an incretin. It acts on the amylin receptor, a separate hormone pathway, which is why combining it with tirzepatide is a different proposition from combining two incretins. Both approved GLP-1 labels advise against combining their drug with another GLP-1 agonist.
Has an amylin combination been tried before?
Yes. Novo's CagriSema pairs cagrilintide with semaglutide and missed non-inferiority against tirzepatide alone in its head-to-head trial. That does not predict EloraTZP's result, which uses different drugs, but it is the one prior readout for this strategy.
When will EloraTZP be available?
Not soon. Lilly says phase 3 will start in the fourth quarter of 2026, using a co-formulated single injection and a revised escalation schedule. Eloralintide on its own is further ahead and already in phase 3 for obesity.
Does this apply to eloralintide bought online?
Not directly. The trial used a Lilly-manufactured product at known doses, mostly alongside tirzepatide, with monitoring. 11 of the sellers we track list eloralintide, and the trial says nothing about what is in those vials.
Sources
- Eli Lilly and Company. Lilly's EloraTZP (combination of eloralintide and tirzepatide) delivered greater weight loss and A1C reduction vs. tirzepatide 15 mg in adults with obesity and type 2 diabetes. 30 September 2026. prnewswire.com. Company release, with results presented at the 62nd Annual Meeting of the European Association for the Study of Diabetes in Milan. Phase 2b trial NCT06603571, 367 adults with obesity or overweight and type 2 diabetes in the US and Argentina, randomised in equal ratio across ten arms to placebo, eloralintide, tirzepatide or EloraTZP, over 48 weeks from a baseline A1C of 8.1%. Average baseline weight 232.4 lbs and baseline A1C 8.1%. Efficacy estimand weight and A1C change: -13.2% and -2.2% (eloralintide 3 mg with tirzepatide 5 mg); -19.4% and -2.7% (6 mg with 5 mg); -19.9% and -2.6% (6 mg with 10 mg); -23.3% and -2.9% (9 mg with 15 mg); -14.8% and -2.4% (tirzepatide 15 mg); -8.2% and -1.1%, -12.3% and -1.4%, -11.1% and -1.3% (eloralintide 3, 6 and 9 mg alone); -3.0% and -0.3% (placebo). A1C change up to -2.9% against -2.4%. Discontinuation due to adverse events 10.8% to 27.0% with EloraTZP, 0% to 10.8% with eloralintide, 2.9% with tirzepatide and 16.7% with placebo. Comparisons between EloraTZP and tirzepatide were secondary endpoints. Eloralintide is already in phase 3 as a single agent for obesity. The release states that eloralintide and tirzepatide were administered as separate injections in this study, and that Lilly plans to advance an EloraTZP co-formulation product into phase 3 by the end of 2026 using an optimised escalation schedule. The primary endpoint was EloraTZP against placebo; all other comparisons were secondary. ↩
- Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2). The Lancet, published 29 September 2026, presented at the same EASD meeting. Phase 3 trial. Weight loss up to 20.8% at 80 weeks. Dose-specific adverse-event discontinuation figures are not compared here because we have not independently verified them from the paper. ↩
- Peptide Decoding vendor price capture, October 5, 2026. peptidedecoding.com/prices/eloralintide. Our own data, counting each live storefront product row as a listing. The current listing, seller, vial-form, most common size and in-stock single-vial median figures are computed from the current price capture. Several listings use an abbreviation rather than the compound name. ↩
Citing this page. Peptide Decoding. EloraTZP Hit 23.3%. It Is Not Beating Retatrutide Yet. Trial figures from Lilly's release of 30 September 2026; listing data from the October 5, 2026 capture. https://peptidedecoding.com/news/eloratzp-phase-2b