Adding an experimental amylin drug to tirzepatide pushed average weight loss to 23.3 percent in a mid-stage trial, Eli Lilly reported Wednesday at the European Association for the Study of Diabetes meeting in Milan, up from 14.8 percent on tirzepatide alone. The extra 8.5 percentage points came with a bill. Adverse-event discontinuation ran as high as 27.0 percent across the combination arms, against 2.9 percent for tirzepatide by itself.
That spread is the Phase 2b story. The amylin add-on works. Keeping patients on it is the open question.
Two hormones, two shots
Tirzepatide ↗, sold as Mounjaro and Zepbound, already hits two gut-hormone receptors, GIP and GLP-1, to suppress appetite and lower blood sugar. Eloralintide ↗, coded LY3841136, is Lilly's selective agonist for a third pathway, the amylin receptor. Amylin is a hormone the pancreas releases alongside insulin that tells the brain the meal is over. The theory behind stacking them is that amylin adds a satiety signal the incretin drugs do not carry. The combination, which Lilly calls EloraTZP, was given in this trial as two separate injections.
The Phase 2b trial enrolled 367 adults with obesity or overweight and type 2 diabetes in the United States and Argentina, split across 10 arms over 48 weeks. The top combination, eloralintide 9 milligrams plus tirzepatide 15 milligrams, produced 23.3 percent weight loss against 14.8 percent for tirzepatide 15 milligrams alone and 3.0 percent for placebo. A1C, the three-month blood-sugar average, fell 2.9 points on the combination versus 2.4 on tirzepatide alone and 0.3 on placebo, from a baseline near 8.1 percent.
The tolerability bill
The efficacy gain is real, but so is the cost. Discontinuation for adverse events ran 10.8 to 27.0 percent across the combination arms, compared with 2.9 percent on tirzepatide alone and 16.7 percent on placebo. Gastrointestinal side effects, the familiar nausea and vomiting of this drug class, were more frequent on the combinations. Ten arms spread across 367 patients leaves roughly three dozen people per arm, small enough that the dose-by-dose safety numbers should be read as directional rather than settled.
The clearest tell is what Lilly plans next. Phase 3 will not test the two-injection regimen from this trial. It will test a co-formulated EloraTZP, a single product combining both molecules, with an adjusted dose-escalation schedule, and Lilly said it plans to start that program by the end of 2026. Reworking the escalation is a direct response to a tolerability problem, not a cosmetic change.
Where the amylin bet stands
Amylin is the most-watched second act in obesity drugs. The amylin obesity case cooled ↗ in early 2026 when the muscle-preservation and tolerability profiles investors expected did not arrive, then reopened ↗ as candidates advanced. Novo's cagrilintide, the amylin half of CagriSema, and Zealand Pharma's petrelintide, partnered with Roche, are chasing the same amylin receptor ↗. EloraTZP's 8.5-point edge over tirzepatide is the kind of number that keeps the bet alive. The up-to-27-percent dropout is the reason the drug goes to Phase 3 reformulated, not as-is.