Next-gen incretins — retatrutide, cagrisema, orforglipron pipeline.

Why the pipeline matters more than the launch

Semaglutide and tirzepatide rewrote what obesity pharmacotherapy can plausibly achieve in adults. The 2024-2026 conversation is no longer whether incretins work — that question is closed. The conversation is which mechanism stack works best, in which patient, with what tradeoffs, and at what cost. The pipeline answers all four questions differently.

Three molecules are doing most of the post-tirzepatide reshaping. Retatrutide (Eli Lilly) is a triple agonist hitting GLP-1 (glucagon-like peptide-1), GIP (glucose-dependent insulinotropic polypeptide), and the glucagon receptor. Cagrisema (Novo Nordisk) is a co-formulation of cagrilintide (a long-acting amylin analog) plus semaglutide. Orforglipron (Eli Lilly) is the first non-peptide, small-molecule oral GLP-1 receptor agonist to clear phase 3. The bet each company is making is structurally different, and the phase-3 readouts are clarifying which bets paid off.

For context on the current standard of care that these candidates are trying to displace, see our overview of tirzepatide vs semaglutide and the broader GLP-1 era.

A mechanism map for the next-gen class

It is worth being precise about what the receptors do. GLP-1 receptor activation slows gastric emptying, augments glucose-dependent insulin secretion, suppresses glucagon, and reduces appetite through both peripheral and central pathways [Drucker 2022]. GIP receptor activation has a more complicated story — historically thought to drive obesity in mice, but in the context of co-agonism appears to augment GLP-1's metabolic effects while attenuating nausea [Samms 2020].

Glucagon receptor activation is the surprise of the triple-agonist program. Activating glucagon at the liver increases energy expenditure, promotes lipolysis, and accelerates hepatic fat loss — provided you simultaneously suppress its diabetogenic effect through co-agonism at GLP-1 [Coskun 2022]. The triple agonist is essentially a thermogenic-plus-anorexigenic combination in one molecule.

Amylin works through a different pathway entirely. Endogenous amylin is co-secreted with insulin from pancreatic beta cells; it slows gastric emptying, suppresses glucagon, and produces a centrally-mediated satiety signal that is mechanistically distinct from GLP-1 [Lutz 2010]. Pairing a long-acting amylin analog with semaglutide is the pharmacologic version of stacking two different satiety pathways.

Orforglipron is structurally the most disruptive. It is not a peptide. It is a small molecule, orally bioavailable, without the dietary restrictions or absorption ceilings that limit oral semaglutide. Mechanism is conventional GLP-1 receptor agonism; the disruption is manufacturing, supply chain, and the patient experience of a pill instead of an injection.

The next-gen incretin race is not really about efficacy at this point. Efficacy is solved. The race is about route, side effects, and supply.

Retatrutide — the triple agonist (TRIUMPH)

Retatrutide (LY3437943) is the most efficacious obesity agent in clinical development as of 2026. The phase-2 readout in adults with obesity reported mean weight reduction of 24.2% at the 12 mg dose over 48 weeks — a result that was unprecedented in obesity pharmacotherapy at the time of publication [Jastreboff 2023].

The TRIUMPH program is the phase-3 registrational series. TRIUMPH-1 (adults with obesity, no diabetes) and TRIUMPH-3 (adults with obesity and cardiovascular disease) are the core obesity readouts. TRIUMPH-2 targets obesity plus type 2 diabetes. TRIUMPH-4 enrolled adults with obesity and knee osteoarthritis, pairing weight loss with a functional endpoint. Across the readouts, the 12 mg dose has reproduced approximately 24-29% mean weight reduction at 68 weeks [Lilly TRIUMPH 2025].

The safety profile is consistent with what you would predict from the mechanism. Gastrointestinal events dominate — nausea reported in roughly 38-43% of participants at the higher doses, diarrhea in roughly 33-35%, constipation in roughly 22-25%. A dysesthesia signal (skin sensitivity, tingling) reported at the 12 mg dose in TRIUMPH-4 is the most discussed unexpected finding and is being tracked across the rest of the program. Modest increases in heart rate, consistent with the class, are reported.

What retatrutide changes: the efficacy ceiling. For the first time, a single pharmacologic agent is producing weight loss in the range that bariatric surgery delivers (mean post-surgical loss of 25-30% body weight at one to two years, depending on procedure). The implication is not that surgery is obsolete — durability, comorbidity-specific outcomes, and cost-effectiveness questions remain open — but that the argument "you should consider surgery because nothing pharmacological gets close" is, in 2026, weaker than it was in 2022.

Cagrisema — amylin plus semaglutide (REDEFINE)

Cagrisema is Novo Nordisk's bet on stacking satiety pathways: a fixed weekly subcutaneous co-formulation of cagrilintide 2.4 mg (a long-acting amylin analog) plus semaglutide 2.4 mg. The hypothesis was that amylin and GLP-1 act through largely non-overlapping CNS pathways, and that co-administration would push weight loss meaningfully past what semaglutide alone could deliver.

REDEFINE 1 is the pivotal phase-3 readout in adults with overweight or obesity without diabetes. The trial reported a mean weight reduction of 22.7% at 68 weeks with cagrisema, compared with 16.1% with semaglutide 2.4 mg alone and 11.8% with cagrilintide alone [Garvey 2025]. Adherent participants reached ≥25% weight loss in roughly 40% of the cohort. By any historical standard, this is a strong result.

By the standard Novo had set publicly going in — a target of >25% mean weight loss — the readout fell short of expectations and prompted a meaningful share-price reaction. The company has since initiated REDEFINE 11 to test extended titration and re-escalation, exploring whether longer exposure or different dosing can close the gap to the triple agonist. Whether the additional 6.6 percentage points of weight loss over semaglutide monotherapy justifies the combination commercially is one question; whether it justifies it clinically — for patients who plateau on semaglutide — is a different and more useful one.

What cagrisema changes: the post-semaglutide pathway for patients who have done well but plateaued. The amylin component adds a satiety signal that does not desensitize on the same timeline as GLP-1, which matters for the durability question covered in our piece on GLP-1 weight regain.

Orforglipron — the oral small-molecule (ACHIEVE)

Orforglipron is the molecule that may reshape the supply side of the category. As a non-peptide small molecule, it can be manufactured at scale using conventional pharmaceutical processes — without the peptide-synthesis bottleneck that has constrained semaglutide and tirzepatide supply since 2022. It is dosed once daily, orally, without the fasting and water restrictions that limit oral semaglutide.

The ACHIEVE program is the phase-3 series in type 2 diabetes; the ATTAIN program is the phase-3 obesity series. ACHIEVE-1 reported A1C reductions of 1.3-1.6 percentage points and weight reductions of roughly 7-8% at the highest dose over 40 weeks [Lilly ACHIEVE 2025]. ATTAIN-1 in adults with obesity reported mean weight reduction of approximately 12% at the higher dose over 72 weeks [Aronne 2025]. In a head-to-head against oral semaglutide in type 2 diabetes (ACHIEVE-3), orforglipron showed superior A1C reduction and superior weight loss.

The efficacy is real but does not match injectable peers. Orforglipron is delivering weight loss in the range of injectable liraglutide or early-dose semaglutide — not tirzepatide, and certainly not retatrutide. The trade is route and access. A pill that produces 12% weight loss at a manufacturing cost a fraction of an injectable peptide is, for population-level prescribing, a different category of intervention.

The unofficial head-to-head

There are no completed direct head-to-head trials between retatrutide, cagrisema, and orforglipron. The numbers below are cross-trial — different populations, different baselines, different durations — and should be read as a rough orientation, not a ranking.

• Retatrutide 12 mg, 68 weeks: approximately 24-29% mean weight loss in obesity populations across TRIUMPH readouts.
• Cagrisema, 68 weeks: 22.7% mean weight loss in REDEFINE 1.
• Tirzepatide 15 mg, 72 weeks (reference comparator): approximately 20-22% mean weight loss in SURMOUNT-1.
• Orforglipron higher dose, 72 weeks: approximately 12% mean weight loss in ATTAIN-1.
• Semaglutide 2.4 mg, 68 weeks (reference comparator): approximately 15-16% mean weight loss in STEP-1.

The cross-trial ranking is reasonably stable: retatrutide first, cagrisema close second, tirzepatide third, semaglutide fourth, orforglipron fifth on weight loss specifically. On route, cost, supply, and dose flexibility, the ranking is different and orforglipron is the most disruptive of the five.

What each one actually changes for prescribing

Stepping back from the absolute weight-loss numbers, each molecule changes a different decision in real-world prescribing.

Retatrutide changes the ceiling. For patients who need the largest possible weight reduction without surgery — class III obesity, severe comorbidities, surgical contraindications — the triple agonist will be the default once approved. Whether the dysesthesia signal becomes a meaningful prescribing constraint or fades into labeling language is the open question.

Cagrisema changes the second-line pathway. The patient who has done well on semaglutide but plateaued at 12-15% weight loss has, historically, been told to add lifestyle effort or switch to tirzepatide. Cagrisema offers a third option: same molecule you tolerated, plus a complementary mechanism, with a continuity-of-care argument.

Orforglipron changes who gets treated. The injectables-only era selected against patients with needle aversion, patients in supply-constrained markets, patients in primary care settings without comfort prescribing weekly injections, and patients in jurisdictions where insurance coverage is gated to oral options first. A scalable oral option will, conservatively, double the prescribable population. Whether that is a clinical good depends on whether the prescribing happens with the same attention to body composition, comorbidity follow-up, and discontinuation planning that the injectable era has slowly built.

A tiered framework

We do not write protocols. We write frameworks. The decision below is between a patient and a prescriber.