Incretin Landscape: The GLP-1 Revolution and Beyond
Side-by-side analysis of the incretin-class drugs discussed at SDDS 2026. Each generation outmodes the last primarily by efficacy — technological obsolescence, not patent cliffs.
The Competitive Landscape
| Drug | Mechanism | Developer | Weight Loss | Dosing | Stage | Differentiator |
|---|---|---|---|---|---|---|
| Semaglutide | GLP-1 mono-agonist | Novo Nordisk | ~15% | Weekly SC or daily oral | Approved | First-mover; massive outcomes data |
| Tirzepatide | Dual GIP/GLP-1 agonist | Lilly | ~21-22% | Weekly SC | Approved | Step-up efficacy over semaglutide |
| Orforglipron | Oral small-molecule GLP-1R agonist | Lilly | ~15% (maintenance) | Daily oral | Approved | Manufacturable at 2B patient scale |
| Maritide | GIPR antagonist + GLP-1 agonist peptides | Amgen | Profound, no plateau at 52 wk | Monthly SC | Phase 3 | Geometry-driven heterodimerization |
| Retatrutide | GIP/GLP-1/glucagon triple agonist | Lilly | 28.7% | Weekly SC | Phase 3 | Highest weight loss recorded |
| Amylin agonist | Amylin receptor | Lilly | ~20% | TBD | Phase 2 | GI vomiting ~1/52 (vs ~21% semaglutide) |
| Survodutide | GLP-1/glucagon dual agonist | BI/Zealand | ~20% | Weekly SC | Phase 3 | MASH indication focus |
Three Strategic Axes
1. Efficacy Escalation
Each generation pushes deeper weight loss:
- ~15% → GLP-1 mono (semaglutide)
- ~21% → GIP/GLP-1 dual (tirzepatide)
- ~29% → GIP/GLP-1/glucagon triple (retatrutide)
Yet as Custer noted: “85% of patients on tirzepatide did not achieve a BMI of 25 or below. As proud as I am of this medicine — it is still not good enough.”
2. The Scale Imperative
Injectable pens require sterile fill-finish serving single-digit millions. To reach 2 billion patients:
- Orforglipron solves this — “like a blood pressure pill,” arrives by train car
- Maritide’s monthly/quarterly dosing reduces injection burden but doesn’t solve manufacturing scale
- The scale argument may matter more than peak efficacy for global impact
3. Tolerability as Differentiator
GI side effects (nausea, vomiting) remain the primary attrition driver:
- Semaglutide: ~21% vomiting rate
- Amylin agonist: ~1 in 52 — orthogonal tolerability for GLP-1 intolerant patients
- Maritide’s monthly dosing may reduce cumulative GI exposure
Beyond Cardiometabolic
Incretin signaling is being reconceived as general-purpose neuromodulation. Lilly’s pipeline extends into:
| Therapeutic Area | Phase | Indications |
|---|---|---|
| Psychiatry | Phase 3 | MDD, schizophrenia, bipolar |
| Substance use | Phase 3 | Alcohol, tobacco, opioid use disorder |
| Pain | Phase 3 | Osteoarthritis, chronic lower back pain |
| Pulmonary | Phase 2/3 | Asthma |
| GI/I&I | Phase 2/3 | IBS, IBD, psoriasis |
The Muscle Loss Debate
- Lean mass loss during major weight loss is physiologically normal (~80/20 fat-to-lean split regardless of mechanism — bariatric surgery shows the same ratio)
- BELIEVE study (semaglutide + bimagrumab): clear bias toward fat loss over lean mass loss
- Key question is functional preservation, not absolute lean mass — resistance training remains the standard of care alongside pharmacotherapy
Cross-References
- Obesity — disease page
- Maritide — GIPR antagonist + GLP-1 agonist (Amgen)
- Retatrutide — GIP/GLP-1/glucagon triple (Lilly)
- GLP-1 receptor — target page
- Jay Bradner — Maritide presentation
- Kenneth Custer — Lilly incretin roadmap
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