■ReadoutUS26 Nov 20241 min read
MariTide shows about 20 percent weight loss with monthly dosing and the market shrugs
Amgen’s antibody-peptide hybrid matches weekly drugs on weight loss at one year without a plateau, but tolerability questions pull the shares down.
Holds at Phase 2 Mixed or neutral: news, but no net change in prospects.
The readThe efficacy is competitive; the side effect profile at the start of treatment is the problem to solve. Monthly dosing only helps if people stay on the drug past the first injections.
The data
In a 52-week phase 2 trial, people with obesity and without type 2 diabetes lost up to about 20 percent of body weight on average on MariTide, based on the efficacy estimand (people who stayed on treatment). The treatment-regimen estimand, which counts everyone, was lower. Weight loss had not plateaued at 52 weeks. People with type 2 diabetes lost less, as with other incretin drugs.
Why shares fell
Investors had hoped for more than 20 percent. Nausea and vomiting were common, mostly after the first dose, and discontinuation for side effects was higher than many expected. Amgen said a lower starting dose with gradual escalation reduced these effects in a part of the study.
The molecule
MariTide is an antibody that blocks the GIP receptor, with two GLP-1 peptides attached. Tirzepatide activates GIP; MariTide blocks it. Both approaches have produced weight loss, and why both work is still debated.
- Stage stays at phase 2; Amgen started the phase 3 MARITIME programme in 2025, which the board now shows.
- Signal flat: strong efficacy, open questions on tolerability.
Phase 3 MARITIME results, especially discontinuation rates with slower dose escalation.
Primary sourceAmgen press release, phase 2 52-week results, November 2024
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