The topline data
The phase 2 trial reported mean weight losses of 16.2%, 18.2% and 19.9% at 52 weeks across the three evaluated doses versus 2.0% on placebo. In T2 diabetics, the figures were 13.4%, 14.5% and 17.0%. Most importantly: the curve did not plateau, suggesting deeper losses with longer treatment.
The differentiator: 1 monthly injection
MariTide is the combination of an anti-GIPR (GIP receptor) monoclonal antibody plus a GLP-1 agonist. The antibody binding extends the pharmacological half-life, enabling a single monthly injection versus the weekly cadence of Wegovy, Mounjaro or Zepbound. In market research, patients prefer monthly over weekly dosing 3:1.
Reaction and next step
Amgen shares jumped 11% in the post-announcement session. Lilly fell 4%. Amgen confirmed it will move straight to phase 3 in 2025 with a pivotal program named MariTime, attempting to reach the FDA before retatrutide. If it succeeds, MariTide could capture the patient slice abandoning weekly treatments due to injection fatigue.
Still to be confirmed
Nausea: 60% at high dose vs ~50% typical for weeklies. Long-term tolerability of the antibody+peptide combination without generating neutralizing antibodies. Manufacturing cost of the monoclonal component — historically 5x to 10x more expensive to produce than a pure synthetic peptide.
Source: Amgen press release