The weight-loss drug market remains firmly in the hands of Eli Lilly (LLY) and Novo Nordisk (NVO). Amgen (AMGN) is attempting to break in with the convenience of a once-monthly injection, but clinical data so far suggest its candidate MariTide poses little near-term threat.
MariTide is an antibody-peptide conjugate that blocks the GIP receptor while activating the GLP-1 receptor, a design that grants it a long half-life and enables monthly dosing. In a phase 2 trial of 592 adults with obesity but no type 2 diabetes, MariTide delivered weight loss of 12.3% to 16.2% at 52 weeks, against 2.5% for placebo. When placed alongside existing therapies, however, the results look less impressive. Eli Lilly’s tirzepatide and Novo Nordisk’s semaglutide achieved weight loss of 20.2% and 13.7% respectively at 72 weeks in head-to-head comparisons. MariTide has never been tested against these drugs in a structured trial, and its phase 2 data do not point to a dramatic efficacy advantage.
Amgen is clearly aware of its competitive position. In April, commercial chief Murdo Gordon told investors the company expects MariTide to be the best agent in the “monthly or less frequently dosed” category, framing the conversation around dosing convenience rather than a head-to-head battle on weight reduction.
That convenience argument, however, is already being squeezed. Eli Lilly’s oral drug orforglipron won approval on April 1, and a once-daily pill may prove even more attractive than a monthly injection. Novo Nordisk submitted its combination candidate CagriSema for approval in December 2025, and both companies have further pipeline assets in development. Amgen has launched a roughly 300-patient open-label phase 3 study testing a switch from existing therapies to MariTide, but results will not arrive until 2028. By then the competitive landscape may have shifted further, leaving even positive data with limited commercial impact.
Amgen’s next key catalyst is Maritime-1, a 3,501-patient phase 3 obesity trial with a primary completion date of January 21, 2027; a concurrent type 2 diabetes study finishes the same day. Until those readouts, the company holds only a presumed dosing-convenience advantage, with no direct evidence that it outperforms the incumbents on efficacy or tolerability.
Shares of Amgen closed 4.48% higher on the day, while Eli Lilly and Novo Nordisk rose 1.93% and 2.60%, respectively — hardly a signal that the market is pricing in a disruption of the duopoly. On the strength of the published data, MariTide is far from shaking up the obesity market, and both incumbents have little reason to worry for now.
