Amgen begins Phase 3 trial of at-home MariTide autoinjector

ClinicalTrials.gov lists a primary completion date of June 2027 for the study, which Amgen began as another Phase 3 trial in its MariTide programme. TD Cowen analysts said in a 3 November note that the trial could let Amgen launch MariTide as an autoinjector.

An autoinjector would put MariTide on the same footing as Novo Nordisk's Wegovy and Eli Lilly's Zepbound, which are sold as weekly pens. Amgen's pitch rests on dosing frequency: its long-acting design supports starting with monthly dosing, with the potential to stay on therapy with as few as four or six doses per year, the company has said.

Phase 2 set the bar

In phase 2, MariTide produced up to about 20% average weight loss over 52 weeks without reaching a plateau in people who were obese or overweight but did not have type 2 diabetes, according to Amgen's trial summary. In patients with type 2 diabetes who were obese or overweight, weight loss was about 17% at 52 weeks.

MariTide is an antibody-peptide conjugate designed to block the GIP receptor and activate the GLP-1 pathway. Amgen built it using human genetics data from its deCODE Genetics unit in Iceland, which pointed to GIP receptor blockade as a promising strategy.

Device and manufacturing plans

Jay Bradner, Amgen's executive vice president of R&D, said on the third-quarter earnings call that MariTide is expected ultimately to be delivered in a "patient-friendly single-chamber handheld autoinjector." Amgen has "significant experience" with such devices and has "taken a fairly standard approach," he said.

CFO Thomas Dittrich reaffirmed that Amgen expects capital expenditure of about $2.6 billion this year to scale manufacturing capacity for commercial growth and to prepare for a potential MariTide launch. Asked whether biosimilar production capacity could support MariTide, CEO Robert Bradway said Amgen considers all options but is confident it can remain a reliable biosimilar supplier. A series of readouts will determine how much capacity Amgen needs.

Tolerability is the open question

Ahead of the readouts, BMO Capital Markets analysts said in a 3 November note that MariTide differentiation is "still more of a show-me story." Management emphasized monthly dosing, potentially extending to four or six annual doses, and described gastrointestinal symptoms as generally short-lived despite prolonged pharmacologic activity, the analysts said. Those observations are encouraging but "do not substitute for Phase 3 tolerability data," they wrote.

Truist Securities analysts made a related point the same day, saying dose-escalation tolerability, durability and maintenance are needed to validate differentiation.

What happens next

Amgen is expected to publish the first Phase 3 MariTide data next year, before the autoinjector study completes. The MARITIME programme features 10 trials, and two more studies are scheduled to start this year, BioSpace reported. Amgen recently completed enrollment in two Phase 3 sleep apnea studies and a cardiovascular outcomes trial, according to its earnings release.

A phase 3 switch study will test patients moving from weekly tirzepatide or semaglutide to MariTide given every eight or 12 weeks. Amgen's phase 3 maintenance extension studies will evaluate how patients stay on MariTide to maintain weight loss while moving from monthly dosing to as few as four or six doses per year.