Pfizer has reported promising developments regarding its experimental obesity drug, PF’3944, acquired through its partnership with Metsera. In a mid-stage trial, patients administered this drug once a month achieved an impressive weight loss of up to 12.3% compared to those receiving a placebo at the 28-week mark. When taking into account all patients, including those who discontinued treatment, the average weight loss remained significant at 10.5%.
Importantly, the data suggests that there was no plateau in weight loss for patients who transitioned to monthly dosing, indicating that the potential for continued weight loss remains as the study extends to 64 weeks. This finding could position PF’3944 as an appealing alternative in the market, which is currently dominated by Eli Lilly and Novo Nordisk, known for their weekly injections, alongside Novo’s newly introduced daily pill. The once-monthly dosage presents a more convenient option for patients, potentially expanding Pfizer’s reach in this competitive landscape.
Dr. Jim List, Pfizer’s chief internal medicine officer, highlighted the topline results, reinforcing the drug’s potential as a monthly treatment that holds competitive efficacy. The company is preparing to advance ten phase three trials for PF’3944 in the coming year. During a recent earnings call, Chris Boshoff, Pfizer’s Chief Scientific Officer, mentioned projections based on modeling that indicate a higher monthly dose could yield up to 16% weight loss by week 28 in late-stage trials.
This announcement coincided with Pfizer’s release of fourth-quarter earnings, which exceeded expectations, though the company’s shares fell nearly 3% in premarket trading. PF’3944 is categorized as an ultra-long-acting GLP-1 drug, designed to maintain its efficacy in the body longer than current treatments such as Novo’s Wegovy. Pfizer is exploring both weekly and once-monthly formulations and is also combining PF’3944 with other treatments that target different gut hormones.
The trial’s design incorporated an initial 12-week phase of weekly injections before transitioning to a monthly dose, aiming to determine if weight loss could continue post-transition. Patients generally tolerated the drug well, reporting mild to moderate gastrointestinal side effects, consistent with the experiences associated with other GLP-1 medications. No new safety issues were identified during the trial.
For the phase three studies, Pfizer has selected two distinct dosing regimens—a low and a medium monthly maintenance dose—for testing. Over the course of the phase two trial, there were ten discontinuations due to side effects, with five patients discontinuing during both the weekly and monthly phases. Notably, in a previous mid-stage trial last year, the highest dose of PF’3944 demonstrated an average weight loss of 14.1% after 28 weeks of weekly doses, further underscoring the drug’s potential efficacy in obesity treatment.
