Pfizer (PFE) Study update summary

Key study results and efficacy insights

• Phase IIb trials of berobenatide showed monthly dosing achieved weight loss on par with weekly tirzepatide and potentially superior to semaglutide at matched time points and doses.

• At the medium Phase III dose (4.8 mg monthly), berobenatide delivered up to 12.3% placebo-corrected weight loss at week 28 in VESPER-3 arms.

• High-dose extension data (2.4 mg weekly) showed mean weight loss of ~16% at 32 weeks, with modeling predicting even greater loss at higher doses.

• In VESPER-1 OLE, continued berobenatide led to 10.3–14.9% weight reduction at week 60; placebo switchers achieved 15.9–16.8% reduction.

• Model-based meta-analysis using data from 69 trials and 32,000+ patients supports berobenatide's efficacy and aligns with observed results, predicting efficacy similar to tirzepatide and potentially better than semaglutide at 72 weeks.

Study design and population

• Berobenatide was evaluated in multiple Phase IIb trials (VESPER-1, -2, -3) in adults with overweight/obesity, with and without type 2 diabetes, using weekly and monthly dosing regimens.

• Participants were adults aged 18–75 years, BMI ≥27–50 kg/m², with additional criteria for comorbidities.

• Trials included randomized, placebo-controlled periods and open-label extensions, with primary endpoints focused on percent change in body weight.

Tolerability and dosing strategy

• Phase IIb data showed excellent GI tolerability: 96% of participants had no or only mild GI adverse events in VESPER-1 extension; in VESPER-2 and VESPER-3, 83–88% reported no or mild GI AEs.

• No treatment discontinuations due to GI events in any arm; discontinuation due to AEs was ≤14.8% in any group and <10% in VESPER-3.

• Tolerability improved with gradual titration; phase III will use smaller dose increments and allow down-titration for GI events.

• Mild, transient increases in GI events occurred at the weekly-to-monthly transition but resolved quickly.

• Dose escalation protocols in Phase III are designed to further enhance GI tolerability.