MBX Biosciences (MBX) Status update summary

Progress on obesity portfolio and clinical programs

• MBX 4291, a GLP-1/GIP co-agonist prodrug, demonstrated promising phase I blinded data with a mean weight loss of 7% over 8 weeks, dose-proportional pharmacokinetics, and minimal GI-related adverse events, supporting once-monthly dosing.

• The 12-week MAD cohort for MBX 4291 is on track for top-line results in Q4 2026, with a second cohort planned.

• MBX 5765, a multi-mechanism amycretin/GLP-1/GIP/glucagon/DACRA agonist, and a triple agonist candidate are advancing, with preclinical and nomination milestones expected in Q2–Q3 2026.

• Imapextide achieved proof of concept in post-bariatric hypoglycemia, but no further resources are committed to phase II-B.

• The proprietary PEP platform enables differentiated pharmacokinetics, improved tolerability, and self-titrating regimens.

Market landscape and unmet needs

• Obesity prevalence is rising globally, with projections of 25% of the world population affected by 2035 and a market size expected to exceed $90 billion by 2031.

• U.S. adult obesity rates are expected to reach 40% by 2030, with the highest growth in those with BMI >35.

• Key drivers include investment in next-generation GLP-1-based treatments, improved access, affordability, and increased awareness.

• Unmet needs include greater efficacy, prevention of weight regain, improved tolerability, convenience, and preservation of lean body mass.

• High discontinuation rates highlight the need for more tolerable and convenient therapies.

Differentiation and competitive positioning

• MBX 4291’s PK profile features delayed Tmax (~2 weeks) and t half Cmax of 26 days, supporting true monthly dosing and reduced peak-to-trough variability.

• Preliminary data show only one GI-related adverse event in the MAD cohort, suggesting improved tolerability over existing therapies.

• The PEP platform enables self-titrating regimens, potentially reducing the need for lengthy titration and improving patient adherence.

• Flexibility in dosing frequency (weekly or monthly) offers clinicians options to tailor treatment to patient needs.

• No notable injection site reactions observed in phase I SAD/MAD data.