MBX Biosciences Obesity Day Spotlights Monthly GLP-1 Hope and Pipeline Push

Key Points

• MBX Biosciences said its lead obesity candidate, MBX 4291, is showing preliminary phase 1 data consistent with once-monthly dosing potential, including delayed absorption, sustained active peptide levels and early weight loss signals with limited GI side effects.
• The company also introduced MBX 5765, a new preclinical “amycretin” program, and said its broader obesity pipeline remains active, including a triple G co-agonist candidate expected to be selected in the third quarter.
• Management reiterated that MBX has $440 million in cash to fund operations into 2029 and said key near-term milestones include a phase 3 start for canvuparatide in the third quarter and top-line MBX 4291 data in fourth-quarter 2026.

MBX Biosciences NASDAQ: MBX used its Obesity Day event to outline preliminary clinical data for its lead obesity candidate MBX 4291, introduce a new preclinical obesity program and reiterate key development milestones across its endocrine and metabolic disease pipeline.

President and CEO Kent Hawryluk said the company is focused on once-weekly canvuparatide and its expanding obesity portfolio, which is built on MBX’s proprietary Precision Endocrine Peptide, or PEP, technology. He said the company has $440 million in cash, which it expects will fund operations into 2029.

MBX 4291 Data Point to Monthly Dosing Potential

Chief Medical Officer Sam Azoulay presented preliminary blinded data from an ongoing phase 1 study of MBX 4291, a GLP-1/GIP co-agonist prodrug designed for once-monthly dosing. Azoulay said the goal of the program is to create “gradual, flattened, and sustained exposure” that could improve tolerability and support monthly administration.

The phase 1 trial includes single ascending dose, multiple ascending dose and 12-week multiple-dose components. In the single ascending dose portion, MBX evaluated doses from 15 mg to 180 mg, with a 120 mg cohort still ongoing. Azoulay said the drug showed dose-proportional pharmacokinetics, gradual increases in drug concentration and sustained active peptide concentrations.

Azoulay said MBX 4291 reached a delayed Tmax of up to 13 to 14 days, compared with a maximum of about two days for tirzepatide and MET-097i in the comparisons he presented. He described the profile as “self-titrating” and said it is expected to improve tolerability.

In the first multiple ascending dose cohort, subjects received 30 mg weekly for four weeks followed by a single 120 mg dose. The blinded data, which include placebo, showed mean weight loss of 7% over eight weeks, with a range of 0% to 16%, among eight subjects. Azoulay said there was one GI-related adverse event, diarrhea, and no nausea, vomiting or serious adverse events in that cohort.

The company said MBX 4291 had a time to half Cmax of 26 days in the cohort, compared with 20 to 21 days reported for MET-097i. Hawryluk said MBX remains on track to report top-line results from a 12-week multiple ascending dose cohort in the fourth quarter of 2026.

Company Introduces MBX 5765 Amycretin Program

Scientific co-founder Richard DiMarchi introduced MBX 5765, which the company described as an “amycretin” that combines GLP-1, GIP, amylin and calcitonin receptor activity, with some glucagon activity, in a single molecule. DiMarchi said the program applies the PEP platform to extend duration of action and reduce peak-to-trough variability.

DiMarchi presented preclinical data in lean cynomolgus monkeys showing what he called a flat, pump-like exposure profile for the active amycretin. He said the data support once-monthly dosing potential and showed body weight effects in non-obese monkeys at doses used in toxicology assessments. MBX said MBX 5765 demonstrated a differentiated pharmacokinetic profile, expected pharmacodynamic effects and improved tolerability in preclinical work.

Hawryluk also said MBX’s GLP-1/GIP/glucagon “triple G” co-agonist program remains on track for candidate selection in the third quarter.

Obesity Market and Unmet Need

Katherine Saunders, co-founder of FlyteHealth and clinical assistant professor of medicine at Weill Cornell Medicine, described obesity as a large and growing global chronic disease. Citing World Health Organization and World Obesity Federation figures, she said one in eight people worldwide are living with obesity, including nearly 900 million adults and 160 million children.

Saunders said the obesity market is about $60 billion today and is projected to rise to more than $90 billion through 2031. She said key unmet needs include greater response, prevention of weight regain, better tolerability, improved convenience, weight-loss quality and outcomes across subpopulations such as pediatric and older adult patients.

Saunders emphasized gastrointestinal side effects as a major issue for current therapies, saying nausea, vomiting and diarrhea can affect adherence and persistence. She said 65% of patients using obesity medications stop within one year and 84% stop within two years, according to the figures she presented.

Canvuparatide and Imapextide Updates

Hawryluk said MBX remains on track to begin enrolling a confirmatory registrational phase 3 study of canvuparatide in the third quarter. He said one-year open-label extension data are expected to be presented at ENDO in June, and that Mark Hope was recently appointed chief commercial officer to lead launch planning.

MBX also provided proof-of-concept data for imapextide in post-bariatric hypoglycemia. Hawryluk said imapextide led to an approximately 20% to 35% increase in glucose nadir and a 10% to 45% decrease in insulin peak in the phase 2A STEADY study. He said glucose nadir increased in 90% of patients at the 100 mg dose and 100% of patients at the 200 mg dose.

However, Hawryluk said MBX is not committing additional resources to a phase 2B study of imapextide, citing the company’s growing number of peptide-based therapeutic candidates and its strategic focus on canvuparatide and obesity.

Analyst Questions Focus on Dosing and Tolerability

During the question-and-answer session, analysts asked about MBX 4291’s dosing strategy, tolerability, injection-site reactions and competitive positioning against other obesity drugs. Azoulay said the 30 mg weekly induction followed by a 120 mg monthly dose was selected based on learnings from earlier cohorts, but MBX has not finalized dosing for the 12-week portion.

In response to an online question, Azoulay said there was “no concern” regarding injection-site reactions in the MBX 4291 data, noting that some reactions were observed because the drug is a peptide but nothing was considered worrisome.

Saunders said both tolerability and dosing convenience are important for patient adherence and persistence. She said many patients on weekly injections would prefer monthly administration, while DiMarchi added that the profile could provide dosing optionality, including more frequent use if a flatter exposure profile were desired.

About MBX Biosciences NASDAQ: MBX

We are a clinical-stage biopharmaceutical company focused on the discovery and development of novel precision peptide therapies for the treatment of endocrine and metabolic disorders. Our company was founded by global leaders with a transformative approach to peptide drug design and development. Leveraging this expertise, we designed our proprietary Precision Endocrine Peptide™, or PEPTM, platform to overcome the key limitations of unmodified and modified peptide therapies and to improve clinical outcomes and simplify disease management for patients.

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