IBio has reported results from an eight-week study in obese nonhuman primates testing whether its antibody candidate IBIO-610 changes the composition of weight lost on semaglutide. The company says lean mass accounted for 6% of weight lost in animals given IBIO-610 plus semaglutide, compared with 22% in animals on semaglutide alone.

The work was done in monkeys, with six animals per group, and first-in-human trials have not started. IBio says it expects to begin them in the first half of 2027. Semaglutide is the GLP-1 drug sold as Ozempic and Wegovy, and IBIO-610 is designed to block Activin E, a signaling protein the company is targeting to shift weight loss toward fat.

What the numbers say

Alongside the lean mass figures, IBio says additional analysis found fat made up 93% of weight lost with a single dose of IBIO-610 plus twice-weekly semaglutide, against 77% for semaglutide alone. Those are company-reported figures from company-run analysis, and they come with the denominators that matter: six animals per group, eight weeks.

The pharmacology numbers are the more interesting half. IBio reports a 97% reduction in serum active Activin E at week eight after a single intravenous dose, and a 33.2-day half-life in nonhuman primates. The company claims the projected human half-life could support twice-yearly dosing.

Why muscle loss is the live question

The muscle question is the one the GLP-1 field has been circling for three years, and it is the commercial opening every biotech in this space is now aiming at. A drug that lets patients keep the lean mass while losing the fat would be a meaningful addition rather than a me-too, which is exactly why this data set deserves scrutiny rather than applause.

Six animals per arm is a small group, and this is a preclinical result presented by the sponsor. The data were shown at the European Association for the Study of Diabetes annual meeting on 1 October 2026, which is a real venue, not a press release alone.

Bottom line

What IBio has is a primate signal and a long half-life, both of which it generated itself. Whether either survives contact with human trials is the only question that counts, and nobody will know before 2027 at the earliest.