Corbus prepares to report Phase 1b results for its CB1 obesity drug CRB-913

Corbus Pharmaceuticals expects to report topline results in September 2026 from CANYON-1, a 240-participant Phase 1b trial of CRB-913, an experimental obesity drug that targets the CB1 receptor. The trial's final patient visit took place in August 2026 ^[1].

CRB-913 is described as a peripheral CB1 drug, meaning it is designed to act outside the brain. That makes the September readout an early test of whether CB1 can be revived as an obesity target without the central nervous system side effects that have been a concern for the class ^[1]. CB1 antagonists are one of several mechanisms now under study in obesity and weight-related conditions, alongside amylin receptor agonists, RNAi therapies targeting INHBE and ALK7, muscle-preservation approaches and treatments for rare forms of obesity ^[1]. More than 150 active programs are being tracked across those areas, ranging from preclinical development through Phase 3 ^[1].

CB1-targeted drugs sit well behind the leading experimental medicines. Most of the most advanced new obesity drugs still rely on GLP-1 signaling, and CB1-targeted drugs — along with RNAi therapies targeting INHBE or ALK7 and therapies affecting muscle and fat signaling — are further from approval ^[1].

What the September results will show has not been disclosed. No efficacy or tolerability data for CRB-913 have been reported, and the trial's endpoints, dose levels and participant characteristics have not been made public ^[1]. Phase 1b studies are small and generally focus on safety, tolerability and how a drug behaves in the body, so even a clean readout would not establish how much weight the drug helps people lose.

For context on where the approved market stands, cross-trial results reported for currently available medicines range from an average 12.4% body-weight loss at 72 weeks for Foundayo (orforglipron) to 22.5% at 72 weeks for Zepbound (tirzepatide) ^[1]. Oral Wegovy produced 16.6% at 64 weeks, and injectable Wegovy 16.9% at 68 weeks ^[1]. Those figures come from separate trials with different populations, durations and doses, and should not be read as head-to-head rankings ^[1].

Why it matters for patients

Many of the most advanced experimental obesity drugs still use GLP-1 signaling, so moving from semaglutide to another incretin-based medicine does not remove the possibility of nausea, vomiting or other gastrointestinal effects. Changing the delivery method does not make a drug a different therapeutic class, and Foundayo, for example, still commonly causes gastrointestinal side effects ^[1].

A CB1 drug that worked without brain-related side effects would come from a different mechanism entirely. If non-GLP-1 approaches succeed, obesity treatment could eventually become much less dependent on a single drug class, giving patients who do not respond well to GLP-1 medicines a separate route ^[1]. That is the potential, not the current reality: CB1-targeted drugs are characterized as further from approval than the incretin-based options, and a Phase 1b result is an early step rather than evidence that a new treatment is close to reaching pharmacies ^[1].

What happens next

September 2026 is the near-term milestone, when Corbus says it expects topline CANYON-1 results ^[1]. No Phase 2 start date, dosing plan or regulatory timeline for CRB-913 has been reported.

Other pipeline events are dated further out. Eli Lilly says it plans to submit its obesity application for retatrutide to the FDA in the first quarter of 2027 ^[1]. Novo Nordisk's CagriSema, a combination of semaglutide and the amylin analog cagrilintide, is under FDA review after being submitted in December 2025 ^[1].