Corbus Pharmaceuticals Initiates Phase 1 Trial of Peripherally Restricted CB1 Inverse Agonist for Obesity
Key Insights
Corbus Pharmaceuticals has dosed the first subject in a Phase 1 trial of CRB-913, a second-generation CB1 inverse agonist designed to treat obesity (search) while avoiding neuropsychiatric side effects.
Pre-clinical data shows CRB-913 is significantly more peripherally restricted than previous compounds, with a brain-to-plasma ratio fifty times lower than rimonabant and fifteen times lower than monlunabant.
The SAD/MAD portion of the trial is expected to complete in Q3 2025, followed by a Phase 1b dose-range finding study scheduled for completion in H2 2026.
Corbus Pharmaceuticals has announced the dosing of the first subject in a Phase 1 clinical trial evaluating CRB-913, a novel second-generation cannabinoid type-1 (CB1) receptor inverse agonist for the treatment of obesity (search). The single ascending dose/multiple ascending dose (SAD/MAD) study is being conducted in the United States under an open Investigational New Drug (IND) application.
CRB-913 represents a potential advancement in obesity (search) treatment by leveraging the clinically validated weight loss mechanism of CB1 inverse agonism while addressing the safety concerns that led to the abandonment of first-generation compounds like rimonabant.
Improved Peripheral Restriction Profile
The key innovation of CRB-913 lies in its enhanced peripheral restriction, designed to minimize central nervous system exposure that caused problematic neuropsychiatric adverse events with earlier compounds. Pre-clinical data presented at Obesity (search) Week 2024 demonstrated that CRB-913 has a brain-to-plasma ratio fifty times lower than rimonabant and is fifteen times more peripherally restricted than monlunabant, another second-generation compound in development.
"We are pleased to reach this important milestone with our CRB-913 obesity (search) program," said Yuval Cohen, Ph.D., Chief Executive Officer of Corbus. "We believe that the ability to address weight loss with this orthogonal mechanism of action and via an oral small molecule could address several key unmet needs."
Development Timeline and Strategic Positioning
The company has outlined a clear development pathway for CRB-913:
- The SAD/MAD portion of the Phase 1 trial is scheduled for completion in Q3 2025
- A Phase 1b dose-range finding study is expected to commence in Q4 2025
- The dose-range finding study is projected to complete in the second half of 2026
Based on pre-clinical findings, Corbus envisions multiple potential clinical applications for CRB-913, including use as monotherapy, in combination with incretin analogs (such as GLP-1 receptor agonists), or as maintenance therapy following incretin analog induction treatment.
CB1 Inverse Agonism: A Validated Mechanism with Historical Challenges
The CB1 receptor (search) pathway represents a distinct approach to weight management compared to the currently dominant incretin-based therapies. First-generation CB1 inverse agonists demonstrated significant efficacy in weight reduction but were withdrawn from development due to concerns about psychiatric side effects, including depression and suicidal ideation.
The development of peripherally restricted compounds aims to retain the metabolic benefits while eliminating these central nervous system effects. This approach could potentially address limitations of current obesity (search) treatments, including the need for injectable administration of many leading therapies.
Corbus's Diversified Portfolio
CRB-913 is part of Corbus Pharmaceuticals' diversified portfolio, which also includes oncology assets CRB-701 (a next-generation antibody-drug conjugate targeting Nectin-4 (search)) and CRB-601 (an anti-integrin monoclonal antibody that blocks TGF-β (search) activation). The company is headquartered in Norwood, Massachusetts.
The advancement of CRB-913 into clinical trials represents a significant milestone for Corbus as it pursues novel approaches to address the global obesity (search) epidemic, which affects over 650 million adults worldwide according to World Health Organization estimates.
Market Context and Unmet Needs
The obesity (search) therapeutics market has seen tremendous growth with the success of GLP-1 receptor agonists, but significant unmet needs remain. Oral small molecule therapies with different mechanisms of action could complement existing treatments by addressing issues such as injection fatigue, cost concerns, and variable response rates.
If successful in clinical development, peripherally restricted CB1 inverse agonists like CRB-913 could potentially offer advantages in certain patient populations or treatment scenarios, particularly given the chronic nature of obesity (search) management.