The weight-loss drug market saw a dramatic shift on Friday as Novo Nordisk, a pharmaceutical giant, released trial results for its experimental drug, monlunabant. While the drug demonstrated significant weight loss in participants, the market reacted with concern, sending Novo Nordisk’s stock down by 5.5%. The ripple effect was even more pronounced for Corbus Pharmaceuticals, a company developing a similar drug targeting the same CB1 receptor. Corbus shares plummeted by nearly 60%, reflecting investor anxiety.
Both companies are developing drugs that act on the CB1 receptor, a crucial element in the endocannabinoid system that regulates appetite and metabolism. Novo Nordisk’s monlunabant and Corbus’s CRB-913 belong to the same class of drugs, known as CB1 inverse agonists. These drugs effectively block the CB1 receptor, much like cannabis-related compounds, to regulate appetite and potentially aid in weight loss.
The trial results for monlunabant, while demonstrating substantial weight loss, raised concerns about safety and efficacy. Participants taking the 10 mg dose of monlunabant experienced an average weight loss of 7.1 kg compared to 0.7 kg in the placebo group. However, the trial also revealed dose-dependent adverse events, particularly neuropsychiatric side effects like anxiety, irritability, and sleep disturbances. These side effects, though considered mild to moderate, fueled concerns about the drug’s long-term safety and its ability to compete in the already saturated obesity drug market.
Further concerns emerged regarding the limited additional weight loss seen at higher doses of monlunabant. This indicated diminishing returns for increased dosages, raising questions about the drug’s scalability and effectiveness at higher or sustained doses. Investors also expressed skepticism about monlunabant’s ability to compete effectively with existing obesity treatments, such as Novo Nordisk’s blockbuster drug Wegovy, which demonstrates a clearer dose-response benefit.
Despite these concerns, Novo Nordisk has committed to advancing monlunabant into a larger Phase 2b trial in 2025. This indicates that the company is committed to further refining dosing and obtaining a better understanding of the drug’s safety profile. However, the need for further trials is likely to prolong investor uncertainty, especially considering the presence of competitors like Corbus Pharmaceuticals also developing drugs targeting the same CB1 receptor pathway.
For Corbus Pharmaceuticals, Novo Nordisk’s struggles present a significant challenge. With CRB-913, also a CB1 inverse agonist, the setbacks faced by Novo Nordisk may have intensified concerns about whether Corbus can successfully develop a commercially viable product. The market’s negative reaction to Novo Nordisk’s trial results highlights the inherent risks and uncertainties associated with drug development, particularly in a competitive market. Investors will be closely watching the progress of both companies as they navigate the complex landscape of obesity treatment.
