Novo obesity drug candidate achieves modest results, raises concerns about side effects

A potential next-generation anti-obesity drug from Novo Nordisk led to modest weight loss but also a higher incidence of some psychiatric side effects such as anxiety and sleep disturbances. These results pose a challenge to the pharmaceutical giant's efforts to find novel anti-obesity drugs that could build on the success of its blockbuster Wegovy.

A Phase 2a trial tested monlunabant, a drug that inhibits CB1 receptors that Novo acquired last year through its acquisition of Inversago Pharma. People who received the lowest dose of 10 milligrams lost an average of 6.4 percent of their weight after 16 weeks, compared with 0.6 percent in the placebo group, Novo said Friday. The trial also tested higher doses of 20 and 50 milligrams, but Novo said “limited additional weight loss” was observed at those higher doses and did not disclose specific data.

The most common side effects were gastrointestinal in nature, in most cases mild to moderate in severity and dose-dependent, similar to the side effects observed with marketed GLP-1 anti-obesity drugs.