Vanda's tradipitant cut Wegovy-induced vomiting by 27% in Phase 3 trial

Vanda Pharmaceuticals said its drug Nereus (tradipitant) reduced vomiting in people who received a single 1 milligram dose of Wegovy (semaglutide), lowering the rate to 43% from 58.5% among those given a placebo in a Phase 3 trial ^[1]. The company announced top-line results from the study, called Study 3601, on October 27, 2026, and said it plans to file a supplemental new drug application asking the FDA to expand the drug's label ^[1].

Study 3601 was designed to produce high rates of vomiting. Every participant first received either tradipitant or placebo, and then all of them were given 1 mg of Wegovy in a single dose, without the gradual dose increases used in routine practice. That design was intended to make vomiting more likely ^[1]. The primary endpoint was whether vomiting happened at all, and Vanda said tradipitant reduced it significantly, which works out to a 27% reduction ^[1].

On the secondary endpoint, severe nausea and vomiting occurred in 33.1% of people taking tradipitant compared with 50.6% on placebo, a 35% reduction ^[1]. Two other results came from post-hoc analyses, which are comparisons defined after a trial is designed and are generally treated as weaker evidence than the main endpoints. Frequent vomiting, defined as three or more episodes on more than one day, occurred in 6.3% of the tradipitant group versus 15.9% on placebo, which Vanda called a 60% reduction ^[1]. Extreme vomiting, defined as more than 10 total episodes after the GLP-1 dose, occurred in 2.8% versus 14.6%, an 81% reduction ^[1].

"Nereus can meaningfully reduce vomiting and frequent multi-day vomiting induced by GLP-1 therapy, which are key contributors to treatment discontinuation," Vanda chief executive Mihael H. Polymeropoulos, M.D., said in a statement ^[1].

Tradipitant is an NK-1 receptor antagonist. Vanda won its first FDA approval for the drug in December, for motion-induced vomiting, and other medicines in the same class are used to treat nausea and vomiting caused by chemotherapy ^[1]. The announcement did not disclose how many people were enrolled in Study 3601, how long they were followed, or whether any GLP-1 drug other than Wegovy was tested ^[1]. The full results have not been published in a peer-reviewed journal.

Why it matters for patients

Nausea and vomiting are among the biggest obstacles to staying on GLP-1 drugs. Roughly half of patients stop treatment within the first year, and gastrointestinal problems are among the reasons they cite ^[1]. Vomiting is especially likely when a GLP-1 drug is started at a full dose rather than built up slowly, which is the situation Study 3601 deliberately created ^[1].

A drug that prevents those symptoms would address a different problem than the GLP-1 medicines themselves: it would be given for the side effect, not for weight loss or diabetes. Tradipitant is not approved for GLP-1-related nausea or vomiting, so any such use now would be outside its label ^[1]. It has not been reported whether the drug would be taken daily or only around a dose increase, how it would be priced, or whether insurers would cover it for this purpose. It also has not been reported how tradipitant performed in people who develop nausea later in treatment rather than after a single dose.

What happens next

Vanda said it intends to submit a supplemental new drug application to the FDA to expand the label ^[1]. The company did not give a date for that filing, and no date for an FDA decision has been disclosed ^[1].