With FDA rejection to treat hives disorder, Sanofi and Regeneron's Dupixent suffers rare setback

Regeneron and Sanofi are anxious to bring Dupixent as an answer for chronic spontaneous urticaria (CSU), a severe inflammatory condition that causes hives and deep swelling on or under the skin.

But the companies have more work to do to gain approval for the blockbuster. In a rare setback for Dupixent—which has raked in sales of $5.3 billion in the first half of this year—the FDA has rejected the companies’ bid for a green light for the monoclonal antibody to treat CSU.

In a complete response letter (CRL), the FDA requested the companies bring more efficacy data, they said. The U.S. regulator didn’t identify any manufacturing or safety issues with the biologics license application, the partners said.

Regeneron and Sanofi are conducting a third phase 3 trial of Dupixent in the indication, LIBERTY-CUPID C. The results are expected by the end of next year and are “anticipated to provide the additional efficacy data,” they said.

The LIBERTY-CUPID A study, which compared Dupixent plus standard-of-care antihistamines to antihistamines alone in moderate to severe CSU patients, achieved its primary and secondary endpoints.

But the LIBERTY-CUPID B program, for patients who did not have success with the lone treatment approved in the indication—Novartis and Roche’s Xolair—came up short. Because Dupixent failed to significantly reduce symptoms, the trial was stopped for futility in February of 2022. The companies noted, however, that Dupixent provided numerical improvements in the each of the main evaluation criteria, including itching.

Xolair, which was approved for CSU in 2014 and covers most of the same indications as Dupixent, generated sales of $4 billion last year. In 2021, Sanofi said another biologic could thrive on the market because only a small fraction of eligible patients were taking Xolair.

Novartis has responded to the threat, preparing TK inhibitor remibrutinib for approval. In August, the company reported successful results from two phase 3 trials, which put remibrutinib on track for approval next year.