Sanofi receives complete response letter from FDA for MS drug tolebrutinib

Paris – Sanofi has received a complete response letter (CRL) from the U.S. Food and Drug Administration (FDA) for the new drug application of tolebrutinib, intended to treat adult patients with non-relapsing secondary progressive multiple sclerosis (nrSPMS).

This decision represents a significant shift from previously received feedback. On December 15, 2025, Sanofi updated that the FDA's review was expected to extend beyond the revised target action date of December 28, 2025, with further guidance anticipated by the end of Q1 2026. In response to an FDA request, Sanofi had also submitted an expanded access protocol for tolebrutinib in nrSPMS.

"Today's FDA decision is a significant and meaningful change in direction from the feedback the agency previously provided to Sanofi. We are very disappointed by the FDA's action," stated Houman Ashrafian, Executive Vice President, Head of Research & Development at Sanofi. "Disability progression remains a large unmet medical need in MS, and tolebrutinib was previously awarded breakthrough therapy designation by the FDA in recognition of its potential to address this critical gap. We believe that the FDA should also take the advice of scientific experts, clinicians, and patients in this matter to ensure all perspectives are considered."

Tolebrutinib received provisional approval in the United Arab Emirates in July 2025 for the treatment of nrSPMS. The drug is currently under regulatory review in the EU and other global jurisdictions. Sanofi will conduct an impairment test on the intangible asset value of tolebrutinib, with results to be provided with Q4 and FY 2025 results in January 2026. This test is not expected to impact business net income or EPS, and there is no change to the 2025 financial guidance.