French healthcare company Sanofi S.A. (Euronext Paris:SAN) (Nasdaq:SNY) said on Wednesday that the US Food and Drug Administration (FDA) has issued a complete response letter for the new drug application for tolebrutinib in non-relapsing secondary progressive multiple sclerosis (nrSPMS) in adults.

This follows an update on 15 December 2025 in which Sanofi noted that the review was expected to extend beyond the revised target action date of 28 December 2025, with further FDA guidance anticipated by the end of the first quarter of 2026. Sanofi had also submitted an expanded access protocol in response to an FDA request.

The company said the FDA's latest decision represents a significant change from prior feedback, noting that tolebrutinib previously received breakthrough therapy designation. Tolebrutinib was provisionally approved in the United Arab Emirates in July 2025 and remains under regulatory review in the EU and other jurisdictions.

Sanofi is conducting an impairment test on the intangible asset value of tolebrutinib under IFRS, with an update expected alongside its fourth-quarter and full-year 2025 results in January 2026. The company said the review will not affect business net income, business EPS, or its 2025 financial guidance.