Sanofi's Stock Plummets 9.14% on Underwhelming Amlitelimab Trial Results Trading Volume Ranks 256th in Market Activity

On September 4, 2025, Sanofi (SNY) fell 9.14% with a trading volume of $0.41 billion, ranking 256th in market activity. The decline followed underwhelming phase 3 trial results for amlitelimab, a potential successor to its dermatology flagship Dupixent, which is due to lose patent protection in 2031. The drug met primary endpoints but failed to meet investor expectations, raising concerns about the company’s ability to sustain its dermatology revenue stream. Amlitelimab showed EASI-75 scores of 35.9% and 46% at Q4W versus 19.1% on placebo, with vIGA-AD 0/1 scores of 21.1% and 22.5% versus 9.2%. While safety data was favorable, the results were seen as weaker compared to Dupixent’s performance, a critical factor for market confidence.

Analysts noted that amlitelimab’s 12-week dosing schedule and safety profile could still support adoption, but the phase 3 data fell short of earlier trial benchmarks and rival therapies. The COAST 1 trial is part of a broader OCEANA program with additional phase 3 studies expected through 2026. However, the immediate market reaction underscored investor skepticism about Sanofi’s pipeline depth to replace Dupixent’s revenue. The stock’s sharp decline reflected heightened scrutiny over the company’s long-term growth strategy in immunology, with amlitelimab positioned as a key replacement candidate.

Price Action: SNY stock dropped 8.52% to $45.64 in premarket trading following the data release. The sell-off highlighted the market’s focus on Sanofi’s ability to innovate in a competitive dermatology landscape, where patent expirations and pipeline risks remain significant challenges.