Sanofi has achieved study goals with its hopeful Amlitelimab, but investors are clearly disappointed. The Phase 3 data show no decisive advantages over Dupixent, the blockbuster drug of the French pharmaceutical company, whose patent protection expires in 2031. The result: the stock plummeted by more than 9 percent on Thursday morning and is down almost 18 percent since the beginning of the year.

Dupixent currently generates over 10 billion euros annually and is estimated to reach peak sales of 22 billion dollars across all applications. Expectations for Amlitelimab were accordingly high, though analysts estimate it may only achieve sales in the low single-digit billion range. "The data suggests more of a niche role than a blockbuster," said Naresh Chouhan of Intron Health Research.

Sanofi had recently increased its research and development expenditures to address pipeline pressure. In the current study, Amlitelimab showed statistically significant improvements over placebo in both skin appearance and severity. The safety and a possible dosing of only four injections per year were particularly highlighted.

But analysts like Matthew Weston from UBS rated the results as "lower end of expectations." Compared to Dupixent and competing products, the effectiveness appears weaker. He also pointed out that the test group included patients who were at times more difficult to treat, and other medications were used during the study.

Amlitelimab shows sustained improvements beyond 24 weeks, but the data is not sufficient to answer the central question: Can the drug fill the impending gap after the Dupixent patent expires?