Core Viewpoint - Sanofi's experimental drug amlitelimab for treating atopic dermatitis failed to meet Wall Street expectations in late-stage clinical trials, resulting in a stock price drop of over 9% [1]. Group 1: Drug Development and Clinical Trials - Sanofi is developing amlitelimab to treat atopic dermatitis, a severe form of eczema, aiming for it to complement or potentially replace its blockbuster drug Dupixent, which has patent protection until 2031 [1]. - Analysts from Jefferies noted that while amlitelimab has good safety data and a convenient dosing schedule of once every 12 weeks, its efficacy in the Phase III trial was inferior to previous trial data and less effective compared to competing biologics [1]. - JPMorgan analysts indicated that the data shows amlitelimab's efficacy is not as strong as Dupixent [1]. Group 2: Market Impact - Sanofi's stock fell by 8.9%, making it the largest decliner among the constituents of the STOXX 600 index [2].