Sanofi and Regeneron Pharmaceuticals faced notable share price declines after mixed results from late-stage clinical trials of their experimental drug, itepekimab, targeting chronic obstructive pulmonary disease (COPD) in former smokers. On Friday, Sanofi disclosed that its phase III trials produced diverging efficacy data. In one study, the drug demonstrated a 27% reduction in the rate of COPD exacerbations, suggesting meaningful therapeutic potential. However, parallel research failed to replicate these benefits, despite earlier, more positive interim outcomes.