Regeneron Pharmaceuticals saw a decline in its shares by 9% following the release of mixed results from late-stage trials of its experimental drug, itepekimab. This drug, developed in collaboration with Sanofi, is aimed at treating chronic obstructive pulmonary disease (COPD). Reuters reported on the trials, with one study of 1,127 patients showing a 27% reduction in disease flare-ups over 52 weeks compared to a placebo. However, a second study did not meet its primary endpoint, casting doubt on the drug's approval prospects.

The market reacted to this news, with Regeneron's stocks trading at $549.69, reflecting a 15% decline this year so far. Sanofi's shares also dipped nearly 5% in premarket trading. Analysts express skepticism about the drug's path forward, with Emily Field from Barclays hinting at the challenge of securing approval with these results, and Richard Vosser from J.P. Morgan suggesting that further studies may be needed.

Itepekimab aims to counteract inflammation by inhibiting the interleukin-33 protein, a factor in COPD. The drug was anticipated to reach up to $5 billion in peak annual sales, potentially addressing a larger patient market than Dupixent, another treatment by Regeneron and Sanofi that's already approved for COPD. Following the trials' outcomes, it seems Dupixent will maintain its position as the go-to treatment.