AnaptysBio shares sag as Sanofi-Regeneron trial stokes IL-33 doubts

A 12% dip in AnaptysBio's share price Friday suggests investors are concerned that a Phase II readout for a rival IL-33 inhibitor could indicate that the drug class may not provide a differentiated clinical benefit in asthma compared with marketed drug Dupixent.

Sanofi (Euronext:SAN; NASDAQ:SNY) and Regeneron Pharmaceuticals Inc. (NASDAQ:REGN) said Friday that although REGN3500 beat placebo on the Phase II study's primary endpoint, the anti-IL-33 mAb did not show a greater benefit compared with the companies' Dupixent dupilumab head-to-head in another study arm. A combination of REGN3500 and Dupixent, a mAb targeting the alpha subunit of IL-4R and the IL-13 receptor, also failed to show a benefit compared with Dupixent alone. Sanofi and Regeneron said the trial was not powered to detect differences between active arms...