FDA Rejects Alnylam's Expanded Heart Disease Treatment Application

The FDA has rejected Alnylam Pharmaceuticals' plans to expand the label of its siRNA injection Onpattro for the treatment of ATTR cardiomyopathy, issuing a complete response letter. This decision comes after an advisory committee voted 9 to 3 in favor of the drug's benefits outweighing its risks. The FDA raised concerns about the effect size in this indication, with independent experts agreeing that while Onpattro's benefit was small, the risks were smaller for patients experiencing malformed protein buildup in the heart.