The U.S. Food and Drug Administration launched an investigation into Takeda’s recombinant ADAMTS13 replacement therapy Adzynma after post‑marketing reports described neutralizing antibodies and one pediatric patient death that may be related. The agency said clinical assays cannot yet distinguish antibodies against the therapeutic enzyme from those targeting endogenous ADAMTS13. Takeda stated it has not confirmed causality and emphasized ongoing safety assessments. Regulators warned clinicians and patients while evaluating whether additional actions, labeling changes or further studies are required to address the risk of neutralizing immune responses.