09:50 AM EST, 11/21/2025 (MT Newswires) -- Takeda Pharmaceutical's ( TAK ) Adzynma is being investigated by the US Food and Drug Administration following the death of a pediatric patient related to the drug, which is intended to treat congenital thrombotic thrombocytopenic purpura, the regulator said Friday.

"Prior to treatment with Adzynma, this patient had severe allergic reactions to fresh frozen plasma," the FDA said. "The patient presented with neurologic symptoms which progressed, and the presence of neutralizing antibodies to ADAMTS13 was identified approximately 10 months after starting prophylactic treatment with Adzynma."

The FDA said the probe will investigate the risk of patients developing neutralizing antibodies with "serious, including life-threatening or fatal, outcomes following treatment with Adzynma." It also said it will determine if additional regulatory action is needed.

The FDA also said current assays cannot distinguish neutralizing antibodies to recombinant ADAMTS13 from neutralizing antibodies to endogenous ADAMTS13.

In November 2023, Takeda said the FDA approved Adzynma for the prophylactic and on-demand treatment of adult and pediatric patients with congenital thrombotic thrombocytopenic purpura.

Price: 14.13, Change: +0.06, Percent Change: +0.39