The US Food and Drug Administration (FDA) is investigating reports of serious immune reactions, including one death, in patients treated with Adzynma (ADAMTS13, recombinant-krhn) for congenital thrombotic thrombocytopenic purpura (cTTP).

 

Adzynma, approved for both adults and children with cTTP, is a recombinant enzyme therapy designed to replace the deficient ADAMTS13 enzyme. It contains two forms of the enzyme: the native sequence and a variant with a single amino acid change.

 

The reported fatality occurred in a pediatric patient with a history of severe allergic reactions to standard plasma treatments. 

 

The child developed neurologic symptoms and was later found to have neutralizing antibodies against ADAMTS13 approximately 10 months after starting Adzynma therapy. Current lab tests cannot distinguish antibodies targeting the drug from those targeting the body’s own enzyme.

 

While clinical trials for Adzynma did not report neutralizing antibodies, postmarketing data now suggest the therapy may trigger serious immune responses. The FDA’s prescribing guidance already warns of potential antibody development, advising patients to undergo regular blood monitoring.

 

The FDA is actively evaluating the risk of life-threatening or fatal outcomes linked to neutralizing antibodies from Adzynma and is considering additional regulatory actions.