Adzynma Side Effects May Be Linked to Child’s Death, FDA Warns

Health officials indicate patients may face severe and life-threatening side effects from Adzynma, due to the risk of developing neutralizing antibodies.

Federal health officials say they are investigating the potential side effects of Adzynma, a medication used to treat a rare genetic blood-clotting disorder, after a potential risk associated with the treatment may have contributed to the death of one child.

Adzynma (ADAMTS13) is manufactured by Takeda and was first approved by the U.S. Food and Drug Administration (FDA) in 2023 to treat congenital thrombotic thrombocytopenia purpura, a rare blood disorder caused by low ADAMTS13 enzyme levels. The medication contains two versions of the recombinant ADAMTS13 (rADAMTS13) protein that differ only by a single amino acid.

However, a new report by the FDA indicates a child who was on Adzynma developed neutralizing antibodies to the medication and subsequently died. The agency warns it has received multiple postmarking reports of instances where patients have this response to the drug, and announced the launch of an investigation in a safety warning issued late last month.

The investigation to date suggests the child developed severe allergic reactions to fresh frozen plasma, followed by neurological symptoms that continued to progress. Health care professionals identified neutralizing antibodies to Adzynma 10 months later.

Neutralizing antibodies are immune proteins that can block a medication from working and, in some cases, trigger harmful reactions by interfering with how the treatment interacts with the body.

While Takeda reported the death to the FDA, and the agency launched its investigation to determine the risk other patients may face, the manufacturer never reported neutralizing antibodies in the clinical trials that led to Adzynma’s approval. Additionally, current labeling for Adzynma does not include information regarding postmarking reports of neutralizing antibodies.

However, the label does warn that the development of neutralizing antibodies is a risk. Adzynma’s label also warns patients to talk to their doctors about being monitored with blood tests for the development of neutralizing antibodies.

The FDA indicates the investigation into Adzynma and the development of neutralizing antibodies is ongoing, warning that patients may face a risk of developing serious or fatal side effects. The agency said it continues to evaluate the need for further regulatory action.

Patients should contact a doctor if they experience side effects after taking Adzynma, according to the agency, which asks those who experience adverse effects after taking the drug to report the incidents to the FDA’s MedWatch Adverse Event Reporting program.

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