RegulatoryOfficial

FDA orders boxed warning on Adzynma over blocking antibodies and a child's death

🇺🇸 FDA CBER · Mon 26 Oct 2026

The US regulator has directed Takeda to add its most serious label warning to the recombinant ADAMTS13 therapy for congenital TTP after a postmarketing safety signal.

The US Food and Drug Administration has directed Takeda Pharmaceuticals to add a Boxed Warning to the prescribing information for Adzynma, a recombinant ADAMTS13 enzyme replacement therapy for congenital thrombotic thrombocytopenic purpura (cTTP). The agency's safety communication is dated 23 September 2026. The warning addresses the development of neutralizing (blocking) antibodies that can stop the drug from working. In serious cases these have led to death, including that of a 7-year-old child.

The signal was identified through the FDA Adverse Event Reporting System (FAERS). The fatal case involved a child who developed neurologic symptoms that progressively worsened. Neutralizing antibodies to ADAMTS13 were found about 10 months after prophylactic treatment began. The patient had a history of severe allergic reactions to fresh frozen plasma.

The FDA approved Adzynma on 9 November 2023 for routine prevention and on-demand treatment of cTTP in adults and children. It is the only FDA-approved recombinant ADAMTS13 therapy for the rare inherited disorder. The product contains two slightly modified forms of the ADAMTS13 protein, one of which matches the natural human sequence.

The agency says patients on Adzynma should not stop treatment without first speaking to their healthcare provider. Clinicians should monitor all patients with regular laboratory testing to detect blocking antibodies as early as possible. The revised labelling recommends a baseline blood test before treatment and regular follow-up tests to check for inhibitors and confirm the drug is still working. It also tells patients to contact their provider right away, and stop treatment, if they develop symptoms such as rash or hives, throat or chest tightness, difficulty breathing, dizziness or fainting.

What it means for your team

  • PV teams should expect Adzynma labelling changes and review how antibody-related loss of efficacy and fatal outcomes are captured and reported.
  • Regulatory and medical affairs teams should prepare updated risk communication for prescribers, patients and caregivers, reflecting the baseline and ongoing inhibitor testing recommendations.
  • QA and clinical operations teams should check that monitoring protocols and patient materials for cTTP reflect the new Boxed Warning once the revised label is in force.

Official source: FDA CBER ↗

Article written by VigiEye from the official source (FDA CBER). AI-assisted; check the source before acting.

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