FDA Probes Takeda’s Adzynma After Pediatric Death

In November 2025, the U.S. Food and Drug Administration (FDA) initiated an investigation into a pediatric death associated with Takeda Pharmaceuticals’ Adzynma (ADAMTS13, recombinant-krhn), a therapy approved for treating congenital thrombotic thrombocytopenic purpura (cTTP).
The patient, a child with cTTP, developed neutralizing antibodies to ADAMTS13 approximately 10 months after starting Adzynma treatment, leading to fatal complications. (fda.gov)

Understanding cTTP and Adzynma

Congenital thrombotic thrombocytopenic purpura is a rare genetic disorder characterized by a deficiency in the ADAMTS13 enzyme, essential for regulating blood clotting. (takeda.com)

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Without adequate ADAMTS13 activity, patients are at high risk for acute thrombotic events, organ damage, and death.
Adzynma, approved by the FDA in November 2023, is the first recombinant ADAMTS13 enzyme replacement therapy for cTTP. (takeda.com)
It aims to replace the missing enzyme, preventing harmful blood clots.

The Pediatric Case and FDA’s Response

The pediatric patient in question had a history of severe allergic reactions to fresh frozen plasma, the traditional treatment for cTTP. (fda.gov)
Approximately 10 months into Adzynma therapy, the patient developed progressive neurological symptoms and was found to have neutralizing antibodies against ADAMTS13.
These antibodies blocked the therapeutic enzyme’s activity, leading to fatal complications.

The FDA’s investigation focuses on the risk of developing neutralizing antibodies following Adzynma treatment and evaluates the need for further regulatory action. (fda.gov)

Implications for Pediatric Care

This incident underscores the importance of monitoring for immunogenic responses in pediatric patients undergoing enzyme replacement therapies.
Healthcare providers should be vigilant for signs of antibody development and consider alternative treatments if necessary.

References

• FDA Investigating Death Due to Neutralizing Antibodies to ADAMTS13 following Adzynma Treatment of Congenital Thrombotic Thrombocytopenic Purpura, FDA, November 21, 2025, https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/fda-investigating-death-due-neutralizing-antibodies-adamts13-following-adzynma-treatment-congenital

• Takeda Provides Update on ADZYNMA (ADAMTS13, recombinant-krhn), Takeda, November 21, 2025, https://www.takeda.com/newsroom/statements/2025/update-on-adzynma/

• Takeda’s ADZYNMA (ADAMTS13, recombinant-krhn) Approved by U.S. FDA as the First and Only Recombinant ADAMTS13 Enzyme Replacement Therapy for the Treatment of Congenital Thrombotic Thrombocytopenic Purpura (cTTP), Takeda, November 2023, https://www.takeda.com/en-us/newsroom/news-releases/2023/takeda-adzynma-approved-by-fda-as-the-first-and-only-recombinant-adamts13-enzyme-replacement-therapy-for-the-treatment-of-congenital-thrombotic-thrombocytopenic-purpura/

• FDA Investigates Fatal Adverse Event Linked to Takeda’s Adzynma Enzyme Replacement Therapy, MedPath, November 21, 2025, https://trial.medpath.com/news/bce0987daac7cef4/fda-investigates-fatal-adverse-event-linked-to-takeda-s-adzynma-enzyme-replacement-therapy

• FDA Probing Patient Death Linked to Takeda’s Enzyme Replacement Therapy, PharmaLive, November 21, 2025, https://www.pharmalive.com/fda-probing-patient-death-linked-to-takedas-enzyme-replacement-therapy/

• FDA Investigation: FDA Probes Takeda’s Adzynma After Pediatric Patient Death Linked to Antibody Development, ETPharma, November 21, 2025, https://pharma.economictimes.indiatimes.com/news/pharma-industry/us-fda-investigates-takedas-blood-disorder-drug-after-pediatric-death/125497897

• Apadamtase alfa, recombinant Safety Alerts, Recalls & Warnings – Drugs.com, https://www.drugs.com/fda-alerts/4561-0.html

• FDA Probes Safety of Takeda’s Adzynma After Reported Death, Fierce Pharma, November 21, 2025, https://www.fiercepharma.com/pharma/fda-launches-investigation-takedas-adzynma-following-reported-pediatric-death

• Takeda’s ADZYNMA (ADAMTS13, recombinant-krhn) Now Available for the Prophylactic and On-Demand Treatment of Congenital Thrombotic Thrombocytopenic Purpura (cTTP) in the U.S., Takeda, https://www.takeda.com/en-us/newsroom/news-releases/2023/Takeda-ADZYNMA-ADAMTS13-recombinant-krhn-Now-Available-for-the-Prophylactic-and-On-Demand-Treatment-of-Congential-Thrombotic-Thrombocytopenic-Purpura-cTTP-in-the-US/

• FDA Investigates Death of 8-Year-Old Boy Who Received Elevidys, FDA, July 25, 2025, https://www.fda.gov/news-events/press-announcements/fda-investigating-death-8-year-old-boy-who-received-elevidys