FDA Added Boxed Warning to Adzynma Therapy
Regulators issued a new safety warning for the enzyme replacement therapy due to neutralizing antibodies.
Updated on Sept. 23, 2026 in Allergies
The FDA has directed Takeda Pharmaceuticals to include a Boxed Warning on the labeling for Adzynma, a treatment for congenital thrombotic thrombocytopenic purpura. This update follows reports of neutralizing antibodies that can render the medication ineffective.
Why it matters
Neutralizing antibodies may prevent the therapy from functioning, posing a significant risk to patients who rely on the drug for treatment. The move underscores the need for ongoing vigilance and monitoring in patients receiving biologic enzyme replacements.
A fatal case occurred in a 7-year-old patient who developed neutralizing antibodies 10 months after starting treatment. The child had a prior history of allergic reactions to fresh frozen plasma.
The players
FDA
The Food and Drug Administration is a federal agency within the U.S. Department of Health and Human Services responsible for protecting public health.
Takeda Pharmaceuticals
Takeda Pharmaceuticals is a global, research-driven pharmaceutical company that manufactures Adzynma.
The details
Health care providers are now directed to monitor patients regularly with laboratory testing to screen for the presence of blocking antibodies. Adzynma, which received FDA approval in 2023, is a recombinant ADAMTS13 enzyme replacement therapy.
Timeline
November 9, 2023: The FDA originally approved Adzynma for patient use.
September 23, 2026: The FDA issued the new Boxed Warning requirement.
The Big Picture
This regulatory update follows a pattern set by the FDA Adverse Event Reporting System to identify and respond to post-market safety concerns in biologic therapies. It marks a shift toward more stringent monitoring for long-term immunogenic responses to recombinant enzyme treatments.
Patients currently receiving Adzynma should consult their healthcare provider to discuss mandatory laboratory testing for neutralizing antibodies. This monitoring is essential to ensure the therapy remains safe and effective for individual treatment plans.
The takeaway
Patients and providers must remain alert to the risk of developing neutralizing antibodies even months after beginning long-term enzyme replacement therapy. Regular laboratory screening is a critical step in identifying these blocking factors early to avoid treatment failure.
Further reading
For more information on managing immune-related treatment responses, visit the Allergies section.
More information
Review the full FDA safety communication and labeling updates for detailed guidance.
Source note: This article includes information reported by U.S. Food and Drug Administration.
