A Takeda logo is seen in its research hub in Cambridge, Massachusetts, U.S., November 26, 2018. REUTERS/Julie Steenhuysen
FILE PHOTO: Takeda Pharmaceutical Co's logo is seen at its new headquarters in Tokyo, Japan, July 2, 2018. REUTERS/Kim Kyung-Hoon/File Photo

(Reuters) -The U.S. Food and Drug Administration said on Friday it is investigating the death of a child who developed harmful antibodies after receiving Takeda Pharmaceuticals' therapy for a rare blood disorder.

The health regulator said it is investigating the risk of developing neutralizing antibodies, including potential life-threatening outcomes, following treatment with Takeda's Adzynma.

Approved in 2023 as the first therapy for congenital thrombotic thrombocytopenic purpura (cTTP), Adzynma works by replacing the missing ADAMTS13 protein to prevent dangerous clot formation.

The inherited condition causes blood clots in small blood vessels, which can lead to strokes, kidney damage and other serious complications.

The agency is also evaluating whether additional regulatory action is needed.

"We reported this event to the U.S. Food and Drug Administration and have been providing them with updates since we became aware in July", a Takeda spokesperson said in an emailed response.

The company has also conducted a thorough assessment and determined that there was no confirmed causal relationship to the use of Adzynma  and the patient death, the spokesperson added.

The pediatric patient with cTTP had neurologic symptoms that progressed and developed antibodies that blocked the activity of ADAMTS13. The death occurred about 10 months after starting Takeda's therapy.

Before beginning treatment with Adzynma, the patient had previously experienced severe allergic reactions to fresh frozen plasma, which is a traditional treatment for the condition.

The FDA said it has received multiple postmarketing reports of patients developing such antibodies after treatment with Adzynma, though these were not observed during clinical trials.

While the current prescribing information warns about the potential risk of antibody development, it does not include details about postmarketing cases involving serious or fatal outcomes.

(Reporting by Kamal Choudhury and Sriparna Roy in Bengaluru; Editing by Vijay Kishore)