FDA Approves Prophylactic Treatment for Adults, Pediatric Patients With Extremely Rare Blood-Clotting Disorder

The FDA recently approved ADAMTS13, recombinant-krhn (rADAMTS13; Adzynma, Takeda Pharmaceuticals) as prophylactic or on-demand enzyme replacement therapy (ERT) for adult and pediatric patients with life-threatening congenital thrombotic thrombocytopenic purpura (cTTP), according to a recent FDA press release. rADAMTS13 was granted a Rare Pediatric Disease Priority Review Voucher, as well as receiving Priority Review, Fast Track, and Orphan designations.

cTTP is a blood-clotting disorder caused by a mutation of the ADAMTS₁₃ gene. The gene typically makes enzyme ADAMTS₁₃ to regulate blood clotting, but the mutation causes a reduction in enzyme production; as a result, the patient will start to have blood clots develop throughout their small blood vessels.

“Without treatment, cTTP is ultimately fatal,” said Peter Marks, MD, PhD, director of the Center for Biologics Evaluation and Research at the FDA, in the press release.

In a recent global cross-over study, the therapeutic protein reduced acute and subacute thrombotic thrombocytopenic purpura (TTP) events for patients who received it either as aprophylactic treatment to reduce symptoms or as an on-demand treatment to resolve an acute event, according to the press release.

rADAMTS13 was evaluated in a study that compared prophylactic and on-demand ERT rADAMTS13 with plasma-based therapies in patients with cTTP. The randomized trial enrolled 46 patients and evaluated safety and efficacy endpoints; efficacy endpoints included incidence of TTP event, TTP manifestations, and the need for supplemental doses.

During the trial, patients received rADAMTS13 or plasma-based therapy for 6 months; after 6 months, patients in each cohort switched to the other therapeutic agent for an additional 6 months (ie, at 6 months, patients on rADAMTS13 switched to plasma-based therapy, and vice versa). Both rADAMTS13 and plasma-based therapy were shown to decrease acute and subacute TTP events.

The most common adverse events associated with the prophylactic and on-demand ERT were headache, diarrhea, migraine, abdominal pain, nausea, upper respiratory tract infection, dizziness, and vomiting. However, none of the patients experienced AEs (or allergic reaction) during the administration process.

cTTP is a rare disorder that affects less than 1000 US patients every year. Symptoms of cTTPmay include severe bleeding episodes, stroke, or damage to the vital organs; treatment is geared toward reducing the risk of clotting and/or bleeding by increasing production of enzyme ADAMTS_13, and prophylactic plasma-based therapy is the most common.

rADAMTS13 is a purified recombinant type of ADAMTS13 that can replace low levels of enzyme ADAMTS13 in the prophylactic or on-demand setting. In the prophylactic setting, rADAMTS13 is administered intravenously once every 2 weeks. As an on-demand treatment, it should be administered once daily.

“Today’s approval reflects important progress in the development of much-needed treatment options for patients affected by this life-threatening disorder,” Marks said in the press release.

Reference

FDA Approves First Treatment for Patients with Rare Inherited Blood Clotting Disorder. FDA. News Release. November 9, 2023. Accessed on November 10, 2023. https://www.fda.gov/news-events/press-announcements/fda-approves-first-treatment-patients-rare-inherited-blood-clotting-disorder?utm_medium=email&utm_source=govdelivery