Optimizing ADAMTS13 prophylaxis to reduce relapse and organ failure in congenital thrombotic thrombocytopenic purpura.

Congenital thrombotic thrombocytopenic purpura (cTTP) is caused by a severe inherited ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 motif, member 13) deficiency. Although acute episodes are life-threatening, long-term burden of ischemic complications, and effectiveness of prophylactic strategies remain underexplored. We conducted a 25-year national, multicenter study of 88 patients with cTTP enrolled in the French Thrombotic Microangiopathy registry. Patients were stratified by age and clinical context at disease onset: pediatric (n = 42), pregnancy (n = 33), and adult onset (n = 13). Clinical features, genotypes, treatment regimens, and long-term ischemic outcomes were analyzed. Pediatric patients exhibited early-onset disease (median age at diagnosis, 2 years [interquartile range, 0-13]) with recurrent episodes and a high burden of neurological complications. In patients with pregnancy-onset disease, no relapses were observed outside pregnancy. Adult-onset patients, typically diagnosed aged >50 years, showed prevalent cardiovascular disease, stroke, and kidney injury. Mental health disorders were common across all groups. Despite long-term plasma prophylaxis, organ dysfunction persisted, particularly in pediatric- and adult-onset groups. In pregnancy-onset cTTP, tailored midterm prophylaxis during pregnancy reduced maternal and fetal complications. Thirty-nine patients received recombinant human ADAMTS13 (rhADAMTS13) prophylaxis (median follow-up, 5 months [interquartile range, 6-17]). Prophylactic treatment significantly improved relapse-free survival, with a comparable outcome using intensive plasma-derived products and rhADAMTS13 in pediatric-onset cases, although adverse events were more prevalent using plasma therapy. Our findings highlight the clinical and genetic heterogeneity of cTTP and the burden of organ dysfunction. Intensive prophylaxis improves relapse-free survival. rhADAMTS13 represents a safe and promising first-line option that should help reduce long-term organ damage and improve quality of life.