Anti‐ ADAMTS13 Antibodies Trajectory is Associated With ADAMTS13 Recovery in Immune‐Mediated TTP

Le résumé fourni par la source

Current triplet regimens associating therapeutic plasma exchange (TPE), immunosuppression with corticosteroids and rituximab, and caplacizumab have dramatically improved the outcome of immune-mediated thrombotic thrombocytopenic purpura (iTTP). However, nearly half of the patients require extended caplacizumab treatment (i.e., > 30 days) due to persistent ADAMTS13 deficiency, raising cost and tolerance concerns. Therefore, we investigated whether anti-ADAMTS13 antibodies titer and their trajectory during the acute phase of the disease could predict ADAMTS13 improvement (i.e., activity ≥ 20% before day-30 post-TPE). From a cohort of 286 patients receiving the triplet regimen, we identified on diagnosis a cut-off value for anti-ADAMTS13 IgG antibodies of 90.5 U/mL, with a modest discriminating ability (AUC: 0.57) for predicting long-term response, precluding its use to guide therapeutic strategies. Nonetheless, the analysis of anti-ADAMTS13 IgG antibodies titer trajectory from diagnosis revealed that the proportion of iTTP patients with ADAMTS13 activity improvement was higher in patients who decreased (Dec+) their antibodies titer within the 7-14 days interval post-TPE compared to those without decrease (Dec-) (65% vs. 25% of cases, respectively, p < 0.001), a finding confirmed in a validation cohort (N = 51). These results highlight the possibility of intensifying immunosuppression in an early period post-TPE to shorten time to ADAMTS13 activity recovery. Close monitoring of anti-ADAMTS13 antibodies titer may guide immunomodulation strategies, including additional courses of B-cell depleting agents when appropriate.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.