PMC9987240_01
Medication timeline and response of platelet count and ADAMTS13 levels. The graph summarizes medications administered during the refractory TTP episode. Initial treatment was prednisone (day 1), PLEX and caplacizumab (day 2). Prednisone 1 mg/kg PO daily was continued d1-d10; PLEX daily d2-d9; and caplacizumab 11 mg SC daily d2-d115. By d20 the platelet count was 400,000/microL and the ADAMTS13 activity remained <5%. Rituximab 375 mg/m2 IV weekly for 4 doses was given d28-d50. Vincristine 2 mg IV was given on d69 and d117. Cyclophosphamide was given 400 mg/m2 IV every 3 weeks for 3 doses between d75-d117 before accessory spleen removal on d140. Caplacizumab was continued every other day from d117-d135 due to drug procurement issues. Daily caplacizumab was resumed post-splenectomy from d143-d162. Platelets remained stable during this time; however, ADAMTS13 activity remained undetectable. To conserve caplacizumab drug supply, alternate-day dosing was again used between d164-d210. Bortezomib 1.3 mg/m2 SC was administered for refractory disease on d166, d169, d173, d177, d195, d198, and d202. ADAMTS13 activity increased after the fourth bortezomib dose. After stopping all medications, ADAMTS13 activity rose into the normal range.
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During the last 2 months of caplacizumab therapy, dosage was changed from daily to every other day (Figure 1).