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Wolfgang Miesbach: Rituximab Dose Optimization in iTTP – Why Standard Dose is Preferred?
Wolfgang Miesbach/LinkedIn
Dec 17, 2025, 23:55

Wolfgang Miesbach: Rituximab Dose Optimization in iTTP – Why Standard Dose is Preferred?

Wolfgang Miesbach, Professor of Medicine at Frankfurt University Hospital, shared on LinkedIn:

“ASH25 Data: Rituximab Dose Optimization in iTTP. Exciting results from Mari Thomas and colleagues on rituximab dosing strategies in immune thrombotic thrombocytopenic purpura (iTTP)—the first randomized trial comparing low-dose versus standard-dose preemptive rituximab in this life-threatening condition.

The Clinical Problem
iTTP remains devastating, with 74% relapse rates at 7 years in patients with persistent severe ADAMTS13 deficiency. While preemptive rituximab has transformed outcomes, optimal dosing remained uncertain—until now.

Wolfgang Miesbach: Rituximab Dose Optimization in iTTP - Why Standard Dose is Preferred?

Study Design

  • Standard dose: 375 mg/m² weekly × 4 weeks
  • Low dose: 200 mg weekly × 4 weeks
  • Population: 68 adults with iTTP in remission, ADAMTS13 activity ≤15%
  • Primary objective: Non-inferiority for time to retreatment

Efficacy Outcomes and median time to retreatment:
Low dose: 19.7 months
Standard dose: 20.1 months
HR 0.93 (95% CI: 0.56-1.53), p=0.799
ADAMTS13 normalization: 31 days (low dose) vs. 21 days (standard dose)—HR 0.73, p=0.187
Duration of ADAMTS13 response: 17.3 months vs. 19.1 months (p=0.864)

Clinical relapse rates (remarkably low in both arms):
– Low dose: 6.3%
– Standard dose: 0%

Critical Treatment Effect Dynamics
Non-constant treatment effect: More retreatments observed in the first 12 months with low-dose rituximab
After 12 months: Curves converge—suggesting early vulnerability with dose reduction

Immune Reconstitution
B cell return: 12.2 months (low dose) vs. 16.1 months (standard dose), p=0.151

Safety Profile: Reassuring News

  • Infusion reactions: Predominantly mild with both regimens
  • Delayed adverse effects: Well-managed across both arms
  • Pre-emptive rituximab remains safe, effective, and well-tolerated with repeated dosing

Results
This rigorous trial demonstrates that while low-dose rituximab shows activity, standard dosing (375 mg/m² weekly × 4) provides more consistent protection against early ADAMTS13 relapse—a critical insight for optimizing long-term management.

Recommendation: Standard-dose remains the preferred preemptive regimen in iTTP.”

Read more from Wolfgang Miesbach on Hemostasis Today.

ADAMTS13 American Society of Hematology (ASH) ASH2025 ASH25 Health Hemostasis Hemostasis Today Immune thrombotic thrombocytopenic purpura (iTTP) Mari Thomas Medicine rituximab thrombosis Wolfgang Miesbach
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