TTP/HUS: observational studies generate hypotheses that lead to randomized controlled trials

Area of Science:

• Hematology
• Clinical Trials
• Observational Studies

Background:

• Thrombotic thrombocytopenic purpura (TTP)/hemolytic uremic syndrome (HUS) is a rare but serious condition.
• The historical progression of TTP/HUS research highlights the impact of observational studies on clinical trial design.
• Early case reports and observational data were crucial in establishing treatment paradigms.

Purpose of the Study:

• To review the historical evolution of TTP/HUS research, emphasizing the transition from observational studies to randomized controlled trials (RCTs).
• To highlight the pivotal role of plasma exchange over plasma infusion in treating adult TTP/HUS.
• To present evidence supporting the initiation of a new RCT based on continuous plasma exchange and von Willebrand factor-cleaving protease (ADAMTS13) activity.

Main Methods:

• Historical analysis of seminal case reports and observational studies in TTP/HUS.
• Review of a landmark RCT comparing plasma exchange and plasma infusion for TTP/HUS.
• Synthesis of findings from a 25-year observational study on plasma exchange treatment for TTP/HUS.

Main Results:

• Moschowitz's initial case report and subsequent findings by Bukowski and Byrne spurred research.
• The RCT by Rock and the Canadian Apheresis Group demonstrated plasma exchange's superiority over plasma infusion for adult TTP/HUS.
• A single case report on continuous plasma exchange, alongside observations on von Willebrand factor-cleaving protease, supports further investigation.

Conclusions:

• The history of TTP/HUS management exemplifies the successful translation of observational findings into rigorous RCTs.
• Plasma exchange is the established standard of care for TTP/HUS in adults.
• Current evidence warrants a new RCT to further refine TTP/HUS treatment strategies, potentially involving continuous plasma exchange.