Background: Photochemical treatment of fresh-frozen plasma (FFP) with amotosalen and ultraviolet (UV) A light (PCT FFP) results in inactivation of a broad spectrum of pathogens while retaining coagulation factor activity, antithrombotic proteins, and von Willebrand factor-cleaving protease (VWF-CP) activity.
Study design and methods: A randomized, controlled, double-blind Phase III trial was conducted with PCT FFP or control FFP for therapeutic plasma exchange (TPE) in patients with thrombotic thrombocytopenic purpura (TTP). Owing to the rarity of this diagnosis, the trial was not powered to demonstrate small differences between treatment groups. Patients were treated with study FFP for a maximum of 35 days until remission was achieved (for a maximum of 30 daily study TPEs with no remission) plus an additional 5 days after remission.
Results: Among the 35 patients treated, the primary endpoint, remission within 30 days, was achieved by 14 of 17 (82%) PCT patients and 16 of 18 (89%) control patients (p = 0.658) The 90 percent confidence interval for treatment difference in remission rate for test - control was (-0.291 to 0.163). Time to remission, relapse rates, time to relapse, total volume and number of FFP units exchanged, and number of study TPEs were not significantly different between groups. Improvement in VWF-CP and inhibitors was similar for both groups. The overall safety profile of PCT FFP was similar to control FFP. No antibodies to amotosalen neoantigens were detected.
Conclusion: The comparable results between treatment groups observed from this small trial suggest that TPE with PCT FFP was safe and effective for treatment of TTP.