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Efficacy of UVC-treated platelets
Figure 2. Primary endpoint results. Non-inferiority plot comparing the difference in percentage of the 1-hour corrected count increment (CCI) between the control and UVC (test) arms. The point estimates of the difference in percentage and their 95% Confidence intervals are displayed for the per-protocol (PP) analysis and the intention-to-treat (ITT) analysis. The dotted vertical line shows the predefined non-inferiority margin of 30.0%. For both analyses, the 95% Confidence Interval slightly exceeds the non-inferiority margin.
Reduced immunogenicity of pathogen-reduced treated platelets produced using the riboflavin/UV technology was described in animal studies, but this effect was not observed in clinical studies.41-43 The low percentage of immunized patients in our study was too small for any conclusion on the immunogenicity of UVC-treated platelets. A systematic review of the data from 2,075 ran- domized patients enrolled in 12 studies revealed with high-quality evidence that pathogen-reduced platelets increase the risk of platelet refractoriness in adult cancer patients.33 We also found a higher rate of platelet refrac- toriness in the test arm of our study, which may be explained, at least in part, by the lower mean CCI of the UVC-treated platelets. As also observed for other pathogen-reduced platelets, the lower CCI translates into a higher portion of transfusions with a platelet recovery below the threshold that indicates successful transfusion.30
The THERAFLEX UV-Platelets PR technology was
developed for platelets suspended in plasma with SSP+PAS, which has been in routine use in Germany for more than a decade. Although limited data is available in the literature, the CCI of platelets stored in this solution seem to be comparable to those of platelets stored in plas- ma.44 Moreover, some evidence obtained with the riboflavin/UV PR system suggests that the use of SSP+ or a similar additive solution protects platelet quality after PR treatment and results in transfusion success rates which are comparable to those of platelets stored in plasma.45,46 Thus, we expect that the results obtained with UVC-treat- ed platelets compared to untreated platelets in additive solution may also be extended to the comparison with untreated plasma platelets, which are traditionally used as the reference standard.
There are several limitations of our study. The relation- ship between CCI and clinically significant bleeding has never been shown. In addition, it is a general limitation to
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