Transfusion of irradiated red blood cell units with a potassium adsorption filter: A randomized controlled trial

BACKGROUND : The irradiation of red blood cells (RBCs) causes damage of the RBC membrane with increased potassium (K) leak during storage compared with nonirradiated RBC units of similar age. A previous in vitro study showed a mean reduction of K of 94 ± 5% with a potassium adsorption filter (PAF).
STUDY DESIGN AND METHODS : A prospective, single-center, nonblinded, randomized controlled trial (RCT) was designed to evaluate the safety and efficacy of transfusing irradiated RBC units with the PAF. Patients 18 years of age or older who received irradiated RBC units due to chemotherapy-induced anemia were randomly assigned to receive irradiated RBC units with the PAF (PAF group) or with the standard blood infusion set (control group). Primary outcome measures were safety and efficacy of the PAF (absolute change in hemoglobin [Hb] and K, respectively, in patient's blood values after transfusing the irradiated RBC units with or without the PAF).
RESULTS : A total of 63 irradiated RBC units were transfused to 17 patients in the control group, and a total of 56 irradiated RBC units were transfused to 13 patients in the PAF group. The absolute change of Hb (9.3 ± 6.3 g/L vs. 8.1 ± 5.8 g/L; p = 0.3) and the absolute change of K (−0.01 ± 0.4 mmol/L vs. −0.01 ± 0.3 mmol/L; p = 0.2) were comparable between the two groups of the trial.
CONCLUSION : The transfusion of 1 irradiated RBC unit with the PAF was as safe and efficacious as the transfusion of 1 irradiated RBC unit with the standard blood infusion set in patients with chemotherapy-induced anemia (read more)

Caplacizumab for Acquired Thrombotic Thrombocytopenic Purpura

BACKGROUND : Acquired thrombotic thrombocytopenic purpura (TTP) is caused by aggregation of platelets on ultralarge von Willebrand factor multimers. This microvascular thrombosis causes multiorgan ischemia with potentially life-threatening complications. Daily plasma exchange and immunosuppressive therapies induce remission, but mortality and morbidity due to microthrombosis remain high.
METHODS : Caplacizumab, an anti–von Willebrand factor humanized single-variable-domain immunoglobulin (Nanobody), inhibits the interaction between ultralarge von Willebrand factor multimers and platelets. In this phase 2, controlled study, we randomly assigned patients with acquired TTP to subcutaneous caplacizumab (10 mg daily) or placebo during plasma exchange and for 30 days afterward. The primary end point was the time to a response, defined as confirmed normalization of the platelet count. Major secondary end points included exacerbations and relapses.
RESULTS : Seventy-five patients underwent randomization (36 were assigned to receive caplacizumab, and 39 to receive placebo). The time to a response was significantly reduced with caplacizumab as compared with placebo (39% reduction in median time, P=0.005). Three patients in the caplacizumab group had an exacerbation, as compared with 11 patients in the placebo group. Eight patients in the caplacizumab group had a relapse in the first month after stopping the study drug, of whom 7 had ADAMTS13 activity that remained below 10%, suggesting unresolved autoimmune activity. Bleeding-related adverse events, most of which were mild to moderate in severity, were more common with caplacizumab than with placebo (54% of patients vs. 38%). The frequencies of other adverse events were similar in the two groups. Two patients in the placebo group died, as compared with none in the caplacizumab group.
CONCLUSIONS : Caplacizumab induced a faster resolution of the acute TTP episode than did placebo. The platelet-protective effect of caplacizumab was maintained during the treatment period. Caplacizumab was associated with an increased tendency toward bleeding, as compared with placebo (read more)

Predicted effect of selectively testing female donors for HLA antibodies to mitigate transfusion-related acute lung injury risk from apheresis platelets

BACKGROUND : The use of male-donor-predominant plasma has reduced the risk of transfusion-related acute lung injury (TRALI), but the possible benefit of different mitigation strategies for other components is unknown. We evaluated the risk of TRALI from apheresis platelets (PLTs) to predict the effect of selectively testing female plateletpheresis donors who have been pregnant for HLA antibodies.
STUDY DESIGN AND METHODS : The American Red Cross hemovigilance program classified TRALI cases from apheresis PLTs or red blood cells (RBCs) in 2006 to 2013 or from predominantly male-donor (>95%) plasma in 2008 to 2013 and compared the component-specific TRALI rates.
RESULTS : The overall rate of TRALI was significantly higher for apheresis PLTs (6.2 cases per 106 units; OR [95% CI], 3.3 [2.3-4.8]) or plasma (3.8 cases per 106 units; OR [95% CI], 2.0 [1.4-2.9]) compared to RBCs (1.9 per 106 units). Twenty-nine of the 41 apheresis PLT cases involved female donors; 28 had been pregnant, and one had not been pregnant and was not tested. Twenty-five (61%) of the apheresis PLT TRALI cases had female donors with HLA Class I or Class II antibodies. In five of six cases that implicated specific HNA antibodies, the female parous donors also had multiple HLA antibodies.
CONCLUSIONS : TRALI was more likely after transfusion of apheresis PLTs than male-donor-predominant plasma or RBCs. A selective strategy to test all female plateletpheresis donors who have been pregnant for HLA antibodies might reduce the risk of TRALI by approximately 60% and prevent some cases from coexisting HNA antibodies (read more)