Davenport, Robertson D.

Importance Recent case reports suggest that B antigen–containing blood products may be associated with anaphylactic transfusion reactions in recipients with preformed immunoglobulin E to galactose- α -1,3-galactose (alpha-gal). Objective To test the association of local alpha-gal syndrome (AGS) prevalence and allergic transfusion reaction (ATR) in patients with blood type O. Design, Setting, and Participants In this international, multicenter, retrospective cohort study at academic medical centers, sites were assigned to AGS high- or low-prevalence clusters based on the known geographic distribution of AGS. Data were collected on platelet or plasma transfusions and ATRs during 2020 to 2024. Consecutive patients receiving platelet or plasma transfusions were included. Exposures Patients with blood type O who received B or AB units and patients with blood type O who received O units (reference group) in AGS high- and low-prevalence clusters were compared. Main Outcomes and Measures Before data collection, the hypothesis was that if transfusion-related alpha-gal syndrome (TRAGS) is a true clinical entity, excess ATRs to group B or AB units would be detected in AGS high-prevalence regions exclusively. The main measure was the overall risk ratio (RR) for ATRs to B or AB plasma or platelets in AGS high- vs low-prevalence clusters. Results In total, 558 823 platelet and plasma transfusions at 40 sites in 5 countries were analyzed, of which ATRs occurred in 1744 transfusions (0.3%). In the US AGS high-prevalence cluster (9 sites), significantly more ATRs of any severity occurred among patients with blood type O who received B or AB units vs patients with blood type O who received O units (overall RR, 3.93; 95% CI, 2.96-5.21; P < .001). In contrast, in the primary analysis of the AGS low-prevalence cluster (15 sites), excess ATRs to B or AB units were not detected. In subgroup analyses among patients with blood type O receiving B units, the RR for moderate to severe ATRs was 9.14 (95% CI, 5.39-15.52; P < .001) in the AGS high-prevalence cluster vs 2.15 (95% CI, 1.34-3.47; P = .002) in the AGS low-prevalence cluster. Outside the US, a signal consistent with TRAGS was not detected. Conclusions and Relevance This cohort study provides provocative epidemiologic evidence that TRAGS may be a unique manifestation of AGS and a previously unrecognized risk associated with transfusion. In AGS high-prevalence regions, blood collectors and hospital transfusion services should consider approaches to preventing severe ATRs from B or AB plasma or platelet units.

Introduction: Red blood cell (RBC) transfusion is a lifesaving intervention with a low but persistent risk of transfusion-transmitted infection. Amustaline/glutathione RBC pathogen-reduction (PR) technology is designed to proactively inactivate a broad spectrum of viruses, bacteria, protozoa and leukocytes by chemically crosslinking nucleic acids and preventing replication and transcription. The Red Cell Pathogen Inactivation (ReCePI) trial was a Phase III, double-blinded, randomized non-inferiority study comparing PR and conventional RBCs for the support of acute anemia. Methods/Study Design: Complex cardiac or thoracic-aorta surgery patients received conventional (Control) or PR RBCs (Test) during and for 7 days after surgery. The protocol was conducted with ethics committee approval at all participating centers and written informed consent from all participants. Hemoglobin levels, blood utilization and serum creatinine were assessed as indicators of efficacy and oxygenation of tissues (Karkouti et al. Br J Anaesth. 2012; 109 Suppl 1: i29-i38). The primary endpoint was the incidence of acute kidney injury (AKI) measured as change in serum creatinine from baseline within 48 hours of surgery, a predictor of adverse postoperative outcomes including mortality by Day 30 post-surgery (Lassnig et al. Am Soc Nephrol 2004; 1597-1605). Secondary endpoints included AKI occurring up to 7 days post-surgery (KDIGO Clinical Practice Guideline for AKI, Kidney Inter, Suppl. 2012;2:1-138); death or the need for renal replacement therapy by 30 days post-surgery; PR RBC-specific antibodies; and death by day 75 post-surgery. With >292 subjects enrolled, the study had 80% power to demonstrate non-inferiority, assuming an AKI incidence of 30% with conventional RBCs and a non-inferiority margin of half the conventional RBC rate. Under these circumstances, an absolute treatment increase of 5% in the AKI rate in the PR RBC arm would fail the non-inferiority test. This work was supported by a contract with the US Biomedical Advanced Research and Development Authority (HHS010020160009c) with Cerus Corporation. Results: Five-hundred and eighty-one subjects were randomized and 321 (55%) transfused in 18 US hospitals. In the modified intent-to-treat analysis subjects receiving Test and Control RBCs had similar median [IQR] total blood loss (1500 [940-2475] mL Test, 1733 [1060-2880] mL Control, p=0.310) and comparable median hemoglobin levels at baseline and immediately post-surgery (9.8 [8.9-10.9] g/dL Test, 9.6 [8.6-10.6] g/dL Control, p=0.157) and for 7 days after surgery, The PR RBC arm was transfused with fewer RBCs, measured as total RBC Hb transfused over 7-days (169.0 [102.0-240.0] g Hb PR arm, 188.0 [126.0-295.0] g Hb, conventional RBC arm, p=0.008). The incidence of AKI was 29.3% (46/157) for Test and 28.0% (45/161) for Control. The treatment difference was 0.74% (95% CI -8.9, 10.4%, non-inferiority margin 14.0%, p=0.001 for non-inferiority). Non-inferiority was also achieved by the per protocol analysis. Average mean change in serum creatinine within 48 hours of surgery was comparable (Test 0.020, Control 0.23 mg/dL, P=0.515). Adverse events, serious adverse events and deaths on study were not different. Five of 159 (3.1%) PR RBC recipients developed low titer PR RBC-specific antibodies without clinical signs of hemolysis. Flow cytometry analysis revealed persistent circulating PR RBCs with uniform antigen loss (modulation). Low level human IgG antibody binding was demonstrated in 3 of 5 subjects. Conclusions: PR RBCs showed equivalent hemoglobin support for acute bleeding patients undergoing cardiac or thoracic-aorta surgery while using less transfused total RBC Hb over 7 days. The incidence of AKI in patients transfused with PR RBCs was non-inferior to that observed with conventional RBCs, indicative of effective tissue oxygenation. Treatment-related antibodies to PR-RBC were observed only in Test subjects, the antibodies were low titer, transient, without clinical hemolysis, and persistent circulating PR RBCs were detected with modulated low level acridine antigen expression (www.clinicaltrials.gov #NCT03459287).

Abstract Background Red blood cell (RBC) transfusion is a critical supportive therapy in cardiovascular surgery (CVS). Donor selection and testing have reduced the risk of transfusion-transmitted infections; however, risks remain from bacteria, emerging viruses, pathogens for which testing is not performed and from residual donor leukocytes. Amustaline (S-303)/glutathione (GSH) treatment pathogen reduction technology is designed to inactivate a broad spectrum of infectious agents and leucocytes in RBC concentrates. The ReCePI study is a Phase 3 clinical trial designed to evaluate the efficacy and safety of pathogen reduced RBCs transfused for acute anemia in CVS compared to conventional RBCs, and to assess the clinical significance of treatment-emergent RBC antibodies. Methods ReCePI is a prospective, multicenter, randomized, double-blinded, active-controlled, paralleldesign, non-inferiority study. Eligible subjects will be randomized up to 7 days before surgery to receive either leukoreduced Test (pathogen reduced) or Control (conventional) RBCs from surgery up to Day 7 post-surgery. The primary efficacy endpoint is the proportion of patients transfused with at least one study transfusion with an acute kidney injury (AKI) diagnosis defined as any increased serum creatinine (sCr) level ≥0.3 mg/dL (or 26.5 µmol/L) from presurgery baseline within 48±4 hours of the end of surgery. The primary safety endpoints are the proportion of patients with any treatment-emergent adverse events (TEAEs) related to study RBC transfusion through 28 days, and the proportion of patients with treatment-emergent antibodies with confirmed specificity to pathogen reduced RBCs through 75 days after the last study transfusion. With ≥292 evaluable, transfused patients (>146 per arm), the study has 80% power to demonstrate non-inferiority, defined as a Test group AKI incidence increase of no more than 50% of the Control group rate, assuming a Control incidence of 30%. Discussion RBCs are transfused to prevent tissue hypoxia caused by surgery-induced bleeding and anemia. AKI is a sensitive indicator of renal hypoxia and a novel endpoint for assessing RBC efficacy. The ReCePI study is intended to demonstrate the non-inferiority of pathogen reduced RBCs to conventional RBCs in the support of renal tissue oxygenation due to acute anemia and to characterize the incidence of treatment-related antibodies to RBC.