Pathogen inactivation systems are in use in many European countries as routine procedures. However, a pathogen inactivation system for erythrocytes is currently not available. Although significant improvements have been made to decrease the incidence of transfusion-transmitted infections, risks remain for infectious disease agents specific to red blood cell concentrates, such as parasitic infections resulting in babesiosis and malaria. The pathogen inactivation system for erythrocytes utilizes S-303 and glutathione for the treatment of red blood cell concentrates. Preclinical studies to assess the pathogen inactivation efficacy and toxicology as well as preliminary clinical studies have been completed. Preclinical studies have shown log reduction for leukocytes, several viruses and bacteria in excess of 4 to 6 logs. Preclinical toxicology studies were conducted to enable the initiation of two phase III clinical studies in the USA for support of acute and chronic anemia. A second-generation system was developed after observation of an unexpected immune response in two chronic anemia patients. Preclinical pathogen inactivation studies, serological evaluations and a clinical study to evaluate survival of S-303-treated erythrocytes have been completed to support advanced development of the S-303 pathogen inactivation system. A functional system for the inactivation of red blood cell concentrates has been completed and is reaching clinical application.

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RBCs prepared using the S-303 pathogen inactivation process were physiologically and metabolically suitable for transfusion after 35 days of storage, met the FDA guidance criteria for 24-hour recovery, and did not induce antibody formation.

The level of residual S-303 and S-300 in the treated blood component is well below that at which no adverse effects were observed. These results support further clinical development of S-303 RBCs for prevention of transfusion-transmitted infections.

BACKGROUND Nucleic acid–targeted pathogen inactivation technology using amustaline (S‐303) and glutathione (GSH) was developed to reduce the risk of transfusion‐transmitted infectious disease and transfusion‐associated graft‐versus‐host disease with red blood cell (RBC) transfusion. STUDY DESIGN AND METHODS A randomized, double‐blind, controlled study was performed to assess the in vitro characteristics of amustaline‐treated RBCs (test) compared with conventional (control) RBCs and to evaluate safety and efficacy of transfusion during and after cardiac surgery. The primary device efficacy endpoint was the postproduction hemoglobin (Hb) content of RBCs. Exploratory clinical outcomes included renal and hepatic failure, the 6‐minute walk test (a surrogate for cardiopulmonary function), adverse events (AEs), and the immune response to amustaline‐treated RBCs. RESULTS A total of 774 RBC unis were produced. Mean treatment difference in Hb content was –2.27 g/unit (95% confidence interval, –2.61 to –1.92 g/unit), within the prespecified equivalence margins (±5 g/unit) to declare noninferiority. Amustaline‐treated RBCs met European guidelines for Hb content, hematocrit, and hemolysis. Fifty‐one (25 test and 26 control) patients received study RBCs. There were no significant differences in RBC usage or other clinical outcomes. Observed AEs were within the spectrum expected for patients of similar age undergoing cardiovascular surgery requiring RBCs transfusion. No patients exhibited an immune response specific to amustaline‐treated RBCs. CONCLUSION Amustaline‐treated RBCs demonstrated equivalence to control RBCs for Hb content, have appropriate characteristics for transfusion, and were well tolerated when transfused in support of acute anemia. Renal impairment was characterized as a potential efficacy endpoint for pivotal studies of RBC transfusion in cardiac surgery.