Red blood cell pathogen reduction: in search of serological agnosticism

The Mirasol Evaluation of Reduction in Infections Trial (MERIT): study protocol for a randomized controlled clinical trial

BACKGROUND

Transfusion-transmitted infections (TTIs) are a global health challenge. One new approach to reduce TTIs is the use of pathogen reduction technology (PRT). In vitro, Mirasol PRT reduces the infectious load in whole blood (WB) by at least 99%. However, there are limited in vivo data on the safety and efficacy of Mirasol PRT. The objective of the Mirasol Evaluation of Reduction in Infections Trial (MERIT) is to investigate whether Mirasol PRT of WB can prevent seven targeted TTIs (malaria, bacteria, human immunodeficiency virus, hepatitis B virus, hepatitis C virus, hepatitis E virus, and human herpesvirus 8).

METHODS

MERIT is a randomized, double-blinded, controlled clinical trial. Recruitment started in November 2019 and is expected to end in 2024. Consenting participants who require transfusion as medically indicated at three hospitals in Kampala, Uganda, will be randomized to receive either Mirasol-treated WB (n = 1000) or standard WB (n = 1000). TTI testing will be performed on donor units and recipients (pre-transfusion and day 2, day 7, week 4, and week 10 after transfusion). The primary endpoint is the cumulative incidence of one or more targeted TTIs from the Mirasol-treated WB vs. standard WB in a previously negative recipient for the specific TTI that is also detected in the donor unit. Log-binomial regression models will be used to estimate the relative risk reduction of a TTI by 10 weeks associated with Mirasol PRT. The clinical effectiveness of Mirasol WB compared to standard WB products in recipients will also be evaluated.

DISCUSSION

Screening infrastructure for TTIs in low-resource settings has gaps, even for major TTIs. PRT presents a fast, potentially cost-effective, and easy-to-use technology to improve blood safety. MERIT is the largest clinical trial designed to evaluate the use of Mirasol PRT for WB. In addition, this trial will provide data on TTIs in Uganda.

TRIAL REGISTRATION

Mirasol Evaluation of Reduction in Infections Trial (MERIT) NCT03737669 . Registered on 9 November 2018.

The long and winding road to pathogen reduction of platelets, red blood cells and whole blood

Pathogen reduction technologies (PRTs) have been developed to further reduce the current very low risks of acquiring transfusion-transmitted infections and promptly respond to emerging infectious threats. An entire portfolio of PRTs suitable for all blood components is not available, but the field is steadily progressing. While PRTs for plasma have been used for many years, PRTs for platelets, red blood cells (RBC) and whole blood (WB) were developed more slowly, due to difficulties in preserving cell functions during storage. Two commercial platelet PRTs use ultra violet (UV) A and UVB light in the presence of amotosalen or riboflavin to inactivate pathogens' nucleic acids, while a third experimental PRT uses UVC light only. Two PRTs for WB and RBC have been tested in experimental clinical trials with storage limited to 21 or 35 days, due to unacceptably high RBC storage lesion beyond these time limits. This review summarizes pre-clinical investigations and selected outcomes from clinical trials using the above PRTs. Further studies are warranted to decrease cell storage lesions after PRT treatment and to test PRTs in different medical and surgical conditions. Affordability remains a major administrative obstacle to PRT use, particularly so in geographical regions with higher risks of transfusion-transmissible infections.

Red blood cell in vitro quality and function is maintained after S-303 pathogen inactivation treatment

BACKGROUND

Over the past decade there has been a growth in the development of pathogen reduction technologies to protect the blood supply from emerging pathogens. This development has proven to be difficult for red blood cells (RBCs). However the S-303 system has been shown to effectively inactivate a broad spectrum of pathogens, while maintaining RBC quality.

STUDY DESIGN AND METHODS

A paired three-arm study was performed to compare the in vitro quality of S-303-treated RBCs with RBCs stored at room temperature (RT) for the duration of the treatment (18-20 hr) and control RBCs stored at 2 to 6°C. Products were sampled weekly over 42 days of storage (n = 10) and tested using an array of in vitro assays to measure quality, metabolism, and functional variables.

RESULTS

During S-303 treatment there was a slight loss of RBCs and hemoglobin (Hb < 5 g). Hemolysis, glucose consumption, and potassium release were similar in all groups during the 42 days of storage. S-303-treated RBCs had a significantly lower lactate concentration and pH compared to the paired controls. The S-303-treated RBCs had significantly higher adenosine triphosphate than the RT and control RBCs. There was a significant loss of 2,3-diphosphoglycerate in the S-303-treated products, which was also observed in the RT RBCs. Flow cytometry analysis demonstrated similar RBC size, morphology, expression of CD47, and glycophorin A in all groups.

CONCLUSION

RBCs treated with S-303 for pathogen reduction had similar in vitro properties to the paired controls and were within transfusion guidelines.