Donor-type fresh frozen plasma is effective in preventing hemolytic reaction in major ABO incompatible allogeneic stem cell transplant

Rituximab added to conditioning regimen significantly improves erythroid engraftment in major incompatible ABO-group hematopoietic stem cell transplantation

ABO-group major incompatibility hematopoietic stem cell transplantation (HSCT) increases the risk of delayed red cell engraftment and other immunological complications. In this study, we evaluated the efficacy of pre-transplant infusion of rituximab in patients with ABO-incompatibility in improving red blood cell engraftment after HSCT, measured by time to reach transfusion independence. We performed a retrospective, single-center study including 131 consecutive patients transplanted with major or bidirectional ABO-incompatible grafts between 1st January 2013 and 31st December 2019. Fifty-one patients received an infusion of rituximab during the conditioning regimen, while 80 patients did not receive any additional preventive treatment. Time to transfusion independence was significantly reduced for patients treated with rituximab (1 month, 95% CI, 0.5-2) compared with the control group (3.2 months, 95% CI 1.5-3.2, p = 0.02). By multivariable analysis, rituximab use was associated with a faster red blood cell (RBC) engraftment (RR 1.88, 95% CI 1.17-3.03, p = 0.009), while a pre-transplant anti-donor isohemagglutinins titer >1:128 was associated with delayed transfusion independence (RR 0.61, 95% CI 0.37-0.99, p = 0.05). Although limited by the retrospective nature of the study, the results of this analysis suggest that rituximab added to conditioning regimens is feasible, safe, and able to improve post-transplant red blood cell engraftment.

The impact of infused red blood cell volume on major and bidirectional ABO-mismatched bone marrow transplantation

BACKGROUND AIMS

ABO incompatibility does not hinder bone marrow transplantation (BMT), but it has been associated with worse outcomes and additional adverse events. This study aimed to verify the impact of incompatible red blood cells (iRBCs) in allogeneic BMT and to determine a safe number of iRBCs to be infused.

METHODS

We compared ABO-incompatible (iABO) allogeneic BMT (n = 42) with ABO-compatible allogeneic BMT (n = 44) and evaluated the impact of the number of infused iRBCs on outcomes and adverse events.

RESULTS

The iABO patients demonstrated delayed time to transfusion independence at 30 days and 60 days, increased requirement for red blood cell (RBC) transfusion and greater hemolysis signals and incidence of pure red cell aplasia. Neutrophil/platelet engraftment, length of hospitalization post-transplant, platelet units required, graft-versus-host disease occurrence and overall survival were similar in both groups. Patients in the iABO group received 1.03 × 1010 iRBCs/kg (range, 0.36-3.88). Infusion of iRBCs >1.0 × 1010 /kg was related to graft failure or death before neutrophil engraftment or platelet engraftment or both as well as increased plasma requirement and increased creatinine. Our results also suggest that antibody titers impact the transplantation scenario.

CONCLUSIONS

The iABO transplantation showed some unfavorable outcomes. It is important to monitor the value of iRBCs to be infused, considering the recipient antibody titers. We propose using the number of iRBCs (iRBCs/kg) as a dose parameter with regard to infused iRBCs. Further studies are necessary to clarify the maximum safe number of iRBCs in iABO transplants.

Post-Hematopoietic Stem Cell Transplantation Immune-Mediated Anemia: A Literature Review and Novel Therapeutics

Anemia after allogeneic hematopoietic stem cell transplantation (HSCT) can be immune or non–immune mediated. Auto- or alloimmunity resulting from blood group incompatibility remains an important cause in post-HSCT immune-mediated anemia. ABO incompatibility is commonly encountered in HSCT and may lead to serious clinical complications, including acute hemolysis, pure red cell aplasia, and passenger lymphocyte syndrome. It remains controversial whether ABO incompatibility may affect HSCT outcomes, such as relapse, nonrelapse mortality, graft-versus-host disease, and survival. Non-ABO incompatibility is less frequently encountered but can have similar complications to ABO incompatibility, causing adverse clinical outcomes. It is crucial to identify the driving etiology of post-HSCT anemia in order to prevent and treat this condition. This requires a comprehensive understanding of the mechanism of anemia in blood group–incompatible HSCT and the temporal association between HSCT and anemia. In this review, we summarize the literature on post-HSCT immune-mediated anemia with a focus on ABO and non-ABO blood group incompatibility, describe the underlying mechanism of anemia, and outline preventive and treatment approaches.

Pre-transplant donor-type red cell transfusion is a safe and effective strategy to reduce isohemagglutinin titers and prevent donor marrow infusion reactions in major ABO-mismatched transplants

ABO incompatibility is not a barrier to allogeneic stem cell transplant but may result in acute hemolytic reactions. As stem cell product manipulation is cumbersome, we are reporting the effectiveness and safety of donor-type red cell infusion as a method of reducing acute hemolytic reaction while using marrow as stem cell source. In major ABO-mismatched bone marrow transplants, manipulation of marrow product requires expertise and expensive equipment, which may not be readily available to transplant centers in low- and middle-income regions. The aim behind our study is to report a safe and effective strategy to reduce isohemagglutinin titers and prevent donor marrow infusion reactions in major ABO-mismatched transplants. We retrospectively analyzed 303 consecutive allogeneic bone marrow transplants (BMTs) for beta thalassemia major, between August 2015 and March 2020, with either major (n = 41) or bidirectional (n = 14) mismatches. When isohemagglutinin titers were 1:32 or higher, donor-type packed red blood cell was divided into 4 aliquots, irradiated and administered over 4 days at incremental volumes. Patients were observed for hemolytic reaction, and if no reaction, bone marrow was infused without manipulation. Out of 55 patients, 20 received donor-type blood infusion. Twelve patients showed evidence of mild hemolysis. None developed severe hemolytic or anaphylactic reaction. Titers were rechecked in 14 patients and all had reduction in titers, except for one. Our experience demonstrated that donor-type PRBC infusion is safe and effective in preventing acute hemolysis in major ABO-mismatched stem cell transplants even with bone marrow as graft source.