Persistence of recipient plasma cells and anti-donor isohaemagglutinins in patients with delayed donor erythropoiesis after major ABO incompatible non-myeloablative haematopoietic cell transplantation

In vivo tracking of ex vivo generated 89 Zr-oxine labeled plasma cells by PET in a non-human primate model

B cells are an attractive platform for engineering to produce protein-based biologics absent in genetic disorders, and potentially for the treatment of metabolic diseases and cancer. As part of pre-clinical development of B cell medicines, we demonstrate a method to collect, ex vivo expand, differentiate, radioactively label, and track adoptively transferred non-human primate (NHP) B cells. These cells underwent 10- to 15-fold expansion, initiated IgG class switching, and differentiated into antibody secreting cells. Zirconium-89-oxine labeled cells were infused into autologous donors without any preconditioning and tracked by PET/CT imaging. Within 24 hours of infusion, 20% of the initial dose homed to the bone marrow and spleen and distributed stably and equally between the two. Interestingly, approximately half of the dose homed to the liver. Image analysis of the bone marrow demonstrated inhomogeneous distribution of the cells. The subjects experienced no clinically significant side effects or laboratory abnormalities. A second infusion of B cells into one of the subjects resulted in an almost identical distribution of cells, suggesting a non-limiting engraftment niche and feasibility of repeated infusions. This work supports the NHP as a valuable model to assess the potential of B cell medicines as potential treatment for human diseases.

Successful treatment pure red cell aplasia after ABO major mismatched allogeneic hematopoietic stem cell transplantation with avatrombopag and low dose rituximab

BACKGROUND

Pure red cell aplasia (PRCA) following allogeneic hematopoietic stem cell transplantation (allo-HSCT) with ABO major incompatibility is characterized by transfusion dependent anemia. No standard treatment existed for PRCA following allo-HSCT yet.

STUDY DESIGN AND METHODS

We conducted a retrospective study, and reported our experience with the use of avatrombopag and lower dose rituximab to treat five patients with PRCA subsequent to major ABO-incompatible allo-HSCT.

RESULTS

Five cases of PRCA were identified from 72 patients who underwent allo-HSCT with major or bidirectional ABO mismatch. Cumulative incidence at Day +60 was 6.9% (5/72) at our center. All donor and recipient blood groups were A+  and O+ , respectively. In the first three cases we reported, patients received erythropoietin, plasma exchange, and donor lymphocyte infusion, but none of them had any effect. After 4 weeks of treatment with low dose rituximab (100 mg/week) combined with avatrombopag (40 mg/day), favorable outcomes were obtained. According to the aforementioned experience, Cases 4 and 5 were administered low-dose rituximab and avatrombopag in 3 months after transplantation, and erythroid response was observed on 3 weeks after treatment. Our patients tolerated low-dose rituximab and avatrombopag well and experienced rapid efficacy, with a median duration of 3 weeks. Furthermore, no severe infection or thrombocytosis necessitated a dose adjustment.

CONCLUSION

Low-dose rituximab and avatrombopag may be an effective treatment for patients with PRCA after major ABO-incompatible allo-HSCT. The patients should be treated at least 90 days post transplantation if conventional erythropoietin therapy fails.

Refractory Pure Red Blood Cell Aplasia Secondary to Major ABO-Incompatible Allogeneic Stem Cell Transplantation Successfully Treated With Daratumumab

Pure red cell aplasia (PRCA) is a rare hematologic phenomenon that is usually associated with inherited genetic mutations such as in Diamond-Blackfan anemia. However, due to the emergence of allogenic stem cell transplantation in the treatment of various malignant and non-malignant disorders, the incidence of PRCA has increased. PRCA following hematopoietic stem cell transplant (HSCT) is more commonly seen in the setting of a major ABO-incompatible transplant. Treatment of allo-HSCT induced PRCA can be initially supportive as it takes time for the bone marrow to fully recover. However, prolonged and/or failure of the bone marrow to recover, significantly increases patient's risk of iron overload in the setting of frequent transfusions. Iron deposition can potentially lead to severe life-threatening multiorgan involvement which can be fatal. Therefore, earlier recognition and intervention with immunomodulators in patients who undergo frequent transfusions can be beneficial to mitigate this risk. Here, we present a case with severe transfusion-dependent PRCA following major ABO-incompatible allo-HSCT successfully treated with daratumumab.

Case report: Successful treatment with daratumumab for pure red cell aplasia in a patient with mixed lymphoid chimerism after ABO-mismatched stem cell transplant for sickle cell disease

Pure red cell aplasia (PRCA) is a serious complication after ABO-mismatched allogeneic hematopoietic stem cell transplantation (HSCT). Following HSCT, persistent anti-donor isohemagglutinins against donor ABO antigens are considered the immunological cause of PRCA. Patients with post-transplant PRCA are at risk for graft rejection and prolonged red blood cell transfusion dependency. No standard treatment exists. Recently however, the anti-CD38 monoclonal antibody daratumumab has been reported to be an effective treatment for post-transplant PRCA in patients with complete donor chimerism. Here, we describe the first case of PRCA in a patient with mixed lymphoid patient/donor chimerism that was successfully treated with daratumumab. This is also the first report of a transplant recipient with sickle cell disease who was treated with this relatively new approach. Fourteen months post-transplantation and twelve months after treatment with daratumumab, our patient has a normal complete blood count and the anti-donor isohemagglutinins remain undetectable despite mixed lymphoid chimerism. Mixed chimerism is a common manifestation in adult patients with sickle cell disease transplanted with non-myeloablative conditioning and a matched sibling donor. The application of non-myeloablative HSCT for patients with sickle cell disease is steadily increasing. Therefore, the incidence of PRCA in this setting might also increase. As the risk of graft rejection due to PRCA can be especially high in patients with mixed chimerism, clinicians should be aware that daratumumab can be an effective treatment in the setting of mixed chimerism.

[Graft failure, poor graft function erythroblastopenia: Actualization of definitions, diagnosis and treatment: Guidelines from the SFGM-TC]

In this article, we discuss again the definition, the risk factor and guideline to treat the graft failure, the poor graft function and erythrobalstopenia. Graft failure is a severe but rare complication after hematopoietic cell transplantation (HCT). Despite disparity in the literature, we defined this complication and discussed the factor risks and recommendation for treatment based on new studies. Poor graft function is also a more frequent complication after HCT. New studies will soon be available to prove or not the current recommendation suggested in this article based on therapeutics medicine or cellular therapy. Erythroblastopenia, is a rarer complication post HCT. Despite anticipation for a better choice of compatibility donor/recipient, some patients still suffer from this complication.

Pure red cell aplasia after hematopoietic stem cell transplantation - experimental therapeutic approaches

Not relevant.

Kinetics of disappearance and appearance of isoagglutinins A and B after ABO-incompatible hematopoietic stem cell transplantation

ABO-incompatible allogeneic hematopoietic stem cell transplantation (HSCT) can be complicated by poor red cell engraftment and hemolysis, both mediated by isoagglutinins. Anecdotally, isoagglutinins indicates an activation of donor’s immunity or even relapse. Consequently, the routine monitoring of isoagglutinins could help physicians to predict the risk of complications. The purpose of this study is to investigate the time to disappearance and appearance of isoagglutinins after ABO-incompatible allogeneic HSCT. In a one-year follow-up, data of 136 ABO-incompatible hematopoietic stem cell (HSC) allogeneic transplanted patients were studied, of which 60 had major, 61 minor and 15 bidirectional incompatibility. Survival analyses were conducted and association with hematological diseases, HLA-compatibility and transplantation strategy was investigated. We observed a disappearance of isoagglutinin A in 82.0% of cases at one year with a median and 75th percentile of 38.4 and 138.6 days, respectively. For isoagglutinin B, these same values were 96.4%, 15.9 and 29.1 days, respectively. The appearance of isoagglutinin A occurred in 10.7% of cases. Disappearance of isoagglutinin A was significantly slower in patients with myeloid diseases compared to other diseases. The results of this study provide useful values to detect early risks of preventable immunohematological complications and possibly, in exceptional cases, relapse.

Towards a Better Understanding of the Atypical Features of Chronic Graft-Versus-Host Disease: A Report from the 2020 National Institutes of Health Consensus Project Task Force

Alloreactive and autoimmune responses after allogeneic hematopoietic cell transplantation can occur in non-classical chronic graft-versus-host disease (chronic GVHD) tissues and organ systems or manifest in atypical ways in classical organs commonly affected by chronic GVHD. The National Institutes of Health (NIH) consensus projects were developed to improve understanding and classification of the clinical features and diagnostic criteria for chronic GVHD. While still speculative whether atypical manifestations are entirely due to chronic GVHD, these manifestations remain poorly captured by the current NIH consensus project criteria. Examples include chronic GVHD impacting the hematopoietic system as immune mediated cytopenias, endothelial dysfunction, or as atypical features in the musculoskeletal system, central and peripheral nervous system, kidneys, and serous membranes. These purported chronic GVHD features may contribute significantly to patient morbidity and mortality. Most of the atypical chronic GVHD features have received little study, particularly within multi-institutional and prospective studies, limiting our understanding of their frequency, pathogenesis, and relation to chronic GVHD. This NIH consensus project task force report provides an update on what is known and not known about the atypical manifestations of chronic GVHD, while outlining a research framework for future studies to be undertaken within the next three to seven years. We also provide provisional diagnostic criteria for each atypical manifestation, along with practical investigation strategies for clinicians managing patients with atypical chronic GVHD features.

Prevalence of Pure Red Cell Aplasia Following Major ABO-Incompatible Hematopoietic Stem Cell Transplantation

Background

Pure red cell aplasia (PRCA) is one of the important complications in major ABO-incompatible allogeneic hematopoietic stem cell transplantation (HSCT). The established pathogenic factor of PRCA is the persistence of high anti-donor isohemagglutinins. As previously verified, the conditioning regimen and donor type were the factors associated with the development of PRCA in the small-sized studies. Currently, the prevalence, risk factors, and prognosis of PRCA are still worth studying to provide evidence.

Methods

We conducted a prospective nested case-control study to determine the prevalence, donor-related factors, and the outcomes of PRCA following major ABO-incompatible transplantation. A total of 469 patients who underwent ABO-incompatible grafts were observed.

Results

None of the patients were diagnosed with PRCA with minor or bidirectional ABO-incompatible HSCT. Thirteen of the187 patients (7%; 95% confidence interval [CI], 3.9%–11.9%) developed PRCA following major ABO-incompatible HSCT. Eleven of the 13 patients with PRCA recovered entirely. Donor type was an independent factor associated with post-HSCT PRCA (odds ratio [OR]=0.030; 95% CI, 0.003–0.321; P=0.004). The cumulative incidence rates of post-HSCT PRCA in the context of major ABO-incompatible HSCT were 0.8%, 13.1%, and 27.2% for the haploidentical donor (HID), unrelated donor, and matched related donor, respectively. No significant influence of PRCA on transplantation outcomes was observed.

In conclusion, post-HSCT PRCA is a rare and less threatening complication in major ABO-incompatible HSCT. The majority of patients with PRCA could recover. Additionally, HIDs for recipients may have a low risk of post-HSCT PRCA. This trial was registered at www.chictr.org.cn (#ChiCTR2000041412).

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.

Diversity, localization, and (patho)physiology of mature lymphocyte populations in the bone marrow

The bone marrow (BM) is responsible for generating and maintaining lifelong output of blood and immune cells. In addition to its key hematopoietic function, the BM acts as an important lymphoid organ, hosting a large variety of mature lymphocyte populations, including B cells, T cells, natural killer T cells, and innate lymphoid cells. Many of these cell types are thought to visit the BM only transiently, but for others, like plasma cells and memory T cells, the BM provides supportive niches that promote their long-term survival. Interestingly, accumulating evidence points toward an important role for mature lymphocytes in the regulation of hematopoietic stem cells (HSCs) and hematopoiesis in health and disease. In this review, we describe the diversity, migration, localization, and function of mature lymphocyte populations in murine and human BM, focusing on their role in immunity and hematopoiesis. We also address how various BM lymphocyte subsets contribute to the development of aplastic anemia and immune thrombocytopenia, illustrating the complexity of these BM disorders and the underlying similarities and differences in their disease pathophysiology. Finally, we summarize the interactions between mature lymphocytes and BM resident cells in HSC transplantation and graft-versus-host disease. A better understanding of the mechanisms by which mature lymphocyte populations regulate BM function will likely improve future therapies for patients with benign and malignant hematologic disorders.

Treatment for pure red cell aplasia after major ABO-incompatible allogeneic stem cell transplantation: a multicentre study

Pure red cell aplasia (PRCA) following allogeneic haematopoietic stem cell transplantation (aHSCT) with major ABO incompatibility is responsible for transfusion dependent anaemia, impaired quality of life and iron overload. We conducted a retrospective study, over a 10-year period, which included all consecutive patients who received a major ABO mismatched aHSCT, to assess the impact of specific treatment on PRCA. We did not observe any PRCA in the 57 aHSCT issued from cord blood. Among the remaining 631 patients, cumulative incidence of PRCA was 10·5% [range 8·2-13.0]. The median duration of resolved PRCA was 171 days [IQR 116; 261]. Pre-transplant high isohaemagglutinins titre was associated with an increased risk of PRCA (P < 10^-4 ). PRCA did not affect overall survival (P = 0·95). Twenty-two patients (33·3%) received at least one specific treatment. The most commonly used treatments were rituximab (17 patients) and donor lymphocyte infusion (DLI; seven patients). Regarding PRCA resolution, we did not observe a significant difference between treated or untreated subjects (HR = 0·93, 95% confidence interval (CI) 0·48- 1·80; P = 0·82). Similar results were observed with erythropoietin treatment (22 patients, HR = 0·86 95% CI: [0·47-1·57] P = 0·62). Our data do not support the use of erythropoietin, rituximab or DLI for the treatment of PRCA.

Immune cytopenia after allogeneic haematopoietic stem-cell transplantation: challenges, approaches, and future directions

Immune-mediated cytopenia after allogeneic haematopoietic stem-cell transplantation is rare. The pathophysiology of immune-mediated anaemia, thrombocytopenia, and neutropenia, which occur alone or in combination with other cytopenias, is unclear and most probably a consequence of immune dysregulation. Risk factors for this complication have been identified in retrospective studies but these should be interpreted with caution and should not be generalised to this heterogeneous patient population. Diagnosis is challenging, requires awareness of such complications, and has to be differentiated from a multitude of other, and sometimes overlapping, possible complications. The clinical course of immune-mediated cytopenia is highly variable. Treatment requires an interdisciplinary approach and ranges from observation to symptomatic measures and directed therapies. Intensive immunosuppression is associated with an increased risk of infections and relapse, and current treatments are based on approaches in patients who have not undergone transplantation. Plasma cell-directed therapies, immunomodulation, and receptor-stimulating agents can be used to treat immune-mediated cytopenia.

Transfusion and Cellular Therapy in Pediatric Sickle Cell Disease

Red blood cell (RBC) transfusion is critical in managing acute and chronic complications of sickle cell disease. Alloimmunization and iron overload remain significant complications of transfusion therapy and are minimized with prophylactic Rh and K antigen RBC matching and iron chelation. Matched sibling donor hematopoietic stem cell transplant (HSCT) is a curative therapeutic option. Autologous hematopoietic stem cell (HSC)-based gene therapy has recently shown great promise, for which obtaining sufficient HSCs is essential for success. This article discusses RBC transfusion indications and complications, transfusion support during HSCT, and HSC mobilization and collection for autologous HSCT with gene therapy.

Pure red cell aplasia after major or bidirectional ABO incompatible hematopoietic stem cell transplantation: to treat or not to treat, that is the question

Pure red cell aplasia (PRCA) is a complication related to major or bidirectional ABO mismatched hematopoietic stem cell transplantation. This disorder is characterized by anemia, reticulocytopenia, and the absence or virtual absence of erythroid progenitors, other causes such as infections, hemolysis, disease relapse, or drug toxicity having been excluded. Patients with PRCA may become RBC transfusion dependent for long periods, suffering an important long-term iron overload, alloimmunization, and transfusion reactions. The persistence of recipient isoagglutinins against donor ABO antigens produced by host residual plasmatic cells has been considered as the immunological cause of the prolonged erythroid aplasia. PRCA behaves in many cases as a self-limited condition and resolution may occur spontaneously within weeks, months, and even years. Many different therapeutic approaches have been reported for posttransplant PRCA as plasmapheresis, high doses of erythropoietin, donor lymphocyte infusions, anti-thymocyte globulin, Rituximab and steroids, among others. However, to date there is no standard of care and the question if patients with PRCA should be treated and at which point remains. The objective of this article is to review the natural evolution of PRCA, and the treatments that have been used over time focusing on their suitability and efficacy.

Antigen-Specific Immunoadsorption With the Glycosorb® ABO Immunoadsorption System as a Novel Treatment Modality in Pure Red Cell Aplasia Following Major and Bidirectional ABO-Incompatible Allogeneic Hematopoietic Stem Cell Transplantation

Pure red cell aplasia (PRCA) after ABO-incompatible allogeneic hematopoietic stem cell transplantation (HSCT) is caused by persisting host-derived isohemagglutinins directed against donor red blood cell (RBC) antigens. ABO antigen-specific immunoadsorption (ABO-IA) with Glycosorb®, commonly used for desensitization therapy in ABO-incompatible living donor renal transplantation, specifically eliminates circulating isohemagglutinins and might represent a novel treatment option for post-HSCT PRCA. In this prospective observational (n = 3) and retrospective (n = 3) analysis of six adult HSCT-recipients with PRCA, ABO-IA was initiated at 159 (range: 104–186) days following HSCT. The median treatment frequency was 4.5 (range: 3.9–5.5) sessions/week. ABO-IA-treatment led to a continuous decrease in isohemagglutinin titers. Reticulocytes increased to ≥30 G/L after 17.5 (range: 4–37) immunoadsorption sessions over 28.5 (range: 6–49) days and continued to rise after that. By the end of the 3-month follow-up period after discontinuation of ABO-IA, all patients showed a sustained remission of PRCA and were independent of erythropoietin-stimulating agents and transfusions. No case of infection or graft-versus-host disease was observed. After a median follow-up of 22.03 (range: 6.08–149.00) months after ABO-IA-treatment, all patients were alive and showed a stable RBC engraftment of the donor blood group. Our data provide the first evidence for ABO-IA as an effective treatment for post-HSCT PRCA.

Daratumumab for pure red cell aplasia post ABO incompatible allogeneic hematopoietic stem cell transplant for aplastic anemia

Pure red cell aplasia is a known complication after ABO incompatible stem cell transplant. Due to rarity of disease, no established treatment guidelines are available for PRCA. Daratumumab is a monoclonal antibody against CD38 expressed by plasma cells. In this report we present our experience of successfully managing a patient of post-transplant PRCA with daratumumab. Our patient had failed multiple lines of therapy prior to receiving daratumumab. Response was seen after the 3rd weekly dose of daratumumab.

Curability and transferability of atopy with allogeneic hematopoietic cell transplantation

Atopy is excessive production of IgE in response to allergens. We evaluated in patients undergoing allogeneic hematopoietic cell transplantation (HCT) the following hypotheses: (1) Atopy is "curable" in atopic patients receiving HCT from a nonatopic donor (D-R+), and (2) Atopy is transferable from atopic donors to nonatopic recipients (D+R-). Atopic patients with atopic donors (D+R+) and non-atopic patients with non-atopic donors (D-R-) served as controls. We measured levels of multiallergen-specific IgE (A-IgE, atopy defined as ≥0.35 kU_A/L) in sera from 54 patients and their donors pre HCT and from the patients at ≥2 years post HCT. Only 7/12 (58%) D- R+ patients became nonatopic after HCT. Only 1/11 (9%) D+R- patients became atopic. Eleven of 13 (85%) D-R- patients remained nonatopic. Unexpectedly, 11/18 (61%) D+R+ patients became nonatopic. In conclusion, contrary to our hypothesis and previous reports, the "cure" of atopy may occur in only some D-R+ patients and the transfer of atopy may occur rarely. The "cure" may not be necessarily due to the exchange of atopic for nonatopic immune system, as the "cure" may also occur in D+R+ patients.

Modeling Long-Term Erythropoietic Recovery After Allogeneic Stem Cell Transplants in Pediatric Patients

Long term erythropoietic reconstitution after allogeneic hematopoietic stem cell transplantation (alloHSCT) has not been extensively studied. We aimed to describe erythropoietic reconstitution as an indicator of long-term graft function by modeling hemoglobin levels during the first 3 years post HSCT in pediatric patients. We retrospectively included 414 patients and 11,957 measurements. The largest hemoglobin increase was at day 45 and levels reached a steady state at day 648 with a level of 7.48 mmol/L. In patients transplanted for hematological malignancies hemoglobin levels normalized faster (p < 0.0001). Increasing patient age correlated with faster recovery (p < 0.0001), while donor age had no influence. Conditioning, donor type and graft source did not influence recovery significantly. In the ABO mismatched group there was a transient negative effect on hemoglobin levels, and a delay in reticulocyte recovery (21 vs. 19 days; p = 0.012). In contrast, hemoglobin levels reached a higher plateau beyond 9 months in these patients (p < 0.0001). After alloHSCT, experiencing a CMV reactivation negatively affected reconstitution (p = 0.034), while EBV reactivations and acute graft vs. host disease did not. In summary, erythropoietic recovery was mainly influenced by patient factors and primary disease, and less influenced by donor factors.

Characterization of reemergent anti-B red blood cell antibodies in a patient with recurrent acute myeloid leukemia with ABO-incompatible allogeneic peripheral blood stem cell transplantation

BACKGROUND

Isohemagglutinins against ABO antigens absent on both recipient and donor red blood cells (RBCs) increase or decrease after ABO-incompatible hematopoietic stem cell transplantation (HSCT). However, few reports have described the changes in the isohemagglutinin titers and the characteristics in patients with recurrent hematologic conditions after ABO-incompatible HSCT.

CASE REPORT

A 59-year-old female with acute erythroid leukemia received a peripheral blood stem cell transplant from her HLA-haploidentical daughter. The patient was typed as group O with anti- A (4+) and B (4+) isohemagglutinins, while the donor was typed as group B. The bone marrow cells achieved complete donor cell chimerism on Day 13 after HSCT. On Day 120, the patient showed 97% B RBC type with persistent anti-A (3+) and without anti-B antibodies. On Day 375, her leukemia relapsed, and recipient type O RBCs and anti-B antibodies sequentially reemerged. However, clinicolaboratory hemolysis and erythroid aplasia were not detected in the patient.

RESULTS

The post-HSCT sera agglutinated the allo B RBCs, but not the donor B RBCs, while the pre-HSCT sera agglutinated both RBCs. The burst-forming/colony-forming units of erythroid formation from the donor peripheral blood stem cells were impaired by only the pre-HSCT sera and not by the post-HSCT sera.

CONCLUSION

To our knowledge, this is the first report investigating the characteristic changes of isohemagglutinins between the pre- and post-HSCT sera in a patient with recurrent acute myeloid leukemia. The present study suggests that the plasma cells producing anti-donor B RBCs in the patient have been selectively eliminated or induced into an anergic state by the post-HSCT immunologic reconstruction.

Immune Cytopenias after Ex Vivo CD34+-Selected Allogeneic Hematopoietic Cell Transplantation

Immune-mediated cytopenias (ICs), such as immune thrombocytopenia and immune hemolytic anemia, are among the adverse events after allogeneic hematopoietic cell transplantation (allo-HCT). Previous reports suggest that in vivo T cell depletion may increase the incidence of IC after allo-HCT. We evaluated whether a strategy that reduces functional donor T cells via ex vivo CD34⁺-selection associates with the development of IC in a cohort of 408 patients who underwent allo-HCT for hematologic malignancy. The cumulative incidence of IC at 6, 12, and 36 months after the 30-day landmark post-HCT was 3.4%, 4.9%, and 5.8%, respectively. Among 23 patients who developed IC, 7 died of relapse-related mortality and 4 of nonrelapse mortality. A median 2 types of treatment (range, 1 to 5) was required to resolve IC, and there was considerable heterogeneity in the therapies used. In univariable analyses, a hematologic malignancy Disease Risk Index (DRI) score of 3 was significantly associated with an increased risk of IC compared with a DRI of 1 or 2 (hazard ratio [HR], 4.12; P = .003), and IC (HR, 2.4; P = .03) was associated with increased risk of relapse. In a multivariable analysis that included DRI, IC remained significantly associated with increased risk of relapse (HR, 2.4; P = .03). Our findings show that IC events occur with relatively similar frequency in patients after ex vivo CD34⁺-selected allo-HCT compared with unmodified allo-HCT, suggesting that reduced donor T cell immunity is not causative of IC. Moreover, we noted a possible link between its development and/or treatment and increased risk of relapse.

Transfusion support for matched sibling allogeneic hematopoietic stem cell transplantation (1993-2010): factors that predict intensity and time to transfusion independence

BACKGROUND

Patients undergoing allogeneic hematopoietic stem cell transplant require variable, often extensive transfusion support. Identification of factors that predict urgent, intensive, or special needs should improve management of these patients.

STUDY DESIGN AND METHODS

This is a retrospective study of red blood cell (RBC) and platelet transfusion support provided for sequential matched sibling donor allogeneic transplants conducted at the Clinical Center, National Institutes of Health, from 1993 through 2010. Factors potentially important for predicting quantity of RBC and platelet transfusions, and time to transfusion independence through Day 200 following hematopoietic stem cell transplantation were evaluated.

RESULTS

Subjects (n = 800) received 10,591 RBC and 10,199 platelet transfusions. Multivariable analysis demonstrated that the need for RBC pretransplant, CD34+ dose, transplant year, diagnostic category, and ABO match were significantly independently associated with quantity of RBC transfusions during Days 0 through 30. Only pretransplant need for RBCs, CD34+ dose, and transplant year had significance during Days 0 through 100. Similar analyses for quantity of platelet transfusions demonstrated that for both Days 0 through 30 and 0 through 100 significant factors were need for platelet support before transplant, CD34+ dose, transplant year, and transplant regimen. Of note, long term, during Days 101 through 200, only CD34+ dose remained significant for quantity of RBC and platelet transfusions. Analysis of time to transfusion independence demonstrated that patients with ABO major mismatches required longer to achieve freedom from RBC transfusion support compared to identical matches or those with minor mismatches.

CONCLUSION

Patient-specific factors including CD34+ dose and ABO match of the graft should be given particular consideration by transfusion services when planning support of patients receiving allogeneic hematopoietic stem cell transplant.

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

BACKGROUND

Hemolysis at the time of graft infusion is one of the immediate complications in major ABO-incompatible allogeneic hematopoietic stem cell transplants (HSCTs). We conducted a retrospective analysis to evaluate the efficacy of donor-type fresh frozen plasma (FFP) in reducing isohemagglutinin titer and preventing hemolysis, as well as its effect on delayed red cell engraftment.

MATERIALS AND METHODS

This is a single-center study on a series of 380 allogeneic HSCT between 2005 and 2015; of which 99 were either major (n = 74) or bidirectional (n = 25) ABO mismatched. Pre-transplant infusion of FFP, post-transplant complications and transfusion requirements were determined by retrospective review of individual medical records. Laboratory results were also reviewed for evidence of hemolysis and pure red cell aplasia (PRCA).

RESULTS

Clinical manifestation of hemolysis attributable to ABO mismatch was present in one recipient of major ABO-incompatible peripheral blood stem cell (PBSC) with a titer of 64. Another recipient of major ABO-incompatible PBSC with a titer of 64 showed biochemical evidence of hemolysis. Both patients recovered with supportive treatment. Hemolysis did not occur in any patients with titer of 32 or less at the time of stem cell infusion. We were unable to demonstrate the influence of any variables on the incidence of PRCA.

CONCLUSION

Our experience demonstrated that donor-type FFP is safe and effective in preventing acute hemolysis in major ABO-mismatched HSCT. We have also established the titer of 64 as the threshold that may cause hemolysis and therefore efforts should be made to reduce titer to below this level.

Immunohaematological complications in patients with sickle cell disease after haemopoietic progenitor cell transplantation: a prospective, single-centre, observational study

BACKGROUND

Haemopoietic progenitor cell (HPC) transplantation can cure sickle cell disease. Non-myeloablative conditioning typically results in donor-derived erythrocytes and stable mixed chimerism of recipient-derived and donor-derived leucocytes. Exposure to donor antigens from the HPC graft and new red cell antibodies induced by transfusion can lead to immunohaematological complications. We assessed the incidence of such complications among HPC transplant recipients with sickle cell disease.

METHODS

The study population was all patients with sickle cell disease enrolled before March 31, 2015, in the three clinical trials of non-myeloablative HPC transplantation at the National Institutes of Health. We assessed formation of new red cell antibodies after transplantation and red cell incompatibility between donors and recipients.

FINDINGS

61 patients were enrolled, 42 were HLA matched and 19 were haploidentical. Nine (15%) had immunohaematological complications. Before HPC transplantation, three patients had antibodies incompatible with their donors. After HPC transplantation, new red cell antibodies were seen in six patients (11 alloantibodies and two autoantibodies), among whom three developed antibodies incompatible with donor or recipient red cells and three developed compatible antibodies. The clinical course of complications was highly variable, from no severe effects attributable to antibodies, to sustained reticulocytopenia, to near-fatal haemolysis. We found no significant correlation between immunohaematological complications and graft failure, graft rejection, or death.

INTERPRETATION

Clinical effects ranged from seemingly not clinically important to potentially fatal. In patients with sickle cell disease, donor and recipient red cell phenotypes should be carefully assessed before transplantation to minimise and manage the risk of immunohaematological complications.

FUNDING

Intramural Research Program and National Institutes of Health.

Allogeneic transplantation using CD34+ selected peripheral blood progenitor cells combined with non-mobilized donor T cells for refractory severe aplastic anaemia

Allogeneic haematopoietic stem cell transplantation is curative for severe aplastic anaemia (SAA) unresponsive to immunosuppressive therapy. To reduce chronic graft-versus-host disease (GVHD), which occurs more frequently after peripheral blood stem cell (PBSC) transplantation compared to bone-marrow transplantation (BMT), and to prevent graft rejection, we developed a novel partial T-cell depleted transplant that infuses high numbers of granulocyte colony-stimulating factor-mobilized CD34⁺ selected PBSCs combined with a BMT-equivalent dose of non-mobilized donor T-cells. Fifteen patients with refractory SAA received cyclophosphamide, anti-thymocyte globulin and fludarabine conditioning, and were transplanted with a median 8 × 10⁶ CD34⁺  cells/kg and 2 × 10⁷ non-mobilized CD3⁺ T-cells/kg from human leucocyte antigen-matched sibling donors. All achieved sustained engraftment with only two developing acute and two developing chronic GVHD. With a 3·5-year median follow-up, 86% of patients survived and were transfusion-independent. When compared to a retrospective cohort of 56 bone-marrow failure patients that received the identical transplant preparative regimen and GVHD prophylaxis with the exception that the allograft contained unmanipulated PBSCs, partial T-cell depleted transplant recipients had delayed donor T-cell chimerism and relative reduction of 75% in the incidence of acute grade II-IV GVHD (13% vs. 52%; P = 0·010) and of 82% in chronic GVHD (13% vs. 72%; P = 0·0004). In multivariate analysis, partial T-cell depleted transplants remained significantly associated with a reduced risk of GVHD. In conclusion, for patients with refractory SAA, this novel transplant strategy achieves excellent engraftment and survival when compared to unmanipulated PBSC transplants and dramatically reduces the incidence of both acute and chronic GVHD.

Stem cell transplantation during cancer

Hematological malignancies account for approximately 9.5% of new cancers diagnosed annually. Lymphoma is the most frequent of all known categories of hematological malignancies. Worldwide, extensive research has focused on this type of cancer. However, new treatments are investigated in various clinical as well as pre-clinical studies. Hematopoietic stem cell transplantation (HSCT) is a recent and upcoming treatment strategy for patients with hematopoietic malignancies and inborn errors of metabolism or immune deficiencies. Recent studies have revealed that successful clinical outcome of this treatment strategy depends on multiple factors including the protocol applied, disease under treatment, health of the patient, source of the grafts, severity of complications such as graft versus host disease during grafting and associated infections. The scope of this review is to achieve greater understanding of various clinical effects of the disease and related mechanisms. The electronic database Pubmed was searched for pre-clinical as well as clinical controlled trials reporting efficacy of the HSCT against hematological malignancies.

ABO blood group antigen mismatch has an impact on outcome after allogeneic peripheral blood stem cell transplantation

ABO blood group antigen incompatibility (ABO mismatch) is not an obstacle to allogeneic stem cell transplantation (allo-SCT). However, the impact on clinical outcome after allo-SCT remains controversial. We analyzed 512 patients after allogeneic peripheral blood SCT (allo-PBSCT) for an association of ABO mismatch with transfusion requirements, myeloid and platelet engraftment, the incidence of GvHD, relapse, transplant-related mortality (TRM), and overall survival (OS). A total of 260 patients underwent ABO-mismatched transplantation and the control group consisted of 252 patients with ABO-matched allo-PBSCT. We found a significant association between major-0 ABO mismatch (group 0 recipient/group A, B, or AB donor) and increased red blood cell (RBC) and platelet transfusion requirements (both P<.001) as well as delayed platelet engraftment (P<.001). Minor-A (group A recipient/group 0 donor) and minor-AB (group AB recipient/group 0, A, or B donor) ABO mismatch was significantly associated with an increased TRM after allo-PBSCT (P=.001 and P=.02). In multivariate analysis performed using Cox regression, minor ABO mismatch appeared as independent risk factor for TRM after allo-PBSCT. No association was found for ABO mismatch with the incidence of GvHD, relapse, and OS. Our results suggest that ABO blood group mismatch has a significant impact on the outcome and that minor-A and minor-AB ABO mismatch represents a risk factor for increased TRM after allo-PBSCT.

An update on ABO incompatible hematopoietic progenitor cell transplantation

Hematopoietic progenitor cell (HPC) transplantation has long been established as the optimal treatment for many hematologic malignancies. In the setting of allogenic HLA matched HPC transplantation, greater than 50% of unrelated donors and 30% of related donors demonstrate some degree of ABO incompatibility (ABOi), which is classified in one of three ways: major, minor, or bidirectional. Major ABOi refers to the presence of recipient isoagglutinins against the donor's A and/or B antigen. Minor ABOi occurs when the HPC product contains the isoagglutinins targeting the recipient's A and/or B antigen. Bidirectional refers to the presence of both major and minor ABOi. Major adverse events associated with ABOi HPC transplantation includes acute and delayed hemolysis, pure red cell aplasia, and delayed engraftment. ABOi HPC transplantation poses a unique challenge to the clinical transplantation unit, the HPC processing lab, and the transfusion medicine service. Therefore, it is essential that these services actively communicate with one another to ensure patient safety. This review will attempt to globally address the challenges related to ABOi HPC transplantation, with an increased focus on aspects related to the laboratory and transfusion medicine services.

Pure Red Cell Aplasia in Major ABO-Mismatched Allogeneic Hematopoietic Stem Cell Transplantation Is Associated with Severe Pancytopenia

In major ABO-mismatched allogeneic hematopoietic stem cell transplantation (HSCT) persistence of antidonor isohemagglutinins leads to pure red cell aplasia (PRCA). To investigate severe pancytopenia noted in a previous study of PRCA, we analyzed all major ABO-mismatched HSCT between January 2003 and December 2012. Of 83 PRCA patients, 13 (16%) had severe pancytopenia. Severe pancytopenia was defined as an absolute neutrophil count (ANC) < 1.5 K/μL or requiring granulocyte colony-stimulating factor, platelets < 50 K/μL or transfusion dependent, and PRCA with RBC transfusion dependence at post-transplant day 90. In 6 patients (46%) severe pancytopenia resolved after PRCA resolution. Two patients (15%) received a second transplant because of persistent pancytopenia/secondary graft failure, 1 (8%) died from secondary graft failure despite a stem cell boost, 1 (8%) did not recover his platelet counts despite RBC/ANC recovery, and 3 patients (23%) died from disease relapse. We found that severe pancytopenia is frequently associated with PRCA in 16% of major ABO-incompatible HSCT with a higher incidence in males and pancytopenia resolved with resolution of PRCA in 46% of patients.

ABO blood group incompatibility as an adverse risk factor for outcomes in patients with myelodysplastic syndromes and acute myeloid leukemia undergoing HLA-matched peripheral blood hematopoietic cell transplantation after reduced-intensity conditioning

BACKGROUND

ABO incompatibility is not a contraindication to hematopoietic cell transplantation (HCT), but it has been associated with additional risks including delayed engraftment, pure red cell aplasia (PRCA), and higher transfusion needs. Data on these events and on patient survival after reduced-intensity conditioning (RIC) HCT are limited.

STUDY DESIGN AND METHODS

A total of 127 consecutive patients, 86 with acute myeloid leukemia and 41 with myelodysplastic syndromes, who underwent HLA-matched peripheral blood RIC allogenic HCT between 2005 and 2014 were retrospectively analyzed.

RESULTS

Eighty ABO-compatible, 26 major/bidirectional, and 21 minor-ABO-mismatch HCT were identified. Compared to the ABO-compatible group, major/bidirectional mismatches had increased red blood cell (RBC) transfusion requirement during the first 100 days (p = 0.009), delayed RBC and PLT engraftment (p = 0.0011 and p = 0.005, respectively), and higher incidence of grade II to IV acute graft-versus-host disease (aGVHD; p = 0.037). In multivariable analysis, major/bidirectional mismatches had significantly higher non-relapse mortality (NRM) and inferior disease-free survival (DFS) and overall survival (OS) compared with ABO-compatible patients (p = 0.01, p = 0.04, and p = 0.035, respectively). Minor ABO mismatch had no impact on survival (p = 0.99). Four (15%) of 26 major/bidirectional mismatches developed PRCA. There was a significant association between fludarabine plus busulfan conditioning and PRCA (p = 0.0046).

CONCLUSION

Major/bidirectional ABO mismatch is associated with higher NRM and shortened DFS and OS in the setting of RIC HCT. Increased transfusion need, delayed RBC and platelet engraftment, PRCA, and increased severity of aGVHD are additional complications contributing to the morbidity.

Transfusion support issues in hematopoietic stem cell transplantation

BACKGROUND

Patients receiving hematopoietic stem cell transplantation require extensive transfusion support until red blood cell and platelet engraftment occurs. Rare but predictable complications may arise when the transplanted stem cells are incompatible with the native ABO type of the patient. Immediate and delayed hemolysis is often seen.

METHODS

A literature review was performed and the results from peer-reviewed papers that contained reproducible findings were integrated.

RESULTS

A strong body of clinical evidence has developed around the common complications experienced with ABO-incompatible hematopoietic stem cell transplantation. These complications are discussed and the underlying pathophysiology is explained. General treatment options and guidelines are enumerated.

CONCLUSIONS

ABO-incompatible hematopoietic stem cell transplantations are frequently performed. Immune-related hemolysis is a commonly encountered complication; therefore, health care professionals must recognize the signs of immune-mediated hemolysis and understand the various etiologies that may drive the process.

Management of hemolytic anemia following allogeneic stem cell transplantation

Hemolytic anemia (HA) is a frequent condition with variable pathophysiology. Hematopoietic stem cell transplantation (HSCT) is unique because it is performed across the ABO blood group barrier. Thereby, there is a transfer of plasma, red blood cells, and immunocompetent cells from the donor to the recipient, possibly leading to HA, due to red blood cell incompatibility. The underlying disease, drugs (particularly those used for conditioning and immunosuppressants), infections, graft-versus-host disease, and autoimmune diseases may all contribute to the clinical and laboratory picture of HA. Additionally, transplantation-associated thrombotic microangiopathy (TA-TMA) may occur and is associated with significant morbidity and mortality. This review highlights the current knowledge on HA after allogeneic HSCT, particularly due to ABO incompatibility. We follow the timeline of the transplantation process and discuss investigations, differential diagnosis, and prophylactic measures including graft processing to avoid hemolysis in case of ABO incompatibility. Finally, current therapeutic approaches for both TA-TMA and post-HSCT autoimmune HA, which are associated with high morbidity and mortality, are discussed.

Persistence of recipient human leucocyte antigen (HLA) antibodies and production of donor HLA antibodies following reduced intensity allogeneic haematopoietic stem cell transplantation

The effects of reduced intensity conditioning (RIC) on human leucocyte antigen (HLA)-alloimmunization and platelet transfusion refractoriness (PTR) following allogeneic haematopoietic stem cell transplantation (Allo-HSCT) are unknown. We studied HLA-alloantibodies in a cohort of 16 patients (eight HLA-alloimmunized with pre-transplant histories of PTR and eight non-alloimmunized controls) undergoing Allo-HSCT using fludarabine/cyclophosphamide-based RIC. Pre- and post-transplant serum samples were analysed for HLA-antibodies and compared to myeloid, T-cell and bone marrow plasma cell chimaerism. Among alloimmunized patients, the duration that HLA-antibodies persisted post-transplant correlated strongly with pre-transplant HLA-antibody mean fluorescence intensity (MFI) and PRA levels (Spearman's rank correlation = 0·954 (P = 0·0048) and 0·865 (P = 0·0083) respectively). Pre-transplant MFI >10,000 was associated with post-transplant HLA antibody persistence >100 d (P = 0·029). HLA-antibodies persisted ≥100 d in 3/8 patients despite recipient chimaerism being undetectable in all lympho-haematopoietic lineages including plasma cells. Post-transplant de-novo HLA-antibodies developed in three control patients with two developing PTR; the donors for two of these patients demonstrated pre-existing HLA-antibodies of equivalent specificity to those in the patient, confirming donor origin. These data show HLA-antibodies may persist for prolonged periods following RIC. Further study is needed to determine the incidence of post-transplant PTR as a consequence of donor-derived HLA alloimmunization before recommendations on donor HLA-antibody screening can be made.

Analysis of donor and recipient ABO incompatibility and antibody-associated complications after allogeneic stem cell transplantation with reduced-intensity conditioning

Allogeneic hematopoietic stem cell transplantation (HSCT) can be performed across the ABO blood group barrier. The impact of ABO incompatibility on clinical outcome is controversial. A retrospective analysis of 310 patients who underwent HSCT with reduced-intensity conditioning between 1998 and 2011 was performed to investigate the frequency and clinical implications of anti-RBC antibodies in passenger lymphocyte syndrome (PLS) after minor ABO mismatch (mm), persistent or recurring recipient type ABO antibodies (PRABO) after major ABO mm HSCT, and autoimmune hemolytic anemia (AIHA). Transplantation characteristics and clinical outcome were analyzed by univariate and multivariate analysis for groups with or without anti-RBC antibodies. ABO blood group incompatibility did not affect clinical outcome despite an increased requirement of blood transfusion. Twelve patients with AIHA, 6 patients with PLS, and 12 patients with PRABO post-HSCT were identified. AIHA did not affect overall survival (OS) or transplant-related mortality (TRM), but patients with AIHA had a lower incidence of grades II to IV acute graft-versus-host disease (P = .05). OS in the PLS group was 0% compared with 61% in the whole group receiving minor ABO mm transplants (P < .001). Comparing PRABO patients with those receiving a major ABO mm HSCT, the OS was 17% versus 73% (P = .002) and TRM was 50% versus 21% (P = .03). At our center, PLS after minor ABO mm and PRABO antibodies after major ABO mm HSCT are significant risk factors for decreased OS and TRM. Our results suggest that occurrence of unexpected ABO antibodies after HSCT warrant a wider investigation individual to find the underlying cause.

Rapid donor T-cell engraftment increases the risk of chronic graft-versus-host disease following salvage allogeneic peripheral blood hematopoietic cell transplantation for bone marrow failure syndromes

The risk of graft-rejection after allogeneic hematopoietic cell transplantation using conventional cyclophosphamide-based conditioning is increased in patients with bone marrow failure syndromes (BMFS) who are heavily transfused and often HLA-alloimmunized. Fifty-six patients with BMFS underwent fludarabine-based reduced-intensity conditioning and allogeneic peripheral blood progenitor cell (PBPC) transplantation at a single institution. The conditioning regimen consisted of intravenous cyclophosphamide, fludarabine, and equine antithymocyte globulin. Graft-versus-host disease (GVHD) prophylaxis included cyclosporine A alone or in combination with either mycophenolate mofetil or methotrexate. To reduce the risk of graft-rejection/failure, unmanipulated G-CSF mobilized PBPCs obtained from an HLA-identical or single HLA-antigen mismatched relative were transplanted rather than donor bone marrow. Despite a high prevalence of pretransplant HLA-alloimmunization (41%) and a heavy prior transfusion burden, graft-failure did not occur with all patients having sustained donor lympho-hematopoietic engraftment. The cumulative incidence of grade II-IV acute-GVHD and chronic-GVHD was 51.8% and 72%, respectively; with 87.1% surviving at a median follow-up of 4.5 years. A multivariate analysis showed pretransplant alloimmunization and rapid donor T-cell engraftment (≥95% donor by day 30) were both significantly (P < 0.05) associated with the development of chronic-GVHD (adjusted HR 2.13 and 2.99, respectively). These data show fludarabine-based PBPC transplantation overcomes the risk of graft-failure in patients with BMFS, although rapid donor T-cell engraftment associated with this approach appears to increase the risk of chronic-GVHD. (Clinicaltrials.gov identifier: NCT00003838).