Management of refractory autoimmune hemolytic anemia after allogeneic hematopoietic stem cell transplantation: current perspectives

Transfusion support and pre-transfusion testing in autoimmune haemolytic anaemia

Autoimmune haemolytic anaemia (AIHA) is characterized by an increased destruction of red blood cells due to immune dysfunction and auto-antibody production. Clinical manifestations are mainly related to anaemia, which can become life-threatening in case of acute haemolysis. Aiming at counterbalancing severe anaemia, supportive treatments for these patients frequently include transfusions. Unfortunately, free serum auto-antibodies greatly interfere in pre-transfusion testing, and the identification of compatible red blood cell units for AIHA patients can be challenging or even impossible. Problems faced in pre-transfusion testing often lead to delay or abandonment of transfusions for AIHA patients. In this review, we discuss publications concerning global transfusion management in AIHA, with a focus on pre-transfusion testing, and practical clues to manage the selection of transfusion units for these patients. Depending on the degree of transfusion emergency, we propose an algorithm for the selection and laboratory testing of units to be transfused to AIHA patients.

Transfusion Support in Hematopoietic Stem Cell Transplantation: A Contemporary Narrative Review

Hematopoietic stem cell transplantation (HSCT) is a cornerstone of modern medical practice, and can only be performed safely and effectively with appropriate transfusion medicine support. Patients undergoing HSCT often develop therapy-related cytopenia, necessitating differing blood product requirements in the pre-, peri-, and post-transplant periods. Moreover, ensuring optimal management for patients alloimmunized to human leukocyte antigens (HLA) and/or red blood cell (RBC) antigens, as well as for patients receiving ABO-incompatible transplants, requires close collaboration with transfusion medicine and blood bank professionals. Finally, as updated transfusion guidelines and novel blood product modifications emerge, the options available to the transplant practitioner continue to expand. Herein, we detail contemporary blood transfusion and transfusion medicine practices for patients undergoing HSCT.

Warm autoimmune hemolytic anemia and the best treatment strategies

Warm autoimmune hemolytic anemia (wAIHA) is characterized by evidence of red blood cell (RBC) hemolysis and a direct antiglobulin test positive for IgG and sometimes complement. While varying with the extent of the compensatory increase in RBC production, symptoms of anemia predominate, as does jaundice, the latter often exacerbated by concurrent Gilbert's syndrome. Initial treatment with corticosteroids is highly effective, with over 85% of patients responding but with less than one-third maintaining that response upon weaning. Subsequent rituximab administration in those failing corticosteroids provides complete remission in over 75% of patients and may be long-lasting. Over 50% of patients failing rituximab respond to erythropoiesis-stimulating agents or immunosuppressive agents. Splenectomy is best deferred if possible but does offer long-term remission in over two-thirds of patients. A number of new treatments for wAIHA (fostamatinib, rilzabrutinib, and FcRn inhibitors) show promise. A treatment algorithm for wAIHA is proposed to avoid the excessive use of corticosteroids.

Case report: Daratumumab treatment in pre-transplant alloimmunization and severe hemolytic anemia

Daratumumab, a CD38 monoclonal antibody that has been FDA-approved to treat multiple myeloma, has acquired popularity and is used off-label for both auto- and alloantibody mediated disorders, particularly in refractory/resistant circumstances. Much of the published data for its use in pediatric blood disorders has been in post-transplant autoimmune cytopenias. Here we describe three patients in whom daratumumab was used outside of post-transplant autoimmune cytopenias, highlighting further potential uses of this medication.

The effect of HLA matching and donor relatedness on the risk of autoimmune haemolytic anaemia in haematopoietic stem cell transplant recipients: A systematic review and meta-analysis

Recent studies have identified autoimmune haemolytic anaemia (AIHA) as a haematopoietic stem cell transplant (HSCT) complication that represents a significant cause of morbidity and mortality for these patients. In order to understand this autoimmune phenomenon, emerging research has focused on the prognostic factors associated with the development of the disorder. These studies have identified numerous possible associations with often contrasting and conflicting results. A systematic review and meta-analysis were performed in order to determine the effect of human leucocyte antigen (HLA) matching and donor relatedness on the risk of AIHA post-HSCT. PubMed, SCOPUS and ProQuest were searched from 1 January 1995 to 1 August 2021 using a range of keywords. Meta-analysis was performed using OpenMeta-Analyst software using a random effects model and arcsine risk difference (ARD). Eight eligible articles were identified, and meta-analysis showed an increased risk of AIHA in those who received HLA-mismatched transplants (ARD -0.082; 95% confidence interval [CI] -0.157, -0.007; p = 0.031) and those who received donations from unrelated donor sources (ARD -0.097; 95% CI -0.144, -0.051; p < 0.001). Patients who receive HSCT from HLA-matched and related donor sources have a reduced risk of developing AIHA. Healthcare practitioners should be mindful of the risk of AIHA, especially in those who receive HLA-mismatched and unrelated donor-sourced stem cells. While these findings provide further evidence for researchers investigating the pathogenesis of this HSCT complication, more studies are needed to fully understand the cause.

Autoimmune hemolytic anemia: causes and consequences

INTRODUCTION

Autoimmune hemolytic anemia (AIHA) is classified according to the direct antiglobulin test (DAT) and thermal characteristics of the autoantibody into warm and cold forms, and in primary versus secondary depending on the presence of associated conditions.

AREAS COVERED

AIHA displays a multifactorial pathogenesis, including genetic (association with congenital conditions and certain mutations), environmental (drugs, infections, including SARS-CoV-2, pollution, etc.), and miscellaneous factors (solid/hematologic neoplasms, systemic autoimmune diseases, etc.) contributing to tolerance breakdown. Several mechanisms, such as autoantibody production, complement activation, monocyte/macrophage phagocytosis, and bone marrow compensation are implicated in extra-/intravascular hemolysis. Treatment should be differentiated and sequenced according to AIHA type (i.e. steroids followed by rituximab for warm, rituximab alone or in association with bendamustine or fludarabine for cold forms). Several new drugs targeting B-cells/plasma cells, complement, and phagocytosis are in clinical trials. Finally, thrombosis and infections may complicate disease course burdening quality of life and increasing mortality.

EXPERT OPINION

Beyond warm and cold AIHA, a gray-zone still exists including mixed and DAT negative forms representing an unmet need. AIHA management is rapidly changing through an increasing knowledge of the pathogenic mechanisms, the refinement of diagnostic tools, and the development of novel targeted and combination therapies.

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.

Autoimmune diseases after allogeneic stem cell transplantation: a clinician's guide and future outlook

INTRODUCTION

Autoimmune disease (AD) may occur after allogeneic hematopoietic stem cell transplantation (HSCT). The autoimmune mechanism seems to be related to an imbalance of the immune regulation effect of T-regulatory lymphocytes on autoreactive T-lymphocytes.

AREAS COVERED

ADs include hematological ADs (HADs) and nonhematologic ADs (NHADs) involving organs such as thyroid, peripheral and central nervous system, skin, liver, connective tissue, gastrointestinal tract, and kidney. To identify the risk factors for ADs, to report their clinical characteristics, and to discuss new approaches represent the areas covered in this review.

EXPERT OPINION

Some risk factors for HAD and NHAD are common and include nonmalignant diseases, young age, cord blood as a stem cell source, conditioning regimens without total body irradiation, alemtuzumab, antithymocyte globulin, T-cell-depleted transplant, some viral infection, mixed chimerism, and chronic Graft versus Host Disease. In NHADs, the detection of autoantibodies is more frequent and the transfer of autoimmunity from the donor to the recipient represents the pathogenetic mechanism responsible for these complications. New therapeutic approaches such as bortezomib, daratumumab, sirolimus, eculizumab, and eltrombopag appear to be promising in terms of better efficacy and reduced toxicity compared to traditional therapies. New horizons based on personalized therapies will allow us to improve the prognosis of AD.

Development of New Drugs for Autoimmune Hemolytic Anemia

Autoimmune hemolytic anemia (AIHA) is a rare disorder characterized by the autoantibody-mediated destruction of red blood cells, and treatments for it still remain challenging. Traditional first-line immunosuppressive therapy, which includes corticosteroids and rituximab, is associated with adverse effects as well as treatment failures, and relapses are common. Subsequent lines of therapy are associated with higher rates of toxicity, and some patients remain refractory to currently available treatments. Novel therapies have become promising for this vulnerable population. In this review, we will discuss the mechanism of action, existing data, and ongoing clinical trials of current novel therapies for AIHA, including B-cell-directed therapy, phagocytosis inhibition, plasma cell-directed therapy, and complement inhibition.

Type O blood, the MCHC, and the reticulocyte count impact the early recurrence of primary warm-antibody autoimmune hemolytic anemia in children: A retrospective cohort analysis

OBJECTIVE

Primary warm-antibody autoimmune hemolytic anemia (w-AIHA) is prone to recurrence in children. In this study, we aimed to identify risk indicators for the early recurrence of primary w-AIHA and construct an effective recurrence risk assessment model.

METHODS

This was a retrospective cohort study. The clinical data of patients hospitalized with primary w-AIHA in the Department of Hematology and Oncology, Children's Hospital of Chongqing Medical University, between 1 January 2018 and 30 September 2021, were collected at the initial diagnosis. Univariate and multivariate logistic regression analyses were used to determine risk indicators for the early recurrence of primary w-AIHA in children, and ROC curve and Kaplan-Meier survival analyses were used for verification. Finally, a risk assessment model for early recurrence in children with primary w-AIHA was constructed using Cox regression and visualized using a nomogram. The model was also verified internally and externally.

RESULTS

This study included 62 children with primary w-AIHA. Of which, 18 experienced recurrence 1 year after the initial diagnosis. The univariate and multivariate logistic regression analyses showed that type O blood and the reticulocyte count (Ret) were risk indicators for the early recurrence of pediatric primary w-AIHA (P = 0.009, 0.047, respectively). The mean corpuscular hemoglobin concentration (MCHC) is a protective factor (P = 0.040). According to the ROC curve and Kaplan-Meier survival analyses, children with primary w-AIHA whose blood type was O or had an MCHC of <313.5 pg/fL or a Ret of ≥0.161×10¹²/L had a higher risk of early recurrence (HR = 2.640, 4.430 and 4.450, respectively, and P = 0.040, 0.015 and 0.018, respectively). The blood types (O), MCHCs, and Rets of 56 patients were incorporated into the Cox regression model, and the recurrence risk assessment model for children with primary w-AIHA was successfully constructed and visualized using a nomogram. The calibration curves and decision-curve analysis (DCA) suggested that the risk model has clinical applicability and effectiveness.

CONCLUSION

Children with type O blood and an MCHC value of <313.5 pg/fL or a Ret value of ≥0.161×10¹²/L have a higher risk of early recurrence. The risk assessment model for the early recurrence of pediatric primary w-AIHA constructed in this study has good clinical applicability and effectiveness.

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.

Immune Phenomena in Myeloid Neoplasms: An "Egg or Chicken" Question

Immune phenomena are increasingly reported in myeloid neoplasms, and include autoimmune cytopenias/diseases and immunodeficiency, either preceding or complicating acute myeloid leukemia, myelodysplastic syndromes (MDS), chronic myeloproliferative neoplasms, and bone marrow failure (BMF) syndromes. Autoimmunity and immunodeficiency are the two faces of a dysregulated immune tolerance and surveillance and may result, along with contributing environmental and genetic factors, in an increased incidence of both tumors and infections. The latter may fuel both autoimmunity and immune activation, triggering a vicious circle among infections, tumors and autoimmune phenomena. Additionally, alterations of the microbiota and of mesenchymal stem cells (MSCs) pinpoint to the importance of a permissive or hostile microenvironment for tumor growth. Finally, several therapies of myeloid neoplasms are aimed at increasing host immunity against the tumor, but at the price of increased autoimmune phenomena. In this review we will examine the epidemiological association of myeloid neoplasms with autoimmune diseases and immunodeficiencies, and the pivotal role of autoimmunity in the pathogenesis of MDS and BMF syndromes, including the paroxysmal nocturnal hemoglobinuria conundrum. Furthermore, we will briefly examine autoimmune complications following therapy of myeloid neoplasms, as well as the role of MSCs and microbiota in these settings.

Pathogenesis, risk factors and therapeutic options for autoimmune haemolytic anaemia in the post-transplant setting

Autoimmune haemolytic anaemia (AIHA) is a rare complication of allogeneic haematopoietic stem cell transplantation (HSCT), observed with an incidence of 1-5%. Paediatric age, diagnosis of non-malignant disease, lympho-depleting agents in the conditioning regimen, use of unrelated donor, graft versus host disease and infections have been associated with a higher risk of AIHA post HSCT. Post-HSCT AIHA is associated with high mortality and morbidity, and it is often very difficult to treat. Steroids and rituximab are used with a response rate around 30-50%. These and other therapeutic strategies are mainly derived from data on primary AIHA, although response rates in post-HSCT AIHA have been generally lower. Here we review the currently available data on risk factors and therapeutic options. There is a need for prospective studies in post-HSCT AIHA to guide clinicians in managing these complex patients.

Daratumumab: Beyond Multiple Myeloma

Daratumumab (DARA) is the biological name of an Immunoglobulin G1k human monoclonal antibody. DARA the first-in-class therapy targeting CD38 expressing- plasma cells (PC) and plasma blasts. It has been approved for the treatment of multiple myeloma. It is also being examined in the setting of other hematologic malignancies. As DARA targets PCs, it could potentially be used to treat many other disease processes that are antibody mediated. In fact, several case reports and case series report experiences of using DARA to treat a variety of antibody-mediated disorderss. The aim of this review is to present a summary of the literature thus far regarding the application of DARA beyond its uses in multiple myeloma and other hematologic diseases. Specifically, we address uses of DARA as an immunologic modulator in various antibody mediated processes.

Bortezomib for treatment-refractory autoimmune haemolytic anaemia following multivisceral transplantation

A 25-year-old man who received alemtuzumab as induction therapy for a multivisceral transplant experienced delayed onset of warm autoimmune haemolytic anaemia and neutropaenia. Serological testing and bone marrow biopsy excluded alternative causes. Haemolysis was refractory to standard therapies including corticosteroids, intravenous immunoglobulin and rituximab. The patient was successfully treated with bortezomib, a proteasome inhibitor, and has remained well as an outpatient without evidence of ongoing haemolysis.

Daratumumab therapy for post-HSCT immune-mediated cytopenia: experiences from two pediatric cases and review of literature

Background

Immune-mediated cytopenias (AIC) are challenging complications following allogeneic hematopoietic stem cell transplantation (HSCT). While broad-acting immunosuppressive agents like corticosteroids are often standard of care, several novel therapies which target specific immunological pathways have recently been developed and provide hope for patients with steroid-refractory courses and may limit long-term toxicity. The successful off-label use of the plasma cell depleting anti-CD38 antibody daratumumab was published in several case reports, suggesting efficacy, i.e., in patients with antibody-mediated AIC refractory to previous B cell depletion. We want to share our experience with two children, whom we treated with daratumumab, including one fatal course with uncontrolled disease. Given the absence of substantial data from HSCT registries or prospective trials, we furthermore provide a critical review of the literature on daratumumab treatment of AIC.

Case presentations

Patient 1 (P1), an 11-year-old girl with lipopolysaccharide-responsive and beige-like anchor protein (LRBA) deficiency who developed immune-mediated thrombocytopenia (AIT) from day +58 after HSCT, showed a complete response to daratumumab after the fourth of six total daratumumab doses. She remains transfusion independent for over a year of follow-up. Previously, her thrombocytopenia was refractory to corticosteroids, rituximab, intravenous immunoglobulins (IVIG), eltrombopag, cyclosporine A, and sirolimus. Patient 2 (P2), a 6-year-old boy with CD40 ligand (CD40L) deficiency, developed both AIT and hemolytic anemia (AIHA) after HSCT on days +58 and +83, respectively, and was also treated with daratumumab after being previously refractory to prednisolone, rituximab, and IVIG. Yet, he did neither respond to daratumumab nor the concomitantly administered methyprednisolone pulse, plasmapheresis, and eculizumab and succumbed due to refractory disease.

Conclusion

Reviewing the literature on the use of daratumumab for refractory AIC post-HSCT, we consider daratumumab a promising agent for this life-threatening disorder: ten of the twelve patients reached transfusion independency in the literature. However, treatment failures are likely to be underreported. Thus, controlled trials are needed to explore the safety and efficacy of daratumumab in this rare post-HSCT complication.

Characterizing Immune-Mediated Cytopenias After Allogeneic Hematopoietic Cell Transplantation for Pediatric Nonmalignant Disorders

Immune-mediated cytopenias (IMC)-isolated or combined hemolytic anemia, thrombocytopenia, or neutropenia-are increasingly recognized as serious complications after allogeneic hematopoietic cell transplantation (HCT) for nonmalignant disorders (NMD). However, IMC incidence, duration, response to therapy, and risk factors are not well defined. This retrospective chart review identified cases of IMC with serologic confirmation among patients who underwent HCT for NMD at a single institution between 2010 and 2017. IMC after HCT for NMD in a large pediatric cohort (n = 271) was common with a cumulative incidence of 18%, identified at a median of 136 days after HCT. Treatment included prolonged immune suppression (>3 months) in 58% of all IMC cases, 91% when multiple cell lines were affected. Multiple therapeutic agents were used for the majority affected, and median time to resolution of IMC was 118 days from diagnosis. Fine-Gray competing risk multivariate regression analysis identified a combined risk factor of younger age (<3 years) and inherited metabolic disorder, as well as hemoglobinopathy (at any age) associated with 1-year incidence of IMC (P < .01). We expand these findings with the observation of declining donor T-lymphoid chimerism from day 60 to 100 and lower absolute CD4+ counts at day 100 (P < .01), before median onset of IMC, for patients with IMC compared to those without. In this cohort, 4 deaths (8%) were associated with IMC, including 2 requiring second transplantation for secondary graft failure. Although the pathogenesis of IMC post-HCT for NMD remains elusive, further research may identify approaches to prevent and better treat this HCT complication.

Autoimmune Complications in Hematologic Neoplasms

Autoimmune cytopenias (AICy) and autoimmune diseases (AID) can complicate both lymphoid and myeloid neoplasms, and often represent a diagnostic and therapeutic challenge. While autoimmune hemolytic anemia (AIHA) and immune thrombocytopenia (ITP) are well known, other rarer AICy (autoimmune neutropenia, aplastic anemia, and pure red cell aplasia) and AID (systemic lupus erythematosus, rheumatoid arthritis, vasculitis, thyroiditis, and others) are poorly recognized. This review analyses the available literature of the last 30 years regarding the occurrence of AICy/AID in different onco-hematologic conditions. The latter include chronic lymphocytic leukemia (CLL), lymphomas, multiple myeloma, myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), myeloproliferative neoplasms, and acute leukemias. On the whole, AICy are observed in up to 10% of CLL and with higher frequencies in certain subtypes of non-Hodgkin lymphoma, whilst they occur in less than 1% of low-risk MDS and CMML. AID are described in up to 30% of myeloid and lymphoid patients, including immune-mediated hemostatic disorders (acquired hemophilia, thrombotic thrombocytopenic purpura, and anti-phospholipid syndrome) that may be severe and fatal. Additionally, AICy/AID are found in about 10% of patients receiving hematopoietic stem cell transplant or treatment with new checkpoint inhibitors. Besides the diagnostic difficulties, these AICy/AID may complicate the clinical management of already immunocompromised patients.

How I treat warm autoimmune hemolytic anemia

Warm autoimmune hemolytic anemia (wAIHA) is caused by increased erythrocyte destruction by immunoglobulin G (IgG) autoantibodies, with or without complement activation. Antibody-dependent cell-mediated cytotoxicity by macrophages/activated lymphocytes occurs in the lymphoid organs and spleen (extravascular hemolysis). The ability of the bone marrow (BM) to compensate determines clinical severity. The different pathogenic mechanisms, their complex interplay, and changes over time may explain wAIHA's great clinical heterogeneity and unpredictable course. The disease may be primary, drug induced, or associated with lymphoproliferative neoplasms, autoimmune and infectious diseases, immunodeficiencies, solid tumors, or transplants. Therapeutic interventions include steroids, splenectomy, immunosuppressants, and rituximab; the latter is increasingly used in steroid-refractory cases based on evidence from the literature and a few prospective trials. We present 5 patient case studies highlighting important issues: (1) the diagnosis and proper use of steroid therapy, (2) the concerns about the choice between rituximab and splenectomy in second-line treatment, (3) the need of periodical re-evaluation of the disease to assess the possible evolution of relapsed/refractory cases in myelodysplastic and BM failure syndromes, and (4) the difficulties in managing cases of severe/acute disease that are at high risk of relapse. Incorporating novel targeted therapies into clinical practice will be an exciting challenge in the future.

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.

Secondary Hemophagocytic Lymphohistiocytosis and Autoimmune Cytopenias: Case Description and Review of the Literature

Hemophagocytic lymphohistocytosis (HLH) is a rare hyperinflammatory condition which may be primary or secondary to many diseases, including hematologic malignancies. Due to its life-threatening evolution, a timely diagnosis is paramount but challenging, since it relies on non-specific clinical and laboratory criteria. The latter are often altered in other diseases, including autoimmune cytopenias (AIC), which in turn can be secondary to infections, systemic autoimmune or lymphoproliferative disorders. In the present article, we describe two patients presenting at the emergency department with acute AICs subsequently diagnosed as HLH with underlying diffuse large B cell lymphoma. We discuss the diagnostic challenges in the differential diagnosis of acute cytopenias in the internal medicine setting, providing a literature review of secondary HLH and AIC.

The Diagnostic Utility of Splenectomy in Idiopathic Splenomegaly

INTRODUCTION

With increasing frequency, patients with idiopathic splenomegaly are referred to surgeons for splenectomy. We evaluated the diagnostic utility of splenectomy and feasibility of a minimally invasive approach in the face of idiopathic splenomegaly.

METHODS

We retrospectively reviewed 68 patients who underwent splenectomy for idiopathic splenomegaly. The primary endpoint was the rate of definitive diagnosis based on final surgical pathology of the removed spleen.

RESULTS

Preoperative workup included a bone marrow biopsy and peripheral blood smear in 93% and 100% of patients, respectively, with none having lymphadenopathy warranting biopsy. Splenectomy provided a definitive diagnosis for 44 (64.7%) patients. Of these, 34 (50%) patients had an underlying malignancy, of which more than half were splenic marginal zone lymphoma. There were 33 (48.5%) laparoscopic, 23 (33.8%) open, 10 (14.7%) laparoscopic converted to open, and two (2.9%) laparoscopic hand-assist cases. Conversion to open was due to splenic size [median craniocaudal length 21.8 cm (cm)] in eight and staple line bleeding at the splenic hilum in two patients. Overall, the laparoscopic approach was completed in patients with a smaller splenic size compared to open (median craniocaudal length 15.2 vs. 26.0 cm, p < 0.0001). The open group had one (1.5%) intra-operative mortality due to uncontrollable hemorrhage. Thirty-day complication rates were similar for laparoscopic and open approaches (p = 0.10).

CONCLUSION

Splenectomy is an effective diagnostic modality in determining a pathologic cause for splenomegaly in this patient population. Laparoscopic splenectomy can be performed safely in appropriate cases with craniocaudal splenic size having the largest influence on surgical approach.

Infectious Complications in Autoimmune Hemolytic Anemia

Autoimmune hemolytic anemia (AIHA) may be frequently challenged by infectious complications, mainly as a result of immunosuppressive treatments administered. Furthermore, infectious agents are known triggers of AIHA onset and relapse. Although being risk factors for mortality, infections are an underestimated issue in AIHA. This review will collect the available evidence on the frequency and type of infectious complications in AIHA, detailing the risk related to each treatment (i.e., steroids, rituximab, splenectomy, classic immunosuppressive agents, and new target drugs). Moreover, we will briefly discuss the infectious complications in AIHA secondary to other diseases that harbor an intrinsic infectious risk (e.g., primary immunodeficiencies, systemic autoimmune diseases, lymphoproliferative disorders, solid organ and hematopoietic stem cell transplants). Finally, viral and bacterial reactivations during immune suppressive therapies will be discussed, along with suggested screening and prophylactic strategies.

Rituximab Use in Warm and Cold Autoimmune Hemolytic Anemia

Autoimmune hemolytic anemia is a rare condition characterized by destruction of red blood cells with and without involvement of complement. It is associated with significant morbidity and mortality. In warm autoimmune hemolytic anemia, less than 50% of patients remain in long-term remission following initial steroid therapy and subsequent therapies are required. Cold agglutinin disease is a clonal hematologic disorder that requires therapy in the majority of patients and responds poorly to steroids and alkylators. Rituximab has a favorable toxicity profile and has demonstrated efficacy in autoimmune hemolytic anemia in first-line as well as relapsed settings. Rituximab is the preferred therapy for steroid refractory warm autoimmune hemolytic anemia (wAIHA) and as part of the first- and second-line treatment of cold agglutinin disease. This article reviews the mechanism of action of rituximab and the current literature on its role in the management of primary and secondary warm autoimmune hemolytic anemia and cold agglutinin disease.

Difficult Cases of Autoimmune Hemolytic Anemia: A Challenge for the Internal Medicine Specialist

Autoimmune hemolytic anemia (AIHA) is diagnosed in the presence of anemia, hemolysis, and direct antiglobulin test (DAT) positivity with monospecific antisera. Many confounders of anemia and hemolytic markers should be included in the initial workup (i.e., nutrients deficiencies, chronic liver or kidney diseases, infections, and cancers). Besides classical presentation, there are difficult cases that may challenge the treating physician. These include DAT negative AIHA, diagnosed after the exclusion of other causes of hemolysis, and supported by the response to steroids, and secondary cases (infections, drugs, lymphoproliferative disorders, immunodeficiencies, etc.) that should be suspected and investigated through careful anamnesis physical examination, and specific tests in selected cases. The latter include autoantibody screening in patients with signs/symptoms of systemic autoimmune diseases, immunoglobulins (Ig) levels in case of frequent infections or suspected immunodeficiency, and ultrasound/ computed tomography (CT) studies and bone marrow evaluation to exclude hematologic diseases. AIHA occurring in pregnancy is a specific situation, usually manageable with steroids and intravenous (iv) Ig, although refractory cases have been described. Finally, AIHA may complicate specific clinical settings, including intensive care unit (ICU) admission, reticulocytopenia, treatment with novel anti-cancer drugs, and transplant. These cases are often severe, more frequently DAT negative, and require multiple treatments in a short time.

New Insights in Autoimmune Hemolytic Anemia: From Pathogenesis to Therapy Stage 1

Autoimmune hemolytic anemia (AIHA) is a highly heterogeneous disease due to increased destruction of autologous erythrocytes by autoantibodies with or without complement involvement. Other pathogenic mechanisms include hyper-activation of cellular immune effectors, cytokine dysregulation, and ineffective marrow compensation. AIHAs may be primary or associated with lymphoproliferative and autoimmune diseases, infections, immunodeficiencies, solid tumors, transplants, and drugs. The direct antiglobulin test is the cornerstone of diagnosis, allowing the distinction into warm forms (wAIHA), cold agglutinin disease (CAD), and other more rare forms. The immunologic mechanisms responsible for erythrocyte destruction in the various AIHAs are different and therefore therapy is quite dissimilar. In wAIHA, steroids represent first line therapy, followed by rituximab and splenectomy. Conventional immunosuppressive drugs (azathioprine, cyclophosphamide, cyclosporine) are now considered the third line. In CAD, steroids are useful only at high/unacceptable doses and splenectomy is uneffective. Rituximab is advised in first line therapy, followed by rituximab plus bendamustine and bortezomib. Several new drugs are under development including B-cell directed therapies (ibrutinib, venetoclax, parsaclisib) and inhibitors of complement (sutimlimab, pegcetacoplan), spleen tyrosine kinases (fostamatinib), or neonatal Fc receptor. Here, a comprehensive review of the main clinical characteristics, diagnosis, and pathogenic mechanisms of AIHA are provided, along with classic and new therapeutic approaches.

Autoimmune hemolytic anemia: current knowledge and perspectives

Autoimmune hemolytic anemia (AIHA) is an acquired, heterogeneous group of diseases which includes warm AIHA, cold agglutinin disease (CAD), mixed AIHA, paroxysmal cold hemoglobinuria and atypical AIHA. Currently CAD is defined as a chronic, clonal lymphoproliferative disorder, while the presence of cold agglutinins underlying other diseases is known as cold agglutinin syndrome. AIHA is mediated by autoantibodies directed against red blood cells (RBCs) causing premature erythrocyte destruction. The pathogenesis of AIHA is complex and still not fully understood. Recent studies indicate the involvement of T and B cell dysregulation, reduced CD4+ and CD25+ Tregs, increased clonal expansions of CD8 + T cells, imbalance of Th17/Tregs and Tfh/Tfr, and impaired lymphocyte apoptosis. Changes in some RBC membrane structures, under the influence of mechanical stimuli or oxidative stress, may promote autohemolysis. The clinical presentation and treatment of AIHA are influenced by many factors, including the type of AIHA, degree of hemolysis, underlying diseases, presence of concomitant comorbidities, bone marrow compensatory abilities and the presence of fibrosis and dyserthropoiesis. The main treatment for AIHA is based on the inhibition of autoantibody production by mono- or combination therapy using GKS and/or rituximab and, rarely, immunosuppressive drugs or immunomodulators. Reduction of erythrocyte destruction via splenectomy is currently the third line of treatment for warm AIHA. Supportive treatment including vitamin supplementation, recombinant erythropoietin, thrombosis prophylaxis and the prevention and treatment of infections is essential. New groups of drugs that inhibit immune responses at various levels are being developed intensively, including inhibition of antibody-mediated RBCs phagocytosis, inhibition of B cell and plasma cell frequency and activity, inhibition of IgG recycling, immunomodulation of T lymphocytes function, and complement cascade inhibition. Recent studies have brought about changes in classification and progress in understanding the pathogenesis and treatment of AIHA, although there are still many issues to be resolved, particularly concerning the impact of age-associated changes to immunity.

Autoimmune cytopenias following allogeneic hematopoietic stem cell transplant in pediatric patients: Response to therapy and late effects

BACKGROUND

Autoimmune cytopenias (AICs) are rare, but serious complications of allogeneic hematopoietic cell transplantation (allo-HSCT).

PROCEDURE

We performed a case-control study using 20 pediatric AIC cases and 40 controls, matched by stem cell source and primary indication comparing clinical and transplant characteristics, treatment, outcomes, and late effects.

RESULTS

Cases were more likely to be human leukocyte antigen mismatched (P = 0.04). There was no difference in conditioning regimen, serotherapy use, graft-versus-host disease (GVHD) prophylaxis, incidence of acute or chronic GVHD, ABO compatibility, infections, and donor engraftment. The median time to AIC onset was 219 days (range, 97-1205 days) and AIC resolution was 365 days (range, 10 days to 2737.5 days). First-line therapies for AIC patients most commonly included corticosteroids (75%) and rituximab (55%). Only 25% of patients responded to first-line treatment. At a median of 611.5 days from last rituximab dose, 82.5% patients were still receiving intravenous immune globulin for hypogammaglobulinemia compared with 2.5% of controls (P < 0.0001). Iron overload was higher in AIC patients (P = 0.0004), as was avascular necrosis (P = 0.04). There was no difference in overall survival at one year after HSCT (85% vs 82.5%). Two patients with refractory autoimmune hemolytic anemia responded to daratumumab and had resolution of B-cell aplasia.

CONCLUSIONS

In this study, we find poor initial responses to AIC-directed therapies and significant late effects.

Autoimmunity Following Allogeneic Hematopoietic Stem Cell Transplantation

Autoimmune manifestations after allogeneic hematopoietic stem cell transplantation (AHSCT) are rare and poorly understood due to the complex interplay between the reconstituting immune system and transplant-associated factors. While autoimmune manifestations following AHSCT have been observed in children with graft-versus-host disease (GvHD), an alloimmune process, they are distinct from the latter in that they are generally restricted to the hematopoietic compartment, i.e., autoimmune hemolytic anemia, thrombocytopenia, and/or neutropenia. Autoimmune cytopenias in the setting of ASHCT represent a donor against donor immune reaction. Non-hematologic autoimmune conditions in the post-AHSCT setting have been described and do not currently fall under the GvHD diagnostic criteria, but could represent alloimmunity since they arise from the donor immune attack on the antigens that are shared by the donor and host in the thyroid, peripheral and central nervous systems, integument, liver, and kidney. As in the non-transplant setting, autoimmune conditions are primarily antibody mediated. In this article we review the incidence, risk factors, potential pathophysiology, treatment, and prognosis of hematologic and non-hematologic autoimmune manifestations in children after AHSCT.

The Changing Landscape of Autoimmune Hemolytic Anemia

Autoimmune hemolytic anemia (AIHA) is a greatly heterogeneous disease due to autoantibodies directed against erythrocytes, with or without complement activation. The clinical picture ranges from mild/compensated to life-threatening anemia, depending on the antibody's thermal amplitude, isotype and ability to fix complement, as well as on bone marrow compensation. Since few years ago, steroids, immunesuppressants and splenectomy have been the mainstay of treatment. More recently, several target therapies are increasingly used in the clinical practice or are under development in clinical trials. This has led to the accumulation of refractory/relapsed cases that often represent a clinical challenge. Moreover, the availability of several drugs acting on the different pathophysiologic mechanisms of the disease pinpoints the need to harness therapy. In particular, it is advisable to define the best choice, sequence and/or combination of drugs during the different phases of the disease. In particular relapsed/refractory cases may resemble pre-myelodysplastic or bone marrow failure syndromes, suggesting a careful use of immunosuppressants, and vice versa advising bone marrow immunomodulating/stimulating agents. A peculiar setting is AIHA after autologous and allogeneic hematopoietic stem cell transplantation, which is increasingly reported. These cases are generally severe and refractory to standard therapy, and have high mortality. AIHAs may be primary/idiopathic or secondary to infections, autoimmune diseases, malignancies, particularly lymphoproliferative disorders, and drugs, further complicating their clinical picture and management. Regarding new drugs, the false positivity of the Coombs test (direct antiglobulin test, DAT) following daratumumab adds to the list of difficult diagnosis, together with the passenger lymphocyte syndrome after solid organ transplants. Diagnosis of DAT-negative AIHAs and evaluation of disease-related risk factors for relapse and mortality, notwithstanding improvement in diagnostic approach, are still an unmet need. Finally, AIHA is increasingly described following therapy of solid cancers with inhibitors of immune checkpoint molecules. On the whole, the double-edged sword of new pathogenetic insights and therapies has changed the landscape of AIHA, both providing enthusiastic knowledge and complicating the clinical management of this disease.

Autoimmune hemolytic anemia in adults: primary risk factors and diagnostic procedures

INTRODUCTION

Autoimmune hemolytic anemia (AIHA) is due to autoantibodies against erythrocytes that may arise either because of primary tolerance breakage or along with several associated conditions, including genetic predispositions, congenital syndromes, environmental triggers, autoimmune diseases, immunodeficiencies, and neoplasms.

AREAS COVERED

This review evaluated the risk of AIHA development in associated conditions and summarized disease-intrinsic risk factors for relapse and outcome. Diagnostic procedures were analyzed to properly identify primary and secondary forms. A Medline including clinical trials, meta-analyses, guidelines, consensus, and case reports, published in the last 30 years were performed.

EXPERT OPINION

The several associated conditions listed above constitute a risk for AIHA development and should be considered since disease course and therapy may be different. Particularly, AIHA developing after transplant or novel checkpoint inhibitors is an emerging complex entity whose proper therapy is still an unmet need. Concerning intrinsic risk factors, the severity of anemia at onset correlated with the recurrence of relapses, refractoriness, and fatal outcome. This finding reflects the presence of several mechanisms involved in AIHA, i.e. highly pathogenic antibodies, complement activation, and failure of marrow compensation. With the advent of novel target therapies (complement and various tyrosine kinase inhibitors), a risk-adapted therapy for AIHA is becoming fundamental.