Risk Factors, Treatment, and Immune Dysregulation in Autoimmune Cytopenia after Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Patients

Childhood autoimmune hemolytic anemia: A scoping review

BACKGROUND AND OBJECTIVE

Autoimmune hemolytic anemia (AIHA) is a rare but important cause of morbidity in pediatric hematology patients. Given its rarity, there is little high-quality evidence on which to base the investigation and management of pediatric AIHA. This scoping review aims to summarize the current evidence and highlight key gaps to inform future studies.

METHODS

This review searched MEDLINE and the Cochrane CENTRAL Trials Register from 2000 to November 03, 2023. Experimental and observational studies reporting AIHA diagnostic criteria, laboratory workup, or treatment/management in populations with at least 20% of patients ≤18 years were included.

RESULTS

Forty-three studies were included, with no randomized controlled trials identified. AIHA diagnostic criteria, diagnostic tests, and treatments were highly variable. First-line treatment approaches include corticosteroids, intravenous immunoglobulin, or both. Approaches to AIHA resistance to first-line therapy were widely variable between studies, but most commonly included rituximab and/or cyclosporine.

CONCLUSIONS

We identify a heterogenous group of observational studies into this complex, immune-mediated disorder. Standardized definitions and classifications are needed to guide collaborative efforts needed to study this rare disease. The work done by the CEREVANCE group provides an important paradigm for future studies.

Incidence and Outcome of Atypical Manifestations of Chronic Graft-versus-Host Disease: Results From a Retrospective Single-Center Analysis

Chronic graft-versus-host disease (cGVHD) is the leading cause of late nonrelapse mortality (NRM) after allogeneic hematopoietic stem cell transplantation (alloHSCT) and defined by 8 diagnostic target organs. Recently, provisional criteria for atypical manifestations of cGVHD that include manifestations in nonclassic organs as well as atypical manifestations in National Institutes of Health (NIH)-defined organs, were proposed by a NIH task force. Little is known about the incidence, risk factors, and impact on survival of atypical cGVHD, however. The aim of the present study was to analyze these parameters in a sequential patient population. We retrospectively screened 623 patients who underwent alloHSCT at the University Medical Center Regensburg between January 2008 and December 2020 for atypical cGVHD manifestations, applying the provisional NIH taskforce criteria. A total of 102 patients (16.4%) met the criteria, representing 25% of all cGVHD cases, and 14 patients (2.2%) had only atypical cGVHD. The most frequent manifestations were immune-mediated cytopenias (24.5%), renal cGVHD (13.7%) and (poly)serositis (13.7%). Multivariate analysis identified prior acute GVHD (odds ratio [OR], 2.28 and 2.93) and infusion of donor lymphocytes (OR, 1.77 for both) as risk factors for classic cGVHD and atypical cGVHD, whereas total body irradiation was an independent risk factor for atypical cGVHD manifestations only (OR, 1.76). Compared to patients without cGVHD, those with atypical and NIH-defined cGVHD showed similarly better overall survival (P = .034 and < .001) and low relapse-related mortality (P < .001 for both). NRM was significantly increased by atypical GVHD, but not by NIH-defined cGVHD (P = .019 and .10), which was driven only by a few atypical organ manifestations (eg, renal, restrictive lung disease, peripheral neuropathy), whereas others did not contribute to NRM (eg, thyroid gland, musculoskeletal, pancreas). In summary, atypical cGVHD is more common than previously estimated and has both similarities with and differences from NIH-defined cGVHD. In particular, the increased NRM and a subset of patients with only atypical cGVHD point to the urgent need to capture these manifestations in cGVHD cohorts, including analysis of treatment outcomes.

Allogeneic HSCT for Symptomatic Female X-linked Chronic Granulomatous Disease Carriers

X-linked chronic granulomatous disease (XL-CGD) is an inherited disorder of superoxide production, causing failure to generate the oxidative burst in phagocytes. It is characterized by invasive bacterial and fungal infections, inflammation, and chronic autoimmune disease. While XL-CGD carriers were previously assumed to be healthy, a range of clinical manifestations with significant morbidity have recently been described in a subgroup of carriers with impaired neutrophil oxidative burst due to skewed lyonization. Allogeneic hematopoietic stem cell transplantation (HSCT) is the standard curative treatment for CGD but has rarely been reported in individual symptomatic carriers to date. We undertook a retrospective international survey of outcome of HSCT for symptomatic XL-CGD carriers. Seven symptomatic female XL-CGD carriers aged 1-56 years underwent HSCT in four centers, indicated for severe and recurrent infection, colitis, and autoimmunity. Two patients died from transplant-related complications, following donor engraftment and restoration of oxidative burst. All surviving patients demonstrated resolution of their neutrophil oxidative burst defect with concordant reduction in infection and inflammatory symptoms and freedom from further immunosuppressive therapy. In conclusion, allogeneic HSCT may cure the phagocyte defect in symptomatic XL-CGD carriers and improve their recurrent and disabling infective and inflammatory symptoms but risks transplant-related complications.

Immune-mediated cytopenias (IMCs) after HSCT for pediatric non-malignant disorders: epidemiology, risk factors, pathogenesis, and treatment

Hematopoietic stem cell transplantation (HSCT) represents a curative option for pediatric patients affected by malignant and non-malignant disorders. Several complications may arise during the post-transplantation period, including immune-mediated disorders. Immune-mediated cytopenias (IMCs) account for up to 22% of pediatric HSCT complications, representing an important cause of morbidity and mortality post-HSCT. So far, their pathogenesis is not well-understood, and their management may be very challenging. Further, most patients are refractory to first-line treatment which is based on high-dose intravenous steroids, immunoglobulin, and the monoclonal anti-CD20 antibody - rituximab. No clear consensus has been reached for second- and third-line therapeutic options.

CONCLUSION

We reviewed the epidemiology, risk factors, pathogenesis, and treatment of IMCs, aiming to offer a deeper understanding of these complications as a guide to improving the management of these fragile patients and a cue for the design of tailored clinical trials.

WHAT IS KNOWN

• IMCs arising in the post-HSCT setting represent a rare but potentially life-threatening complication. Younger patients affected by non-malignant disorders are at the greatest risk of IMCs arising after HSCT. Corticosteroids, intravenous immunoglobulin, and rituximab represent the undiscussed first-line therapeutic approach.

WHAT IS NEW

• This review highlitghts how children present unique risk factors for post HSCT IMCs, which are the result of the complex relationship between the immaturity of their infantile immune system and all the perturbing agents and factors which characterize the post-HSCT setting. Future efforts are warranted to establish the best option for refractory patients, for whom a standard and validated approach is not currently available. Among new agents, ibrutinib or bortezomib and fostamatinib or low-dose IL-2 could represent a good therapeutic option for patients with graft-versus-host disease and hemolytic anemia or graft-versus-host disease and thrombocytopenia, respectively.

Anti-GD2 Antibody Dinutuximab Beta and Low-Dose Interleukin 2 After Haploidentical Stem-Cell Transplantation in Patients With Relapsed Neuroblastoma: A Multicenter, Phase I/II Trial

PURPOSE

Patients with relapsed high-risk neuroblastoma (rHR-NB) have a poor prognosis. We hypothesized that graft-versus-neuroblastoma effects could be elicited by transplantation of haploidentical stem cells (haplo-SCT) exploiting cytotoxic functions of natural killer cells and their activation by the anti-GD2 antibody dinutuximab beta (DB). This phase I/II trial assessed safety, feasibility, and outcomes of immunotherapy with DB plus subcutaneous interleukin-2 (scIL2) after haplo-SCT in patients with rHR-NB.

METHODS

Patients age 1-21 years underwent T-/B-cell-depleted haplo-SCT followed by DB and scIL2. The primary end point 'success of treatment' encompassed patients receiving six cycles, being alive 180 days after end of trial treatment without progressive disease, unacceptable toxicity, acute graft-versus-host-disease (GvHD) ≥grade 3, or extensive chronic GvHD.

RESULTS

Seventy patients were screened, and 68 were eligible for immunotherapy. Median number of DB cycles was 6 (range, 1-9). Median number of scIL2 cycles was 3 (1-6). The primary end point was met by 37 patients (54.4%). Median observation time was 7.8 years. Five-year event-free survival (EFS) and overall survival from start of trial treatment were 43% (95% CI, 31 to 55) and 53% (95% CI, 41 to 65), respectively. Five-year EFS among patients in complete remission (CR; 52%; 95% CI, 31 to 69) or partial remission (44%; 95% CI, 27 to 60) before immunotherapy were significantly better compared with patients with nonresponse/mixed response/progressive disease (13%; 95% CI, 1 to 42; P = .026). Overall response rate in 43 patients with evidence of disease after haplo-SCT was 51% (22 patients), with 15 achieving CR (35%). Two patients developed GvHD grade 2 and 3 each. No unexpected adverse events occurred.

CONCLUSION

DB therapy after haplo-SCT in patients with rHR-NB is feasible, with low risk of inducing GvHD, and results in long-term remissions likely attributable to increased antineuroblastoma activity by donor-derived effector cells.

Lentiviral Gene Therapy for Artemis-Deficient SCID

BACKGROUND

The DNA-repair enzyme Artemis is essential for rearrangement of T- and B-cell receptors. Mutations in DCLRE1C, which encodes Artemis, cause Artemis-deficient severe combined immunodeficiency (ART-SCID), which is poorly responsive to allogeneic hematopoietic-cell transplantation.

METHODS

We carried out a phase 1-2 clinical study of the transfusion of autologous CD34+ cells, transfected with a lentiviral vector containing DCLRE1C, in 10 infants with newly diagnosed ART-SCID. We followed them for a median of 31.2 months.

RESULTS

Marrow harvest, busulfan conditioning, and lentiviral-transduced CD34+ cell infusion produced the expected grade 3 or 4 adverse events. All the procedures met prespecified criteria for feasibility at 42 days after infusion. Gene-marked T cells were detected at 6 to 16 weeks after infusion in all the patients. Five of 6 patients who were followed for at least 24 months had T-cell immune reconstitution at a median of 12 months. The diversity of T-cell receptor β chains normalized by 6 to 12 months. Four patients who were followed for at least 24 months had sufficient B-cell numbers, IgM concentration, or IgM isohemagglutinin titers to permit discontinuation of IgG infusions. Three of these 4 patients had normal immunization responses, and the fourth has started immunizations. Vector insertion sites showed no evidence of clonal expansion. One patient who presented with cytomegalovirus infection received a second infusion of gene-corrected cells to achieve T-cell immunity sufficient for viral clearance. Autoimmune hemolytic anemia developed in 4 patients 4 to 11 months after infusion; this condition resolved after reconstitution of T-cell immunity. All 10 patients were healthy at the time of this report.

CONCLUSIONS

Infusion of lentiviral gene-corrected autologous CD34+ cells, preceded by pharmacologically targeted low-exposure busulfan, in infants with newly diagnosed ART-SCID resulted in genetically corrected and functional T and B cells. (Funded by the California Institute for Regenerative Medicine and the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT03538899.).

Risk factors and incidence of cytomegalovirus viremia and disease in pediatric patients with allogeneic hematopoietic stem cell transplantation: An 8-year single-center experience in Latin America

BACKGROUND

Cytomegalovirus infection represents a significant cause of morbidity and mortality after hematopoietic stem cell transplantation. This study aimed to evaluate the incidence of viremia and disease due to cytomegalovirus and the risk factors in pediatric patients with hematopoietic stem cell transplantation in our institution.

METHODS

This was a retrospective cohort of patients under 19 years of age who underwent allogeneic hematopoietic stem cell transplantation due to any indication between 2012 and 2019. The analysis included the diagnosis of cytomegalovirus viremia or disease during post-transplant follow-up, evaluation of risk factors, and outcomes. The statistical analysis included univariate and multivariate analyses, and the cumulative incidence of cytomegalovirus viremia was determined by the Kaplan-Meier method using STATA 14 statistical software.

RESULTS

A total of 182 transplants were included. At 100 days, the cumulative incidence of cytomegalovirus viremia was 70.5%, and that of cytomegalovirus disease was 4.7%. Overall survival at 2 years was 74%, and event-free survival was 64%. The remaining demographic characteristics were not predictors of infection. There was no association between viremia and relapse or survival of the patients. Higher mortality was noted in cytomegalovirus disease.

CONCLUSIONS

During the study period, the incidence of cytomegalovirus disease was similar to that of other pediatric reports, but the incidence of viremia was higher. Pre-emptive therapy has diminished disease rates and death due to infection. Viral load cutoff points should be standardized to guide treatment and avoid myelotoxicity.

Anemia in the pediatric patient

The World Health Organization estimates that approximately a quarter of the world's population suffers from anemia, including almost half of preschool-age children. Globally, iron deficiency anemia is the most common cause of anemia. Other important causes of anemia in children are hemoglobinopathies, infection, and other chronic diseases. Anemia is associated with increased morbidity, including neurologic complications, increased risk of low birth weight, infection, and heart failure, as well as increased mortality. When approaching a child with anemia, detailed historical information, particularly diet, environmental exposures, and family history, often yield important clues to the diagnosis. Dysmorphic features on physical examination may indicate syndromic causes of anemia. Diagnostic testing involves a stepwise approach utilizing various laboratory techniques. The increasing availability of genetic testing is providing new mechanistic insights into inherited anemias and allowing diagnosis in many previously undiagnosed cases. Population-based approaches are being taken to address nutritional anemias. Novel pharmacologic agents and advances in gene therapy-based therapeutics have the potential to ameliorate anemia-associated disease and provide treatment strategies even in the most difficult and complex cases.

Emerging approaches to improve allogeneic hematopoietic cell transplantation outcomes for nonmalignant diseases

Many congenital or acquired nonmalignant diseases (NMDs) of the hematopoietic system can be potentially cured by allogeneic hematopoietic cell transplantation (HCT) with varying types of donor grafts, degrees of HLA matching, and intensity of conditioning regimens. Unique features that distinguish the use of allogeneic HCT in this population include higher rates of graft failure, immune-mediated cytopenias, and the potential to achieve long-term disease-free survival in a mixed chimerism state. Additionally, in contrast to patients with hematologic malignancies, a priority is to completely avoid graft-versus-host disease in patients with NMD because there is no theoretical beneficial graft-versus-leukemia effect that can accompany graft-versus-host responses. In this review, we discuss the current approach to each of these clinical issues and how emerging novel therapeutics hold promise to advance transplant care for patients with NMDs.

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 Cytopenias Post Hematopoietic Stem Cell Transplantation in Pediatric Patients With Osteopetrosis and Other Nonmalignant Diseases

Autoimmune cytopenia (AIC) is a rare complication post hematopoietic stem cell transplantation (HSCT), with a higher incidence in nonmalignant diseases. The etiology of post-HSCT AIC is poorly understood, and in many cases, the cytopenia is prolonged and refractory to treatment. Diagnosis of post-HSCT AIC may be challenging, and there is no consensus for a standard of care. In this retrospective study, we summarize our experience over the past five years with post-HSCT AIC in pediatric patients with osteopetrosis and other nonmalignant diseases. All pediatric patients who underwent HSCT for nonmalignant diseases at Hadassah Medical Center over the past five years were screened for post-HSCT AIC, and data were collected from the patient’s medical records. From January 2017 through December 2021, 140 pediatric patients underwent HSCT for osteopetrosis (n=40), and a variety of other nonmalignant diseases. Thirteen patients (9.3%) presented with post-HSCT AIC. Of these, 7 had osteopetrosis (17.5%), and 6 had other underlying nonmalignant diseases. Factors associated with developing AIC included unrelated or non-sibling family donors (n=10), mixed chimerism (n=6), and chronic GvHD (n=5). Treatment modalities included steroids, IVIG, rituximab, bortezomib, daratumumab, eltrombopag, plasmapheresis, and repeated HSCT. Response to treatment was variable; Seven patients (54%) recovered completely, and three patients (23%) recovered partially, still suffering from mild-moderate thrombocytopenia. Three patients died (23%), two following progressive lung disease and one from sepsis and multi-organ failure after a 3^rd HSCT. In our experience, post-HSCT AICs in pediatric patients with nonmalignant diseases may pose a challenging post-transplant complication with a variable presentation and a wide spectrum of severity. A relatively high prevalence is seen in patients with osteopetrosis, possibly due to difficult engraftment and high rates of mixed chimerism. There is a dire need for novel treatment modalities for better management of the more severe and refractory cases.

Allogeneic hematopoietic stem cell transplantation for inherited metabolic disorders

Allogeneic hematopoietic stem cell transplantation (HSCT) has been used to treat patients with inherited metabolic disorders (IMDs) for more than 40 years. In the first two decades, various IMDs were treated by HSCT with a wide variety of donor sources and conditioning regimens selected at the institutional level. However, HSCT was not always successful due to post-transplant complications such as graft failure. In the third decade, myeloablative conditioning with targeted busulfan-based pharmacokinetic monitoring was established as an optimal conditioning regimen, and unrelated cord blood was recognized as an excellent donor source. During the fourth decade, further improvements were made to transplant procedures, including modification of the conditioning regimen, and the survival rate after HSCT markedly improved. Simultaneously, several long-term observational studies for patients after HSCT clarified its therapeutic effects on growth and development of cognitive function, fine motor skills, and activities of daily living when compared with enzyme replacement therapy. Although immune-mediated cytopenia was newly highlighted as a problematic morbidity after HSCT for IMDs, especially in younger patients who received unrelated cord blood, a recent study with rituximab added to the conditioning raised expectations that this issue can be overcome.

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.

Refractory immune thrombocytopenia successfully treated with bortezomib in a child with 22q11.2 deletion syndrome, complicated by Evans syndrome and hypogammaglobulinemia

Treatment of refractory autoimmune cytopenias (AICs) and Evans syndrome (ES) represent a great challenge in pediatric setting, where an underlying primary immunodeficiency is recurrent. Frequently, second or third line treatments are employed, with an increased risk of toxicity and infections. The advent of novel drugs is the object of research in order to modify the management of these patients.We report a case of successful use of bortezomib in a child with 22q11.2 deletion syndrome and CVID-like phenotype with a multi-refractory severe ES. Last flares were prolonged and dominated by severe and symptomatic ITP, refractory to different courses of high dose steroid and IVIG, mofetil mycophenolate, thrombopoietin receptor agonists, sirolimus, and rituximab. Persistence of AICs in subjects with depletion of CD20 + B-cells and IgG strengthens the hypothesis about the production of autoantibodies by terminally differentiated plasma-cells, not targetable from immunosuppressants and rituximab.In the attempt to enhance plasma-cells inhibition, the child was addressed to bortezomib, with a good response at 6 month follow-up without side effects. Nowadays, the use of bortezomib in ES/AICs is based only on small retrospective studies and case reports. Despite the lack of long term follow-up, our work highlights the potential role of bortezomib in the management of pediatric patients with multi-resistant AICs secondary to immune-system impairment.

Characteristics and outcomes of autoimmune hemolytic anemia after pediatric allogeneic stem cell transplant

BACKGROUND

Autoimmune hemolytic anemia (AIHA) after allogeneic hematopoietic stem cell transplant (HSCT) is a rare but complex and serious complication. Detailed descriptions of cases and management strategies are needed due to lack of prospective trials.

OBJECTIVES

Describe the incidence, clinical characteristics, and management of AIHA after HSCT in a pediatric cohort.

METHODS

This is a retrospective cohort study of 33 pediatric patients with AIHA after HSCT at an academic tertiary care center from 2003 to 2019.

RESULTS

The overall incidence of AIHA after allogeneic HSCT was 3.8% (33/868). AIHA was significantly more common after transplant for nonmalignant versus malignant diagnoses (7.0% [26/370] vs. 1.4% [7/498], p < .0001). AIHA developed at a median of 4.7 months (range 1.0-29.7) after transplant. Sixteen of 33 patients (48.5%) required new AIHA-directed pharmacologic therapy; 17 (51.5%) were managed on their current immunosuppression and supportive care. Patients managed without additional therapy were significantly older, more likely to have a malignant diagnosis, and tended to develop AIHA at an earlier time point after transplant. Patients received a median of two red blood cell transfusions within the first 2 weeks of diagnosis and a median of one AIHA-directed medication (range one to four), most commonly corticosteroids and rituximab.

CONCLUSIONS

AIHA after HSCT is rare but occurs more commonly in patients transplanted for nonmalignant diagnoses. While some pediatric patients who develop AIHA after transplant can be managed on current immunosuppression and supportive care, many require AIHA-directed therapy including second-line medications.

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.

New autoimmune diseases after autologous hematopoietic stem cell transplantation for multiple sclerosis

Secondary autoimmune diseases (2ndADs), most frequently autoimmune cytopenias (AICs), were first described after allogeneic hematopoietic stem cell transplantation (HSCT) undertaken for malignant and hematological indications, occurred at a prevalence of ~5-6.5%, and were attributed to allogeneic immune imbalances in the context of graft versus host disease, viral infections, and chronic immunosuppression. Subsequently, 2ndADs were reported to complicate roughly 2-14% of autologous HSCTs performed for an autoimmune disease. Alemtuzumab in the conditioning regimen has been identified as a risk for development of 2ndADs after either allogeneic or autologous HSCT and is consistent with the high rates of 2ndADs when using alemtuzumab as monotherapy. Due to the significant consequences but variable incidence, depending on conditioning regimen, of 2ndADs and similarity in known immune reconstitution kinetics after autologous HSCT for autoimmune diseases and after alemtuzumab monotherapy, we propose that an imbalance between B and T lineage regeneration early after HSCT may underlie the pathogenesis of 2ndADs.

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.

Improved outcomes using unmanipulated haploidentical hematopoietic stem cells combined with third-party umbilical cord blood transplantation for non-malignant diseases in children: The experience of a single center

BACKGROUND

Unmanipulated haploid HSCT for SAA has resulted in improved outcomes over recent years. However, studies related to unmanipulated haploid HSCs combined with tp-UCB transplantation for other types of NMD are rare. Accordingly, we present the outcomes of 109 pediatric patients with life-threatening NMD undergoing unmanipulated haploid HSCs combined with tp-UCB transplantation.

PROCEDURE

We retrospectively investigated 109 pediatric patients with life-threatening NMD treated with unmanipulated haploid HSCs combined with tp-UCB transplantation in a single center.

RESULTS

The median days of neutrophil and platelet engraftment were +13 and +22 days, respectively. None of the cases experienced PGF. The incidence rates for grade I-II, III-IV aGVHD and cGVHD were 44.9%, 24.8%, and 9.3%, respectively. The incidence rates of CMV and EBV viremia were 46.7% and 39.4%, respectively. The median follow-up duration was 997 days. In total, 106 patients survived, including 104 cases with FFS and 2 cases with SGF. Three patients died. The 5-year TRM, OS, and FFS were 2.8%, 97.2%, and 96.2%, respectively.

CONCLUSION

The results of unmanipulated haploid HSCs combined with tp-UCB in pediatric patients with life-threatening NMD were promising. However, further research is now needed to determine specific factors that might influence the engraftment of HSCs.

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.

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.

Tregs and Mixed Chimerism as Approaches for Tolerance Induction in Islet Transplantation

Pancreatic islet transplantation is a promising method for the treatment of type 1 and type 3 diabetes whereby replacement of islets may be curative. However, long-term treatment with immunosuppressive drugs (ISDs) remains essential for islet graft survival. Current ISD regimens carry significant side-effects for transplant recipients, and are also toxic to the transplanted islets. Pre-clinical efforts to induce immune tolerance to islet allografts identify ways in which the recipient immune system may be reeducated to induce a sustained transplant tolerance and even overcome autoimmune islet destruction. The goal of these efforts is to induce tolerance to transplanted islets with minimal to no long-term immunosuppression. Two most promising cell-based therapeutic strategies for inducing immune tolerance include T regulatory cells (Tregs) and donor and recipient hematopoietic mixed chimerism. Here, we review preclinical studies which utilize Tregs for tolerance induction in islet transplantation. We also review myeloablative and non-myeloablative hematopoietic stem cell transplantation (HSCT) strategies in preclinical and clinical studies to induce sustained mixed chimerism and allograft tolerance, in particular in islet transplantation. Since Tregs play a critical role in the establishment of mixed chimerism, it follows that the combination of Treg and HSCT may be synergistic. Since the success of the Edmonton protocol, the feasibility of clinical islet transplantation has been established and nascent clinical trials testing immune tolerance strategies using Tregs and/or hematopoietic mixed chimerism are underway or being formulated.

Consensus opinion on immune-mediated cytopenias after hematopoietic cell transplant for inherited metabolic disorders

Hematopoietic stem cell transplantation (HCT) has been increasingly used for patients with inherited metabolic disorders (IMD). Immune mediated cytopenias (IMCs) after HCT, manifesting as hemolytic anemia, thrombocytopenia, and/or neutropenia, are recognized as a significant complication in this patient population, yet our understanding of the incidence, risk factors, and pathophysiology is currently limited. Review of the published literature demonstrates a higher incidence in younger patients who undergo HCT for a nonmalignant disease indication. However, a few reports suggest that the incidence is even higher among those with IMD (incidence ranging from 10 to 56%). This review summarizes the literature, provides an approach to better understanding of the possible etiology of IMCs, and proposes a diagnostic and management plan for patients with IMD who develop single or multi-lineage cytopenias after HCT.

Expanded utilization of rituximab in paediatric cardiac transplant patients

WHAT IS KNOWN AND OBJECTIVE

Epstein-Barr virus (EBV) viraemia and autoimmune cytopenias (AICs) are significant complications that occur following paediatric solid organ transplantation. A variety of treatment methods have been investigated but limited research has focused on the utilization of rituximab in paediatric cardiac transplant recipients for these indications. Rituximab is a monoclonal antibody that binds the CD20 antigen on the surface of B-type lymphocytes resulting in B-cell cytotoxicity. It is considered a second-line therapy for treatment of autoimmune cytopenias and EBV viraemia following adult solid organ transplant (SOT) and haematopoietic stem cell transplant (HSCT). However, data for its use in the paediatric population for treatment of autoimmune cytopenias are lacking. Dosing is based on adult studies, and the frequency and length of therapy associated with resolution of EVB viraemia and AICs in paediatric cardiac transplant recipients is unknown. The objective of this retrospective study was to describe the dosing and length of therapy of expanded off-label use of rituximab for the management of refractory EBV viraemia and AICs, specifically in paediatric cardiac transplant patients.

METHODS

A retrospective chart review was conducted evaluating children <18 years of age who underwent cardiac transplantation, were diagnosed with EBV viraemia or autoimmune cytopenia, and subsequently received treatment with rituximab between June 1995 and October 2018. Data were analysed descriptively.

RESULTS AND DISCUSSION

Of all (n = 188) paediatric cardiac transplant recipients since 1995, 10 patients met the inclusion/exclusion criteria. Primary diagnoses were EBV viraemia (n = 6), immune haemolytic anaemia (n = 3) and immune thrombocytopenic purpura (n = 1). Complete responses were observed in 83.3% and 100% of patients with EVB viraemia and AICs treated with rituximab, respectively. All patients (n = 10) received rituximab 325 mg/m² at weekly intervals. The number of total doses associated with complete resolution was 4-6 doses for EBV viraemia and 2-4 doses for AICs. The most common adverse events reported were neutropenia (n = 3), thrombocytopenia (n = 4), infusion reactions (n = 1) and significant anaemia (n = 2).

WHAT IS NEW AND CONCLUSION

Although the efficacy of rituximab for treatment of EBV viraemia and autoimmune cytopenia in the paediatric cardiac transplant population remains unclear, our study supported the benefit of rituximab when added to therapy for treatment of EBV viraemia and ACIs.

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.

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.

Outcome of Non-hematological Autoimmunity After Hematopoietic Cell Transplantation in Children with Primary Immunodeficiency

PURPOSE

Knowledge of post-hematopoietic cell transplantation (HCT) non-hematological autoimmune disease (AD) is far from satisfactory.

METHOD

This multicenter retrospective study focuses on incidence, risk factors, and outcomes of post-HCT AD in 596 children with primary immunodeficiency (PID) who were transplanted from 2009 to 2018.

RESULTS

The indications of HCT were severe combined immunodeficiency (SCID, n = 158, 27%) and non-SCID PID (n = 438, 73%). The median age at HCT was 2.3 years (range, 0.04 to 18.3 years). The 5-year overall survival for the entire cohort was 79% (95% cumulative incidence (CIN), 74-83%). The median follow-up of surviving patients was 4.3 years (0.08 to 14.7 years). The CIN of post-HCT AD was 3% (2-5%) at 1 year post-HCT, 7% (5-11%) at 5 years post-HCT, and 11% (7-17%) at 8 years post-HCT. The median onset of post-HCT AD was 2.2 years (0.12 to 9.6 years). Autoimmune thyroid disorder (n = 19, 62%) was the most common post-HCT AD, followed by neuromuscular disorders (n = 7, 22%) and rheumatological manifestations (n = 5, 16%). All patients but one required treatment for post-HCT AD. After multivariate analysis, age at transplant (p = 0.01) and T cell-depleted graft (p < 0.001) were significant predictors of post-HCT AD. None of the T cell-depleted graft recipients developed post-HCT AD. Patients with a lower CD3+ count at 6 months post-HCT had a significant higher incidence of post-HCT AD compared to disease controls. Graft-versus-host disease, viral infection, and donor chimerism had no association with post-HCT AD.

CONCLUSION

Post-HCT AD occurred in 11% at 8 years post-HCT and its occurrence was associated with older age at HCT and unmanipulated graft.

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.

Bortezomib for autoimmune hemolytic anemia after intestinal transplantation

AIHA is rare in the general population and associated with a mortality of 8%. In contrast, AIHA occurs in up to 12.2% of cases after intestinal transplantation and is associated with mortality up to 50%. Treatment entails a "step-up" approach including corticosteroids, IvIg, plasmapheresis, and rituximab. However, AIHA after transplantation often is refractory to this strategy, contributing to a poor outcome. We describe a child with microvillous inclusion disease who developed AIHA 1 year after multivisceral transplantation that was refractory to standard therapy and was subsequently treated with bortezomib.We observed remission of AIHA within 1 week after the start of bortezomib. Bortezomib was associated with transient diarrhea, leucopenia, and elevated liver enzymes. Three years later, he remains in remission without important complications. Published data on bortezomib for autoimmune cytopenias outside SOT are discussed. This is the first report to support bortezomib as an important therapeutic alternative for AIHA after SOT. The occurrence and treatment of AIHA after SOT, and specifically intestinal transplantation, should be the subject of future registry studies to collect additional experience and explore the optimal therapeutic approach.

Outcome of autoimmune cytopenia after hematopoietic cell transplantation in primary immunodeficiency

BACKGROUND

Post hematopoietic cell transplantation (HCT) autoimmune cytopenia (AIC) is a potentially life-threatening complication, but studies focusing on large cohorts of patients transplanted for primary immunodeficiency are lacking.

OBJECTIVES

This study sought to determine the incidence, risk factors, and outcomes of post-HCT AIC and B-lymphocyte function following rituximab.

METHODS

We retrospectively studied 502 children with primary immunodeficiency who were transplanted at our center between 1987 and 2018.

RESULTS

Thirty-six patients (9%) developed post-HCT AIC, with a median onset of 6.5 months post-HCT. On univariate analysis, pre-HCT AIC, mismatched donor, alemtuzumab, anti-thymocyte antiglobulin, and acute and chronic graft versus host disease were significantly associated with post-HCT AIC. After multivariate analysis, alemtuzumab (subdistribution hazard ratio, 9.0; 95% CI, 1.50-54.0; P = .02) was independently associated with post-HCT AIC. Corticosteroid and high-dose intravenous immunoglobulin achieved remission in 50% (n = 18), additional rituximab led to remission in 25% (n = 9), and the remaining 25% were treated with a combination of various modalities including sirolimus (n = 5), bortezomib (n = 3), mycophenolate mofetil (n = 2), splenectomy (n = 2), and second HCT (n = 3). The mortality of post-HCT AIC reduced from 25% (4 of 16) prior to 2011 to 5% (1 of 20) after 2011. The median follow-up of 5.8 years (range, 0.4 to 29.1 years) showed that 26 of 30 survivors (87%) were in complete remission, and 4 were in remission with ongoing sirolimus and low-dose steroids. Of the 17 who received rituximab, 7 had B-lymphocyte recovery, 5 had persistent low B-lymphocyte count and remained on intravenous immunoglobulin replacement, 2 had second HCT, and 3 died.

CONCLUSIONS

The frequency of post HCT AIC in our cohort was 9%, and the most significant risk factors for its occurrence were the presence of graft versus host disease and the use of alemtuzumab.

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.

Diagnosis and treatment of autoimmune hemolytic anemia in adults: Recommendations from the First International Consensus Meeting

Autoimmune hemolytic anemias (AIHAs) are rare and heterogeneous disorders characterized by the destruction of red blood cells through warm or cold antibodies. There is currently no licensed treatment for AIHA. Due to the paucity of clinical trials, recommendations on diagnosis and therapy have often been based on expert opinions and some national guidelines. Here we report the recommendations of the First International Consensus Group, who met with the aim to review currently available data and to provide standardized diagnostic criteria and therapeutic approaches as well as an overview of novel therapies. Exact diagnostic workup is important because symptoms, course of disease, and therapeutic management relate to the type of antibody involved. Monospecific direct antiglobulin test is considered mandatory in the diagnostic workup, and any causes of secondary AIHA have to be diagnosed. Corticosteroids remain first-line therapy for warm-AIHA, while the addition of rituximab should be considered early in severe cases and if no prompt response to steroids is achieved. Rituximab with or without bendamustine should be used in the first line for patients with cold agglutinin disease requiring therapy. We identified a need to establish an international AIHA network. Future recommendations should be based on prospective clinical trials whenever possible.

Immune-Mediated Cytopenias After Hematopoietic Cell Transplantation: Pathophysiology, Clinical Manifestations, Diagnosis, and Treatment Strategies

PURPOSE OF REVIEW

Discuss the pathophysiology, clinical presentation, diagnosis, and treatment of immune-mediated cytopenias (IMC) after hematopoietic cell transplantation (HCT).

RECENT FINDINGS

Key risk factors for post-HCT IMC include younger age, non-malignant disease, and umbilical cord blood stem cell source. While anemia predominates, any or all three hematopoietic cell lines can be affected. In rare cases, IMC can cause graft failure or death. IMC is hypothesized to result from immune dysregulation upon reconstitution of donor hematopoietic cells (i.e., dysfunctional regulatory T cells). Aside from blood product transfusions, IMC treatment includes immune-suppressive or ablative agents. First-line therapies, including corticosteroids and intravenous immunoglobulin, are often inadequate, prompting use of additional agents aimed at antibody production/T cell dysfunction or direct antibody removal via plasmapheresis. IMC occurs in up to 20% of high-risk HCT populations. Morbidity and mortality from IMC post-HCT have been reduced by improved recognition and aggressive early interventions.

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

Autoimmune hemolytic anemia (AIHA) is increasingly observed after allogeneic hematopoietic stem cell transplantation (allo-HSCT), with a reported incidence between 4% and 6%. The disease is generally severe and refractory to standard therapy, with high mortality, and there are neither defined therapies, nor prospective clinical trials addressing the best treatment. Most of the knowledge on the therapy of AIHAs derives from primary forms, which are highly heterogeneous as well, further complicating the management of post-allo-HSCT forms. The review addresses the risk factors associated with post-allo-AIHA, including unrelated donor, the development of chronic extensive graft-versus-host disease, CMV reactivation, nonmalignant diagnosis pre-HSCT, and alemtuzumab use in conditioning regimens. Regarding therapy, we describe standard treatments, such as corticosteroids, intravenous immunoglobulin, splenectomy, rituximab, cyclophosphamide, and plasma exchange, which have lower response rates than those reported in primary forms. New therapeutic options, including sirolimus, bortezomib, abatacept, daratumumab and complement inhibitors, are promising tools for this detrimental complication occurring after allo-HSCT.

Autoimmune hemolytic anemia and immune thrombocytopenia following hematopoietic stem cell transplant: A critical review of the literature

Autoimmune cytopenias (AIC) post-hematopoietic stem cell transplant (HSCT) are rare but exceptionally challenging complication. We conducted a comprehensive literature review and identified a pooled incidence of post-HSCT autoimmune hemolytic anemia and/or immune thrombocytopenia of 2.66% (SE = 0.27) in pediatric patients. Nonmalignant disease, unrelated donor transplant, peripheral or cord blood stem cell source, conditioning regimen without total body irradiation, and presence of chronic graft-versus-host disease were prominent risk factors. Treatment was highly variable, and cytopenias were commonly refractory. AIC represent a significant post-HSCT complication. We report here the incidence, risk factors, and possible biology behind the development of AIC in pediatric post-HSCT patients.

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.

Autoimmune Cytopenias in Pediatric Hematopoietic Cell Transplant Patients

Background: Autoimmune cytopenias (AICs) are potentially life-threatening complications following hematopoietic cell transplantation (HCT), yet little is understood about the mechanism by which they develop. We hypothesized that discordant B cell and T cell recovery is associated with AICs in transplant patients, and that this might differ based on transplant indication. Methods: In this case control study of children who underwent HCT at our institution, we evaluated the clinical and transplant characteristics of subjects who developed AICs compared to a control group matched by transplant indication and donor type. In cases, we analyzed the state of immune reconstitution, including B cell recovery, T cell recovery, and chimerism, immediately prior to AIC onset. Subjects were stratified by primary indication for transplant as malignancy (n = 7), primary immune deficiency (PID, n = 9) or other non-malignant disease (n = 4). We then described the treatment and outcomes for 20 subjects who developed AICs. Results: In our cohort, cases were older than controls, were more likely to receive a myeloablative conditioning regimen and had a significantly lower prevalence of chronic GVHD. There were distinct differences in the state of immune recovery based on transplant indication. None of the patients (0/7) transplanted for primary malignancy had T cell recovery at AIC onset compared to 71% (5/7) of patients with PID and 33% (1/3) of patients with non-malignant disease. The subset of patients with PID and non-malignant disease who achieved T cell reconstitution (6/6) prior to AIC onset, all demonstrated mixed or split chimerism. Subjects with AIHA or multi-lineage cytopenias had particularly refractory courses with poor treatment response to IVIG, steroids, and rituximab. Conclusions: These results highlight the heterogeneity of AICs in this population and suggest that multiple mechanisms may contribute to the development of post-transplant AICs. Patients with full donor chimerism may have early B cell recovery without proper T cell regulation, while patients with mixed or split donor chimerism may have residual host B or plasma cells making antibodies against donor blood cells. A prospective, multi-center trial is needed to develop personalized treatment approaches that target the immune dysregulation present and improve outcomes in patients with post-transplant AICs.

Definition of Opportunistic Infections in Immunocompromised Children on the Basis of Etiologies and Clinical Features: A Summary for Practical Purposes

Opportunistic Infections (OIs) still remain a major cause of morbidity and death in children with either malignant or nonmalignant disease. OIs are defined as those infections occurring due to bacteria, fungi, viruses or commensal organisms that normally inhabit the human body and do not cause a disease in healthy people, but become pathogenic when the body's defense system is impaired. OIs can also be represented by unusually severe infections caused by common pathogens. An OI could present itself at the onset of a primary immunodeficiency syndrome as a life-threatening event. More often, OI is a therapyassociated complication in patients needing immunosuppressive treatment, among long-term hospitalised patients or in children who undergo bone marrow or solid organ transplantation. The aim of the present review is to provide a comprehensive and 'easy to read' text that briefly summarises the currently available knowledge about OIs in order to define when an infection should be considered as opportunistic in pediatrics as a result of an underlying congenital or acquired immune-deficit.