Autoimmune Cytopenias in Chronic Lymphocytic Leukemia: Focus on Molecular Aspects

The Safety of Novel Therapies in Chronic Lymphocytic Leukemia in the Era of Intermittent Fasting: A Pharmacology-Based Review

Intermittent fasting (IF) has recently gained popularity due to its emerging benefits in reducing weight and improving metabolic health. Concurrently, novel agents (NAs) like venetoclax and Bruton tyrosine kinase inhibitors (BTKIs) have revolutionized the treatment of chronic lymphocytic leukemia (CLL). Unfortunately, it is unclear whether the associated risks of tumor lysis syndrome (TLS) and gastrointestinal bleeding (GIB) are increased in IF practitioners receiving NAs. This review explored the literature available on the permissibility of IF in CLL patients undergoing treatment with first-line NAs (FLNAs). Literature was scoped to identify IF patterns and the available data on TLS and GIB risks associated with food and fluid intake in CLL patients receiving FLNAs. Although current evidence is insufficient to recommend IF in this population, it may be possible for patients on venetoclax to conservatively practice fluid-liberal IF, provided that adequate hydration and the consistent administration of food are achieved. In contrast, considering the significant risk of TLS and the pharmacokinetics of venetoclax, patients should be discouraged from practicing fluid-restricted IF, especially during the ramp-up phase. Moreover, patients on BTKIs ought to refrain from IF due to the possible risk of GIB until further data are available. Further research is needed to provide conclusive recommendations.

Clinical and laboratory profile of patients with positive direct antiglobulin test attended at a university hospital in Goias, Brazil

OBJECTIVE

To clinically and laboratory characterize patients with a positive direct antiglobulin test (DAT) treated at the Hospital das Clínicas of the Federal University of Goiás (HC-UFG).

METHODS

A retrospective, descriptive, cross-sectional study was carried out collecting data from medical records of patients with a positive DAT who were treated at HC-UFG between August 2021 and August 2022.

RESULTS

Eighty-four patients with positive polyspecific DAT results were screened in the clinical laboratory. Fifty-four patients had a laboratory profile compatible with autoimmune hemolytic anemia (AIHA), however, among these, 16 patients already had a diagnosis of AIHA in their medical records. The most common symptoms present among AIHA patients were pallor, asthenia, fatigue and dyspnea. For the remaining patients, the most common symptoms were severe thrombocytopenia, anemia, renal dysfunction, fever, myalgia, headache, thrombosis, asthenia, hematuria and joint pain. Only one patient had primary AIHA, that is, he had no evident underlying disease. The majority of AIHA patients (75 %) underwent corticosteroid therapy with 60 % having a positive response. For patients without AIHA, prednisone was the most frequently prescribed medication in 17 (25 %) patients, followed by hydroxychloroquine (14 patients - 20.1 %).

CONCLUSION

It is essential to evaluate patients with positive DAT in detail in order to understand the real clinical case. The DAT serological result alone does not arrive at a conclusive diagnosis of AIHA, and so it must be evaluated in conjunction with both clinical data and other laboratory tests, such as hemoglobin concentration and hemolysis tests (reticulocytes, lactate dehydrogenase and/or haptoglobin).

Collage of cases and brief review of the laboratory diagnosis and molecular testing in autoimmune haemolytic anaemia

Autoimmune haemolytic anaemia (AIHA) is an acquired heterogenous clinical entity with variable presentations like acute haemolysis or mild, chronic haemolysis compounded with acute exacerbation in winters or fatal uncompensated haemolysis. A step-wise approach to the diagnosis and characterisation of AIHA should be undertaken, firstly the diagnosis of haemolysis followed by the establishment of immune nature with the aid of direct agglutination tests (DAT). Simultaneously the other causes of immune haemolysis need to be excluded too. In light of advancements in diagnostics, a wide array of investigations can be used like absolute reticulocyte count, bone marrow responsiveness index to establish the evidence of haemolysis, sensitive gel technology, enhanced DAT assays, e.g., modified DAT with low ionic strength saline solution (LISS) at 4°C, DAT assays utilizing reagents such as anti-IgA and anti-IgM and DAT by flowcytometry, to detect RBC bound autoantibodies (Abs) and monospecific DAT to establish immune causes of haemolysis and characterisation of the autoantibodies. The compensatory role of bone marrow and synchronous pathologies like clonal lymphoproliferation, dyserythropoiesis, fibrosis are important factors in the evolution of the disease and aid in the customisation of treatment modalities. The laboratory work up should aim to diagnose underlying diseases like chronic lymphoproliferative disorders, autoimmune disorders and infectious diseases. Also, tests like autoimmune lymphoproliferative syndromes (ALPS) screening panel and Next-generation sequencing (NGS) panel for RBC membrane disorders, RBC enzymopathies, and congenital dyserythropoietic aneamia have found their place. It is incumbent upon the clinicians to use the all-available diagnostic modalities for the accurate diagnosis, prognostication and customisation of the therapy.

The many facets of immune-mediated thrombocytopenia: Principles of immunobiology and immunotherapy

Immune thrombocytopenia (ITP) is a rare autoimmune condition, due to peripheral platelet destruction through antibody-dependent cellular phagocytosis, complement-dependent cytotoxicity, cytotoxic T lymphocyte-mediated cytotoxicity, and megakaryopoiesis alteration. This condition may be idiopathic or triggered by drugs, vaccines, infections, cancers, autoimmune disorders and systemic diseases. Recent advances in our understanding of ITP immunobiology support the idea that other forms of thrombocytopenia, for instance, occurring after immunotherapy or cellular therapies, may share a common pathophysiology with possible therapeutic implications. If a decent pipeline of old and new agents is currently deployed for classical ITP, in other more complex immune-mediated thrombocytopenic disorders, clinical management is less harmonized and would deserve further prospective investigations. Here, we seek to provide a fresh overview of pathophysiology and current therapeutical algorithms for adult patients affected by this disorder with specific insights into poorly codified scenarios, including refractory ITP and post-immunotherapy/cellular therapy immune-mediated thrombocytopenia.

Normal B cells express ZAP70 in chronic lymphocytic leukemia: A link between autoimmunity and lymphoproliferation?

ZAP70 has a prognostic value in chronic lymphocytic leukemia (CLL), through altered B-cell receptor signaling, which is important in CLL pathogenesis. A good correlation between ZAP70 expression in CLL cells and the occurrence of autoimmune phenomena has been reported. Yet, the great majority of CLL-associated autoimmune cytopenia is due to polyclonal immunoglobulin (Ig) G synthesized by nonmalignant B cells, and this phenomenon is poorly understood. Here, we show, using flow cytometry, that a substantial percentage of CD5- nonmalignant B cells from CLL patients expresses ZAP70 compared with CD5- B cells from healthy subjects. This ZAP70 expression in normal B cells from CLL patients was also evidenced by the detection of ZAP70 mRNA at single-cell level with polyclonal Ig heavy- and light-chain gene transcripts. ZAP70+ normal B cells belong to various B-cell subsets and their presence in the naïve B-cell subset suggests that ZAP70 expression may occur during early B-cell development in CLL patients and potentially before malignant transformation. The presence of ZAP70+ normal B cells is associated with autoimmune cytopenia in CLL patients in our cohort of patients, and recombinant antibodies produced from these ZAP70+ nonmalignant B cells were frequently autoreactive including anti-platelet reactivity. These results provide a better understanding of the implication of ZAP70 in CLL leukemogenesis and the mechanisms of autoimmune complications of CLL.

Case report: Successful treatment of refractory immune thrombocytopenia in chronic lymphocytic leukaemia with venetoclax monotherapy

In chronic lymphocytic leukaemia (CLL), immune dysregulation is common and can manifest as immune thrombocytopenia (ITP). Corticosteroids are the mainstay for front-line management of CLL-associated ITP. Therapy refractoriness represents a clinical challenge and is an indication to commence CLL-directed treatment, historically with anti-CD20 antibody-based chemoimmunotherapy. There is a small but growing body of evidence supporting the use of Bruton's tyrosine kinase (BTK) inhibitors in this setting, but not the B-cell lymphoma-2 inhibitor, venetoclax. Here, we describe two cases of refractory ITP in patients with CLL who successfully achieved and sustained complete remission with fixed-duration venetoclax monotherapy. Responses were rapid and durable and not explained by the concomitant use of an anti-CD20 antibody. This supports a dual role for single-agent venetoclax in managing active CLL and associated ITP as an alternative to BTK inhibitors and anti-CD20 monoclonals.

Acalabrutinib and steroid for autoimmune thrombocytopenia due to relapsed chronic lymphocytic leukemia with severe bone marrow infiltration

Thrombocytopenia is a frequent complication in chronic lymphocytic leukemia (CLL). Differentiating autoimmune thrombocytopenia from thrombocytopenia due to bone marrow infiltration is necessary for appropriate treatment, but sometimes difficult. Here we report a 60-year-old male patient with CLL who had achieved complete response after treatment with fludarabine, cyclophosphamide, and rituximab two years prior to presentation. He was admitted with severe thrombocytopenia that was unresponsive to intravenous immunoglobulin. Imaging studies revealed systemic enlarged lymph nodes and bone marrow aspiration was hypercellular with > 95% lymphocytes and scant megakaryocytes. Acalabrutinib 200 mg/day was administered for the treatment of CLL exacerbation. A gradual decrease in CLL cells and recovery of megakaryocytes in bone marrow were observed, but platelet counts remained low. Systemic administration of prednisolone 0.5 mg/kg, in addition to acalabrutinib, was started, considering the contribution of autoimmune thrombocytopenia; platelet recovery was rapid and sustained for more than a year. Even if bone marrow examination suggested thrombocytopenia due to direct leukemic infiltration, it is difficult to exclude the possibility of concomitant immunogenic thrombocytopenia. We conclude that for CLL patients with severe thrombocytopenia, repeating bone marrow examination and concurrent immunosuppressive therapies and treatment of the underlying CLL may be beneficial.

Ibrutinib in combination with rituximab is highly effective in treatment of chronic lymphocytic leukemia patients with steroid refractory and relapsed autoimmune cytopenias

Autoimmune hemolytic anemia (AIHA) and pure red cell aplasia (PRCA) are common complications of CLL. The optimal treatment of steroid refractory AIHA/PRCA is not well established. We conducted a multicenter study of ibrutinib and rituximab in patients with relapsed/refractory to steroids AIHA/PRCA and underlying CLL. Protocol included induction (ibrutinib 420 mg/day and rituximab, 8 weekly and 4 monthly infusions) and maintenance phase with ibrutinib alone until progression or unacceptable toxicity. Fifty patients were recruited (44-warm AIHA, 2-cold AIHA, 4-PRCA). After the induction 34 patients (74%) have achieved complete response, 10 (21.7%) partial response. Median time to hemoglobin normalization was 85 days. With regards to CLL response 9 (19%) patients have achieved CR, 2 (4%) patients-stabilization and 39 (78%)-PR. The median follow-up was 37.56 months. In AIHA group 2 patients had a relapse. Among 4 patients with PRCA 1 patient did not respond, and 1 patient had a relapse after CR, 2 remained in CR. The most common adverse events were neutropenia (62%), infections (72%), gastrointestinal complications (54%). In conclusion ibrutinib in combination with rituximab is an active second-line treatment option for patients with relapsed or refractory AIHA/PRCA and underlying CLL.

A Peculiar CLL Case with Complex Chromosome 6 Rearrangements and Refinement of All Breakpoints at the Gene Level by Genomic Array: A Case Report

INTRODUCTION

Chronic lymphocytic leukemia (CLL), the most common leukemia in Western countries, is a mature B-cell chronic lymphoproliferative disorder characterized by the accumulation of neoplastic CD5+ B lymphocytes, functionally incompetent and usually monoclonal in origin, in bone marrow, lymph nodes and blood. Diagnosis occurs predominantly in elderly patients, with a median age reported between 67 and 72 years. CLL has a heterogeneous clinical course, which can vary from indolent to, less frequently, aggressive forms. Early-stage asymptomatic CLL patients do not require immediate therapeutic intervention, but only observation; treatment is necessary for patients with advanced disease or when "active disease" is observed. The most frequent autoimmune cytopenia (AIC) is autoimmune haemolytic anaemia (AHIA). The main mechanisms underlying the appearance of AIC in CLL are not fully elucidated, the predisposition of patients with CLL to suffering autoimmune complications is variable and autoimmune cytopenia can precede, be concurrent, or follow the diagnosis of CLL.

CASE PRESENTATION

A 74-year-old man was admitted to the emergency room following the finding of severe macrocytic anaemia during blood tests performed that same day, in particular the patient showed a profound asthenia dating back several months. The anamnesis was silent and the patient was not taking any medications. The blood examination showed an extremely high White Blood Cell count and findings of AIHA in CLL-type mature B-cell lymphoproliferative neoplasia. Genetic investigations: Conventional karyotyping was performed and it obtained a trisomy 8 and an unbalanced translocation between the short arm of chromosome 6 and the long arm of chromosome 11, concurrent with interstitial deletions in chromosomes 6q and 11q that could not be defined in detail. Molecular cytogenetics (FISH) analyses revealed Ataxia Telangiectasia Mutated (ATM) monoallelic deletion (with loss of ATM on derivative chromosome 11) and retained signals for TP53, 13q14 and centromere 12 FISH probes. TP53 and IGHV were not mutated. Array-CGH confirmed trisomy of the entire chromosome 8 and allowed us to resolve in detail the nature of the unbalanced translocation, revealing multiple regions of genomic losses on chromosomes 6 and 11.

DISCUSSION

The present case report is an unusual CLL case with complex karyotype and refinement of all breakpoints at the gene level by the genomic array. From a genetic point of view, the case under study presented several peculiarities.

CONCLUSIONS

We report the genetic findings of a CLL patient with abrupt disease onset, so far responding properly to treatments despite the presence of distinct genetic adverse traits including ATM deletion, complex karyotype and chromosome 6q chromoanagenesis event. Our report confirms that interphase FISH alone is not able to provide an overview of the whole genomic landscape in selected CLL cases and that additional techniques are required to reach an appropriate cytogenetic stratification of patients.

Diffuse large B‑cell lymphoma and monoclonal gammopathy secondary to immune thrombocytopenic purpura: A case report

The present study reports the case of a patient with diffuse large B-cell lymphoma (DLBCL) and monoclonal gammopathy (MG) secondary to immune thrombocytopenia purpura (ITP). The clinical diagnoses and investigations of this case are reported. To the best of our knowledge, this is the first study to report DLBCL and MG secondary to ITP. The patient presented with a rare constellation of diseases, which made the diagnosis and treatment difficult for the physicians. The patient was followed up for 10 years using the morphological examination of bone marrow cells after chemotherapy, and currently continues with follow-up examinations. Treatments and prognoses for ITP, DLBCL and MG are common. However, treatments and prognoses are unclear for patients with all three conditions. The different clinical manifestations and disease processes of DLBCL and MG secondary to ITP cause difficulties for physicians in terms of treatment and prognosis. The present case report describes the comprehensive evaluation, diagnosis and treatment of a patient with DLBCL and MG secondary to, and concurrent with, ITP.

Risks and outcomes of hospitalizations in patients with chronic lymphocytic leukemia admitted with immune thrombocytopenia: an analysis of the National Inpatient Sample Database

Immune thrombocytopenia (ITP) is a known autoimmune complication of chronic lymphocytic leukemia (CLL). Currently, there is limited data regarding the risk CLL confers on hospitalization outcomes in patients admitted with ITP.The National Inpatient Sample (NIS) database was queried using the International Classification of Diseases (ICD) codes to identify hospitalizations for ITP and then subclassified the data into hospitalizations with and without CLL. A multivariate logistic regression was designed to account for patient characteristics and comorbidities. The primary outcome was all-cause mortality. Secondary outcomes included major bleeding, gastrointestinal bleeding, intracranial bleeding, and the need for platelet transfusions, intravenous immunoglobulin, and splenectomy. Among 662,171 cases of ITP between 2005 and 2019, 15,672 had concurrent CLL. CLL patients were significantly older and had more comorbidities compared to patients without CLL. Multivariate analysis revealed CLL patients with ITP had a risk of all-cause mortality (odds ratio: 1.28, 95% CI: 1.19-1.37; p < 0.01). CLL patients also had a higher risk of complications, second-line ITP treatments, blood transfusions, and bleeding, with the exception of intracranial hemorrhage. Our study suggests CLL is an independent risk factor for increased morbidity and mortality among hospitalized patients with ITP. Prospective studies are needed to determine if refractoriness to conventional treatments for ITP can account these results.

U2AF1 and EZH2 mutations are associated with nonimmune hemolytic anemia in myelodysplastic syndromes

Hemolysis is a well-recognized but poorly characterized phenomenon in a subset of patients with myelodysplastic syndromes (MDS). Its pathobiological basis seems to underpin a nonimmune etiology whose clinical significance has not been adequately characterized. Hemolysis in MDS is often attributed to either ineffective intramedullary erythropoiesis or acquired hemoglobinopathies and red blood cell (RBC) membrane defects. These heterogeneous processes have not been associated with specific genetic subsets of the disease. We aimed to describe the prevalence of hemolysis among patients with MDS, their baseline characteristics, molecular features, and resulting impact on outcomes. We considered baseline serum haptoglobin <10 mg/dL a surrogate marker for intravascular hemolysis. Among 519 patients, 10% had hemolysis. The baseline characteristics were similar among both groups. Only 13% of patients with hemolysis were Coombs-positive, suggesting that hemolysis in MDS is largely not immune-mediated. Inferior survival trends were observed among lower-risk patients with MDS undergoing hemolysis. Decreased response rates to erythropoiesis-stimulating agents (ESA) and higher responses to hypomethylating agents (HMA) were also observed in the hemolysis group. U2AF1 and EZH2 hotspot mutations were more prevalent among those undergoing hemolysis (P < .05). U2AF1 mutations were observed in 30% of patients with hemolysis and occurred almost exclusively at the S34 hotspot. Somatic mutations encoding splicing factors may affect erythrocyte membrane components, biochemical properties, and RBC metabolic function, which underpin the development of atypical clones from erythroid precursors in MDS presenting with hemolysis. Future studies will explore the contribution of altered splicing to the development of acquired hemoglobinopathies.

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.

Lymphoma: New Diagnosis and Current Treatment Strategies

Historically, the treatment of patients with lymphoma has been based on three columns, with ascending importance: surgery, radiation, and chemotherapy [...]

Autoimmune Hemolytic Anemia in Chronic Lymphocytic Leukemia: A Comprehensive Review

Simple Summary

This review analyzes the occurrence, clinical characteristics, and prognostic impact and treatment of autoimmune hemolytic anemia (AIHA) in chronic lymphocytic leukemia (CLL). Autoimmune hemolytic anemia is observed in about 10% of CLL. Pathogenesis is multifactorial involving humoral, cellular, and innate immunity, so the different mechanisms are well described in this review which also focuses on drugs associated to CLL-AIHA and on difficulties to diagnose it. There is a comprehensive revision of the main published casistics and then of the treatments; in particular the paper analyzes the main chemo-immunotherapeutic agents used in this setting. Since the therapy depends on the presence and severity of clinical symptoms, disease status, and comorbidities, treatment is nowadays more individualized in CLL and also in CLL-AIHA. Patients not responding to corticosteroids and rituximab are treated with CLL-specific drugs as per current guidelines according to age and comorbidities and new targeted agents against BCR and BCL-2 which can be given orally and have few side effects, are very effective both in progressive CLL and in situations such as AIHA.

Abstract

Chronic lymphocytic leukemia (CLL) patients have a greater predisposition to develop autoimmune complications. The most common of them is autoimmune hemolytic anemia (AIHA) with a frequency of 7–10% of cases. Pathogenesis is multifactorial involving humoral, cellular, and innate immunity. CLL B-cells have damaged apoptosis, produce less immunoglobulins, and could be responsible for antigen presentation and releasing inflammatory cytokines. CLL B-cells can act similar to antigen-presenting cells activating self-reactive T helper cells and may induce T-cell subsets imbalance, favoring autoreactive B-cells which produce anti-red blood cells autoantibodies. Treatment is individualized and it depends on the presence and severity of clinical symptoms, disease status, and comorbidities. Corticosteroids are the standardized first-line treatment; second-line treatment comprises rituximab. Patients not responding to corticosteroids and rituximab should be treated with CLL-specific drugs as per current guidelines according to age and comorbidities. New targeted drugs (BTK inhibitors and anti BCL2) are recently used after or together with steroids to manage AIHA. In the case of cold agglutinin disease, rituximab is preferred, because steroids are ineffective. Management must combine supportive therapies, including vitamins; antibiotics and heparin prophylaxis are indicated in order to minimize infectious and thrombotic risk.

Chronic lymphocytic leukaemia/small lymphocytic lymphoma treatment with rituximab and high-dose methylprednisolone, revisited

High‐dose methylprednisolone plus rituximab (R‐HDMP) is a useful treatment in chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) patients unfit for chemo‐immunotherapy and has proven its utility on the treatment of CLL/SLL complicated by auto‐immune cytopenias. We performed a retrospective, single‐centre study, of CLL/SLL patients treated with R‐HDMP for 9 years. Thirty‐nine patients were included, median age at time of treatment was 77 years. Most patients had stage Rai III/IV and Binet C disease. Twenty‐eight patients had relapsed/refractory disease at time of treatment with a median of 1 previous line of therapy; 53.8% had prior exposure to fludarabine and 25% to rituximab. Grade 3–4 neutropenia and thrombocytopenia were recorded in 10.2% and 17.9% patients, respectively. While on treatment, 51.3% had documented infectious complications, but no other non‐haematological toxicities grades 3–4 were identified. Overall response rate was 64%. Median overall survival and progression‐free survival were 24 and 13 months, respectively. Twenty four patients relapsed and 16 received another line of treatment after R‐HDMP, with median time to next treatment of 13.5 months. Thirteen out of the 24 patients improved performance status and were subsequently considered fit for chemo‐immunotherapy. R‐HDMP is a valuable option for elderly and frail patients, with low risk of severe myelotoxicity and other severe adverse events. It was shown to work as a bridge to other lines of treatment, including chemo‐immunotherapy.

First Report of Severe Autoimmune Hemolytic Anemia During Eltrombopag Therapy in Waldenström Macroglobulinemia-Associated Thrombocytopenia

Autoimmune thrombocytopenia (ITP) and autoimmune hemolytic anemia (AIHA) can be observed in Waldenström macroglobulinemia (WM). The autoimmune disorders are primarily mediated by autoimmune monoclonal gammopathy, but drug-induced hemolysis should also be considered. Herein, we presented the case of a 63-year-old female WM patient complicated with ITP, who was admitted to our department with a complaint of abdominal pain. After first half of bortezomib/dexamethasone/rituximab (BRD) chemotherapy, her platelet level recovered, but subsequently decreased to extremely low level (around 1–2×10⁹/L), and the patient suffered from platelet transfusion refractoriness. During the management of refractory thrombocytopenia, the patient developed severe hemolytic anemia, and further tests confirmed warm AIHA. FcγRIIα polymorphism test showed that the patient had FcγRIIα-131RH, which implied that the AIHA may not be WM-related. Given the effects of ibrutinib in controlling WM, secondary AITP and AIHA, ibrutinib single treatment was started, which quickly corrected the thrombocytopenia within five days, but not hemolysis. With a relatively safe platelet level, eltrombopag was stopped, and the hemolysis relieved three days after eltrombopag withdrawal. This is the first report on eltrombopag-induced AIHA in the management of WM-associated ITP.

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.

Chronic Lymphocytic Leukemia (CLL): Biology and Therapy

Chronic lymphocytic leukemia (CLL), the most common leukemia in the western world, is characterized by the accumulation of monoclonal B-lymphocytes in the bone marrow and lymphoid organs. Signaling via the B-cell receptor and Bruton tyrosine kinase (BTK) as well as resistance to apoptosis mediated by Bcl-2 are hallmarks of CLL biology and have been exploited in recent years to revolutionize management. As a result of the development of novel therapies, most CLL patients now can be spared conventional chemotherapy and can be treated using highly effective regimens consisting of BTK inhibitors, the Bcl-2 inhibitor venetoclax, and anti -CD20 monoclonal antibodies. The impact of novel therapies is particularly pronounced for high-risk cases including those with TP53 deletions/mutations who previously had a dismal outcome with conventional chemoimmunotherapy. Allogeneic HCT is a potentially curative option for selected younger patients with multiply relapsed high-risk disease.

Dysregulated expression of miRNAs in immune thrombocytopenia

In recent years the critical role of miRNAs has been established in many diseases, including autoimmune disorders. Immune thrombocytopenia purpura (ITP) is a predominant autoimmune disease, in which aberrant expression of miRNAs has been observed, suggesting that miRNAs are involved in its development. miRNAs could induce an imbalance in the T helper (Th)1/Th2 cell and Th17/Treg cell-related responses. Moreover, they could also cause alterations in Th9 and Th22 cell responses, and activate Tfh (T follicular helper) cell-dependent auto-reactive B cells, thus influencing megakaryogenesis. Herein, we summarize the role of immune-related miRNAs in ITP pathogenesis, and look forward to clinical applications.

How I treat cold agglutinin disease

The last decades have seen great progress in the treatment of cold agglutinin disease (CAD). Comparative trials are lacking, and recommendations must be based mainly on nonrandomized trials and will be influenced by personal experience. Herein, current treatment options are reviewed and linked to 3 cases, each addressing specific aspects of therapy. Two major steps in CAD pathogenesis are identified, clonal B-cell lymphoproliferation and complement-mediated hemolysis, each of which constitutes a target of therapy. Although drug treatment is not always indicated, patients with symptomatic anemia or other bothersome symptoms should be treated. The importance of avoiding ineffective therapies is underscored. Corticosteroids should not be used to treat CAD. Studies on safety and efficacy of relevant drugs and combinations are briefly described. The author recommends that B cell-directed approaches remain the first choice in most patients requiring treatment. The 4-cycle bendamustine plus rituximab combination is highly efficacious and sufficiently safe and induces durable responses in most patients, but the time to response can be many months. Rituximab monotherapy should be preferred in frail patients. The complement C1s inhibitor sutimlimab is an emerging option in the second line and may also find its place in the first line in specific situations.

Overexpression of helper T cell type 2-related molecules in the skin of patients with eosinophilic dermatosis of hematologic malignancy

BACKGROUND

Eosinophilic dermatosis of hematologic malignancy (EDHM) is a rare dermatosis associated with blood tumors.

OBJECTIVE

To characterize the expression of T-cell and B-cell markers and pruritogenic mediators in EDHM skin.

METHODS

Immunohistochemical and immunofluorescence analysis were performed in 12 skin samples of EDHM, 11 samples of bullous pemphigoid (BP), and 5 samples from healthy controls (HC). Serum levels of interleukin (IL) 4 were analyzed in 11 patients with EDHM, 11 BP patients, and 5 HC by enzyme-linked immunosorbent assay.

RESULTS

T-cell markers, including clusters of differentiation (CD) 3, CD4, CD8, and CD5 were significantly overexpressed in EDHM and BP skin compared to HC. A predominance of CD4⁺ over CD8⁺ cells and GATA3⁺ (helper T cell type 2 [Th2] marker) over T-bet⁺ (Th1 marker) cells were observed. FOXP3 expression was increased but the FOXP3/CD4 ratio was low. B-cell markers were under-represented, without significant differences between the 3 groups. IL-4 and IL-31 were significantly overexpressed in EDHM and BP compared to HC and colocalized with the Th2-associated marker GATA3. Eotaxin-1 was significantly overexpressed in EDHM compared to BP and HC. IL-4 serum concentration was significantly increased in EDHM and BP compared to HC.

LIMITATIONS

Small sample size; retrospective design.

CONCLUSIONS

Targeting Th2-related molecules, in particular IL-4, holds promise for EDHM management.

Autoimmune Cytopenia in CLL: Prognosis and Management in the Era of Targeted Therapies

ABSTRACT

Chronic lymphocytic leukemia (CLL) is frequently associated with autoimmune hemolytic anemia and immune thrombocytopenia and, less frequently, with pure red cell aplasia and immune neutropenia. The emergence of these complications is related to an intertwined and complex relationship between patient, disease, and treatment characteristics. The prognostic repercussion of autoimmune cytopenia (AIC) in patients with CLL mainly depends on its response to therapy. For patients with AIC and nonactive CLL, treatment is as in primary, uncomplicated AIC, keeping in mind that no response is an indication for CLL therapy. The success of treating active CLL-related AIC widely relies on a flexible strategy that should include initial therapy with corticosteroids and a rapid shift to effective CLL therapy in nonresponding patients. Targeted therapies (e.g., ibrutinib) that have already demonstrated to be effective in CLL-related AIC will likely offer a unique possibility of treating both AIC and CLL as a single target.

The Role of Novel Agents in Treating CLL-Associated Autoimmune Hemolytic Anemia

Autoimmune cytopenias (AICs) have been reported as a common complication in chronic lymphocytic leukemia (CLL) with autoimmune hemolytic anemia (AIHA), accounting for most cases. According to iwCLL guidelines, AICs poorly responsive to corticosteroids are considered indication for CLL-directed treatment. Chemo-immunotherapy has classically been employed, with variable results, and little data are available on novel agents, the current backbone of CLL therapy. The use of idelalisib in the setting of AICs is controversial and recent recommendations suggest avoiding idelalisib in this setting. Ibrutinib, through ITK-driven Th1 polarization of cell-mediated immune response, is known to produce an immunological rebalancing in CLL, which stands as a fascinating rationale for its use to treat autoimmunity. Although treatment-emergent AIHA has rarely been reported, ibrutinib has shown rapid and durable responses when used to treat AIHA arising in CLL. There is poor evidence regarding the role of BCL-2 inhibitors in CLL-associated AICs and the use of venetoclax in such cases is debated. Furthermore, their frequent use in combination with anti-CD20 agents might represent a confounding factor in evaluating their efficacy. In conclusions, because of their ability to mitigate an immunological dysregulation that is (at least partly) responsible for autoimmunity in CLL, to date BTK-inhibitors stand out as the most suitable choice when treatment of autoimmune cytopenias is required.

Anti-globulin test positivity indicates advanced disease in Indian CLL patients

Autoimmune Hemolytic Anemia (AIHA) occurs in 10% to 25% of Chronic Lymphocytic Leukemia (CLL) while Direct Antiglobulin Test (DAT) positivity seen in 35% of cases. The prevalence and prognostic significance of DAT positivity is not well documented especially in Indian population. The present study was undertaken to know prevalence and prognostic significance of DAT positivity in CLL in India by associating it with stage and CD 38 expression. The study included fifty-eight newly diagnosed and untreated cases of CLL staged according to Binet and Rai system. Complete hemogram, DAT and immuno-phenotyping by flow cytometry was done to diagnose CLL and to assess CD 38 expression. Student's t test and Chi square test was used to calculate difference between means. p value ≤0.05 was considered significant. Results-DAT positivity was found in 27.58% cases. A positive association was seen between DAT and advanced Rai and Binet stage (P = 0.024 and P = 0.014 respectively). A positive association was also seen between DAT and CD 38 (P = 0.008). The study concluded that DAT positivity in Indian CLL patients is high as compared to West. As DAT correlated with advanced Rai/Binet stage, as well as CD 38 positivity, it can be considered as a surrogate marker for advanced disease and used to select patients needing close follow up especially at places where molecular and flow cytometric set up for prognostication is not available.

Revisiting Autoimmunity in Chronic Lymphocytic Leukemia: Prognostic Value of Positive Direct Antiglobulin Test in a Retrospective Study and Literature Review

Introduction

A positive direct antiglobulin test (DAT) with or without autoimmune hemolytic anemia is a frequent finding in chronic lymphocytic leukemia (CLL). The heterogenic clinical course of CLL mainly depends on different pathogenetic mechanisms which appears in a form of variable biological and clinical features. These features allow stratification of patients into subsets with different outcomes.

Patients and Methods

We evaluated the DAT as a prognostic marker in 120 CLL patients treated with chemoimmunotherapy. Clinical and laboratory features, treatment response, and survival outcomes of CLL patients were assessed in relation to their DAT test status. Additionally, the English literature was extensively reviewed regarding the prognostic impact of a positive DAT in CLL.

Results

DAT positivity was detected in 36 patients (30%) and was associated advanced disease staging (P = 0.03). No correlations were found with other clinical, laboratory, or biological factors such as ZAP-70 or CD38. Both a positive DAT and an Eastern Cooperative Oncology Group performance status >2 were predictors for non-response to first-line treatment in the multivariate analysis (OR = 0.3, 95% CI: 0.12–0.8 and OR = 0.2, 95% CI: 0.08–0.8, respectively). The five-year progression-free survival was significantly lower in the DAT-positive group (P = 0.004). No significant association was found with overall survival (P = 0.2). Sixteen reports analyzing more than 11,000 patients were identified in our review.

Conclusion

In conclusion, DAT positivity in CLL patients is associated with poor response to treatment and disease progression.

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.

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.

Evans' Syndrome: From Diagnosis to Treatment

Evans' syndrome (ES) is defined as the concomitant or sequential association of warm auto-immune haemolytic anaemia (AIHA) with immune thrombocytopenia (ITP), and less frequently autoimmune neutropenia. ES is a rare situation that represents up to 7% of AIHA and around 2% of ITP. When AIHA and ITP occurred concomitantly, the diagnosis procedure must rule out differential diagnoses such as thrombotic microangiopathies, anaemia due to bleedings complicating ITP, vitamin deficiencies, myelodysplastic syndromes, paroxysmal nocturnal haemoglobinuria, or specific conditions like HELLP when occurring during pregnancy. As for isolated auto-immune cytopenia (AIC), the determination of the primary or secondary nature of ES is important. Indeed, the association of ES with other diseases such as haematological malignancies, systemic lupus erythematosus, infections, or primary immune deficiencies can interfere with its management or alter its prognosis. Due to the rarity of the disease, the treatment of ES is mostly extrapolated from what is recommended for isolated AIC and mostly relies on corticosteroids, rituximab, splenectomy, and supportive therapies. The place for thrombopoietin receptor agonists, erythropoietin, immunosuppressants, haematopoietic cell transplantation, and thromboprophylaxis is also discussed in this review. Despite continuous progress in the management of AIC and a gradual increase in ES survival, the mortality due to ES remains higher than the ones of isolated AIC, supporting the need for an improvement in ES management.

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.

The Role of Autoimmune Diseases in the Prognosis of Lymphoma

The connection between autoimmune disease (AID) and lymphoproliferative disorders is a complex bidirectional relationship that has long been a focus of attention by researchers and physicians. Although advances in pathobiology knowledge have ascertained an AID role in the development of lymphoproliferative diseases developing, results about AID influence on the prognosis of lymphoma are discordant. In this review, we collect the most relevant literature debating a direct or indirect link between immune-mediated diseases and lymphoma prognosis. We also consider the molecular, genetic, and microenvironmental factors involved in the pathobiology of these diseases in order to gain a deeper understanding of the nature of this link.

Small Paroxysmal Nocturnal Hemoglobinuria Clones in Autoimmune Hemolytic Anemia: Clinical Implications and Different Cytokine Patterns in Positive and Negative Patients

Autoimmune hemolytic anemia (AIHA) is characterized by immune mediated erythrocytes destruction by autoantibodies with or without complement activation. Additional pathologic mechanisms include cellular cytotoxicity, cytokline dysregulation, and inadequate bone marrow compensation with fibrosis/dyserythropoiesis. The latter resembles that of bone marrow failures, namely aplastic anemia and myelodysplastic syndromes. Paroxysmal nocturnal hemoglobinuria (PNH) clones are increasingly recognized in bone marrow failure syndromes, and their selection and expansion are thought to be mediated by immune mechanisms. In this study, we aimed to evaluate the prevalence of PNH clones in 99 patients with primary AIHA, and their correlations with disease features and outcomes. Moreover, in the attempt to disclose the physiopathology of PNH positivity in AIHA, serum levels of several immunomodulatory cytokines were tested. A PNH clone was found in 37 AIHA patients (37,4%), with a median size of 0.2% on granulocytes (range 0.03-85). Two patients showed a large clone (16 and 85%) and were therefore considered as AIHA/PNH association and not included in further analysis. Compared to PNH negative, PNH positive cases displayed a higher hemolytic pattern with adequate bone marrow compensation. AIHA type, response to therapy, complications and outcome were comparable between the two groups. Regarding cytokine levels, IFN-γ and IL-17 were lower in PNH positive vs. PNH negative AIHAs (0.3 ± 0.2 vs. 1.33 ± 2.5; 0.15 ± 0.3 vs. 3,7 ± 9.1, respectively, p = 0.07 for both). In PNH positive AIHAs, IFN-γ positively correlated with reticulocytes (r = 0.52, p = 0.01) and with the bone marrow responsiveness index (r = 0.69, p = 0.002). Conversely, IL-6 and IL-10 showed the same pattern in PNH positive and PNH negative AIHAs. IL-6 levels and TGF-β positively correlated with clone size (r = 0.35, p = 0.007, and r = 0.38, p = 0.05, respectively), as well as with LDH values (r = 0.69, p = 0.0003, and r = 0.34, p = 0.07, respectively). These data suggest testing PNH clones in AIHA since their prevalence is not negligible, and may correlate with a prominent hemolytic pattern, a higher thrombotic risk, and a different therapy indication. PNH testing is particularly advisable in complex cases with inadequate response to AIHA-specific therapy. Cytokine patterns of PNH positive and negative AIHAs may give hints about the pathogenesis of highly hemolytic AIHA.

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.

New Insights in the Pathogenesis and Therapy of Cold Agglutinin-Mediated Autoimmune Hemolytic Anemia

Autoimmune hemolytic anemias mediated by cold agglutinins can be divided into cold agglutinin disease (CAD), which is a well-defined clinicopathologic entity and a clonal lymphoproliferative disorder, and secondary cold agglutinin syndrome (CAS), in which a similar picture of cold-hemolytic anemia occurs secondary to another distinct clinical disease. Thus, the pathogenesis in CAD is quite different from that of polyclonal autoimmune diseases such as warm-antibody AIHA. In both CAD and CAS, hemolysis is mediated by the classical complement pathway and therefore can result in generation of anaphylotoxins, such as complement split product 3a (C3a) and, to some extent, C5a. On the other hand, infection and inflammation can act as triggers and drivers of hemolysis, exemplified by exacerbation of CAD in situations with acute phase reaction and the role of specific infections (particularly Mycoplasma pneumoniae and Epstein-Barr virus) as causes of CAS. In this review, the putative mechanisms behind these phenomena will be explained along with other recent achievements in the understanding of pathogenesis in these disorders. Therapeutic approaches have been directed against the clonal lymphoproliferation in CAD or the underlying disease in CAS. Currently, novel targeted treatments, in particular complement-directed therapies, are also being rapidly developed and will be reviewed.

Immune Response Dysfunction in Chronic Lymphocytic Leukemia: Dissecting Molecular Mechanisms and Microenvironmental Conditions

Representing the major cause of morbidity and mortality for chronic lymphocytic leukemia (CLL) patients, immunosuppression is a common feature of the disease. Effectors of the innate and the adaptive immune response show marked dysfunction and skewing towards the generation of a tolerant environment that favors disease expansion. Major deregulations are found in the T lymphocyte compartment, with inhibition of CD8⁺ cytotoxic and CD4⁺ activated effector T cells, replaced by exhausted and more tolerogenic subsets. Likewise, differentiation of monocytes towards a suppressive M2-like phenotype is induced at the expense of pro-inflammatory sub-populations. Thanks to their B-regulatory phenotype, leukemic cells play a central role in driving immunosuppression, progressively inhibiting immune responses. A number of signaling cascades triggered by soluble mediators and cell–cell contacts contribute to immunomodulation in CLL, fostered also by local environmental conditions, such as hypoxia and derived metabolic acidosis. Specifically, molecular pathways modulating T-cell activity in CLL, spanning from the best known cytotoxic T lymphocyte antigen-4 (CTLA-4) and programmed cell death 1 (PD-1) to the emerging T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibition motif domains (TIGIT)/CD155 axes, are attracting increasing research interest and therapeutic relevance also in the CLL field. On the other hand, in the microenvironment, the B cell receptor (BCR), which is undoubtedly the master regulator of leukemic cell behavior, plays an important role in orchestrating immune responses, as well. Lastly, local conditions of hypoxia, typical of the lymphoid niche, have major effects both on CLL cells and on non-leukemic immune cells, partly mediated through adenosine signaling, for which novel specific inhibitors are currently under development. In summary, this review will provide an overview of the molecular and microenvironmental mechanisms that modify innate and adaptive immune responses of CLL patients, focusing attention on those that may have therapeutic implications.