High response rate and durable remissions following fludarabine and rituximab combination therapy for chronic cold agglutinin disease

Stay Away From the Cold: An Unusual Case of Cold Agglutinin Disease Presenting as Recurrent Transient Ischemic Attacks

Cold agglutinin disease (CAD) is a rare autoimmune hemolytic anemia caused by cold-reactive IgM antibodies leading to complement-mediated hemolysis. While CAD-associated venous thromboembolism is recognized, its role in arterial thromboembolic events, particularly ischemic stroke, is poorly defined. We report an 84-year-old woman who developed acute onset upper left extremity weakness following exposure to sub-zero temperatures. She had a history of similar transient episodes during cold seasons and recurrent anemia. Physical examination revealed decreased muscle strength in the upper left extremity (Grade 4+ out of 5) and scleral icterus. Laboratory findings showed normocytic anemia, elevated reticulocytes, high lactate dehydrogenase, indirect hyperbilirubinemia, and undetectable haptoglobin levels. Peripheral smear showed erythrocyte agglutination. Direct antiglobulin test was positive for C3d and IgM, confirming CAD. Vascular imaging showed significant atherosclerotic disease with near-occlusive (>80%) stenosis of the right internal carotid artery. The patient's transient ischemic attacks were attributed to compromised cerebral perfusion due to severe carotid artery stenosis, exacerbated by anemia from cold-induced hemolysis in CAD. Cold exposure precipitated hemolysis, leading to acute anemia and increased blood viscosity, further reducing cerebral blood flow and oxygen delivery. Spontaneous resolution of symptoms upon rewarming supported the role of CAD in her neurological deficits. This case underscores the potential for CAD to induce neurological deficits in patients with significant carotid artery stenosis. Clinicians should consider CAD as a contributory factor in patients presenting with transient neurological deficits precipitated by cold exposure, especially when significant arterial stenosis is present.

Autoimmune Hemolytic Anemias: Challenges in Diagnosis and Therapy

Background

Autoimmune hemolytic anemia (AIHA) is a rare disease due to increased destruction of erythrocytes by autoantibodies, with or without complement activation.

Summary

AIHA is usually classified in warm AIHA (wAIHA) and cold agglutinin disease (CAD), based on isotype and thermal amplitude of the autoantibody. The direct antiglobulin test (DAT) or Coombs test is the cornerstone of AIHA diagnosis, as it is positive with anti-IgG in wAIHA, and with anti-C3d/IgM antisera plus high titer cold agglutinins in CAD. Therapy is quite different, as steroids and rituximab are effective in the former, but have a lower response rate and duration in the latter. Splenectomy, which is still a good option for young/fit wAIHA, is contraindicated in CAD, and classic immunosuppressants are moving to further lines. Several new drugs are increasingly used or are in trials for relapsed/refractory AIHAs, including B-cell (parsaclisib, ibrutinib, rilzabrutinib), and plasma cell target therapies (bortezomib, daratumumab), bispecific agents (ianalumab, obexelimab, povetacicept), neonatal Fc receptor blockers (nipocalimab), and complement inhibitors (sutimlimab, riliprubart, pegcetacoplan, iptacopan). Clinically, AIHAs are highly heterogeneous, from mild/compensated to life-threatening/fulminant, and may be primary or associated with infections, neoplasms, autoimmune diseases, transplants, immunodeficiencies, and drugs. Along with all these variables, there are rare forms like mixed (wAIHA plus CAD), atypical (IgA or warm IgM driven), and DAT negative, where the diagnosis and clinical management are particularly challenging.

Key Messages

This article covers the classic clinical features, diagnosis, and therapy of wAIHA and CAD, and focuses, with the support of clinical vignettes, on difficult diagnosis and refractory/relapsing cases requiring novel therapies.

Navigating cold agglutinin-induced hemolytic anemia in developing countries: A case report and literature review

Cold agglutinin-induced hemolytic anemia presents diagnostic and management challenges, particularly in resource-limited settings like Pakistan. A 92-year-old male presented with altered consciousness, fever, weakness, and severe asthenia. Laboratory findings revealed severe anemia, elevated mean corpuscular volume, and deranged renal function tests. The diagnosis was confirmed via a positive Direct Coombs test and elevated cold agglutinin titers. Multidisciplinary management led to symptom resolution, including blood transfusions and immunosuppressive therapy. This case report and literature review emphasize the complexities of diagnosing and managing cold agglutinin-induced hemolytic anemia in Pakistan. By enhancing awareness and understanding of this condition, clinicians can optimize patient outcomes through timely intervention and multidisciplinary care.

Cold-antibody Autoimmune Hemolytic Anemia: its Association with Neoplastic Disease and Impact on Therapy

PURPOSE OF REVIEW

Cold-antibody mediated autoimmune hemolytic anemia (cAIHA) is subclassified as cold agglutinin disease (CAD), secondary cold agglutinin syndrome (CAS), and paroxysmal cold hemoglobinuria (PCH). This review aims to address the occurrence of neoplastic disorders with these three entities and analyze the impact of such neoplasias on treatment for cAIHA.

RECENT FINDINGS

"Primary" CAD is a distinct clonal B-cell lymphoproliferative disorder in probably all cases, although not classified as a malignant lymphoma. CAS is secondary to malignant lymphoma in a minority of cases. Recent findings allow a further clarification of these differential diagnoses and the therapeutic consequences of specific neoplastic entities. Appropriate diagnostic workup is critical for therapy in cAIHA. Patients with CAD should be treated if they have symptomatic anemia, significant fatigue, or bothersome circulatory symptoms. The distinction between CAD and CAS and the presence of any underlying malignancy in CAS have essential therapeutic implications.

The impact of individual clinical features in cold agglutinin disease: hemolytic versus non-hemolytic symptoms

INTRODUCTION

During the last decades, the pathogenesis of cold agglutinin disease (CAD) has been well elucidated and shown to be complex. Several documented or investigational therapies have been made available. This development has resulted in major therapeutic advances, but also in challenges in choice of therapy.

AREAS COVERED

In this review, we address each step in pathogenesis: bone marrow clonal lymphoproliferation, composition and effects of monoclonal cold agglutinin, non-complement mediated erythrocyte agglutination, complement-dependent hemolysis, and other effects of complement activation. We also discuss the heterogeneous clinical features and their relation to specific steps in pathogenesis, in particular with respect to the impact of complement involvement. CAD can be classified into three clinical phenotypes with consequences for established treatments as well as development of new therapies. Some promising future treatment approaches - beyond chemoimmunotherapy and complement inhibition - are reviewed.

EXPERT OPINION

The patient's individual clinical profile regarding complement involvement and hemolytic versus non-hemolytic features is important for the choice of treatment. Further development of treatment approaches is encouraged, and some candidate drugs are promising irrespective of clinical phenotype. Patients with CAD requiring therapy should be considered for inclusion in clinical trials.

Long-term efficacy and safety of continued complement C1s inhibition with sutimlimab in cold agglutinin disease: CADENZA study Part B

Background

Cold agglutinin disease (CAD) is a rare autoimmune haemolytic anaemia mediated by the classical complement pathway (CP). Sutimlimab selectively targets complement C1s inhibiting classical CP activation. In CADENZA Part A (26-weeks), a placebo-controlled study in patients without recent transfusion history, sutimlimab reduced haemolysis, anaemia, and fatigue, and was generally well tolerated.

Methods

The CADENZA study (NCT03347422) started in March 2018 (Part A) and completed in December 2021 (Part B). All patients in Part B were eligible to receive sutimlimab for up to 1 year after the last patient completed Part A. Efficacy and safety was assessed throughout Part B, until the last on-treatment visit with available assessment (LV), and after a 9-week washout.

Findings

In total, 32/39 patients completed Part B; median treatment duration: 99 weeks. Similar sustained improvements in haemolysis, anaemia, and quality of life were observed in patients switching to sutimlimab and those continuing sutimlimab. Mean LV values for the combined group (ie, placebo-to-sutimlimab group and sutimlimab-to-sutimlimab group) improved from baseline for haemoglobin (≥11.0 g/dL on-treatment vs 9.3 g/dL at baseline), bilirubin (≤20.0 μmol/L on-treatment vs 35.0 μmol/L at baseline), and FACIT-Fatigue scores. Following a 9-week washout, inhibition of CP activity was reversed, and haemolytic markers approached baseline levels. Overall, sutimlimab was generally well tolerated throughout the study. No patients developed systemic lupus erythematosus or meningococcal infections. During the 9-week washout, most adverse events could be attributed to recurrence of underlying CAD.

Interpretation

The CADENZA Part B results support the sustained efficacy and safety of sutimlimab for treatment of CAD; however, upon discontinuation disease activity reoccurs.

Funding

Sanofi.

Cost-effectiveness of sutimlimab in cold agglutinin disease

Primary cold agglutinin disease (CAD) is a rare autoimmune hemolytic anemia caused by cold-reactive antibodies that bind to red blood cells and lead to complement-mediated hemolysis. Patients with primary CAD experience the burden of increased health resource utilization and reduced quality of life. The standard-of-care (SOC) in patients with primary CAD has included cold avoidance, transfusion support, and chemoimmunotherapy. The use of sutimlimab, a humanized monoclonal antibody that selectively inhibits C1-mediated hemolysis, was shown to reduce transfusion-dependence and improve quality of life across two pivotal phase 3 studies, further supported by 2-year extension data. Using data from the transfusion-dependent patient population that led to sutimlimab's initial FDA approval, we performed the first-ever cost-effectiveness analysis in primary CAD. The projected incremental cost-effectiveness ratio (ICER) in our Markov model was $2 340 000/QALY, significantly above an upper-end conventional US willingness-to-pay threshold of $150 000/QALY. These results are consistent across scenarios of higher body weight and a pan-refractory SOC patient phenotype (i.e., treated sequentially with bendamustine-rituximab, bortezomib, ibrutinib, and eculizumab). No parameter variations in deterministic sensitivity analyses changed our conclusion. In probabilistic sensitivity analysis, SOC was favored over sutimlimab in 100% of 10 000 iterations. Exploratory threshold analyses showed that significant price reduction (>80%) or time-limited treatment (<18 months) followed by lifelong clinical remission off sutimlimab would allow sutimlimab to become cost-effective. The impact of sutimlimab on health system costs with longer term follow-up data merits future study and consideration through a distributional cost-effectiveness framework.

The evolving management algorithm for the patient with newly diagnosed cold agglutinin disease

INTRODUCTION

Cold agglutinin disease (CAD) is driven by IgM autoantibodies reactive at <37°C and able to fix complement. The activation of the classical complement pathway leads to C3-mediated extravascular hemolysis in the liver and to intravascular hemolytic crises in case of complement amplifying conditions. C3 positivity at direct Coombs test along with high titer agglutins are required for the diagnosis. Treatment is less standardized.

AREAS COVERED

This review recapitulates CAD diagnosis and then focus on the evolving management of the disease. Both current approach and novel targeted drugs are discussed. Literature search was conducted in PubMed and Scopus from 2000 to 2024 using 'CAD' and 'autoimmune hemolytic anemia' as keywords.

EXPERT OPINION

Rituximab represents the frontline approach in patients with symptomatic anemia or disabling cold-induced peripheral symptoms and is effective in 50-60% of cases. Refractory/relapsing patients are an unmet need and may now benefit from complement inhibitors, particularly the anti-C1s sutimlimab, effective in controlling hemolysis thus improving anemia in >80% of patients, but not active on cold-induced peripheral symptoms. Novel drugs include long-acting complement inhibitors, plasma cells, and B-cell targeting agents (proteasome inhibitors, anti-CD38, BTKi, PI3Ki, anti-BAFF). Combination therapy may be the future answer to CAD unmet needs.

[The treatment strategies of autoimmune hemolytic anemia]

Autoimmune hemolytic anemia (AIHA) is characterized by the accelerated destruction of erythrocytes due to the presence of antibodies and/or complement that bind to antigens on erythrocytes. It can be subdivided into warm, cold or mixed AIHA based on the type of autoantibody and the optimal temperature of antigen-antibody reaction. Glucocorticoid with or without rituximab is the first-line treatment of warm AIHA (wAIHA), and splenectomy was once the preferred second-line treatment for relapsed or refractory wAIHA. However, due to the various complications of splenectomy, rituximab has gradually become the preferred treatment for patients who have failed glucocorticoid therapy. Other available treatments including immunosuppressants and plasma exchange can be chosen. Rituximab with or without bendamustine is generally taken as the first-line regimen for cold autoimmune hemolytic anemia (cAIHA), while glucocorticoid and splenectomy are ineffective. Sutimlimab, a kind of complement inhibitor, has been approved for the treatment of cold agglutinin disease (CAD). In recent years, many new drugs have emerged as treatment options for AIHA. Emerging therapies, including B-cell-directed therapies, plasma cell-directed therapies, complement inhibitors, and phagocytosis inhibition, provide a new perspective for AIHA therapy, showing great potential for clinical applications.

C1-inhibitor treatment in patients with severe complement-mediated autoimmune hemolytic anemia

Complement-mediated (CM) autoimmune hemolytic anemia (AIHA) is characterized by the destruction of red blood cells (RBCs) by autoantibodies that activate the classical complement pathway. These antibodies also reduce transfusion efficacy via the lysis of donor RBCs. Because C1-inhibitor (C1-INH) is an endogenous regulator of the classical complement pathway, we hypothesized that peritransfusional C1-INH in patients with severe CM-AIHA reduces complement activation and hemolysis, and thus enhances RBC transfusion efficacy. We conducted a prospective, single-center, phase 2, open-label trial (EudraCT2012-003710-13). Patients with confirmed CM-AIHA and indication for the transfusion of 2 RBC units were eligible for inclusion. Four IV C1-INH doses (6000, 3000, 2000, and 1000 U) were administered with 12-hour intervals around RBC transfusion. Serial blood samples were analyzed for hemolytic activity, RBC opsonization, complement activation, and inflammation markers. Ten patients were included in the study. C1-INH administration increased plasma C1-INH antigen and activity, peaking at 48 hours after the first dose and accompanied by a significant reduction of RBC C3d deposition. Hemoglobin levels increased briefly after transfusion but returned to baseline within 48 hours. Overall, markers of hemolysis, inflammation, and complement activation remained unchanged. Five grade 3 and 1 grade 4 adverse event occurred but were considered unrelated to the study medication. In conclusion, peritransfusional C1-INH temporarily reduced complement activation. However, C1-INH failed to halt hemolytic activity in severe transfusion-dependent-CM-AIHA. We cannot exclude that posttransfusional hemolytic activity would have been even higher without C1-INH. The potential of complement inhibition on transfusion efficacy in severe CM-AIHA remains to be determined.

Antibody based therapeutics for autoimmune hemolytic anemia

INTRODUCTION

Autoimmune hemolytic anemia (AIHA) treatment has been revolutionized by the introduction of target therapies, mainly monoclonal antibodies (MoAbs).

AREAS COVERED

The anti-CD20 rituximab, which targets Ab production by B-cells, induces 80% of response in warm-type AIHA (wAIHA) and 50-60% in cold agglutinin disease (CAD). Other B-cell targeting MoAbs including ianalumab, povetacicept, and obexelimab are under active study. The anti-CD38 MoAb daratumumab has been used in several reports to target long-lived plasma-cells responsible for AIHA relapse, being effective even in multi-refractory cases. Anti-complement MoAbs will soon change the treatment paradigm in CAD; the anti-C1s sutimlimab rapidly increased Hb in more than 80% of the cases. Finally, MoAbs inhibiting the neonatal Fc receptor (FcRn), such as nipocalimab, can reduce the half-life of the pathogenic autoAbs, representing a promising treatment for wAIHA.

EXPERT OPINION

MoAbs offer the potential to improve efficacy by reducing toxicity. However, there is a huge need for clinical trials exploring response duration rather than short-term efficacy. Complement inhibitors and anti-FcRns do not abrogate autoAb production and are being developed as long-term therapies. Thus, the combination of B-cell/plasma cell targeting drugs deserves to be explored. On the other hand, their rapid efficacy should be exploited for the acute AIHA phase.

Monoclonal antibodies for treatment of cold agglutinin disease

INTRODUCTION

Cold agglutinin disease (CAD) is a difficult-to-treat autoimmune hemolytic anemia and B cell lymphoproliferative disorder associated with fatigue, acrocyanosis and a risk of thromboembolic events. Cold-induced binding of autoantibodies agglutinates red blood cells and triggers the classical complement pathway, leading to predominantly extravascular hemolysis.

AREAS COVERED

This review summarizes clinical and experimental antibody-based treatments for CAD and analyzes the risks and benefits of B cell and complement directed therapies, and discusses potential future treatments for CAD.

EXPERT OPINION

Conventional treatment of CAD includes a B cell targeted treatment approach with rituximab, yielding only limited treatment success. Addition of a cytotoxic agent (e.g. bendamustine) increases efficacy but this is accompanied by an increased risk of neutropenia and infection. Novel complement-directed therapies have emerged and were shown to have a good efficacy against hemolysis and safety profile but are expensive and unable to address circulatory symptoms. Complement inhibition with sutimlimab may be used as a bridging strategy until B cell directed therapy with rituximab takes effect or continued indefinitely if needed. Future antibody-based treatment approaches for CAD involve the further development of complement-directed antibodies, combination of rituximab and bortezomib, and daratumumab. Non-antibody based prospective treatments may include the use of Bruton tyrosine kinase inhibitors.

The choice of new treatments in autoimmune hemolytic anemia: how to pick from the basket?

Autoimmune hemolytic anemia (AIHA) is defined by increased erythrocyte turnover mediated by autoimmune mechanisms. While corticosteroids remain first-line therapy in most cases of warm-antibody AIHA, cold agglutinin disease is treated by targeting the underlying clonal B-cell proliferation or the classical complement activation pathway. Several new established or investigational drugs and treatment regimens have appeared during the last 1-2 decades, resulting in an improvement of therapy options but also raising challenges on how to select the best treatment in individual patients. In severe warm-antibody AIHA, there is evidence for the upfront addition of rituximab to prednisolone in the first line. Novel agents targeting B-cells, extravascular hemolysis, or removing IgG will offer further options in the acute and relapsed/refractory settings. In cold agglutinin disease, the development of complement inhibitors and B-cell targeting agents makes it possible to individualize therapy, based on the disease profile and patient characteristics. For most AIHAs, the optimal treatment remains to be found, and there is still a need for more evidence-based therapies. Therefore, prospective clinical trials should be encouraged.

[Hemolytic anemia in emergency and intensive care medicine]

Hemolytic anemia (HA) is caused by premature destruction or degradation of red blood cells (RBC). Low hemoglobin, suppressed haptoglobin, reticulocytosis as well as an elevation of lactate dehydrogenase and bilirubin are common laboratory findings in HA. Intracorpuscular HA due to defects of the RBC themselves are distinguished from extracorpuscular HA due to external factors. Severity of symptoms such as fatigue and dyspnea depend on the degree of anemia. For optimal treatment of HA, a detailed evaluation of the patient history (including hereditary RBC defects, B symptoms and travel history) is necessary. Additional diagnostics (hematological diagnostics, infectious disease diagnostics, immunological diagnostics, computed tomography [CT] scan) should be performed according to the patient's individual requirements. Treatment of HA depends on the etiology. If HA is immune-mediated, immunosuppressive therapy is indicated, whereas HA due to infections usually improves after adequate anti-infective therapy. Anti-infective therapy should also be considered in patients with sickle cell disease who present with severe HA. In general, HA can be treated effectively in most cases.

Cold AIHA and the best treatment strategies

Cold-reactive autoimmune hemolytic anemia (AIHA) is rare among the hemolytic anemias. It results when 1 of a variety of processes causes the generation of immunoglobulin M (IgM) autoantibodies against endogenous erythrocytes, resulting in complement activation and predominantly intravascular hemolysis. Cold AIHA is typically a primary lymphoproliferative disorder with marrow B-cell clones producing pathogenic IgM. More rarely, secondary cold AIHA (cAIHA) can develop from malignancy, infection, or other autoimmune disorders. However, in children cAIHA is typically post infection, mild, and self-limited. Symptoms include a sequelae of anemia, fatigue, and acrocyanosis. The severity of disease is variable and highly dependent on the thermal binding range of the autoantibody. In adults, treatment has most commonly focused on reducing antibody production with rituximab-based regimens. The addition of cytotoxic agents to rituximab improves response rates, but at the expense of tolerability. Recent insights into the cause of cold agglutinin disease as a clonal disorder driven by complement form the basis of newer therapeutic options. While rituximab-based regimens are still the mainstay of therapy, options have now expanded to include complement-directed treatments and other B-cell-directed or plasma-cell-directed therapies.

Sutimlimab improves quality of life in patients with cold agglutinin disease: results of patient-reported outcomes from the CARDINAL study

Patients with cold agglutinin disease (CAD) experience fatigue and poor quality of life. However, previous CAD-related studies have not explored patient-reported outcomes such as the Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue. Sutimlimab, a C1s complement inhibitor, has been shown to halt haemolysis in CAD. Here, we present 26-weeks' patient-reported data from CARDINAL Part A (ClinicalTrials.gov, NCT03347396), which assessed efficacy and safety of sutimlimab in patients with CAD and recent history of transfusion. Aside from measuring changes in haemolytic markers, FACIT-Fatigue was measured at the treatment assessment timepoint (TAT; average of weeks 23, 25, and 26). Exploratory endpoints included the change in EuroQol 5-dimension 5-level questionnaire (EQ-5D-5L) and the 12-Item Short Form Health Survey (SF-12) at TAT, and Patient Global Impression of Change (PGIC), and Patient Global Impression of (fatigue) Severity (PGIS) at week 26. Mean (range) FACIT-Fatigue scores increased from 32.5 (14.0-47.0) at baseline (a score indicative of severe fatigue) to 44.3 (28.0-51.0) at TAT. Considerable improvements were reported for EQ-5D-5L at TAT, SF-12 scores at TAT, and PGIC and PGIS scores at week 26. Sutimlimab treatment resulted in sustained improvements in symptoms of fatigue and overall quality of life in patients with CAD. NCT03347396. Registered 20 November, 2017.

Sutimlimab in patients with cold agglutinin disease: results of the randomized placebo-controlled phase 3 CADENZA trial

Sutimlimab, a first-in-class humanized immunoglobulin G4 (IgG4) monoclonal antibody that selectively inhibits the classical complement pathway at C1s, rapidly halted hemolysis in the single-arm CARDINAL study in recently transfused patients with cold agglutinin disease (CAD). CADENZA was a 26-week randomized, placebo-controlled phase 3 study to assess safety and efficacy of sutimlimab in patients with CAD without recent (within 6 months prior to enrollment) transfusion history. Forty-two patients with screening hemoglobin ≤10 g/dL, elevated bilirubin, and ≥1 CAD symptom received sutimlimab (n = 22) or placebo (n = 20) on days 0 and 7 and then biweekly. Composite primary endpoint criteria (hemoglobin increase ≥1.5 g/dL at treatment assessment timepoint [mean of weeks 23, 25, 26], avoidance of transfusion, and study-prohibited CAD therapy [weeks 5-26]) were met by 16 patients (73%) on sutimlimab, and 3 patients (15%) on placebo (odds ratio, 15.9 [95% confidence interval, 2.9, 88.0; P < .001]). Sutimlimab, but not placebo, significantly increased mean hemoglobin and FACIT-Fatigue scores at treatment assessment timepoint. Sutimlimab normalized mean bilirubin by week 1. Improvements correlated with near-complete inhibition of the classical complement pathway (2.3% mean activity at week 1) and C4 normalization. Twenty-one (96%) sutimlimab patients and 20 (100%) placebo patients experienced ≥1 treatment-emergent adverse event. Headache, hypertension, rhinitis, Raynaud phenomenon, and acrocyanosis were more frequent with sutimlimab vs placebo, with a difference of ≥3 patients between groups. Three sutimlimab patients discontinued owing to adverse events; no placebo patients discontinued. These data demonstrate that sutimlimab has potential to be an important advancement in the treatment of CAD. This trial was registered at www.clinicaltrials.gov as #NCT03347422.

[Autoimmune haemolytic anemias]

Autoimmune haemolytic anemia (AIHA) is defined as the immune-mediated destruction of red blood cells. In most cases, antibodies that target surface antigens on erythrocytes lead to their premature degradation in the spleen or, less commonly, in the liver. The term includes a heterogenous group of diseases, which differ largely in pathophysiology and treatment. The two most common entities are warm AIHA and cold AIHA. Diagnostic testing involves the analysis of haemolytic markers like lactate dehydrogenase, haptoglobin and unconjugated bilirubin as well as a hemoglobin and reticulocytes. In case of a haemolytic anemia, further testing like a blood smear and a direct antiglobulin test should follow. As diagnostic testing and treatment of AIHA are complex, affected patients should always be referred to a hematologist.In warm AIHA, mainly IgG autoantibodies bind to their antigen on the erythrocyte surface at body temperature, leading to their premature destruction in the spleen. First line treatment options include the administration of steroids which mitigate the destruction of red blood cells by macrophages in the spleen. In contrast, IgM autoantibodies in cold AIHA lead to intravasal agglutination of erythrocytes and complement activation. The IgM antibodies have their highest affinity below body temperature which is why patients experience symptoms mainly in cold-exposed body areas. Although the IgM antibodies dissolve at body temperature, the complement-loaded erythrocytes are destroyed in the liver. Therapeutic options include protection from cold and immunosuppressive agents or complement inhibition.

Practical therapy for primary autoimmune hemolytic anemia in adults

BACKGROUND AND AIM

Autoimmune hemolytic anemias (AIHA) constitute a rare and heterogeneous group of diseases whose therapy differs according to the type of antibody involved in the genesis of the disease and the existence or not of an identified cause. With the aim of providing a practical guide for the therapy of AIHA, we summarize the emergency therapy and general measures habitually used in all forms of AIHA, as well as the specific treatment of the most frequent primary forms of AIHA: primary warm AIHA and AIHA from cold agglutinin disease (AIHA from CAD). We discuss the dependence of the treatment of the secondary forms on their underlying causes and the changes in the treatment of the primary forms in recent years.

METHODS

We examined the options available for the treatment of primary warm AIHA and AIHA from CAD.

RESULTS

We found many differences and only one similarity in their treatment.

DISCUSSION

The differences, particularly due to the non-responsiveness of AIHA from CAD to many treatments useful for primary warm AIHA, such as steroids, splenectomy and immunosuppressive agents, must be considered in the face of each, single case of AIHA. Preliminary identification of the type of antibody involved in the genesis of the disease and careful exclusion of a secondary form are particularly important. Rituximab plays a central role in the treatment of primary warm AIHA and AIHA from CAD.

Sutimlimab for treatment of cold agglutinin disease: why, how and for whom?

Therapies for cold agglutinin disease have been directed at the pathogenic B-cell clone. Sutimlimab, a monoclonal antibody that targets C1s, is the first complement inhibitor to be extensively studied in cold agglutinin disease. Sutimlimab selectively blocks the classical activation pathway and leaves the alternative and lectin pathways intact. Trials have documented high response rates with rapid improvement in hemolysis, hemoglobin levels and fatigue scores and low toxicity. Sutimlimab was recently approved in the USA. This drug appears to be particularly useful in severely anemic patients who require a rapid response, in acute exacerbations that do not resolve spontaneously and in patients in whom chemoimmunotherapy is contraindicated or has failed. The choice of therapy in cold agglutinin disease should be individualized.

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.

Autoimmune Hemolytic Anemia in Children: Laboratory Investigation, Disease Associations, and Treatment Strategies

Autoimmune hemolytic anemia is a relatively uncommon pediatric clinical condition. As such, the evaluation and management of these cases can be challenging for even the most seasoned pediatrician. In this review, the 3 major forms of autoimmune hemolytic anemia in children will be discussed: warm autoimmune hemolytic anemia, cold agglutinin disease, and paroxysmal cold hemoglobinuria. After a general description of the laboratory approach to these entities, the pathophysiology of these disease processes, including important disease associations, will be described, and treatment strategies will be discussed. This will provide the reader with a rational approach to identifying and managing pediatric patients with these uncommon autoimmune conditions.

How I manage autoimmune cytopenias in patients with lymphoid cancer

Autoimmune conditions can occur in a temporary relationship with any malignant lymphoma. In many instances, treatment at diagnosis is not required, but symptomatic autoimmune conditions represent an indication for treatment, particularly in chronic lymphoproliferative diseases. Treatment is selected depending on the predominant condition: autoimmune disease (immunosuppression) or lymphoma (antilymphoma therapy). Steroids and anti-CD20 antibodies are effective against both conditions and may suppress the autoimmune complication for a prolonged period. The efficacy of B-cell receptor inhibitors has provided us with novel insights into the pathophysiology of antibody-producing B cells. Screening for underlying autoimmune conditions is part of the lymphoma workup, because other drugs, such as immunomodulators and checkpoint inhibitors, should be avoided or used with caution. In this article, we discuss diagnostic challenges and treatment approaches for different situations involving lymphomas and autoimmune cytopenias.

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.

Thromboembolic complications in autoimmune hemolytic anemia: Retrospective study

Introduction

A small number of retrospective studies suggest AIHA to be associated with an increased risk to suffer from thromboembolic events. However, based on these studies it remains unclear whether the complement activation per is a risk factor to develop thromboembolic events in AIHA patients. The aim of this retrospective study is to investigate the incidence of thromboembolic events and the relation to complement activation in a cohort of AIHA patients.

Patients and Methods

We included 77 patients in this study with a positive DAT and hemolytic parameters or with AIHA diagnosis based on the medical report. The included patients were screened for thromboembolic events (TEE) and have been stratified in groups with and without complement activation based on the positivity for complement in the DAT.

Results

Of the 77 included patients, 51 (66%) had warm AIHA, 13 (17%) cold‐AIHA, 5 (7%) mixed AIHA, and 8 (10%) atypical AIHA, respectively. Primary and secondary AIHA was diagnosed in 44% and 56%, respectively. Twenty patients (26%) suffered from TEE. The majority (80%) of these patients suffered from warm AIHA and 10% from cold‐AIHA. Hemolysis parameters did not differ in patients with and without TEE. There was no correlation with complement activation as evidenced by a positivity for complement in the monospecific DAT with the occurrence of TEE.

Conclusion

AIHA is associated with an increased risk of TEE. Based on these results prophylactic anticoagulation might be considered as soon as the diagnosis of AIHA is confirmed.

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.

Inhibition of complement C1s in patients with cold agglutinin disease: lessons learned from a named patient program

Cold agglutinin disease (CAD) causes predominantly extravascular hemolysis and anemia via complement activation. Sutimlimab is a novel humanized monoclonal antibody directed against classical pathway complement factor C1s. We aimed to evaluate the safety and efficacy of long-term maintenance treatment with sutimlimab in patients with CAD. Seven CAD patients treated with sutimlimab as part of a phase 1B study were transitioned to a named patient program. After a loading dose, patients received biweekly (once every 2 weeks) infusions of sutimlimab at various doses. When a patient's laboratory data showed signs of breakthrough hemolysis, the dose of sutimlimab was increased. Three patients started with a dose of 45 mg/kg, another 3 with 60 mg/kg, and 1 with a fixed dose of 5.5 g every other week. All CAD patients responded to re-treatment, and sutimlimab increased hemoglobin from a median initial level of 7.7 g/dL to a median peak of 12.5 g/dL (P = .016). Patients maintained near normal hemoglobin levels except for a few breakthrough events that were related to underdosing and which resolved after the appropriate dose increase. Four of the patients included were eventually treated with a biweekly 5.5 g fixed-dose regimen of sutimlimab. None of them had any breakthrough hemolysis. All patients remained transfusion free while receiving sutimlimab. There were no treatment-related serious adverse events. Overlapping treatment with erythropoietin, rituximab, or ibrutinib in individual patients was safe and did not cause untoward drug interactions. Long-term maintenance treatment with sutimlimab was safe, effectively inhibited hemolysis, and significantly increased hemoglobin levels in re-exposed, previously transfusion-dependent CAD patients.

Sutimlimab in Cold Agglutinin Disease

BACKGROUND

Cold agglutinin disease is a rare autoimmune hemolytic anemia characterized by hemolysis that is caused by activation of the classic complement pathway. Sutimlimab, a humanized monoclonal antibody, selectively targets the C1s protein, a C1 complex serine protease responsible for activating this pathway.

METHODS

We conducted a 26-week multicenter, open-label, single-group study to assess the efficacy and safety of intravenous sutimlimab in patients with cold agglutinin disease and a recent history of transfusion. The composite primary end point was a normalization of the hemoglobin level to 12 g or more per deciliter or an increase in the hemoglobin level of 2 g or more per deciliter from baseline, without red-cell transfusion or medications prohibited by the protocol.

RESULTS

A total of 24 patients were enrolled and received at least one dose of sutimlimab; 13 patients (54%) met the criteria for the composite primary end point. The least-squares mean increase in hemoglobin level was 2.6 g per deciliter at the time of treatment assessment (weeks 23, 25, and 26). A mean hemoglobin level of more than 11 g per deciliter was maintained in patients from week 3 through the end of the study period. The mean bilirubin levels normalized by week 3. A total of 17 patients (71%) did not receive a transfusion from week 5 through week 26. Clinically meaningful reductions in fatigue were observed by week 1 and were maintained throughout the study. Activity in the classic complement pathway was rapidly inhibited, as assessed by a functional assay. Increased hemoglobin levels, reduced bilirubin levels, and reduced fatigue coincided with inhibition of the classic complement pathway. At least one adverse event occurred during the treatment period in 22 patients (92%). Seven patients (29%) had at least one serious adverse event, none of which were determined by the investigators to be related to sutimlimab. No meningococcal infections occurred.

CONCLUSIONS

In patients with cold agglutinin disease who received sutimlimab, selective upstream inhibition of activity in the classic complement pathway rapidly halted hemolysis, increased hemoglobin levels, and reduced fatigue. (Funded by Sanofi; CARDINAL ClinicalTrials.gov number, NCT03347396.).

Cold agglutinin disease revisited: a multinational, observational study of 232 patients

We retrospectively studied 232 patients with cold agglutinin disease (CAD) at 24 centers in 5 countries. In Norway and a northern region of Italy, the study was close to being population-based. For the first time, we demonstrate fourfold differences between cold and warmer climates regarding prevalence (20 vs 5 cases/million) and incidence (1.9 vs 0.48 cases/million per year). Mean baseline hemoglobin level was 9.3 g/dL, but 27% had hemoglobin <8 g/dL. Identification of typical features of CAD-associated lymphoproliferative disorder in the bone marrow was greatly increased by centralized biopsy assessment. CAD seems to be associated with a slightly increased risk of venous thrombosis. This work includes a follow-up study of therapies, focusing on the long-term outcomes of the rituximab plus bendamustine and rituximab plus fludarabine regimens. Rituximab plus bendamustine therapy resulted in responses in 35 (78%) of 45 patients; 24 (53%) achieved complete response. Interestingly, these rates were still higher than observed in the original (2017) prospective trial, and we also found a shift toward deeper responses with time. This is explained by the prolonged time to response seen in many patients, probably related to long-lived plasma cells. In patients responding to rituximab-bendamustine, median response duration was not reached after 88 months, and estimated 5-year sustained remission was 77%. The regimen appeared safe regarding late-occurring malignancies. Rituximab plus fludarabine therapy seems to carry a higher risk of long-term adverse effects.

Infectious Complications in Autoimmune Hemolytic Anemia

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

Rituximab Use in Warm and Cold Autoimmune Hemolytic Anemia

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

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

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

Autoimmune hemolytic anemia: current knowledge and perspectives

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

Rituximab-containing therapy for cold agglutinin disease: a retrospective study of 16 patients

Cold agglutinin disease (CAD) is a rare form of autoimmune haemolytic anaemia, and because of its rareness, there is no standard treatment for CAD patients. We retrospectively analysed the response to rituximab-containing therapy in CAD patients at our hospital. All patients received rituximab-containing therapy for at least 1 month. A total of 16 patients (11 males and 5 females) were included. The median age at the onset of the disease was 63.5 years (range 41–79). Most patients had manifestations including anaemia (81.3%) or cold-induced circulatory symptoms (75.0%). The median haemoglobin level was 72 g/L (range 29–101), and the median cold agglutinin titre was 1,024 (range 64–2,048). Thirteen of 16 patients (81%) responded to the therapy. Responders achieved a median increase in haemoglobin levels of 45 g/L. Grade 3–4 neutropenia occurred in 3 patients (19%), but only 1 (6%) of them experienced infection. Anaphylaxis related to rituximab occurred in 1 patient. During follow-up, five patients experienced relapse, and two patients died. The estimated median progression-free survival was 36 months, and median overall survival was not yet reached. In conclusion, A rituximab-based therapy in accordance with individual patient characteristics may be a reasonable choice for CAD patients.

Cold Agglutinin Disease

Cold agglutinin disease (CAD) is an uncommon form of cold autoimmune hemolytic anemia (AIHA). It should be considered in the differential diagnosis of elderly patients with unexplained chronic anemia presenting with or without cold-induced symptoms in the extremities, such as the fingers, ears, and nose. CAD is a complement-mediated process which leads to intravascular and extravascular hemolysis. A stepwise approach to laboratory testing can help confirm the diagnosis. Nearly all cold agglutinins are positive for the C3d direct antiglobulin test (DAT). A negative C3d DAT should prompt investigation of a possible warm AIHA. Ninety percent of cold agglutinins are of the IgM immunoglobulin class and should have a titer of 1:64 or higher at 4°C. Distinction from a warm AIHA is important, as therapy differs for the two entities. Corticosteroids are not effective at treating CAD and should not be used as therapy in these patients. Approximately 45–60% of patients with CAD respond to rituximab monotherapy. Combination therapy of rituximab and fludarabine has been shown to be effective in up to 76% of patients; however, patients experience more mild side effects with this treatment. New anti-complement drugs, such as eculizumab and sutimlimab, are currently in phase-3 trials to determine their efficacy and safety in patients with CAD.

Defining autoimmune hemolytic anemia: a systematic review of the terminology used for diagnosis and treatment

The terminology applied to autoimmune hemolytic anemia (AIHA) seems inconsistent. We aimed to evaluate the consistency of definitions used for diagnosis and treatment. In this systematic review of literature from January 2006 to December 2015, we assessed heterogeneity in the definition of AIHA and its subtypes, refractory disease, disease phase, severity, criteria for treatment response, and response durability. A Medline search for anemia, hemolytic, autoimmune was supplemented with keyword searches. Main exclusions were conference abstracts, animal and non-English studies, and studies with <10 cases. Of 1371 articles retrieved, 1209 were excluded based on titles and abstracts. Two authors independently reviewed 10% and 16% of abstracts and full papers, respectively. After full-paper review, 84 studies were included. AIHA was most frequently (32 [52%] of 61) defined as hemolytic anemia with positive direct antiglobulin test (DAT) and exclusion of alternatives, but 10 of 32 also recognized DAT-negative AIHA. A lower threshold for diagnosis of DAT-negative AIHA was observed in literature on chronic lymphocytic leukemia. Definitions of anemia, hemolysis, and exclusion criteria showed substantial variation. Definitions of primary/secondary cold agglutinin disease/syndrome were not consistent. Forty-three studies provided criteria for treatment response, and other than studies from 1 center, these were almost entirely unique. Other criteria were rarely defined. Only 7, 0, 3, 2, 2, and 3 studies offered definitions of warm AIHA, paroxysmal cold hemoglobinuria, mixed AIHA, AIHA severity, disease phase, and refractory AIHA, respectively. Marked heterogeneity in the time period sampled indicates the need to standardize AIHA terminology.

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.

Efficacy and safety of rituximab in autoimmune and microangiopathic hemolytic anemia: a systematic review and meta-analysis

Background

The efficacy and safety of rituximab (RTX) on hemolytic anemia (HA) is unknown. Therefore we retrospectively analyze the efficacy and safety of RTX in autoimmune hemolytic anemia (AIHA) and microangiopathic hemolytic anemia (MAHA) from the previous literature.

Methods

Data in clinical trials and observational studies were collected from PubMed, Cochrane, Embase, and Google Scholar until Oct 15, 2018. The efficacy and safety of RTX in patients with AIHA or MAHA were assessed and overall response rates (ORRs), complete response rates (CRRs), adverse events (AEs) and relapse rates (RRs) were extracted if available. A meta-analysis was performed with a random-effects model, estimating mean proportions in all studies, and relative rates in comparative studies.

Results

After quality assessment, a total of 37 investigations encompassing 1057 patients eligible for meta-analysis were included. Pooled mean proportion of ORR was 0.84 (95% confidence interval [CI] 0.80–0.88), and that of CRR was 0.61 (95% CI 0.49–0.73). Mean AE rate was 0.14 (95% CI 0.10–0.17), and mean RR was 0.21 (95% CI 0.15–0.26). Relative ORR was 1.18 (95% CI 1.02–1.36), and relative CRR was 1.17 (95% CI 0.98–1.39) fold more than the respective non-RTX counter parts. Relative AE rate was 0.77 (95% CI 0.36–1.63), and relative RR was 0.93 (95% CI 0.56–1.55) fold less than the respective non-RTX counter parts.

Conclusion

RTX is more effective than the treatments without RTX for AIHA and MAHA and is well-tolerated.

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.

Autoimmune Cytopenias in Chronic Lymphocytic Leukemia: Focus on Molecular Aspects

Autoimmune cytopenias, particularly autoimmune hemolytic anemia (AIHA) and immune thrombocytopenia (ITP), complicate up to 25% of chronic lymphocytic leukemia (CLL) cases. Their occurrence correlates with a more aggressive disease with unmutated VHIG status and unfavorable cytogenetics (17p and 11q deletions). CLL lymphocytes are thought to be responsible of a number of pathogenic mechanisms, including aberrant antigen presentation and cytokine production. Moreover, pathogenic B-cell lymphocytes may induce T-cell subsets imbalance that favors the emergence of autoreactive B-cells producing anti-red blood cells and anti-platelets autoantibodies. In the last 15 years, molecular insights into the pathogenesis of both primary and secondary AIHA/ITP has shown that autoreactive B-cells often display stereotyped B-cell receptor and that the autoantibodies themselves have restricted phenotypes. Moreover, a skewed T-cell repertoire and clonal T cells (mainly CD8+) may be present. In addition, an imbalance of T regulatory-/T helper 17-cells ratio has been involved in AIHA and ITP development, and correlates with various cytokine genes polymorphisms. Finally, altered miRNA and lnRNA profiles have been found in autoimmune cytopenias and seem to correlate with disease phase. Genomic studies are limited in these forms, except for recurrent mutations of KMT2D and CARD11 in cold agglutinin disease, which is considered a clonal B-cell lymphoproliferative disorder resulting in AIHA. In this manuscript, we review the most recent literature on AIHA and ITP secondary to CLL, focusing on available molecular evidences of pathogenic, clinical, and prognostic relevance.