Short course of bortezomib in anemic patients with relapsed cold agglutinin disease: a phase 2 prospective GIMEMA study

Autoimmune haemolytic anaemias

Adult autoimmune haemolytic anaemias (AIHAs) include different subtypes of a rare autoimmune disease in which autoantibodies targeting autoantigens expressed on the membrane of autologous red blood cells (RBCs) are produced, leading to their accelerated destruction. In the presence of haemolytic anaemia, the direct antiglobulin test is the cornerstone of AIHA diagnosis. AIHAs are classified according to the isotype and the thermal optimum of the autoantibody into warm (wAIHAs), cold and mixed AIHAs. wAIHAs, the most frequent type of AIHAs, are associated with underlying conditions in ~50% of cases. In wAIHA, IgG autoantibody reacts with autologous RBCs at 37 °C, leading to antibody-dependent cell-mediated cytotoxicity and increased phagocytosis of RBCs in the spleen. Cold AIHAs include cold agglutinin disease (CAD) and cold agglutinin syndrome (CAS) when there is an underlying condition. CAD and cold agglutinin syndrome are IgM cold antibody-driven AIHAs characterized by classical complement pathway-mediated haemolysis. The management of wAIHAs has long been based around corticosteroids and splenectomy and on symptomatic measures and non-specific cytotoxic agents for CAD. Rituximab and the development of complement inhibitors, such as the anti-C1s antibody sutimlimab, have changed the therapeutic landscape of AIHAs, and new promising targeted therapies are under investigation.

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.

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.

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.

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.

Sutimlimab for the Treatment of Cold Agglutinin Disease

Cold agglutinin disease (CAD) is a rare autoimmune hemolytic anemia and a bone marrow clonal lymphoproliferative disorder. Hemolysis in CAD is complement-dependent and mediated by the classical activation pathway. Patients also frequently suffer from fatigue and cold-induced circulatory symptoms. Although not all patients need treatment, the symptom burden has previously been underestimated. Effective therapies target the clonal lymphoproliferation or the complement activation. Sutimlimab, a humanized monoclonal IgG4 antibody that binds and inactivates complement protein C1s, is the most extensively investigated complement inhibitor for the treatment of CAD. This review addresses the preclinical studies of sutimlimab and the studies of pharmacokinetics and pharmacodynamics. We then describe and discuss the prospective clinical trials that established sutimlimab as a rapidly acting, highly efficacious, and low-toxic therapeutic agent. This complement inhibitor does not improve the cold-induced circulatory symptoms, which are not complement-mediated. Sutimlimab is approved for the treatment of CAD in the US, Japan, and the European Union. A tentative therapeutic algorithm is presented. The choice of therapy for CAD should be based on an individual assessment, and patients requiring therapy should be considered for inclusion in clinical trials.

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.

Rise of the planet of rare anemias: An update on emerging treatment strategies

Therapeutic options for rare congenital (hemoglobinopathies, membrane and enzyme defects, congenital dyserythropoietic anemia) and acquired anemias [warm autoimmune hemolytic anemia (wAIHA), cold agglutinin disease CAD, paroxysmal nocturnal hemoglobinuria (PNH), and aplastic anemia (AA)] are rapidly expanding. The use of luspatercept, mitapivat and etavopivat in beta-thalassemia and pyruvate kinase deficiency (PKD) improves transfusion dependence, alleviating iron overload and long-term complications. Voxelotor, mitapivat, and etavopivat reduce vaso-occlusive crises in sickle cell disease (SCD). Gene therapy represents a fascinating approach, although patient selection, the toxicity of the conditioning regimens, and the possible long-term safety are still open issues. For acquired forms, wAIHA and CAD will soon benefit from targeted therapies beyond rituximab, including B-cell/plasma cell targeting agents (parsaclisib, rilzabrutinib, and isatuximab for wAIHA), complement inhibitors (pegcetacoplan and sutimlimab for CAD, ANX005 for wAIHA with complement activation), and inhibitors of extravascular hemolysis in the reticuloendothelial system (fostamatinib and FcRn inhibitors in wAIHA). PNH treatment is moving from the intravenous anti-C5 eculizumab to its long-term analog ravulizumab, and to subcutaneous and oral proximal inhibitors (anti-C3 pegcetacoplan, factor D and factor B inhibitors danicopan and iptacopan). These drugs have the potential to improve patient convenience and ameliorate residual anemia, although patient compliance becomes pivotal, and long-term safety requires further investigation. Finally, the addition of eltrombopag significantly ameliorated AA outcomes, and data regarding the alternative agent romiplostim are emerging. The accelerated evolution of treatment strategies will need further effort to identify the best candidate for each treatment in the precision medicine era.

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.

New Therapies for the Treatment of Warm Autoimmune Hemolytic Anemia

In this review article we provide a critical insight into recent reports evaluating innovative therapies for warm type autoimmune hemolytic anemia (wAIHA). Among published articles, we selected two reports on the use of the proteasome inhibitor bortezomib in association with dexamethasone or rituximab, one study on the spleen tyrosine kinase inhibitor fostamatinib, and a retrospective study on recombinant erythropoietin (rEPO). Among recent scientific communications, we discussed a report on the phosphoinositide 3-kinase delta inhibitor (PI3Kδi) parsaclisib. All studies highlighted a good efficacy although to be confirmed in larger trials and with limitations due to the heterogeneity of wAIHA patients enrolled, the small number of subjects, the concomitant medications allowed, and the short follow-up. Ongoing trials include new B-cell/plasma-cell targeting agents such as the Bruton tyrosine kinase inhibitors ibrutinib and rilzabrutinib, and the anti-CD38 MoAbs daratumumab and its analogue isatuximab. Further drugs in clinical trials target the complement cascade in wAIHA with complement activation, such as the C3 inhibitor pegcetacoplan and the C1q inhibitor ANX005. Finally, an interesting and non-immuno-toxic strategy is to remove the pathogenic autoantibodies via blocking the neonatal Fc receptor, by intravenous nipocalimab and subcutaneous RVT-1401. Such novel agents targeting the several immunopathological mechanisms acting in wAIHA and their possible combination, will increase the therapeutic armamentarium and possibly fill the gap of wAIHA relapsed after/refractory to rituximab. Moreover, these new target therapies may represent a tool for the unmet need of very acute cases.

[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.

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.

Updates on the Diagnosis and Management of Cold Autoimmune Hemolytic Anemia

Cold agglutinin disease represents a form of immune-mediated hemolytic anemia whereby an IgM protein either monoclonal or polyclonal deposits complement on the surface of the red blood cell. Once complement is deposited, the 3rd component of complement is recognized by receptors in the mononuclear phagocyte system resulting in spherocytic extravascular hemolysis. This results in a Coombs positive hemolytic anemia with the peripheral blood film showing agglutination. In many instances, the source is a clonal population of lymphoplasmacytic cells in the bone marrow producing a monoclonal IgM protein. Traditional and emerging therapies directed against the production of the IgM may have a positive effect on hemolytic anemia. Success in the management of cold agglutinin disease with rituximab, fludarabine, bortezomib, and bendamustine has all been reported. Recent studies have demonstrated that the blockade of complement with sutimlimab can stop the hemolysis without the use of systemic chemotherapy.

Clinical and surgical outcomes of splenectomy for autoimmune hemolytic anemia

INTRODUCTION

We investigated short and long-term remission rates after splenectomy in patients with primary and secondary autoimmune hemolytic anemia (AIHA).

METHODS

All adults who underwent splenectomy for primary or secondary AIHA at a single center (2004-2018) were retrospectively reviewed. Short-term response was determined at 30-day postoperatively and long-term at one year. Complete response was defined as hemoglobin > 10 g/dL without hemolysis, transfusions, or need for additional medical therapy for > 6 months.

RESULTS

Short-term complete response was attained in 22 of 36 patients (61%), partial response in 3 (8%), no response in 11 (31%). The response rate at 1 year was complete in 14/36 (39%), partial in 14 (39%), and 8 non-response (22%). At last available follow-up (median 33.1 months (IQR 19-59), 16/37 patients had experienced a complete response (43%), 14 partial response (38%), 7 non-response (19%). 80% of partial responders with primary AIHA required maintenance therapy compared to 100% with secondary AIHA.

CONCLUSION

Splenectomy is associated with short- and long-term improvement in anemia and hemolysis in the majority of patients with AIHA. Immunosuppressants remain important supplemental therapy.

Combination of low-dose rituximab, bortezomib and dexamethasone for the treatment of autoimmune hemolytic anemia

Autoimmune hemolytic anemia (AIHA) therapy may be associated with severe complications such as diabetes, hypertension, obesity, osteoporosis, peptic ulcers, infection, and some other diseases. To reduce those effects, we used low-dose rituximab, bortezomib and dexamethasone (LowR-BD regimen) to treat AIHA. The purpose of this study was to evaluate the efficacy and safety of this regimen.Seven patients with warm AIHA (wAIHA) admitted from March 2020 to October 2020 were treated with LowR-BD regimen: Rituximab 100 mg by intravenous infusion on day 1 combined with bortezomib 1.3 mg/m2 by subcutaneous injection on day 2 plus dexamethasone 20 mg by intravenous infusion on days 2, 3. Clinical efficacy and safety were assessed at the regular reexamination of relevant indicators and follow-up.After 4 cycles of the LowR-BD regimen, the overall response rate (ORR) was 85.71% with a complete response (CR) of 28.57% and a partial response (PR) of 57.14%. After a median follow-up of 12 (range 7-13) months, 5 patients achieved CR and 2 patients had PR status, including 1 patient who did not respond to LowR-BD treatment and reached CR after using methylprednisolone combined with cyclophosphamide. One patient relapsed and achieved PR after retreatment of 2 cycles LowR-BD regimen. The patients tolerated the treatment well and did not complain of apparently adverse reactions except a patient with Sjogren's syndrome and bronchiectasis who developed a severe infection during treatment.Low-dose rituximab combined with bortezomib and dexamethasone is effective and relatively safe in patients with wAIHA.

Bortezomib in autoimmune hemolytic anemia and beyond

Bortezomib is a first-in-class, potent, selective and reversible proteasome inhibitor approved for the treatment of multiple myeloma (MM) and relapsed/refractory mantle cell lymphoma. In these diseases, bortezomib targets plasma cells and lymphocytes reducing tumor burden. Recently, preclinical evidence highlighted its efficacy in reducing long-lived plasma cells responsible of autoantibodies production in several models of autoimmune conditions. These findings paved the way to a number of experiences of bortezomib use in patients with various autoimmune conditions, including autoimmune hemolytic anemia (AIHA). The latter is a nice model of autoimmunity in hematology and is caused by the production of autoantibodies against erythrocytes resulting in various degrees of hemolytic anemia. AIHA is classified in warm and cold forms according to the thermal characteristics of the autoantibody, and first-line treatment mainly relies on steroids for warm cases and the anti-CD20 rituximab for cold ones. Relapsed/refractory cases are still an unmet need, and bortezomib has been proposed in this setting with intriguing efficacy. In this review, we collected available literature on bortezomib use in AIHA and in other immune-mediated hematologic and non-hematologic diseases. Overall, most experiences highlight bortezomib efficacy even in multi-relapsed/refractory patients and suggest to consider its use in AIHA after rituximab failure.

Advanced Cell Mapping Visualizations for Single Cell Functional Proteomics Enabling Patient Stratification

Highly multiplexed single-cell functional proteomics has emerged as one of the next-generation toolkits for a deeper understanding of functional heterogeneity in cell. Different from the conventional population-based bulk and single-cell RNA-Seq assays, the microchip-based proteomics at the single-cell resolution enables a unique identification of highly polyfunctional cell subsets that co-secrete many proteins from live single cells and most importantly correlate with patient response to a therapy. The 32-plex IsoCode chip technology has defined a polyfunctional strength index (PSI) of pre-infusion anti-CD19 chimeric antigen receptor (CAR)-T products, that is significantly associated with patient response to the CAR-T cell therapy. To complement the clinical relevance of the PSI, a comprehensive visualization toolkit of 3D uniform manifold approximation and projection (UMAP) and t-distributed stochastic neighbor embedding (t-SNE) in a proteomic analysis pipeline is developed, providing more advanced analytical algorithms for more intuitive data visualizations. The UMAP and t-SNE of anti-CD19 CAR-T products reveal distinct cytokine profiles between nonresponders and responders and demonstrate a marked upregulation of antitumor-associated cytokine signatures in CAR-T cells from responding patients. Using this powerful while user-friendly analytical tool, the multi-dimensional single-cell data can be dissected from complex immune responses and uncover underlying mechanisms, which can promote correlative biomarker discovery, improved bioprocessing, and personalized treatment development.

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.

Managing complications secondary to Waldenström's macroglobulinemia

Introduction: Waldenström's macroglobulinemia (WM) is a rare lymphoma characterized by the accumulation of IgM-secreting lymphoplasmacytic cells in the bone marrow and other organs. Clinical sequelae relate to direct tissue infiltration by malignant cells but also to the physicochemical and immunological properties of the monoclonal IgM, resulting in a variety of disease-related complications.Areas covered: This narrative review, following a thorough Pubmed search of pertinent published literature, discusses complications secondary to WM, related to direct tumor infiltration, monoclonal IgM circulation, and deposition, as well as other less common ones. The description and pathophysiology of these complications were described together with their specific management strategies and in the context of available treatment options for WM (anti-CD20 monoclonal antibody-based combinations, proteasome inhibitors, BTK inhibitors, and other emerging ones).Expert opinion: The availability of many novel, active and less toxic regimens for the treatment of WM allows the management of the disease with strategies that depend on clinical presentation and disease-related complications, age, toxicity considerations, and presence of comorbidities.

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

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

Bortezomib for treatment-refractory autoimmune haemolytic anaemia following multivisceral transplantation

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

Disease-modifying treatments for primary autoimmune haemolytic anaemia

BACKGROUND

Primary autoimmune haemolytic anaemia (AIHA) is an autoantibody mediated condition characterised by a variable disease course. A myriad of immunomodulatory agents have been employed but there is a paucity of evidence to support their use or compare their effectiveness.

OBJECTIVES

To determine the effects of various disease-modifying treatment modalities in people with AHIHA.

SEARCH METHODS

We searched MEDLINE (Ovid) (1946 to 2021), Embase (Ovid) (1974 to 2021), Latin American and Caribbean Health Sciences Literature (LILACS) (1982 to 2021), and the Cochrane Library (CENTRAL). Clinical trial registries and relevant conference proceedings were also reviewed. Records were included as of 7 March 2021. We did not impose any language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing immunosuppressive or immunomodulatory treatments against no treatment, placebo, or another immunosuppressive or immunomodulatory treatment, for people of all age with idiopathic AIHA.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. The prioritised pre-defined outcomes included complete haematological response at 12 months, frequency of adverse events at two, six and 12 months, partial haematological response at 12 months, overall survival at six and 12 months, relapse-free survival (RFS) at six and 12 months, red blood cel (RBC) transfusion requirement after treatment at 12 months, and quality of life (QOL) as measured by validated instruments at 12 months. Based on data availability, we were only able to perform meta-analysis on frequency of complete haematological response.

MAIN RESULTS

Two trials were included, enrolling a total of 104 adult participants (96 randomised) with warm AIHA in the setting of tertiary referral centres, both comparing the effectiveness between rituximab (375 mg/m2 weekly for four weeks, or 1000 mg for two doses two weeks apart) plus glucocorticoid (prednisolone 1.5 or 1mg/kg/day with taper) and glucocorticoid monotherapy. The average age of participants in the two trials were 67 and 71, respectively. One of the included studies had good methodological quality with low risk of bias, whereas the other study had high risk of performance and detection bias due to lack of blinding. Compared with glucocorticoid alone, adding rituximab may result in a large increase of complete response at 12 months (n = 96, risk ratio (RR) 2.13, 95% confidence interval (CI) 1.34 to 3.40, GRADE: low-certainty evidence). Rates of adverse effects at prespecified time-points were not reported. Limited data on partial haematological response were reported. The evidence is very uncertain about the effect of adding rituximab to glucocorticoids on partial haematological response at 12 months (n = 32; study = 1; RR 3.00, 95% CI 0.13 to 68.57; GRADE very low-certainty evidence). RBC transfusion need at 12 months was reported in one study, with four participants (mean number of packed red cell units 4.0 ± 2.82) from the rituximab group and five participants from the placebo (corticosteroid only) (mean number of packed red cell units 5.6 ± 4.15) group requiring transfusion, indicating very uncertain evidence about the effect of adding rituximab to glucocorticoids (n = 32, RR 0.80, 95% CI 0.26 to 2.45, GRADE very low-certainty evidence). The other study did not report transfusion requirement at prespecified time points but reported no difference in transfusion requirement between the two groups when comparing responders from enrolment to end of response or to the end of study follow-up (34 units versus 30 units, median [range]: 0 [1 to 6] versus 0 [1 to 5], P = 0·81). Overall survival and RFS rates at prespecified time-points were not explicitly reported in either study. Data on QOL were not available.

AUTHORS' CONCLUSIONS

Available literature on the effectiveness of immunomodulatory therapy for primary AIHA is restricted to comparison between rituximab plus glucocorticoid and glucocorticoid alone, in patients with newly diagnosed warm AIHA, calling for need for additional studies. The current result suggests that combinatory therapy with rituximab and glucocorticoid may increase the rate of complete haematological response over glucocorticoid monotherapy.

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.

The Immunomodulatory Effect and Clinical Efficacy of Daratumumab in a Patient With Cold Agglutinin Disease

Daratumumab is a monoclonal antibody directed against the transmembrane glycoprotein CD38 expressed on plasma cells and lymphoplasmocytes, with a proven efficacy in multiple myeloma. Here we show its clinical efficacy in a patient with cold agglutinin disease (CAD) relapsed after multiple lines of therapy. CAD is caused by cold reactive autoantibodies that induce complement mediated hemolysis and peripheral circulatory symptoms. The disease is also characterized by the presence of monoclonal IgM gammopathy and of a lymphoid bone marrow infiltration that benefits from B-cell targeting therapies (i.e., rituximab) but also from plasma cell directed therapies, such as proteasome inhibitors. In the patient described, we also show that daratumumab therapy influenced the dynamics of several immunoregulatory cytokine levels (IL-6, IL-10, IL-17, IFN-γ, TNF-α, TGF-β) indicating an immunomodulatory effect of the drug beyond plasma cell depletion. In addition, we provide a literature review on the use of daratumumab in autoimmune conditions, including multi-treated and refractory patients with autoimmune hemolytic anemia (both CAD and warm forms), Evans syndrome (association of autoimmune hemolytic anemia and immune thrombocytopenia) and non-hematologic autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis.

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.

Waldenström macroglobulinemia: 2021 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

Waldenström macroglobulinemia (WM) is a lymphoplasmacytic lymphoma with immunoglobulin M (IgM) monoclonal protein. Clinical features include anemia, thrombocytopenia, hepatosplenomegaly, lymphadenopathy, and rarely hyperviscosity.

DIAGNOSIS

Presence of IgM monoclonal protein associated with ≥10% clonal lymphoplasmacytic cells in bone marrow confirms the diagnosis. The L265P mutation in MYD88 is detectable in more than 90% of patients and is found in the majority of IgM MGUS patients.

RISK STRATIFICATION

Age, hemoglobin level, platelet count, β₂ microglobulin, LDH and monoclonal IgM concentrations are characteristics that are predictive of outcomes.

RISK-ADAPTED THERAPY

Not all patients who fulfill WM criteria require therapy; these patients can be observed until symptoms develop. Rituximab-monotherapy is inferior to regimens that combine it with bendamustine, an alkylating agent, a proteosome inhibitor, or ibrutinib. Purine nucleoside analogues are active but usage is declining in favor of less toxic alternatives. The preferred Mayo Clinic induction is rituximab and bendamustine.

MANAGEMENT OF REFRACTORY DISEASE

Bortezomib, fludarabine, thalidomide, everolimus, Bruton Tyrosine Kinase inhibitors, carfilzomib, lenalidomide, and bendamustine have all been shown to have activity in relapsed WM. Given WM's natural history, reduction of therapy toxicity is an important part of treatment selection.

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.

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.

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.

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

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

Dynamic Profiling of Antitumor Activity of CAR T Cells Using Micropatterned Tumor Arrays

Cancer immunotherapy based on the engineering of chimeric antigen receptors (CAR) on T cells has emerged as one of the most promising new therapies for patients with B-cell malignancies. Preclinical assessments of essential CAR T cell functions such as trafficking and cytotoxicity are critical for accelerating the development of highly effective therapeutic candidates. However, current tools for evaluating CAR-T functions lack sufficient precision. Here, a micropatterned tumor array (MiTA) is described that enables detailed and dynamic characterization of CAR T cell trafficking toward tumor-cell islands and subsequent killing of tumor cells. It is shown that CAR T cells often merge into large clusters that envelop and kill the tumor cells with high efficiency. Significant differences are also measured between CAR T cells from different donors and between various CAR T cell constructs. Overall, the assay allows for multifaceted, dynamic, high-content evaluation of CAR T trafficking, clustering, and killing and could eventually become a useful tool for immune-oncology research and preclinical assessments of cell-based immunotherapies.

Framing technology challenges associated with improving cancer immunotherapies

Thought leader Jim Heath introduces the Lab on a Chip Immunotherapy thematic collection.

Novel insights into the treatment of complement-mediated hemolytic anemias

Complement-mediated hemolytic anemias can either be caused by deficiencies in regulatory complement components or by autoimmune pathogenesis that triggers inappropriate complement activation. In paroxysmal nocturnal hemoglobinuria (PNH) hemolysis is entirely complement-driven. Hemolysis is also thought to be complement-dependent in cold agglutinin disease (CAD) and in paroxysmal cold hemoglobinuria (PCH), whereas warm antibody autoimmune hemolytic anemia (wAIHA) is a partially complement-mediated disorder, depending on the subtype of wAIHA and the extent of complement activation. The pathophysiology, clinical presentation, and current therapies for these diseases are reviewed in this article. Novel, complement-directed therapies are being rapidly developed. Therapeutic terminal complement inhibition using eculizumab has revolutionized the therapy and prognosis in PNH but has proved less efficacious in CAD. Upstream complement modulation is currently being investigated and appears to be a highly promising therapy, and two such agents have entered phase II and III trials. Of these, the anti-C1s monoclonal antibody sutimlimab has shown favorable activity in CAD, while the anti-C3 cyclic peptide pegcetacoplan appears to be promising in PNH as well as CAD, and may also have a therapeutic potential in wAIHA.

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

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