[Rituximab in cold agglutinin disease]

Cold agglutinin disease: current challenges and future prospects

Cold agglutinin disease (CAD) is a complement-dependent, classical pathway-mediated immune hemolytic disease, accounting for 15–25% of autoimmune hemolytic anemia, and at the same time, a distinct clonal B-cell lymphoproliferative disorder of the bone marrow. The disease burden is often high, but not all patients require pharmacological treatment. Several therapies directed at the pathogenic B-cells are now available. Rituximab plus bendamustine or rituximab monotherapy should be considered first-line treatment, depending on individual patient characteristics. Novel treatment options that target the classical complement pathway are under development and appear very promising, and the C1s inhibitor sutimlimab is currently being investigated in two clinical Phase II and III trials. These achievements have raised new challenges and further prospects, which are discussed. Patients with CAD requiring therapy should be considered for clinical trials.

[Digital necrosis revealing cold agglutinin disease: Treatment with rituximab]

BACKGROUND

Digital necrosis is rarer than lower limb necrosis and constitutes a medical or surgical emergency. Etiological evaluation is required. Cold agglutinin disease is a cause of digital necrosis but diagnosis is difficult.

PATIENTS AND METHODS

Herein we report the case of a 57-year-old man presenting recent paroxysmal acrosyndrome of the left hand subsequently complicated by digital necrosis following occupational exposure to cold in his work as a forklift driver. After etiological evaluation, a diagnosis of primary cold agglutinin disease was made. Intravenous rituximab and topical treatment resulted in complete healing.

DISCUSSION

Cold agglutinin disease is a rare type of auto-immune hemolytic anemia. Following exposure to cold, paroxysmal cutaneous signs are frequent. The disease may be either primary or secondary with B-cell lymphoproliferative disorder, auto-immune disease or infection. A thorough workup is required. To date, the treatment combining the best positive response rate and good safety is rituximab in weekly perfusions over a 1-month period.

New treatment options for immune-mediated hematological disorders

In recent years, there has been a tremendous increase in the number of clinical studies with monoclonal antibodies and small molecules in the treatment of hematological malignancies. Clinical observations have shown that some of these molecules may also aid in the treatment of immune-mediated hematological disorders. Moreover, immunotherapy has become an important treatment cornerstone in other, non-hematological, auto-immune diseases. This paper reviews the current state of the use of these new molecules in the treatment of the most frequently encountered immune-mediated hematological disorders: auto-immune hemolytic anemia (AIHA), idiopathic thrombocytopenic purpura (ITP), and thrombotic thrombocytopenic purpura (TTP).

Primary chronic cold agglutinin disease: an update on pathogenesis, clinical features and therapy

Chronic cold agglutinin disease (CAD) is a subgroup of autoimmune hemolytic anemia. Primary CAD has traditionally been defined by the absence of any underlying or associated disease. The results of therapy with corticosteroids, alkylating agents and interferon-a have been poor. Cold reactive immunoglobulins against erythrocyte surface antigens are essential to pathogenesis of CAD. These cold agglutinins are monoclonal, usually IgMκ auto antibodies with heavy chain variable regions encoded by the V_H4-34 gene segment. By flowcytometric and immunohistochemical assessments, a monoclonal CD20⁺κ⁺B-lymphocyte population has been demonstrated in the bone marrow of 90% of the patients, and lymphoplasmacytic lymphoma is a frequent finding. Novel attempts at treatment for primary CAD have mostly been directed against the clonal B-lymphocytes. Phase 2 studies have shown that therapy with the chimeric anti-CD20 antibody rituximab produced partial response rates of more than 50% and occasional complete responses. Median response duration, however, was only 11 months. In this review, we discuss the clinical and pathogenetic features of primary CAD, emphasizing the more recent data on its close association with clonal lymphoproliferative bone marrow disorders and implications for therapy. We also review the management and outline some perspectives on new therapy modalities.

Management of cold haemolytic syndrome

Most haemolytic disease is mediated by immunoglobulin G (IgG) antibodies and leads to red blood cell destruction outside of the circulatory system. However, rare syndromes, such as paroxysmal cold haemoglobinuria, show IgG antibodies causing intravascular destruction. Haemolysis may also occur because of immunoglobulin M antibodies. Historically, these antibodies have been termed 'cold agglutinins' because they cause agglutination of red blood cells at 3 degrees C. Cold agglutinin haemolytic anaemia has been associated with a number of autoimmune and lymphoproliferative disorders, and its management differs substantially from warm antibody-mediated haemolytic anaemia. This review of cold haemolytic syndromes describes new therapies and clinical strategies to determine a correct diagnosis.

Cold Agglutinin Disease and Cryoglobulinemia

Cold agglutinin disease is a form of direct, extravascular, antiglobulin-positive hemolysis. In vivo, immunoglobulin (Ig) M fixes complement molecules to the red cell membrane. Successive passages through the mononuclear phagocyte system result in loss of red cell membrane. The resultant spherocytes lose resiliency and are ultimately lost from the circulation extravascularly. The high concentration of complement molecules on the red cell surfaces makes this syndrome resistant to the standard therapies for immune-mediated hemolysis. Rituximab has been reported to reduce the severity of hemolysis. Type II cryoglobulins are composed of a monoclonal IgM and a polyclonal IgG. These complexes have rheumatoid factor activity and can produce immune-complex vasculitis. The target organs are the skin, nerves, kidney, liver, and joints. More than 80% of patients have evidence of hepatitis C infection. Interferon and interferon plus ribavirin have been shown to produce serologic responses. When vasculitis is active, corticosteroids are often required to permit healing of ulcers in the skin or to treat the membranoproliferative glomerulonephritis that is seen, thereby preventing loss of renal function. Rituximab therapy has been found to be effective in mixed cryoglobulinemia, with decreases in cryoglobulin values and improvement in complement values.

Monoclonal antibodies in the treatment of autoimmune cytopenias

In recent years, clinical studies have been undertaken with selected monoclonal antibodies (MoAbs) in the treatment of several hematological diseases, especially in malignant disorders. However, some clinical observations indicate that MoAbs may be an important alternative for the conventional therapy of some autoimmune disorders. Two MoAbs directed against CD20 antigen (rituximab, Rituxan, Mabthera) and CD52 antigen (alemtuzumab, Campath-1H) seem to be especially useful for this purpose. Autoimmune cytopenias have been investigated in the last few years with positive preliminary results. Rituximab seems to be an effective and safe agent for the treatment of immune thrombocytopenias, autoimmune hemolytic anemia, cold agglutinin disease and pure red cell aplasia. Although the case series are small, rituximab seems to be an effective and safe agent for the treatment of these diseases. Clinical experience with alemtuzumab in patients with autoimmune cytopenias is even more limited than with rituximab. However, preliminary results indicate that further studies with this MoAb are warranted. A longer follow-up and the studies on larger number of patients are needed to determine the real value of these new approaches in autoimmune cytopenias. Recent experiences with the use of MoAbs in treatment of these diseases are the subject of this review.