Introduction
Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell disorder characterized by overlapping features of myelodysplastic syndromes and myeloproliferative neoplasms. Autoimmune and inflammatory diseases (AID) are classical complications of CMML, occurring in up to 20% of patients in monocentric retrospective studies (1,2). These complications can precede the onset of CMML, be concomitant to the diagnosis or occur later during the course of the disease. CMML-associated AID are as various as systemic vasculitis, connective tissue diseases, skin diseases such as neutrophilic dermatosis, polychondritis or seronegative inflammatory arthritis (1–3). Autoimmune cytopenias (AIC) have also been reported, encompassing mainly immunologic thrombocytopenias and AIHA (2–4). Based on the optimal binding temperature of autoantibodies, AIHA can be classified into three categories, warm AIHA (wAIHA), cold AIHA and mixed forms AIHA. The few reported cases of CMML-associated AIHA were wAIHA and their rarity precludes definite therapeutic recommendations to be drawn. As with AIHA observed in other settings, frontline treatment is mainly based on corticosteroids but steroid dependence is frequent. Efficacy of subsequent treatments has not been reported, conversely to CMML-associated ITP where the second line treatments used in primary ITP have proved efficacy. Eculizumab (Soliris®, Alexion Pharmaceuticals) is a humanized monoclonal antibody that binds with high affinity to the C5 complement protein and blocks its cleavage in two components: C5a and C5b (5). It is approved for the treatment of paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome. Because of the pivotal role of complement in cold agglutinin disease (CAD), eculizumab has also been evaluated in this disease and provided responses in rituximab refractory cases. Eculizumab has also been used in anecdotal cases of wAHAI but none of them were associated with CMML. We report herein the efficacy of eculizumab in a case of life-threatening refractory wAIHA associated with CMML.