Nonimmune Hemolysis in Myelodysplastic Syndromes

Anemia is identified in most patients with myelodysplastic syndromes (MDS), often due to ineffective red cell production. Rarely, patients with MDS have increased red cell destruction, owing to hemolysis. From a mechanistic standpoint, autoimmune hemolysis is rarely identified, as is an acquired hemoglobinopathy (acquired alpha thalassemia). To better characterize prevalence and clinical and molecular associations among MDS patient with hemolysis, investigators conducted a retrospective single-center analysis of 519 patients with MDS and measured haptoglobin. The 54 patients (10%) with haptoglobin <10 mg/dL were defined as having hemolysis. Only 13% of patients with low haptoglobin had a positive Coombs test.

Patients with MDS-hemolysis, compared with those without, were younger and had lower platelet counts. Responses to erythropoietin-stimulating agents also were slightly lower (16% vs. 30%; P=0.2). However, there was a trend suggesting improved response to hypomethylating agents (70% vs. 45%; P=0.05). Finally, there was a nonsignificant trend towards reduced median overall survival in the MDS-hemolysis group (30.8 vs. 38.5 months).

The molecular profile significantly differed between patients with MDS-hemolysis and those without: U2AF1 and EZH2 hotspot mutations were more commonly identified in patients with hemolysis (P<0.05). In particular, patients with MDS-hemolysis harbored a U2AF1 serine 34 hotspot mutation.