Response to mercaptopurine for refractory autoimmune cytopenias in children

BACKGROUND: Several treatment strategies are available for children with severe immune thrombocytopenic purpura (ITP) and other immune cytopenias refractory to initial therapies. 6-Mercaptopurine (6MP) is one option, however it has not been well studied in children, especially as a single agent, and no pediatric case series have been reported since 1970. PATIENTS AND METHODS: We reviewed the experience at our institution over 8 years, using 6MP as a steroid sparing treatment for children with ITP, auto-immune hemolytic anemia (AIHA) or Evans syndrome. A total of 29 pediatric patients were treated with 6MP from 2000 to 2007. RESULTS: Response was defined as a rise in hemoglobin by at least 1.5 g/dl and to a level of 10 g/dl or greater in patients treated for anemia, or a platelet count >or=50 x 10(9)/L in patients treated for thrombocytopenia. We found an overall response rate of 83% among all patients. Fourteen percent of patients stopped drug because of side effects. CONCLUSIONS: These results suggest that 6MP can be an effective single-agent treatment for refractory immune cytopenias in children. Prospective studies are warranted to determine long-term efficacy and toxicity and to more clearly define patient populations most likely to respond.