Expression of CD20 in B-cell Precursor Acute Lymphoblastic Leukemia and Its Correlation with Clinical Outcomes

Objective To determine whether expression of CD20 is associated with clinical outcomes of childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Methods 271 newly diagnosed childhood BCP-ALL during January 2009 to May 2013 were enrolled in this study.The patients were treated in line with the Chinese Childhood Leukemia Group ALL 2008 protocol (CCLG-ALL 2008). The clinical feature, early therapeutic response and clinical outcomes of the patients with a CD20 positive (CD20⁺BCP) expression were compared with those with a CD20 negative (CD20^-BCP) expression. Results CD20⁺BCP accounted for 45.76% (124 cases) of all participants. There were no significant differences between CD20⁺BCP and CD20^-BCP patients in gender distribution, age,WBC counts when diagnosis was made, proportion of prednisone poor responders, and distribution of risk categories (P>0.05). Patients of 10 years or older comprised 25.81% and 14.29% of CD20⁺BCP and CD20^-BCP patients, respectively (P=0.017). Pro-B and pre-B cases accounted for 43.55% and 59.86% of CD20⁺BCP patients respectively, compared with 56.45 and 40.14% in CD20^-BCP patients (P=0.007). CD20⁺BCP patients had 12.20% Philadelphia positive ALL and 6.50% BCP-ALL with TEL-AML1 fusion gene,compared with 4.86%(P=0.03) and 18.06% (P=0.005) in those of CD20^-BCP. No significant differences were found between the two groups of patients in 15-day (77.50% vs. 74.13%, P=0.525) and 33-day (95.04% vs. 95.83%, P=0.757) complete remission rates. No significant differences (P>0.05) were found in predicted 4-year event-free survival 〔EFS (78.00%±4.96%) vs. (79.05%±5.40%)〕 and predicted 4-year overall survival 〔OS (83.01%±6.13%) vs. (93.64%±2.46%)〕 between the two groups of patients either. Conclusion CD20 positivity was not found to be associated with worse prognosis of children with BCP-ALL. More studies are needed to validate the correlation between CD20 and unfavorable outcomes in BCP-ALL.