Immunophenotypic classification of leukemia has important therapeutic and prognostic implications. In B-cell malignancies, CD20 and CD22 also represent therapeutic targets. CD20 expression in adult patients with B lineage ALL has been associated with a poor prognosis. The data are conflicting in the pediatric population and may be impacted by the type of therapy employed. A recent study of pediatric patients treated in consecutive St Jude Children’s Research Hospital Total Therapy ALL regimens observed excellent outcomes and no prognostic significance for CD20 expression (

Jeha et al.
Blood
2006
,
108
:
3302
–3304
). We retrospectively analyzed 50 consecutive patients aged 4 months to 28 years with precursor-B ALL treated with contemporary risk-adapted BFM-based ALL regimens for whom flow cytometric, genetic, and early response data were available. Cases were defined as positive for CD20 and/or CD22 expression if surface expression was identified in more than 20% of leukemic blasts. We found that CD22 was expressed at high levels (68–99%) in all patients evaluated. CD20 expression was positive in 27 (54%) of patients. CD20 expression did not correlate with known NCI prognostic features, including presenting white blood count or age. All 3 patients with BCR-ABL translocation ALL were CD20 positive. Consistent with previously published data, neither of the 2 patients with MLL-AF4 translocation were CD20 positive. There was no association of CD20 expression with trisomy 4/10/17 or TEL-AML1 status. We did not observe an association between CD20 expression and rapid early bone marrow response to therapy at day 8 or 15; 47/50 patients were in remission at day 29. At a median follow-up time of 48 months 46/50 patients were alive without relapse. These limited data do not suggest a strong association between CD20 expression and known prognostic features or early treatment response in pediatric precursor-B ALL treated with contemporary BFM therapy platforms. However, our findings of frequent expression of CD22 on precursor-B ALL blasts from children supports its consideration as a target for immunotherapy approaches in high risk or relapsed disease.

Topics:
burkitt's lymphoma, cd20 antigens, leukemia, b-cell, acute, pediatrics, cancer, disease remission, follow-up, immunotherapy, leukemia, bcr/abl translocation

Disclosures: No relevant conflicts of interest to declare.

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2008, The American Society of Hematology
2008
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