Clinical and Biological Significance of CD56 Antigen Expression in Acute Promyelocytic Leukemia

Abstract

The biological significance of CD56 antigen expression in patients with acute promyelocytic leukemia (APL) has been under investigation. We investigated the clinical and biologic features of CD56+APL. In our series, CD56 antigen was positive in 4 of 28 (14%) APL patients. No differences were found regarding age, gender, performance status (PS), initial leukocyte and platelet counts, lactate dehydrogenase (LDH) and fibrinogen (Fbg) levels according to CD56 expression. CD34 antigen was co-expressed in 3 of the 4 patients with CD56+ APL, in contrast to 2 of the 24 patients with CD56- APL (P = .01). Extramedullary relapse occurred in 3 of the 4 patients with CD56+ APL, in contrast to none of the 24 patients with CD56- APL (P = .001). Median remission duration was 4 months in CD56+ APL and was not reached in CD56- APL. The CD56+ population had a shorter remission duration (P < .0001) and disease-free survival (P < .0001). In contrast, no difference was found in overall survival. These results suggested that CD56 expression was associated with the leukemogenetic mutation at the primitive hematopoietic progenitor cell level and extramedullary relapse in APL patients treated with ATRA and chemotherapy.