Predictable prognostic factor of CD56 expression in patients with acute myeloid leukemia with t(8:21) after high dose cytarabine or allogeneic hematopoietic stem cell transplantation.

CD56 expression in acute myeloid leukemia (AML) has been associated with extramedullary leukemia and multidrug resistance, but its clinical and prognostic significance has not been clearly identified. This study examined CD56 expression in 37 adult de novo AML patients with t(8:21). CD56 was expressed in 25 cases (67.6%). Complete remission (CR) rates were similar in both groups (91.7% vs. 88.7%; P = 0.73), but the relapse rates differed considerably (60% vs. 25%; P = 0.02). The median duration of disease-free survival (DFS) was significantly shorter in the CD56+ (median, 12.2 +/- 6.4 months) than in the CD56- group (median, not reached) (P = 0.02). In addition, the median duration of survival differed significantly in the CD56+ group (median, 14.9 +/- 4.4 months) compared with the CD56- group (median, not reached) (P = 0.01). Of the fifteen transplanted patients who achieved CR, allogeneic HST was performed from their siblings. The median duration of DFS in the CD56+ patients was significantly shorter than the CD56- patients (median, 24.4 +/- 4.5 months vs. median, not reached; P = 0.02). We concluded that CD56 expression correlates to a reduced DFS and survival for AML patients with t(8:21), including those patients who underwent transplantation.