CD56 antigenic expression in acute myeloid leukemia identifies patients with poor clinical prognosis

CD56 antigen, a 200-220 kDa cell surface glycoprotein, identified as an iso form of the neural adhesion molecules (NCAM), has been found frequently exp ressed in several lympho-hematopoietic neoplasms including acute myeloid le ukemias (AML). In fact, in these latter diseases it has been reported that the presence of CD56 antigen on the blasts of AML patients with t(8;21) (q2 2;q22), and in those with M3 subtype, identifies a subgroup of patients wit h a more unfavorable prognosis. On the basis of these findings, we evaluate d in 152 newly diagnosed AML patients CD56 surface expression, and results were correlated with morphology, immunophenotype, cytogenetic pattern and c linical outcome. CD56 antigen was recorded in 37 out of 152 cases (24%) and particularly in those with M2 and M5 cytotypes. Moreover, CD56 expression was significantly associated with P-glycoprotein (PGP) hyperexpression (P = 0.007), unfavorable cytogenetic abnormalities (P = 0.008) and with a reduc ed probability of achieving complete remission (CR) (36% vs 68%) (P = 0.035 ) as well as with a shorter survival (6 vs 12 months) (P = 0.032). In concl usion, CD56 antigenic expression on AML cells represents an important adver se prognostic factor and therefore its presence should be regularly investi gated for a better prognostic assessment of AML patients at diagnosis.