Unfavorable presenting clinical and laboratory features are associated with CALLA-negative non-T, non-B lymphoblastic leukemia in children.

Twenty-four (5.7%) of 424 children with newly diagnosed acute lymphoblastic leukemia (ALL) were found to have blast cells that expressed HLA-DR antigens but not the common ALL antigen (CALLA), E-rosette receptors, T-cell antigens, or cytoplasmic or surface immunoglobulins. Each of the eight cases tested expressed the B-cell associated antigen B4, but not B1 or B2 antigen. Myeloid-associated antigens were not present in any of the 10 cases tested. By comparison with common (CALLA+ B-cell precursor) ALL, patients having this immunophenotype were more likely to be children less than 2 yr of age (p less than 0.001), to have higher initial leukocyte counts (p less than 0.001), and to have blast cells with a DNA index less than 1.16 (p = 0.05), a pseudodiploid karyotype (p = 0.01) and a chromosomal translocation (p = 0.003). The presence of any chromosomal translocation in these CALLA- ALL was related to measures of increased leukemic cell burden including higher leukocyte counts, larger liver and spleen sizes and higher serum lactic dehydrogenase levels. While the patients were entered into several treatment arms of two protocols, the CALLA- cases appeared to have lower remission rate (p = 0.06) and shorter event-free survival time (p = 0.05) than did those with common ALL. The association with clinical and laboratory features of known adverse prognostic significance provides some explanation for the poor treatment outcome of CALLA- ALL.