IMMUNOLOGICAL, CYTOGENETIC, AND CLINICAL CHARACTERIZATION OF CHILDHOOD ACUTE LYMPHOBLASTIC-LEUKEMIA WITH THE T(1-19)(Q23-P13) OR ITS DERIVATIVE

Purpose: To evaluate the immunophenotypes, karyotypes, and clinical features, including treatment responses, of patients with childhood acute lymphoblastic leukemia (ALL) and either a t(1;19)(q23;p13) or a der(l9)t(1;19)(q23;p13) translocation. Patients and Methods: The lymphoblasts of 45 patients with a balanced translocation, t(1;19) or its derivative form, der (19)t(1;19), were analyzed by cytogenetic and immunologic methods for differences that might suggest distinct subtypes of ALL. This cohort was treated in four consecutive clinical trials with a median overall follow-up duration of 7 years. Results: A pre-B immunophenotype was found in 10 cases with the balanced t(1;19) and 31 with the unbalanced der(19)t(1;19). The four remaining cases, each with a derivative t(1;19), were classified as early pre-B ALL. The characteristic surface antigen profile of the 41 pre-B cases was CD19(+)/CD10(+)/CD22(+)/CD34(-)/CD20(+/-), whether the translocation was balanced or derivative. In contrast to the four early pre-B cases, which held hyperdiploid karyotypes (> 50 chromosomes), the pre-B cases were primarily pseudodiploid, Comparison of presenting clinical and laboratory features, as well as event-free survival, failed to disclose any differences that would warrant separation of pre-B cases with a balanced or derivative translocation. However, neither subgroup responded to therapy as well as patients with early pre-B ALL, each of whom remains in complete remission for greater than or equal to 3 years. Conclusion: The t(1;19) and the der(19)t(1;19) identify a relatively homogeneous group of patients with pre-B ALL, who can be expected to respond similarly to intensive chemotherapy. The exceptional cases have an early pre-B phenotype with hyperdiploid karyotypes and appear to have favorable prognosis. (C) 1994 by American Society of Clinical Oncology.