A comprehensive genetic classification of adult acute lymphoblastic leukemia (ALL): analysis of the GIMEMA 0496 protocol.

The Gruppo Italiano Malattie Ematologiche dell'Adulto (GIMEMA) 0496 protocol, through the central handling of bone marrow samples at presentation, allowed us to combine cytogenetic and molecular information on a large series of adults with acute lymphoblastic leukemia (ALL) treated homogeneously, enabling us to define as broadly as possible their genetic profile and to determine the impact on outcome of the cytogenetic-molecular signature. Of 414 patients centrally processed, 325 were considered for the categorization into the following cytogenetic-molecular subgroups: normal, t(9;22)/BCR-ABL, t(4;11)/MLL-AF4, t(1;19)/E2A-PBX1, 9p/p15-p16 deletions, 6q deletions, miscellaneous structural abnormalities, and hyperdiploid. The inclusion into each subgroup was based on a hierarchical approach: molecular abnormalities with adverse prognosis had precedence over karyotypic changes with less-defined prognosis and the latter over ploidy. Patients without abnormalities and those with isolated 9p/p15-p16 deletions showed a relatively favorable outcome (median disease-free survival [DFS], > 3 years). The t(9;22)/BCR-ABL, t(4;11)/MLL-AF4, t(1; 19)/E2A-PBX1 defined a group with dismal prognosis (median DFS, 7 months), whereas 6q deletions, miscellaneous aberrations, and hyperdiploidy predicted an intermediate prognosis (median DFS, 19 months). This study highlights the importance of a combined cytogenetic-molecular profiling of adult ALL at presentation as a critical independent determinant of their outcome, providing further evidence of the necessity of a risk-adapted therapeutic algorithm for an optimal management of these patients.

A new complex rearrangement involving the ETV6, LOC115548, and MN1 genes in a case of acute myeloid leukemia.

A new complex rearrangement involving chromosome bands 5q13, 12p13, 22q11, and 3q12 was identified and characterized in a patient with acute myeloid leukemia. Fluorescence in situ hybridization showed the involvement of the ETV6 gene in 12p13. ETV6 primers were specifically designed for 3'- and 5'-RACE-PCR experiments, which led to the identification of the other two rearranged genes. The derivative chromosome 5 harbored a fusion of the ETV6 sequence with that of the LOC115548 gene. The two genes were placed in opposite orientation and did not encode a fusion protein. On the derivative chromosome 12, ETV6 was fused to the MN1 gene on chromosome 22. Also in this case, the insertion, within the MN1 sequence, of a portion of chromosome 3 prevented the formation of a fusion protein. Finally, the derivative chromosome 22 contained the 3' portions of both LOC115548 and MN1, and no fusion transcript with coding potential could be predicted. In conclusion, all chromosome breakpoints led to the truncation of the three involved genes in the absence of predicted fusion proteins. This study lends further support to the hypothesis that gene disruption resulting in either loss of function or haploinsufficiency may be relevant in acute myeloid leukemia pathogenesis.

Trisomy 13 in a patient with common acute lymphoblastic leukemia: description of a case and review of the literature.

Trisomy 13 occurring as a single cytogenetic abnormality has been associated with undifferentiated or biphenotypic acute leukemias and with an adverse prognostic outcome. We describe for the first time a case of B-cell common acute lymphoblastic leukemia (ALL) with trisomy 13 at diagnosis in an 18-year-old boy. The leukemic cells did not express myelocytic or T-cell associated antigens and no molecular abnormalities were detected. Following treatment, according to the GIMEMA ALL 0496 protocol, the patient achieved a brief (2 months) complete remission. At relapse, cytogenetic analysis showed karyotypic evolution that included two novel subclones carrying a del(6q), a del(7q), and an add(17q) in association with trisomy 13. In addition, immunophenotypic analysis revealed the coexpression of the CD33 and CD7 antigens on common ALL blasts, in accordance with other reported cases that displayed a predominant biphenotypic leukemia profile. The patient failed to obtain a second remission and died soon after due to infective complications. This report indicates that trisomy 13 can be found also in B-lineage ALL and underlines that this cytogenetic abnormality may identify a subgroup of male patients with clonal evolution potential and an adverse clinical outcome.