E2A-PBX1 fusion in adult acute lymphoblastic leukaemia: biological and clinical features

Molecular and cytogenetic studies performed in 305 adult acute lymphoblastic leukaemia (ALL) patients enrolled in the gimema (Gruppo Italiano Malattie EMatologiche dell'Adulto) multicentric protocols identified an E2A-PBX1 fusion and/or t(1;19) in 10 patients (3.3%). All had common ALL, were mostly CyIg+ and were CD34/CD13/CD33-. Nine patients achieved a complete remission (CR); five patients showed a haematological relapse after 7 months (median). Four patients are alive in first CR with a median follow-up of 29 months; three patients are molecularly negative. This abnormality is frequently associated with early treatment failure. E2A-PBX1+ adult ALL should be considered for intensified treatment strategies and monitoring of minimal residual disease.     

Clinical characteristics and treatment outcome of childhood acute lymphoblastic leukemia with the t(4;11)(q21;q23): a collaborative study of 40 cases

The t(4;11)(q21;q23) chromosomal abnormality was identified in 40 (2%) of 1,986 children with newly diagnosed acute lymphoblastic leukemia (ALL). This translocation was associated with female sex (63%), age less than 1 year (60%), hyperleukocytosis (median leukocyte count, 156.5 x 10(9)/L), CD10-/CD19+ B-precursor cell immunophenotype, and myeloid-associated antigen (CD15) expression (63%). Nearly all cases had at least some CD24- blast cells. The CD10-/CD15%/CD19+/CD24/+ phenotype was found in 20 of the 32 t(4;11) cases tested. None of the 40 cases had the cytogenetic finding of hyperdiploidy greater than 50, which is a favorable prognostic feature. For clinical comparison, the t(4;11) cases were divided into three groups according to age at diagnosis: less than 1 year (n = 24), 1 to 9 years (n = 8), and greater than or equal to 10 years (n = 8). Compared with older patients, infants were more likely to have initial central nervous system leukemia (P = .05) and less likely to have pre-B-cell ALL (P = .05). Complete continuous remission has been maintained in only 7 of 24 infants and 2 of 8 patients aged greater than or equal to 10 years, in contrast to 7 of 8 children in the intermediate age group (P = .048). These findings suggest that the t(4;11) is an adverse prognostic feature in these two age groups.     

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.     

Mutations of the p53 and ras genes in childhood t(1;19)-acute lymphoblastic leukemia

We have investigated the alterations of p53 and ras genes including H-, K-, and N-ras genes in 22 acute lymphoblastic leukemia (ALL) cases and five cell lines carrying t(1;19) by use of polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) analysis and direct sequencing. The mutations of the p53 gene were found in 2 of 20 t(1;19)-ALL cases at diagnosis (10%), all of 4 cases at relapse (100%), and 4 of the 5 cell lines (80%). Four of the five patients who died had missense mutations at codons 49, 177, 179, and 248. In cases examined sequentially, one had the same point mutation at codon 179 at both diagnosis and relapse, and another had the same p53 gene mutation at codon 240 both in leukemic cells at relapse and in a cell line derived at that time. The other case had no mutation at diagnosis but had the mutation at codon 177 at relapse and cell lines derived from blast cells at diagnosis, suggesting that a small number of leukemic cells with the p53 gene mutation at diagnosis might have escaped PCR-SSCP analysis. In cell lines, SCMC-L9 had three point mutations in the p53 gene at codons 175, 248, and 358, whereas SCMC-L10 had frame shift at codons 209-211. One case had a rare polymorphism at codon 11. We found only one mutation of the N-ras gene that was a 2-bp substitution of GGT(Gly) to GTC(Val) at codon 13 among 22 t(1;19)-ALL cases and five cell lines. This case showed no mutation of the p53 gene and has had a good course. These results suggest that in t(1;19)-ALL, mutations of the p53 and ras genes are infrequent at diagnosis and that p53 gene alterations may be associated with relapse phase or progression of t(1;19)-ALL.     

Acute lymphoblastic leukaemia.

In acute lymphoblastic leukaemia (ALL) the karyotype provides important prognostic information which is beginning to have an impact on treatment. The most significant structural chromosomal changes include: the poor-risk abnormalities; t(9;22)(q34;q11), giving rise to the BCR/ABL fusion and rearrangements of the MLL gene; abnormalities previously designated as poor-risk; t(1;19)(q23;p13), producing the E2A/PBX1 and rearrangements of MYC with the immunoglobulin genes; and the probable good risk translocation t(12;21)(p13;q22), which results in the ETV6/AML1 fusion. These abnormalities occur most frequently in B-lineage leukaemias, while rearrangements of the T cell receptor genes are associated with T-lineage ALL. Abnormalities of the short arm of chromosome 9, in particular homozygous deletions involving the tumour suppressor gene (TSG) p16(INK4A), are associated with a poor outcome. Numerical chromosomal abnormalities are of particular importance in relation to prognosis. High hyperdiploidy (51-65 chromosomes) is associated with a good risk, whereas the outlook for patients with near haploidy (23-29 chromosomes) is extremely poor. In view of the introduction of risk-adjusted therapy into the UK childhood ALL treatment trials, an interphase FISH screening programme has been developed to reveal chromosomal abnormalities with prognostic significance in childhood ALL. Novel techniques in molecular cytogenetics are identifying new, cryptic abnormalities in small groups of patients which may lead to further improvements in future treatment protocols.     

Distinctive immunophenotypic features of t(8;21)(q22;q22) acute myeloblastic leukemia in children.

Thirty cases of newly diagnosed pediatric acute myeloblastic leukemia (AML) with French-American-British (FAB) M2 morphology were analyzed with cytogenetics and a comprehensive panel of monoclonal antibodies reactive with lymphoid-, natural killer (NK)-cell-, and myeloid-associated antigens. The t(8;21)(q22;q22), or t(8;21;V)(q22;q22;V), translocation was identified in 16 of the 30 cases. Cases with the t(8;21) did not differ significantly from the remaining M2 cases with respect to expression of CD11b, CD13, CD14, CD15, CD33, CD34, CD36, CD41a, CD42b, CDw65, TdT, or HLA-DR. Expression of the B-cell antigen CD19 was detected in 13 of the 16 t(8;21) cases (81%), but in only 1 of the 14 (7%) other M2 cases (P = .00006). Expression of the CD56 NK-cell antigen was also significantly more frequent among t(8;21) cases (63% v 14%; P = .01). Coexpression of CD19 and CD56 was found only in the t(8;21) group (9 of 16 cases, P = .0009). Furthermore, this phenotype was not found in 48 evaluable cases of de novo AML of the FAB M1, M3, M4, M5, or M7 subtypes. The 14 M2 AML cases lacking the t(8;21) commonly expressed CD2 (n = 5) or CD7 (n = 8). However, no case with the t(8;21) expressed either antigen (P = .01 and .0005, respectively). Thus, the t(8;21) biologic subgroup of pediatric M2 AML has distinct immunophenotypic characteristics that distinguish it from other types of de novo AML.     

MICM分型诊断在鉴别M2和M3型急性髓性白血病中的意义

目的：探讨形态学、免疫学、细胞遗传学和分子生物学(MICM)分型诊断在鉴别M2、M3型急性髓性白血病(AML)中的意义。方法：对10例按FAB方案难以区分M2、M3型的AML及2例在基层医院诊断为M3b，用全反式维甲酸(ATRA)治疗未获缓解的患者应用常规细胞遗传学(CC)进行核型分析；以筑巢式逆转录聚合酶链反应(nested—RT—PCR)技术检测PML／RARa及AML1／ETO融合基因转录本；以流式细胞术检测白血病细胞免疫表型。对2例在基层医院诊断为M3b而用ATRA治疗效果不好的病例用间期双色FISH技术检测AML1／ETO融和基因。结果：12例患者中，4例有t(8；21)．AML1／ETO融合基因转录本阳性，确诊为M2；2例有t(15；17)，PML／RARa融合基因转录本阳性，确诊为M3；其他6例患者为正常核型，其中，3例AML1／ETO阳性，确诊为M2；1例PML／RARa阳性，确诊为M3；2例PML／RARa及AML1／ETO均为阴性．1例免疫表型为CD13、CD33^ 、CD34^ 、CD19^ ，最后诊断为M2，另1例免疫表型为CD13^ 、CD33^ 、CD34^ 、CD19^ ．最后诊断为M3。2例行FISH检测的患者AML1／ETO融和基因均为阳性。结论：对形态学无法鉴别M2、M3的AML进一步进行细胞遗传学、分子生物学及免疫学检测，可提高确诊率，并为治疗提供可靠的依据。     

The spectrum of adult B-lymphoid leukemias with BCR-ABL: molecular diagnostic, cytogenetic, and clinical laboratory perspectives

The Philadelphia (Ph) chromosome is characteristic of chronic myelogenous leukemia (CML), but it is also the most frequent cytogenetic abnormality in precursor B-lymphoblastic leukemia (ALL) of adults. The vast majority of CML patients have a BCR-ABL translocation that yields a 210 kD (p210) oncoprotein, whereas adult Ph-positive ALL cases can present with either a p190 or a p210 oncoprotein, or both. Considering that 30% of the patients with CML that progress to blast crisis will have a lymphoblastic presentation, adults presenting with a p210 ALL may have either a de novo ALL or CML presenting for the first time in lymphoblastic phase. To identify the distinguishing features, cases of p190-ALL, p210-ALL, and lymphoblastic CML were compared. In spite of significant overlap between the three entities, a number of features were found to aid in their differentiation. p210-ALL patients present at a younger age with blasts that frequently show loss of expression of CD34, whereas p190-ALL patients present with marked increase in peripheral blast percentage. Interestingly, bone marrow findings characteristic of a myeloproliferative disorder are specific, but are not sensitive for lymphoblastic CML. This study suggests that despite the similarities between these leukemias, p190-ALL, p210-ALL, and lymphoblastic phase CML likely represent three distinct diseases.