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Activation-induced cytidine deaminase (AICDA) initiates somatic hypermutation and class-switch recombination of immunoglobulin (Ig) genes and induces mutations also in non-Ig genes. AICDA aberrant expression was detected in B-lineage acute lymphoblastic leukaemia (B-ALL), particularly BCR/ABL1+ B-ALL; patients expressing AICDA carried more copy number alterations than 'AICDA-negative' cases. To determine the role of AICDA, AICDA expression and gene expression profiling were studied in adult BCR/ABL1+ B-ALL. Patients displaying the full-length isoform AICDA are characterized by up-regulation of DNA repair/replication and cell cycle genes, suggesting their involvement in the genetic instability of BCR/ABL1+ B-ALL., (© 2011 Blackwell Publishing Ltd.)

Metaphase (M-) and array (A-) Comparative Genomic Hybridization (CGH) were used to investigate 40 cases of T- and 32 of B-cell acute lymphoblastic leukaemia (ALL) with normal/failed cytogenetics. M-CGH was performed in all cases and A-CGH in 10/12 T-ALL cases with uncertain/normal M-CGH results. M-CGH was abnormal in 38/72 cases, with a total of 110 imbalances (60 gains, 50 losses). 25/40 patients with T-ALL (62.5%) showed 77 imbalances, with at least 1 genomic imbalance and a mean of 3 aberrations/patient (range 1-12). 13/32 patients with B-ALL (40.6%) presented 34 imbalances, with a mean of 2.6 imbalances (range 1-8). A-CGH detected 4 more T-ALL cases with genomic imbalances. A-CGH identified NF1/17q11.2 deletion and interphase fluorescence in situ hybridization provided a 10.8% estimated overall incidence of NF1/17q11.2 deletion in T-ALL. In all but one case (6/7) with NF1 deletion, denaturing high-performance liquid chromatography and direct sequencing detected NOTCH1 gene mutations. Three or more imbalances in CGH-positive cases were significantly associated with resistance to treatment and death during or after induction therapy. We suggest that the work-up for ALL at diagnosis should include CGH investigations, particularly when cytogenetics is uninformative, because they may provide potentially valuable information with prognostic and therapeutic implications.

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.

In this study, we examined myeloperoxidase (MPO) gene expression in a series of 31 non-infant pro-B acute lymphoblastic leukaemia (ALL) patients that included 16 cases with the t(4;11) translocation and/or the resultant ALL1/AF4 chimaeric gene. Sixteen out of 31 cases (51%) were MPO mRNA positive/enzyme negative. MPO mRNA was detected in nine out of 16 (56%) and seven out of 15 (47%) patients with and without the ALL1/AF4 fusion transcript respectively. The comparative study between MPO mRNA positive and negative cases showed statistically significant differences with regard to age and white blood cell (WBC) count, and was 39.5 years vs. 26.3 years (P = 0.016) and 71.4 x 10(9)/l vs. 157.8 x 10(9)/l (P = 0.046) in the MPO mRNA positive and negative groups respectively. The correlation analysis between MPO mRNA expression, age, WBC count and leukaemic relapse according to the presence/absence of the ALL1/AF4 fusion showed that the statistically significant differences observed in the whole group were related mostly to the ALL1/AF4-positive ALL patients. In fact, in this latter group, the mean WBC count and patients' age were 85 +/- 79 x 10(9)/l vs. 289.8 +/- 102 x 10(9)/l (P = 0.0005) and 44.8 +/- 15.3 years vs. 26.7 +/- 13.7 years (P = 0.01) in patients with and without MPO mRNA expression respectively. It appears, therefore, that the assessment of MPO mRNA expression enables a further dissection of leukaemia heterogeneity in apparently homogeneous genetic/immunophenotypic ALL subsets.

We prospectively studied the chimaerism status in the bone marrow (BM) and peripheral blood (PB) of 23 patients receiving umbilical cord (UCB, 14 cases) or BM (nine cases) transplants from unrelated donors by PCR amplification of four individual-specific VNTR genetic loci. Haematological engraftment, with persistent full donor pattern. was observed in 10/14 (72%) patients receiving UCB and in 9/9 (100%) patients transplanted with marrow from an unrelated donor (MUD). In contrast, the remaining four patients converted to an autologous pattern. Three out of these four patients had an early autologous haematological reconstitution reaching a neutrophil level >0.5 x 10(9)/l at days 27, 33 and 37 after transplant, respectively. In all three of these patients, chimaerism analysis demonstrated an early appearance of donor cells (i.e. within 35 d after UCB transplant) showing a transient full donor (one case) or mixed chimaerism condition (two cases). Despite the early autologous haemopoietic reconstitution, one of the three patients died of GVHD at day 60, which was explained by the demonstration of low levels of donor lymphoid cells. In the MUD group all nine patients converted to a persistent full donor pattern with haematological reconstitution, accompanied in two of them by transient mixed chimaerism lasting to days 60 and 270 after transplant. Our data show that monitoring of chimaerism may predict graft failure with or without early autologous haemopoietic reconstitution in patients receiving unrelated UCB transplants. Furthermore, chimaerism analysis may identify, in patients with autologous reconstitution, those at risk of severe GVHD in whom immunosuppressive therapy should not be discontinued.

In this study we investigated the presence of structural lesions in the ALL-1, p53 and p16 (cyclin-dependent kinase 4 inhibitor) genes in leukaemic cells obtained from 22 patients with infant acute leukaemia (aged < 18 months). Of these, 18 cases were classified as acute lymphoblastic leukaemia (ALL) and four as acute myeloid leukaemia (AML). Tumour DNAs were analysed by a combination of Southern blot. polymerase chain reaction (PCR), single-strand conformation polymorphism (SSCP), and direct sequence analyses. The results showed ALL-1 gene rearrangements in 15/22 (68%) cases, p53 gene mutations in 5/22 (26%), and a homozygous deletion of p16 in a single T-ALL case. p53 and p16 alterations were all found in the group of patients with ALL-1 gene rearrangements. p53 mutations were more often associated with a myeloid phenotype (3/5). In summary, multiple molecular alterations were found in 6/15 (40%) infant acute leukaemias with ALL-1 rearrangements. As to the clinical course, patients with additional lesions had similar clinical outcome with respect to patients with ALL-1 gene rearrangement as the sole genetic aberration. This may support the hypothesis that ALL-1 alterations are genetic events per se sufficient to confer a fully malignant phenotype to the leukaemic clone.

In this study we used reverse transcriptase-polymerase chain reaction (RT-PCR) for the longitudinal monitoring of minimal residual disease in 12 patients with All-1/AF-4 positive ALL. Of these, seven also showed at presentation a typical t(4;11) cytogenetic translocation. Seven patients were infants <18 months of age and five were adults. Eleven patients were treated with high-dose intensive induction and consolidation chemotherapy without bone marrow transplantation and one received conservative treatment due to poor performance status. Three had resistant disease, four relapsed within 12 months after achieving complete remission, and five are in continuous complete remission (CCR) at 32, 39, 52, 53 and 61 months from diagnosis, respectively. The sequential analysis of the ALL-1/AF-4 hybrid transcript showed a persistently negative RT-PCR in the five CCR long-term survivors. The PCR analysis resulted persistently positive in the remaining seven cases, including the four cases who relapsed after the achievement of clinical CR. These data emphasize the clinical relevance of PCR monitoring analysis in t(4;11) ALL patients and should be considered in order to better determine variable post-remission treatment according to risk prediction.