Prognostic relevance ofTLX3 (HOX11L2)expression in childhood T-cell acute lymphoblastic leukaemia treated with Berlin–Frankfurt–Münster (BFM) protocols containing early and late re-intensification elements

Cytogenomic characterization of pediatric T-cell acute lymphoblastic leukemia reveals TCR rearrangements as predictive factors for exceptional prognosis

BACKGROUND

T-cell acute lymphoblastic leukemia (T-ALL) represents a rare and clinically and genetically heterogeneous disease that constitutes 10-15% of newly diagnosed pediatric ALL cases. Despite improved outcomes of these children, the survival rate after relapse is extremely poor. Moreover, the survivors must also endure the acute and long-term effects of intensive therapy. Although recent studies have identified a number of recurrent genomic aberrations in pediatric T-ALL, none of the changes is known to have prognostic significance. The aim of our study was to analyze the cytogenomic changes and their various combinations in bone marrow cells of children with T-ALL and to correlate our findings with the clinical features of the subjects and their treatment responses.

RESULTS

We performed a retrospective and prospective comprehensive cytogenomic analysis of consecutive cohort of 66 children (46 boys and 20 girls) with T-ALL treated according to BFM-based protocols and centrally investigated cytogenetics and immunophenotypes. Using combinations of cytogenomic methods (conventional cytogenetics, FISH, mFISH/mBAND, arrayCGH/SNP and MLPA), we identified chromosomal aberrations in vast majority of patients (91%). The most frequent findings involved the deletion of CDKN2A/CDKN2B genes (71%), T-cell receptor (TCR) loci translocations (27%), and TLX3 gene rearrangements (23%). All chromosomal changes occurred in various combinations and were rarely found as a single abnormality. Children with aberrations of TCR loci had a significantly better event free (p = 0.0034) and overall survival (p = 0.0074), all these patients are living in the first complete remission. None of the abnormalities was an independent predictor of an increased risk of relapse.

CONCLUSIONS

We identified a subgroup of patients with TCR aberrations (both TRA/TRD and TRB), who had an excellent prognosis in our cohort with 5-year EFS and OS of 100%, regardless of the presence of other abnormality or the translocation partner. Our data suggest that escalation of treatment intensity, which may be considered in subsets of T-ALL is not needed for nonHR (non-high risk) patients with TCR aberrations.

Epigenetic Silencing Affects l-Asparaginase Sensitivity and Predicts Outcome in T-ALL

PURPOSE

Biological explanation for discrepancies in patient-related response to chemotherapy depending on the underlying oncogenic events is a promising research area. TLX1- or TLX3-deregulated T-cell acute lymphoblastic leukemias (T-ALL; TLX1/3⁺) share an immature cortical phenotype and similar transcriptional signatures. However, their prognostic impacts differ, and inconsistent clinical outcome has been reported for TLX3. We therefore hypothesized that the overlapping transcriptional profiles of TLX1⁺ and TLX3⁺ T-ALLs would allow identification of candidate genes, which might determine their distinct clinical outcomes.

EXPERIMENTAL DESIGN

We compared TLX1⁺ and TLX3⁺ adult T-ALL outcome in the successive French national LALA-94 and GRAALL-2003/2005 multicentric trials and analyzed transcriptomic data to identify differentially expressed genes. Epigenetic regulation of asparagine synthetase (ASNS) and in vitro l-asparaginase sensitivity were evaluated for T-ALL cell lines and primary samples.

RESULTS

We show that TLX1⁺ patients expressed low levels of ASNS when compared with TLX3⁺ and TLX-negative patients, due to epigenetic silencing of ASNS by both DNA methylation and a decrease of active histone marks. Promoter methylation of the ASNS gene correlated with l-asparaginase sensitivity in both T-ALL cell lines and patient-derived xenografts. Finally, ASNS promoter methylation was an independent prognostic factor for both event-free survival [HR, 0.42; 95% confidence interval (CI), 0.24-0.71; P = 0.001] and overall survival (HR, 0.40; 95% CI, 0.23-0.70; P = 0.02) in 160 GRAALL-2003/2005 T-ALL patients and also in an independent series of 47 LL03-treated T lymphoblastic lymphomas (P = 0.012).

CONCLUSIONS

We conclude that ASNS methylation status at diagnosis may allow individual adaptation of l-asparaginase dose.

Clinical significance of cytogenetic changes in childhood T-cell acute lymphoblastic leukemia: results of the multicenter group Moscow-Berlin (MB)

The prognostic significance of genetic lesions in T-cell ALL still needs to be elucidated. Karyotyping and FISH were performed in samples from 120 patients with T-cell ALL registered in the trial Moscow-Berlin 2008. Most frequent rearrangements were TLX3 (N = 29; 24%) and TAL1 (N = 18; 15%), followed by KMT2A (N = 6; 5%), TLX1 (N = 5; 4.2%), and 11p13-15 (N = 5; 4.2%). In 16.7% of patients, the karyotype was normal, and in 30.8% 'other' aberrations were seen. Patients with a normal karyotype, TAL1, or KMT2A rearrangements had the most favorable outcome (probability of event free survival (pEFS): 82% ± 6%), while prognosis for patients with TLX3 and TLX1 rearrangements and 'other' aberrations was less favorable (pEFS: 62% ± 6%). Worst outcome was observed for five patients with 11p rearrangements (pEFS: 20% ± 18%). In summary, three subgroups of patients with T-cell ALL with significantly different outcomes could be defined by cytogenetic profiling.

MEF2C-dysregulated pediatric T-cell acute lymphoblastic leukemia is associated with CDKN1B deletions and a poor response to glucocorticoid therapy

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological disease in which multiple genetic abnormalities cooperate in the malignant transformation of T-lymphoid progenitors. Although in pediatric T-ALL, CDKN1B deletions occur in about 12% of the cases and represent one of the most frequent copy number alterations, neither their association with other genetic alterations nor the clinical characteristics of these patients have been determined yet. In this study, we show that loss of CDKN1B increased the prevalence of cell cycle regulator defects in immature T-ALL, usually only ascribed to CDKN2A/B deletions, and that CDKN1B deletions frequently coincide with expression of MEF2C, considered as one of the driving oncogenes in immature early T-cell precursor (ETP) ALL. However, MEF2C-dysregulation was only partially associated with the immunophenotypic characteristics used to define ETP-ALL. Furthermore, MEF2C expression levels were significantly associated with or may even be predictive of the response to glucocorticoid treatment.

Recurrent Cytogenetic Abnormalities in Acute Lymphoblastic Leukemia

Both B-cell and T-cell acute lymphoblastic leukemia (ALL) exhibit recurrent cytogenetic alterations, many with prognostic implications. This chapter overviews the major recurrent categories of cytogenetic abnormalities associated with ALL, with an emphasis on the detection and characterization of these cases by G-band and FISH analyses.

Update on biology and treatment of T-cell acute lymphoblastic leukaemia

PURPOSE OF REVIEW

In this article, new insights into the clinical and biological features of paediatric T-lineage acute lymphoblastic leukaemia (ALL) and their impact on treatment outcome have been described.

RECENT FINDINGS

T-lineage ALL has considerable phenotypic and biological heterogeneity. Compared with B-lineage ALL, the prognostic significance of the presenting white cell count is weaker and the rate of decline in minimal residual disease is slower in patients with T-lineage ALL. Contemporary, response stratified, treatment protocols incorporating dexamethasone have been associated with significant improvements in outcomes and demonstrated that cranial radiotherapy is not essential for preventing central nervous system relapse. Relapse risk remains higher than for B-lineage ALL and outcome after relapse is poor. Early T-precursor phenotype and genetic abnormalities such as activating ABL1 fusions, NOTCH1/FBXW7, and cytosolic 5'-nucleotidase II gene mutations identify patient groups who may benefit from alternative treatment. New agents such as nelarabine, bortezomib, and clofarabine may be effective in preventing unsalvageable relapses identified by slow response to first-line therapy.

SUMMARY

Around 85% of children and young people with T-lineage ALL are cured by current therapy. Further improvements in outcome can be expected from genetic profile and response-targeted therapeutics.

The inferior prognosis of adolescents with acute lymphoblastic leukaemia (ALL) is caused by a higher rate of treatment-related mortality and not an increased relapse rate--a population-based analysis of 25 years of the Austrian ALL-BFM (Berlin-Frankfurt-Münster) Study Group

Adolescents aged 15-18 years with acute lymphoblastic leukaemia (ALL) have been historically reported to have a poorer prognosis than younger children. We retrospectively analysed the characteristics and outcome of 67 adolescents included in a population-based series of 1125 non-infant cases that were enrolled into four Austrian ALL-BFM (Berlin-Frankfurt-Münster) multicentre trials at paediatric institutions within a 25-year period. Five-year event-free survival (EFS) and overall survival (OS) were 66 ± 6% and 76 ± 5% respectively, and thus lower than in younger children (83 ± 1%, 91 ± 1%; P < 0·001). This was not due to an increased cumulative incidence of relapse (CIR) (5-year CIR: 19 ± 5% vs. 13 ± 1%; P = 0·284), but due to an increased incidence of treatment-related death [5-year cumulative incidence of death (CID): 15 ± 4% vs. 3 ± 0%; P < 0·001] as a first event. Furthermore, while 44/67 (66%) non-high-risk adolescents had favourable 5-year EFS and OS rates (76 ± 7%, 89 ± 5%), 18/67 (27%) high-risk adolescents had an inferior outcome (5-year EFS: 56 ± 12%, OS 61 ± 11%, P < 0·05). Among the latter patients the CID was significantly higher than in younger high-risk children (22 ± 10% vs. 6 ± 2%; P = 0·020). Given that adolescent age is an independent risk factor for death as a first event, this specific age group may need particular vigilance when receiving intense BFM-type chemotherapy, as relapse-free survival is similar to younger children.

Absence of biallelic TCRγ deletion predicts induction failure and poorer outcomes in childhood T-cell acute lymphoblastic leukemia

BACKGROUND

The absence of biallelic TCRγ deletion (ABD) is a characteristic of early thymocyte precursors before V(D)J recombination. The ABD was reported to predict early treatment failure in T-cell acute lymphoblastic leukemia (ALL). This study aimed to investigate its prognostic value in Taiwanese patients with T-cell ALL.

PROCEDURE

Forty-five children with T-cell ALL were enrolled from six medical centers in Taiwan. Quantitative DNA polymerase chain reaction (Q-PCR) was performed to check the status of TCRγ deletion. The threshold for homozygous deletions by Q-PCR was defined as a fold-change <0.35.

RESULTS

ABD was found in 20 patients [20:45] who had higher incidences of induction failure than those without ABD (P = 0.03; hazard ratio [HR] = 8.13; 95% confidence interval [95% CI] = 1.23-53.77) after multivariate regression analysis. Patents with ABD also had inferior EFS and OS (P = 0.071 and 0.0196, respectively). Multivariate Cox analysis indicated that the association between ABD and overall survival was independent of age and leukocyte count on presentation (P = 0.036; HR = 4.25; 95% CI = 1.10-16.42).

CONCLUSIONS

The absence of TCRγ deletion is a predictor of a poor response to induction chemotherapy for pediatric patients with T-cell ALL in Taiwan. Providing patients with T-cell ALL and ABD with alternative regimens may be worthwhile to test in future clinical trials.

Clinical significance of early T-cell precursor acute lymphoblastic leukaemia: results of the Tokyo Children's Cancer Study Group Study L99-15

Early T-cell precursor acute lymphoblastic leukaemia (ETP-ALL) is a recently identified subtype of T-ALL with distinctive gene expression and cell marker profiles, poor response to chemotherapy and a very high risk of relapse. We determined the reliability of restricted panel of cell markers to identify EPT-ALL using a previously classified cohort. Then, we applied the cell marker profile that best discriminated ETP-ALL to a cohort of 91 patients with T-ALL enrolled in the Tokyo Children's Cancer Study Group L99-15 study, which included allogeneic stem cell transplantation (allo-SCT) for patients with poor prednisone response. Five of the 91 patients (5·5%) met the ETP-ALL criteria. There were no significant differences in presenting clinical features between these and the remaining 86 patients. Response to early remission induction therapy was inferior in ETP-ALL as compared with T-ALL. The ETP-ALL subgroup showed a significantly poorer event-free survival (4-year rate; 40%) than the T-ALL subgroup (70%, P=0·014). Of note, three of four relapsed ETP-ALL patients survived after allo-SCT, indicating that allo-SCT can be effective for this drug-resistant subtype of T-ALL.