Incidence, clinical characteristics and early treatment outcome in Indian patients of childhood acute lymphoblastic leukemia with ALL-1 gene rearrangement

Epidemiology of childhood and adolescent cancer in Bangladesh, 2001-2014

BACKGROUND

Cancer burden among children and adolescents is largely unknown in Bangladesh. This study aims to provide a comprehensive overview on childhood and adolescent cancers and to contribute to the future strategies to deal with these diseases in Bangladesh.

METHODS

Data on malignant neoplasms in patients aged less than 20 years diagnosed between 2001 and 2014 (N = 3143) in Bangladesh was collected by the National Institute of Cancer Research and Hospital and ASHIC Foundation. The age pattern and distribution of cancer types were analysed and the incidence rates were calculated.

RESULTS

The age-standardised incidence rate was 7.8 per million person-years for children (0-14 years) in the last time period (2011-2014). Retinoblastoma (25%) and leukaemia (18%) were the most common childhood cancers. For adolescents (15-19 years), the age-specific incidence rate was 2.1 per million person-years in the same time period. Most common adolescent cancers were malignant bone tumours (38%), germ cell and gonadal tumours (17%), and epithelial tumours (16%). There were more boys affected (M: F ratio 2.0 in children and 1.4 in adolescents) than girls.

CONCLUSION

Cancer incidences were lower than expected most likely due to a low level of awareness about cancer among clinicians and the population, inadequate access to health care, lack of diagnostic equipment and incomplete recording of cases. Improvements on different levels should be made to get a better epidemiologic insight and to detect cancer earlier resulting in a better outcome for affected children and adolescents.

Detection and clinical relevance of BCR-ABL fusion gene in childhood T-lineage acute lymphoblastic leukemia: a report on 4 cases

The bcr-abl rearrangement has rarely been reported in T-lineage acute lymphoblastic leukemia and the clinical significance of this translocation is currently unknown. We screened 28 children with T-lineage acute lymphoblastic leukemia at diagnosis by reverse transcription polymerase chain reaction for major and minor break point regions of bcr-abl fusion gene. Four out of 28 patients (14.2%) were bcr-abl positive for the minor breakpoint transcript. One of these patients was refractory to therapy, whereas the other 3 relapsed on therapy.

Treatment of acute lymphoblastic leukaemia in countries with limited resources; lessons from use of a single protocol in India over a twenty year peroid

In the 1970s, survival rates after treatment for acute lymphoblastic leukaemia (ALL) in children and young adults (less than 25 years) in India were poor, even in specialised cancer centres. The introduction of a standard treatment protocol (MCP841) and improvements in supportive care in three major cancer centres in India led to an increase in the event-free survival rate (EFS) from less than 20% to 45-60% at 4 years. Results of treatment with protocol MCP841 between 1984 and 1990 have been published and are briefly reviewed here. In addition, previously unpublished data from 1048 patients treated between 1990 and 1997 are reported. Significant differences in both patient populations and treatment outcome were noted among the centres. In one centre, a sufficiently large number of patients were treated each year to perform an analysis of patient characteristics and outcome over time. Although steady improvement in outcome was observed, differences in the patient populations in the time periods examined were also noted. Remarkably, prognostic factors common to all three centres could not be defined. Total white blood cell count (WBC) was the only statistically significant risk factor identified in multivariate analyses in two of the centres. Age is strongly associated with outcome in Western series, but was not a risk factor for EFS in any of the centres. Comparison of patient characteristics with published series from Western nations indicated that patients from all three Indian centres had more extensive disease at presentation, as measured by WBC, lymphadenopathy and organomegaly. The proportions of ALLs with precursor T-cell immunophenotypes, particularly in Chennai, were also increased, even when differences in the age distribution were taken into consideration (in <18-year olds, the range was 21.1-42.7%), and in molecular analyses performed on leukaemic cells from over 250 patients less than 21-years-old with precursor B-cell ALL, a lower frequency of TEL-AML1-positive ALL cases than reported in Western series was observed. The worse outcome of treatment in Indian patients compared with recent Western series was probably due to the higher rate of toxic deaths in the Indian patients, and possibly also due to their more extensive disease - which is, at least partly, a consequence of delay in diagnosis. Differences in the spectrum of molecular subtypes may also have played a role. The higher toxic death rates observed are likely to have arisen from a combination of more extensive disease at diagnosis, co-morbidities (e.g., intercurrent infections), differences in the level of hygiene achievable in the average home, poor access to acute care, and more limited supportive care facilities in Indian hospitals. Toxic death was not associated with WBC at presentation, and hence would tend to obscure the importance of this, and, potentially, other risk factors, as prognostic indicators. Since the prevalence of individual risk factors varies in different populations and over time, their relative importance would also be expected to vary in different centres and in different time periods. This was, in fact, observed. These findings have important implications for the treatment of ALL in countries of low socioeconomic status; it cannot be assumed that risk factors defined in Western populations are equally appropriate for patient assignment to risk-adapted therapy groups in less affluent countries. They also demonstrate that heterogeneity in patient populations and resources can result in significant differences in outcome, even when the same treatment protocol is used. This is often overlooked when comparing published patient series.

Identification of various MLL gene aberrations that lead to MLL gene mutation in patients with acute lymphoblastic leukemia (ALL) and infants with acute leukemia

Studies were done to investigate MLL gene aberrations using Conventional Cytogenetics, Southern blotting as well as FISH using a panel of probes on 218 cases which included 206 cases of pediatric/young adult ALL and 12 cases of infantile acute leukemias from Tata Memorial Hospital, India. The incidence of MLL gene rearrangements in acute lymphoblastic leukemia (ALL) was 9.4% which included infants as well as pediatric/young adults. In infantile group which included ALL as well as AML cases, MLL gene rearrangement was very common (75% frequency). Application of metaphase-FISH helped unravel MLL rearrangements not only as a result of translocations but also inversions, insertions, partial deletion, duplications, partial duplication-->self-fusion. Besides age, MLL gene rearrangements showed significant association with hyperleukocytosis, peripheral blood blast percentage and early Pre-B phenotype. Clinical outcome of patients with MLL gene rearrangements revealed unfavorable prognosis.

Clonal T-cell receptor gamma and delta gene rearrangements in T-cell acute lymphoblastic leukemia at diagnosis: predictor of prognosis and response to chemotherapy

Risk-based treatment assignment requires the availability of prognostic factors that reliably predict clinical outcome. Junctional regions of T-cell receptor (TCR) genes provide the best tool to study clonality, lineage association and minimal residual disease (MRD) in T-ALL. In this study, we have analyzed the suitability of clonal TCR gamma and delta junctional gene rearrangement status of T-ALL patients at diagnosis as a prognostic marker for T-ALL. We studied peripheral blood samples of 50 newly diagnosed patients with T-ALL in India for incidence of clonal TCR gamma and delta junctional region gene rearrangements by PCR-coupled heteroduplex analysis. Of these, 17 T-ALL patients uniformly treated on MCP 841 protocol were followed for more than 40 months (range: 41.26-55.82 months; mean: 49.26) and their clonal TCRgammadelta genotype was correlated with clinical outcome with respect to duration of complete remission, disease-free survival (DFS) and event-free survival. We also compared the clinical and biological features of TCRgammadelta + T-ALL and TCRalphabeta + T-ALL for their relative order of significance. Thirty per cent (15 of 50) of Indian T-ALL patients exhibited clonal rearrangements of both TCR gamma and delta genes. A significant proportion of these patients (73.3%, 11 of 15 P < 0.005) showed predominant usage of VgammaI-Jgamma1.3/2.3 with Vdelta1-Jdelta1 genes. A statistically significant association of L2 and L1 FAB blast morphology with TCRgammadelta + T-ALL and TCRalphabeta + T-ALL, respectively was observed (P = 0.001 by Fisher's Exact Test). The survival rate in DFS group was higher for TCRgammadelta + T-ALL compared to TCRalphabeta + T-ALL (P = 0.1378 by Log rank test). Thus we have identified clonal TCR gamma and delta junctional gene rearrangement status of T-ALL patients at diagnosis as a prognostic marker and predictor of response to chemotherapy. In future, this may help in designing tailored and risk-adjusted (less aggressive and less toxic) therapies for subset of T-ALL patients.

Study on ALL-1 gene alterations in Indian childhood acute leukemias: non-isotopic Southern blotting and molecular cytogenetics

We carried out this study to detect ALL-1 gene alterations in Indian childhood leukemias (n-84) using non-radioactive Southern blotting and FISH techniques. 18 (21.4%) patients showed altered ALL-1 gene. All 18 patients with altered ALL-1 gene did not have high WBC count and or typical CD10-/19+ phenotype. 4/18 were infants, while 14 were of 1-12 years of age. 13/18 children were boys. 14/18 expired within 1 year. Karyotyping detected abnormal chromosome 11 only in 4/43 patients and Classical t(4:11) in one AML patient but combination of Painting FISH and LS-FISH confirmed ALL-1 gene alteration in 17/18 cases. In addition, FISH identified nine translocations and multiple copies of ALL-1 gene in three cases which conventional cytogenetics had failed to detect. Our result indicates that a combination of Southern blotting, cytogenetic and FISH techniques are useful to identify ALL-1 gene alterations in childhood leukemias.