Simplifying treatment for children with ALL.
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Antineoplastic Combined Chemotherapy Protocols↗
Biomedical subjects
Vaskar Saha
Publications and source records attributed to Vaskar Saha.
Complex genomic alterations and gene expression in acute lymphoblastic leukemia with intrachromosomal amplification of chromosome 21.
We have previously identified a unique subtype of acute lymphoblastic leukemia (ALL) associated with a poor outcome and characterized by intrachromosomal amplification of chromosome 21 including the RUNX1 gene (iAMP21). In this study, array-based comparative genomic hybridization (aCGH) (n = 10) detected a common region of amplification (CRA) between 33.192 and 39.796 Mb and a common region of deletion (CRD) between 43.7 and 47 Mb in 100% and 70% of iAMP21 patients, respectively. High-resolution genotypic analysis (n = 3) identified allelic imbalances in the CRA. Supervised gene expression analysis showed a distinct signature for eight patients with iAMP21, with 10% of overexpressed genes located within the CRA. The mean expression of these genes was significantly higher in iAMP21 when compared to other ALL samples (n = 45). Although genomic copy number correlated with overall gene expression levels within areas of loss or gain, there was considerable individual variation. A unique subset of differentially expressed genes, outside the CRA and CRD, were identified when gene expression signatures of iAMP21 were compared to ALL samples with ETV6-RUNX1 fusion (n = 21) or high hyperdiploidy with additional chromosomes 21 (n = 23). From this analysis, LGMN was shown to be overexpressed in patients with iAMP21 (P = 0.0012). Genomic and expression data has further characterized this ALL subtype, demonstrating high levels of 21q instability in these patients leading to proposals for mechanisms underlying this clinical phenotype and plausible alternative treatments.
Alleles↗
Early response to induction is predictive of survival in childhood Philadelphia chromosome positive acute lymphoblastic leukaemia: results of the Medical Research Council ALL 97 trial.
We report on the outcome of children with Philadelphia positive acute lymphoblastic leukaemia (Ph+ ALL) treated on the UK Medical Research Council (MRC) trial for childhood ALL, MRC ALL 97, between January 1997 and June 2002. Forty-two (2.3%) patients were Ph+. Nineteen (45%) had <25% blasts in bone marrow (BM) within the first 2 weeks of treatment and were defined as a good response group (GRG), the others as a poor response group (PRG). Thirty-six (86%) achieved first complete remission (CR1) at the end of induction, of which 28 underwent BM transplantation (BMT). The median follow-up was 42 months (range, 21-84). The 3-year event-free survival (EFS; 52%, 95% CI, 36-66%) was a considerable improvement on the previous MRC UKALL XI trial (27%). EFS for the GRG and PRG were 68% (43-84%) and 39% (18-59%), respectively (P = 0.03); presenting white cell count <50 x 10(9)/l (P = 0.02) was predictive for overall survival. Changes in the MRC ALL97 trial within the study period resulted in some Ph+ ALL receiving daunorubicin and either prednisolone or dexamethasone during induction. Though the use of daunorubicin during induction was not a prospective study question, EFS was significantly better for those whose induction included this drug (P = 0.02). Steroid randomization was not stratified for Ph+ ALL patients and was not predictive for EFS. BMT in CR1 appeared to reduce the risk of a subsequent BM relapse. These results show significant improvement on previous MRC trials; future therapeutic strategies should include early intensive therapy and BMT in CR1.
Adolescent↗
LISA: a web-based decision-support system for trial management of childhood acute lymphoblastic leukaemia.
Continuation chemotherapy is a key component of the treatment of childhood acute lymphoblastic leukaemia. During this treatment phase, weekly dose adjustments are carried out based on current and historical full blood counts (FBCs). The dose decision pathway is complex and suboptimal therapy may result if information on FBC results is not readily available and/or the prescriber is inexperienced. A web-based decision-support system (Leukaemia Intervention Scheduling and Advice, 'LISA') was designed to facilitate access to FBC information across geographical locations and to assist with dosage adjustments. A balanced-block crossover analysis was performed to evaluate the system. Thirty-six clinicians with varying degrees of experience were each asked to decide on appropriate oral chemotherapy dosages for eight simulated cases: four using LISA and four without. LISA significantly reduced the number of erroneous prescriptions (zero of 144 with LISA vs. 54 of 144 without; P < 0.0001) without affecting the number of times subjects deliberately overrode the protocol (seven of 144 times using LISA and six of 144 without). Using LISA reduced the time taken by novices to reach a decision for each case but increased the time taken by experts. Thirty-five of 36 subjects said they would be likely to use the system if it were available. A system like LISA is likely to be acceptable to clinicians, and has the potential to increase protocol compliance and decrease prescribing errors while allowing clinicians to override the protocol in specific cases where sound reasons exist for doing so.
Antineoplastic Agents↗
Prospective gene expression analysis accurately subtypes acute leukaemia in children and establishes a commonality between hyperdiploidy and t(12;21) in acute lymphoblastic leukaemia.
We have prospectively analysed and correlated the gene expression profiles of children presenting with acute leukaemia to the Royal London and Great Ormond Street Hospitals with morphological diagnosis, immunophenotype and karyotype. Total RNA extracted from freshly sorted blast cells was obtained from 84 lymphoblastic [acute lymphoblastic leukaemia (ALL)], 20 myeloid [acute myeloid leukaemia (AML)] and three unclassified acute leukaemias and hybridised to the high density Affymetrix U133A oligonucleotide array. Analysis of variance and significance analysis of microarrays was used to identify discriminatory genes. A novel 50-gene set accurately identified all patients with ALL and AML and predicted for a diagnosis of AML in three patients with unclassified acute leukaemia. A unique gene set was derived for each of eight subtypes of acute leukaemia within our data set. A common profile for children with ALL with an ETV6-RUNX1 fusion, amplification or deletion of ETV6, amplification of RUNX1 or hyperdiploidy with an additional chromosome 21 was identified. This suggests that these rearrangements share a commonality in biological pathways that maintains the leukaemic state. The gene TERF2 was most highly expressed in this group of patients. Our analyses demonstrate that not only is microarray analysis the single most effective tool for the diagnosis of acute leukaemias of childhood but it has the ability to identify unique biological pathways. To further evaluate its prognostic value it needs to be incorporated into the routine diagnostic analysis for large-scale clinical trials in childhood acute leukaemias.
Acute Disease↗
Outcome after first relapse in childhood acute lymphoblastic leukaemia - lessons from the United Kingdom R2 trial.
A retrospective analysis of children with first relapse of acute lymphoblastic leukaemia (ALL), treated on the UKALL R2 protocol at four different hospitals, between June 1995 and December 2002 was performed. Of the 150 children 139 (93%) achieved a second complete remission. The overall survival (OS) and event-free survival (EFS) for the whole group was 56% and 47% respectively. The duration of first complete remission and immunophenotype, but not sites of relapse, were predictive for survival. Using the Berlin-Frankfürt-Münster risk stratification for relapsed ALL, the OS and EFS for standard, intermediate (IR) and high risk (HR) groups were 92% and 92%, 64% and 51%, and 14% and 15%, respectively; P < 0.0001 for both OS and EFS. In the IR group, those with a very early isolated central nervous system relapse also had a significantly worse outcome (P = 0.0001). Given the poor outcome of a second relapse, clear strategies are required to identify those in the IR group who will most benefit from stem cell transplantation (SCT). A higher proportion (16%) of induction failures in the HR group suggest the need for novel agents during this phase of treatment, but SCT was associated with a lower relapse rate and better outcome than those treated with chemotherapy alone.
Antineoplastic Combined Chemotherapy Protocols↗
Philadelphia positive acute lymphoblastic leukaemia of childhood.
On current chemotherapeutic regimens, children with Philadelphia positive acute lymphoblastic leukaemia show a heterogeneous response to treatment. A few respond quickly to treatment and achieve long-term remission. Some fail to achieve remission after induction and the majority respond slowly to treatment. Relapse on treatment is common and remission is sustained in a proportion of cases only after allogeneic stem cell transplantation (allo-SCT). The use of imatinib along with conventional cytoreductive therapy, prior to allo-SCT appears to be the most promising strategy. The future lies in the molecular evaluation of response to treatment and combination targeted chemotherapy.
Antineoplastic Agents↗
Qualified predictions for microarray and proteomics pattern diagnostics with confidence machines.
We focus on the problem of prediction with confidence and describe a recently developed learning algorithm called transductive confidence machine for making qualified region predictions. Its main advantage, in comparison with other classifiers, is that it is well-calibrated, with number of prediction errors strictly controlled by a given predefined confidence level. We apply the transductive confidence machine to the problems of acute leukaemia and ovarian cancer prediction using microarray and proteomics pattern diagnostics, respectively. We demonstrate that the algorithm performs well, yielding well-calibrated and informative predictions whilst maintaining a high level of accuracy.
Algorithms↗
TEL deletion analysis supports a novel view of relapse in childhood acute lymphoblastic leukemia.
PURPOSE: TEL (ETV6)-AML1 (RUNX1) chimeric gene fusions are frequent genetic abnormalities in childhood acute lymphoblastic leukemia (ALL). They often arise prenatally as early events or initiating events and are complemented by secondary postnatal genetic events of which deletion of the non-rearranged, second TEL allele is the most common. This consistent sequence of molecular pathogenesis facilitates an analysis of the clonal origins of relapse in this leukemia, which has some unusual clinical features. EXPERIMENTAL DESIGN: We compared the boundaries, by microsatellite mapping, of TEL deletions at relapse versus diagnosis in 15 informative patients. Moreover, we compared the relatedness of diagnostic and relapse clones using immunoglobulin and T-cell receptor genes rearrangements and clonotypic TEL-AML1 genomic fusion. RESULTS: Five patients retained the apparent same size TEL deletion, seven had larger deletions, and three had smaller deletions at relapse. In all of the cases evaluated, the clonal relatedness of diagnostic and relapse cells was confirmed by the retention of clonotypic TEL-AML1 genomic sequence and/or at least one identical immunoreceptor gene rearrangement. CONCLUSIONS: These data provide further evidence that TEL deletions are secondary to TEL-AML1 fusions in ALL. They are compatible with the novel idea that in at least some cases of childhood ALL, remission occurs with persistence of a preleukemic "fetal" clone, and subsequent relapse reflects the emergence of a new subclone from this reservoir after an independent "second hit," i.e., independent TEL deletion. To our knowledge, the study is the most extensive and comprehensive analysis of the relationship between diagnostic and relapse clones in childhood ALL presented thus far.
Artificial Gene Fusion↗
Molecular techniques to improve outcome in childhood ALL.
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Child↗
A quantitative and qualitative evaluation of LISA, a decision support system for chemotherapy dosing in childhood acute lymphoblastic leukaemia.
OBJECTIVES: To assess the acceptability to clinicians of a web-based decision support system designed to assist with dosage adjustments during maintenance therapy for childhood Acute Lymphoblastic Leukaemia (ALL), and to evaluate the potential impact of the system on decision-making and dosage calculations. DESIGN: Balanced-block crossover experiment with simulated cases; questionnaire study and semi-structured interviews. PARTICIPANTS: 36 clinicians with differing experience in the management of ALL. INTERVENTIONS: Subjects were asked to decide on appropriate levels of chemotherapy dosing for 8 simulated cases, 4 using the LISA decision support system, 4 using conventional paper-based records and guidance. MAIN OUTCOME MEASURES: Number of protocol-consistent dosage decisions made; time taken to manage each case; accuracy of dosage calculations; subjects' opinions as to whether or not they would use the system in practice. ADDITIONAL OUTCOME MEASURES: Functions subjects would like to see in an idealised system; subjects' satisfaction with the implementation of the functions provided by LISA; qualitative data on issues subjects felt would impact upon the successful deployment of the system.
Antineoplastic Agents↗
Expression profile of wild-type ETV6 in childhood acute leukaemia.
Comparative expression analysis of wild-typeETV6 in the disease state showed an absence of expression in ETV6-CBFA2 acute lymphoblastic leukaemia (ALL) when compared with non-ETV6-CBFA2 ALL and acute myeloid leukaemia. Fluorescent in-situ hybridization and loss of heterozygosity studies showed that 73% of the ETV6-CBFA2 samples had a fully or partially deleted second ETV6 allele, explaining the lack of wild-type expression in these patients. Although the second ETV6 allele was identified in the remaining patients, no ETV6 expression was detected. These observations support the hypothesis that loss of ETV6 expression is a critical secondary event for leukaemogenesis in ETV6-CBFA2 ALL.
Acute Disease↗
Routine blood counts in children with acute lymphoblastic leukaemia after completion of therapy: are they necessary?
Children who have completed treatment for acute lymphoblastic leukaemia (ALL) are commonly followed up for the first 5 years with regular full blood counts (FBCs) to monitor for relapse of disease. There is little evidence to suggest that this practice improves the detection rate of unexpected relapse. Surveillance FBCs, performed on 43 children with relapsed ALL between 1990 and 1999, were analysed. Of the 42 relapses in children off therapy, only two were detected by an abnormal FBC. Routine FBCs in asymptomatic children off therapy lacks specificity in detecting unexpected relapses and maybe safely discontinued.
Blood Cell Count↗
Veno-occlusive disease in patients receiving thiopurines during maintenance therapy for childhood acute lymphoblastic leukaemia.
The case records of 99 consecutive children with acute lymphoblastic leukaemia who received either 6-thioguanine (6-TG) or 6-mercaptopurine (6-MP) as maintenance therapy for at least 1 year were reviewed for hepatic veno-occlusive disease (VOD). Overall, 12% of those on 6-TG developed VOD (all boys). Isolated persistent thrombocytopenia appeared to be the earliest indicator of incipient VOD. Multivariate analysis identified male sex and 6-TG as risk factors. In all cases, VOD was mild and reversible on withdrawing 6-TG or replacing it with 6-MP. The data implicate a sex-linked polymorphic variation in xenobiotic pathways of thiopurine metabolism in the pathogenesis of VOD.
Antimetabolites, Antineoplastic↗
Evidence that continued remission in patients treated for acute leukaemia is dependent upon autologous natural killer cells.
Although it has been known for more than 40 years that allogeneic immune responses cure leukaemias after bone marrow transplantation, autologous leukaemia-specific immunity remains controversial and its impact upon survival has not been established. Here we have tested 25 patients with de novo acute leukaemias, while in remission at completion of their anti-leukaemia therapy, for evidence of autologous cytolytic immunity to their leukaemic cells taken and cryopreserved at disease presentation. We have measured this degree of cell-mediated cytotoxicity in vitro and termed it "leukaemia cytolytic activity" (LCA). Patients whose disease ultimately relapsed had significantly lower LCA than those who remained in remission beyond 2 years (P < 0.001); the absence of LCA when in remission predicted subsequent relapse within 2 years with a sensitivity of 100% and specificity of 77%. LCA was mediated in vitro by CD56+/CD8alpha+/CD3- natural killer cells. We propose that it is this immune response, rather than the chemotherapy per se, which is responsible for continued remission and that measurement of LCA in patients at completion of therapy may be used as an indicator of risk of subsequent relapse. Patients lacking this response will require further treatment, either with an allogeneic donor transplant or an alternative immunotherapeutic strategy.
Acute Disease↗
Chromatin modification, leukaemia and implications for therapy.
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Apoptosis↗
Making paediatric oncological research relevant.
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Child↗