Thesis (Ph.D.)--University of Western Australia, 2007.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Relapsed ALL remams one of the most common causes of death from disease in children. Broad-range drug resistance is often associated with relapse, although its underlying molecular mechanisms remained poorly understood. The aim of this thesis was to establish an in vivo model using the non-obese diabetic/severe combined immunodeficient (NOD/SCID) mouse strain, to facilitate the engraftment, expansion and characterisation of childhood ALL cells, obtained from patients at diagnosis or relapse. Mice were inoculated with leukaemia cells from patients' biopsies and engraftment was monitored by the proportion of human CD45+ cells in the blood. Successful leukaemia engraftment was achieved for 20/20 patient biopsies. Continuous passaging of ten xenografts has also been achieved. Immunophenotypic analysis showed only minor changes in cell surface markers after passage in mice. Leukaemia dissemination in murine bone marrow, liver, spleen and blood was consistent with the human disease. The in vivo responses of ten continuous xenografts to dexamethasone and vincristine, but not methotrexate, significantly correlated with patient outcome (p<0.05). Xenograft sub-lines resistant to vincristine, dexamethasone, methotrexate and cytosine arabinoside were also selected by in vivo drug treatments, although these sublines were not found to be cross resistant to structurally unrelated drugs. Resistance to vincristine, either in in vivo selected sub-lines or inherently resistant xenografts, was not associated with increased activity of drug efflux pumps such as P-gp or MRPl. Class I ?? tubulin levels remained unchanged when compared between vincristine resistant sublines and their parental xenografts. Decreased expression of stathmin and increased polymerised tubulin were observed in vincristine resistant sub-lines, suggesting a possible mechanism of counteracting the depolymerising effects of vincristine. In summary, this study has shown that primary ALL cells engraft efficiently into NOD/SCID mice, and indicates that their response to vincristine and dexamethasone mimics the clinical situation. This model appears to be highly relevant for the study of childhood ALL and will provide the foundation to delineate clinically relevant mechanisms of drug resistance.

Thesis (M. Med. Sc.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 36-41).

Thesis (M.Med.Sc.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 36-41). Also available in print.

Long-term survival and probable cure have become norms in acute lymphoblastic leukaemia of childhood. The adverse effects of treatment for leukaemia are diverse and complex. In many cases, treatment effects come to light 1 ong after the end of therapy. These so-ca 11 ed 1 ate effects (which are yet obscure and incompletely understood) have become increasingly important as the number of children surviving leukaemia increases. This thesis describes a comprehensive study of leukaemia survivors attending the Oncology Clinic of the Red Cross War Memorial Children's Hospital. The study sample consisted of all leukaemia survivors in long-term remission, disease free and off treatment up to January 1st, 1984. The study is introduced by a chapter which describes acute lymphoblastic leukaemia and pays particular attention to the effects of the primary disease on organs which may subsequently exhibit late effects of treatment. Treatment of acute lymphoblastic leukaemia is described in some detail and the reasons for current treatment strategies are outlined. Individual modalities of treatment are then discussed with reference to their mechanisms of action and potential for damage to non-neoplastic tissue. The study then examines all systems likely to have been damaged during therapy, in order to achieve a comprehensive impression of the late effects of leukaemia treatment. In each chapter, pertinent literature was reviewed up to January 1987. Growth is a major task of childhood. Many chronic diseases are potential causes of growth failure. A longitudinal retrospective study showed that statured growth in leukaemia survivors was stunted during treatment. Catch-up growth did not occur at the end of treatment, although normal growth velocity was resumed. Adult height was expected to be reduced as a result. In addition to temporary stunting of statured growth, leukaemia survivors showed a progressive increase in weight-for-height during treatment. This trend continued after treatment had ended. These changes in weight and height were peculiar to leukaemia survivors. Control groups of children with solid tumours in long term remission showed less stunting during treatment and had catch-up growth after treatment, except when they had undergone spinal i rradi ati on. Normal endocrine function is a prerequisite for normal growth and development. Although growth hormone responses to insulin-induced hypoglycaemia were frequently and significantly abnormal in survivors of childhood leukaemia, these children grew normally once treatment had stopped. Impaired growth hormone secretion appeared to be a marker of hypothalamic damage caused by leukaemia therapy. Testicular and ovarian function was normal in the absence of irradiation of these organs. Thyroid function was normal in leukaemia survivors although a minority showed evidence of hypothalamic damage in their response to thyrotropin releasing hormone. Normal prolactin levels in children showing other hormonal evidence of hypothalamic damage were thought to indicate the selectivity of damage caused by leukaemia treatment. Adrenal control and function were normal in leukaemia survivors. In the absence of a growth disorder, only thyroid status may need long-term assessment in leukaemia survivors. Intellectual development is a further major task of childhood. A sibling-controlled study of intellectual function indicated an intelligence deficit in children surviving leukaemia and its treatment. This deficit was thought to be the consequence of therapy, since children surviving solid tumours showed no such deficit in comparison with their sibling controls. Survivors of childhood leukaemia also had an increased incidence of visual perceptual difficulty and more school prob 1 ems than survivors of solid tumours, particularly in early primary grades. Intellectual outcome and school performance in leukaemia survivors may be improved by early visual perceptual training. Children surviving acute lymphoblastic leukaemia had significantly more minor motor abnormalities than children surviving solid tumours. Minor motor abnormalities were frequently and significantly associated with abnormalities of the brain visualized by computerized tomography. Neurophysiologic measurement (EEG, VER, BAER) did not contribute to the assessment of neurological outcome and correlated poorly with clinical and CT scan findings. A functional assessment of neurological outcome in leukaemia survivors should include a clinical examination for minor motor dysfunction. Some children manifested other organ-specific damage due to chemotherapy or radiotherapy. These isolated cases are discussed in the form of case reports and literature reviews. Patients have received treatment with cytotoxic drugs in addition to standard leukaemia therapy need to be followed for treatment-specific late effects. The psychological outcome of leukaemia survivors was assessed by means of parent interviews and teacher questionnaires. In terms of a low frequency of behaviour problems reported by these observers, psychosocial adaptation in leukaemia survivors vas surprisingly good. Children surviving solid tumours and healthy school children from the same community (the latter from a literature report) had similar frequencies of behavioural problems. In both leukemic children ana solid tumour control patients, certain patterns of family behaviour ~ere predictive of a poor psychological outcome. It appears that an early family assessment may identify families 'at risk'. If needs to be shewn whether such families would benefit from professional psychological support. In the final chapter a 'functional deficit score' is offered as a measure of overall outcome in terms of late effects of therapy. Patients were rated in five categories (growth, intellectual outcome, neurological status, miscellaneous organ damage and psychosocial adaptation) according to the severity of persistent late effects. Children surviving acute lymphoblastic leukaemia were shown to have been more seriously damaged by their treatment than children surviving solid tumours. The difference in overall damage was the consequence of central nervous system injury. Available evidence indicates that this central nervous system injury is caused by radiotherapy (with or ·thought a synergistic effect with i intrathecal 1 methotrexate) given as central nervous system 'prophylaxis'. With few exceptions, leukaemia survivors in this study had received L400 rads of deep x-ray therapy as cranial irradiation. This dosage has since been reduced world-wide. Current cranial irradiation 'prophylaxis' consists of 1800 rad of megavoltage radiotherapy. Fa 11 ow-up studies of survivor cohorts given such radiotherapy should include the measures embodied in the 'functional deficit score' described above.

No description available.

Thesis (Ph.D.)--Murdoch University, 2003. / Thesis submitted to the Division of Health Sciences. Bibliography: leaves 177-201.

[Truncated abstract] Acute lymphoblastic leukaemia (ALL) is the most common form of cancer that affects children and the leading cause of child cancer-related death. There have been dramatic improvements in the 5-year event free survival (EFS) for childhood ALL in recent years, with EFS reaching 75-90% for some forms of the disease. Despite this success, treatment for the disease is aggressive with numerous long and short-term side effects. Many cases of ALL are characterised by chromosomal defects including translocations, variations in chromosome number and the deletion of the tumour suppressor genes. Although these gross chromosomal changes have been extensively studied in childhood ALL, the cascade of altered gene expression that results from these changes has not. Further improvements in survival and the quality of life of survivors relies on a better understanding of the underlying biology of ALL. The primary aim of this study was to determine the gene expression profile of pre-B ALL specimens and normal, or non-malignant, control cells using microarrays in order to further examine the underlying biology of childhood ALL. ... Analysis of the ALL profile with two normal haematopoietic populations demonstrated that ALL specimens have a profile similar to that of CD34+ cells. Specifically, specimens of the MLL subtype had a profile that uniformly resembled that of CD34+ cells. Other subgroups contained specimens with profiles that ranged in similarity to that of CD34+ cells, however, the gene expression profile of all ALL specimens analysed more closely resembled the CD34+ cells than the more differentiated CD19+IgM- cells. This study identified exceptionally high expression of connective tissue growth factor (CTGF/CCN2) in ALL specimens compared to control cells. CTGF expression was v restricted to B-lineage ALL specimens, however, specimens containing the E2A-PBX1 translocation showed low or no expression. Protein studies by Western blot analysis demonstrated the presence of CTGF in ALL cell-conditioned media. The study presented here provides insight into the biology of ALL including the observation that ALL cells have an immature gene expression profile similar to that of CD34+ cells and the possible existence of an autocrine loop involving CTGF. The findings may also have clinical application in the future treatment of ALL, such as the use of metabolic inhibitors or the blocking of CTGF expression. This study provides an important insight into many aspects of ALL disease biology and may offer potential new therapeutic targets for the treatment of ALL.

[Truncated abstract] Childhood acute lymphoblastic leukaemia (ALL) accounts for the largest number of cases of childhood cancer (25-35%) and is the primary cause of cancer related morbidity. Today more than 76% of children with ALL are alive and disease free at 5 years. Approximately one in 900 individuals between the ages of 16 and 44 years is a survivor of childhood cancer. In contrast, those patients who relapse with childhood ALL currently have a 6-year event free survival of 20-30%. The short arm of chromosome 9p is mutated or deleted in many cancers including leukaemia. Aberrations of the INK4A/ARF and INK4B loci at the 9p21 band are linked to the development and progression of cancer. In murine cancer models there is evidence to suggest that mutations of Ink4a/Arf and p53 gene loci promote resistance to chemotherapeutic drugs known to trigger apoptosis. The initial aim of this project was to develop an accurate, reproducible method to detect deletions at the INK4A/ARF locus in patient bone marrow specimens. This technique was then applied to detect the incidence of deletions of this locus in childhood ALL specimens. The hypothesis developed was that deletion at the INK4A/ARF locus at diagnosis in childhood ALL is an independent prognostic marker and is involved in disease progression. A secondary aim of this study was to determine which deletions at the INK4A/ARF and INK4B loci are the most relevant in leukaemogenesis in childhood ALL. ... This study has shown that deletion of the INK4A/ARF locus is an independent prognostic indicator in childhood ALL. In addition, the frequency of deletion at the INK4A/ARF and INK4B loci is increased at relapse compared to diagnosis in childhood ALL. In the relapse study group, deletion of the p16INK4A gene at diagnosis was associated with a decreased median time to relapse compared to other genes analysed. Murine studies suggest that such deletions may result in an increased resistance to chemotherapy. If the findings from this study are confirmed in a larger cohort, it is expected that therapeutic interventions based on assessment of the p16INK4A gene in diagnostic childhood ALL specimens will be implemented to prevent relapse in standard risk patients and help to improve the outcome in high risk patients.