ABSTRACT
Acute lymphoblastic leukaemia (ALL) is the most common of the paediatric leukaemias. It is estimated that the use of modern combination chemotherapy results in long-term remission in nearly 80% of children diagnosed with ALL. Despite therapy advances, approximately 20% of children with ALL, experience leukaemia relapse. Clofarabine (2-chloro-2’-fluoro-2’-deoxy-9-?-D-arabinofuranosyladenine) is a second-generation nucleoside analogue and is structurally related to fludarabine and cladribine which are widely used in the treatment of lymphoproliferative disorders. Clofarabine exhibits greater affinity to deoxycytidine kinase (dCyd kinase) and prolonged retention in leukaemic blasts compared to fludarabine and cladribine. Clofarabine inhibits both DNA polymerases and ribonucleotide reductase (RNR). This results in impaired DNA synthesis through inhibition of DNA elongation as well as depletion of deoxyribonucleotides. Accumulation of clofarabine triphosphate, in the blasts of patients with refractory leukemia has been demonstrated. Prolonged intracellular half-life of 24 hours for clofarabine triphosphate. Clofarabine is indicated for the treatment of pediatric patients 1 to 21 years old with relapsed or refractory acute lymphoblastic leukemia after at least two prior regimens.
ABSTRACT
Soluble HLA (sHLA) are potential tumour markers released in order to counter immune surveillance. sHLA-class II is less known especially in acute lymphoblastic leukaemia (ALL). This study aimed to investigate soluble, surface and allelic expression of HLA Class II (sHLA-DR) in B-cell ALL patients and compare with soluble expression in normal individuals. A sandwich enzyme-linked immunosorbent assay (ELISA) was developed to measure soluble HLA-DRB1 in plasma. Flow cytometric analysis was performed to determine median fluorescence intensity in HLA-DR surface expression. HLA-DNA typing by polymerase chain reaction, sequence specific oligonucleotides, PCRSSO was performed to determine HLA-DRB1 type in ALL samples. Results showed sHLA-DRB1 (mean+SEM) was significantly increased (p=0.001) in plasma of ALL patients (0.260±0.057 μg/mL; n=30) compared to healthy controls (0.051±0.007μg/mL; n=31) of Malay ethnicity. However, these levels did not correlate with percentage or median fluorescence intensity of HLA-DR expressed on leukemia blasts (CD19+CD34+/-CD45loHLA-DR+) or in the normal B cell population (CD19+CD34- CD45hiHLA-DR+) of patients. No significant difference was observed in gender (male/female) or age (paediatric/adult). Only a trend in reduced sHLA was observed in patients carrying HLA-DR04. These results have to be validated with a larger number of samples.
ABSTRACT
Residual disease in patients with acute leukaemia indicates unfavorable prognosis. The evaluation of remission using flow cytometry allows a better estimation of minimal residual disease (MRD) after induction chemotherapy in childhood acute lymphoblastic leukaemia (ALL) cases. Patients in morphological marrow remission with presence of blast cells of less than 5%, may still have up to 1010 leukaemic cells. However with flow cytometric analysis, lower levels of the residual leukaemic cells (1 in 104 cells) can be detected and it can be used as a tool to predict relapse. This study compared the presenting clinical and haematological features of children with ALL and their residual disease status determined by flow cytometry. Analysis of their MRD status following remission-induction chemotherapy were done at day-28, week-12 and week-20. The cases were also followed up to five years, to determine their survival status. Their residual disease status by flow cytometric immunophenotyping was also compared with their bone marrow findings morphologically. Thirty-eight cases of precursor B-ALL in pediatric patients from UKM Medical Centre (UKMMC) were analyzed. There was no significant correlation between demographic, clinical and haematological features with MRD status at day-28. However, there was a significant correlation between MRD status by flow cytometry and by morphological marrow examination at week-12. Three cases showed persistent MRD findings until week-20 where two of the cases relapsed and died subsequently. Twenty four patients were still alive after five years of follow up.