Correlation between Early Treatment Failure and Ki67 Antigen Expression in Blast Cells of Children with Acute Lymphoblastic Leukaemia before Commencing Treatment

Abstract

Objectives: An attempt has been made to demonstrate the value of the immunocytochemical assay of Ki67 antigen expression in blast cells in children with acute lymphoblastic leukaemia (ALL) before initiation of treatment and its correlation with early treatment failure. Methods: Bone marrow specimens were obtained before treatment from children hospitalised in the years 1997–2000. A total of 60 children diagnosed with ALL have been examined. Immunocytochemical staining for Ki67 expression was based on the ABC technique. Results: Out of 45 children assigned to the low risk group, the presence of Ki67 Ag was demonstrated in 31 cases (68.8%). Out of 15 patients in the high risk group, Ki67 Ag expression in blast cells was positive in 8 children (53.3%). The fraction of immunopositive cells in these groups ranged from 19.8 to 81.3% compared to 5% in the control group. Early treatment failure was observed in both groups and these were closely related to the lack of Ki67 expression observed at the beginning of treatment. Conclusion: The results indicate a possible connection between the Ki67 immunonegative blast pattern and early leukaemia progression. It may also justify routine determination of Ki67 Ag before the treatment of ALL is initiated.