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.

Cell Division Rates of Primary Human Precursor B Cells in Culture Reflect In Vivo Rates

“…Leukemic cells with low division rate had <5% Ki67-positive cells. Although unusual, other cases of precursor B lymphoblastic leukemias with <5% Ki67-positive cells have been reported and correlate with high frequency of treatment failure; in contrast, biopsies of most other precursor B lymphoblastic leukemias had >30% Ki67-positive cells [13]. These findings suggest that the division rates of precursor B lymphoblastic leukemia cells in culture reflect their rates in vivo.…”

“…In support, mutations or aberrant expression of the cell-cycle regulatory genes INK4A, INK4B, retinoblastoma, and possibly p21(CIP1/WAF1/SDI1) are frequently seen in both pediatric and adult precursor B lymphoblastic leukemias [24][25][26][27][28][29]. In pediatric leukemias, low rate of cell division and high expression of INK4A may be associated with in vitro drug resistance or poor clinical outcome [12,13,30]. Hence, additional understanding of the regulation of cell division in precursor B cells may provide insight into therapy-resistant precursor B lymphoblastic leukemias.…”

“…Studies of freshly isolated bone marrow cells demonstrate that the rates of cell division are similar among normal human precursor B cells but variable among leukemic precursor B cells. Furthermore, low rates of cell division in leukemic cells may correlate with poor response to chemotherapy [12] and poor clinical outcome [13]. As with apoptosis, stroma-based cultures provide a potentially powerful model for studying cell pathways that regulate cell division of primary normal and leukemic human precursor B cells.…”

“…Four-µm sections of paraffin-imbedded tissue were stained with hematoxylin and eosin (H&E) for morphologic evaluation. Ki67 was detected using a modification of previously described protocol [13]. Slides were microwaved for antigen retrieval in citrate buffer, pH 6.0, for 10 minutes and then incubated with a monoclonal antibody (M7240; DAKO, Carpinteria, CA) for 30 minutes, biotin-conjugated horse anti-mouse antibody (Vector, Burlingame, CA) for 20 minutes, horseradish peroxidase-conjugated strepavidin (Vector) for 30 minutes, and diaminobenzidine (DAKO) for 5 minutes.…”

Frequency of regulatory T cells determines the outcome of the T-cell-engaging antibody blinatumomab in patients with B-precursor ALL

“…In addition, no correlation was seen for CD4+ T-cell ( P -value 0.42) and CD8+ T-cell subsets ( P -value 0.6), and also with these compartments of both naive and effector T cells marked by CD45RA/RO expression (naive T cells P -value 0.69; effector T cells P -value 0.68) ( Supplementary Figure 1 ). The proliferation marker Ki67, which is postulated to be a marker for therapy failure in ALL induction therapy, 23 could be assessed by immunohistochemistry in bone marrow infiltrates in 26 of the 42 ALL patients. There was again no association between the Ki67 values and response to blinatumomab ( P -value 0.92; Supplementary Figure 1 ).…”