Hydrocortisone does Not Influence in Vitro Glucocorticoid Sensitivity of Acute Lymphoblastic Leukemia Blasts

Introduction: Dexamethasone-induced neuropsychological side effects on mood, behavior and cognition seriously affect quality of life in children with acute lymphoblastic leukemia (ALL) during a long treatment period. Based on recent studies in animals, we hypothesized that these neuropsychological side effects are mediated by dexamethasone-induced cortisol depletion of the mineralocorticoid receptor (MR) in the brain. Therefore, we hypothesize that these side effects could be ameliorated by an intervention with hydrocortisone. For clinical application settings however, an absolute prerequisite is that MR activation does not interfere with the efficacy of the glucocorticoids, dexamethasone and prednisolone, on ALL cells.

Materials and Methods: To investigate responsiveness of leukemic cell lines and fresh patients’ leukemic cells to dexamethasone and prednisolone in the presence of hydrocortisone, MTT-assays were performed. In addition MR and the glucocorticoid receptor (GR) expression on leukemic cells of different ALL subtypes was studied with a microarray-based gene expression profiling and validated by quantitative real-time PCR.

Results: Leukemic cells expressed the MR at a very low level with a significantly higher (P≤0.001) expression in ETV6-RUNX1⁺ patients (median: 160.7 [AU] of fluorescence intensity, range: 38.1 - 760.6 [AU]) versus other ALL subtypes (median: 41.8 [AU] of fluorescence intensity, range: 25.1 - 276.2 [AU]). MR expression did not differ between glucocorticoid resistant and sensitive patients’ cells. Hydrocortisone addition did not affect glucocorticoid sensitivity of leukemic cell lines and patients’ leukemic cells of different leukemic subtypes also including ETV6-RUNX1⁺. Glucocorticoid sensitive patients’ cells became significantly more sensitive by hydrocortisone addition (prednisolone: P≤0.01, dexamethasone: P≤0.05).

Conclusion: This present study shows that hydrocortisone does not interfere with efficacy of dexamethasone and prednisolone in vitro. These findings support a clinical randomized trial to study whether addition of hydrocortisone decreases the neuropsychological side effects of dexamethasone in children with ALL.

Acknowledgments: The financial support of the KiKa^® (Kinderen Kankervrij) foundation is highly appreciated.