In vivo resistance to dexamethasone in a model of acute lymphoblastic leukaemia

Although paediatric acute lymphoblastic leukaemia (ALL) has a favourable prognosis, relapsed disease does not have such good survival rates. The development of drug resistance is one of the major problems associated with relapsed ALL and the underlying reasons are not well understood. The pre B ALL cell line 697 (t(1;19)) is a good model to study glucocorticoid (GC) sensitivity in vitro as unlike many other ALL cell lines the 697 cells are sensitive to dexamethasone (dex) (IC50˜20nM). However, when we transplanted NSG mice with 697 cells, this sensitivity did not translate into increased survival despite reachin…