Dose increases from 340 mg/ m2 daily to 570 mg/ m2 daily (not to exceed the total dose of 800 mg) may be considered in children in the absence of severe adverse drug reaction and severe non-leukaemia- related neutropenia or thrombocytopenia in the following circumstances: disease progression (at any 51 time); failure to achieve a satisfactory haematological response after at least 3 months of treatment; failure to achieve a cytogenetic response after 12 months of treatment; or loss of a previously achieved haematological and/ or cytogenetic response.