Because it is not necessary to use second-generation tyrosine kinase inhibitors front-line for all patients with chronic myeloid leukaemia, and molecular criteria have now been defined to guide decisions about if and when to use dasatinib or nilotinib. These come from the TIDEL II study data released at the EHA meeting. Tim Hughes tells ecancer tv about molecular response rates to initial therapy with imatinib which indicate when to switch therapy. Using these indicators the group has confirmed that first use of imatinib — with delayed introduction of second generation agents — is equivalent in effectiveness to using dasatinib or nilotinib as initial therapy.