Different response to imatinib and nilotinib in relationship with the time of administration

Here we describe a case of a young patient with chronic myeloid leukemia at low risk, according to the Sokal index. After cytoreduction with hydroxyurea, the patient started imatinib at standard dose (400 mg/day) obtaining a minor cytogenetic response (Ph+ 42.5%) after six months of treatment.Considering the low imatinib concentration evaluated with the blood level testing, we increased the dose of imatinib at 600 mg/day. After about 3 months treatment the patient presented a partial cytogenetic response (Ph+ 30%). Therefore he was considered suboptimal responder according to European LeukemiaNet (ELN) recommendations 2006. For this reason he switched to second generation tyrosine kinase inhibitor nilotinib, at dose 800 mg/die. After switching to nilotinib the patient reached complete cytogenic response and major molecular response, maintained until last molecular evaluation.This kind of patient shows a different response for imatinib and nilotinib, whereas nilotinib therapy has shown to be safe and efficacy.