Early switch to nilotinib in a case of non-optimal response to imatinib

Abstract

We report a case of excellent response to nilotinib in a 22 years old man with chronic myeloid leukemia in suboptimal response to imatinib. After diagnosis he started cytoreductive therapy with cytarabine and hydroxyurea, then he begun therapy with imatinib 400 mg/day. After 3 months of treatment, he obtained a complete hematologic response (CHR) and a minor cytogenetic response (minor CyR). At 6 months CHR was confirmed, but bone marrow analysis showed increasing number of Ph+ cells (minimal CyR) and non significant reduction of BCR-ABL levels. According to ELN (European LeukemiaNet) guidelines, this is considered a suboptimal response. Clonal evolution, kinase domain mutations and reduced drug intake were excluded, thus we decided to early switch to nilotinib at 400 mg/BID. After 3 months of treatment we obtained a complete cytogenetic response (CCyR) and a strong reduction of BCR-ABL transcript, almost reaching a major molecular response (MMR).