Delayed achievement of cytogenetic and molecular response is associated with increased risk of progression among patients with chronic myeloid leukemia in early chronic phase receiving high-dose or standard-dose imatinib therapy.

Responses can be achieved with dasatinib or nilotinib after failure of 2 prior tyrosine kinase inhibitors (TKIs). We report on 48 chronic myeloid leukemia patients sequentially treated with 3 TKIs: 34 with dasatinib after imatinib/nilotinib failure and 14 with nilotinib after imatinib/dasatinib failure. Before the third TKI, 25 patients were in chronic phase (CP), 10 in accelerated phase (AP), and 13 in blast phase (BP). Best response to third TKI in CP was 5 major molecular responses (MMR), 3 complete cytogenetic (CCyR), 2 partial cytogenetic (PCyR), 3 minor cytogenetic (mCyR), 6 complete hematologic responses (CHR), and 6 with no response (NR). In AP, 1 patient achieved MMR, 1 CCyR, 2 PCyR, 1 mCyR, 4 CHR, and 1 NR. In BP, 1 achieved MMR, 2 CCyR, 1 PCyR, 1 mCyR, 2 returned to CP, and 6 NR. Median CCyR duration was 16.3 months; 3 CP patients achieving CCyR had a response more than 12 months. Median failure-free survival was 20 months for patients in CP, 5 months in AP, and 3 months in BP. Use of second-generation TKI after failure to 2 TKIs may induce responses, but these are usually not durable except in some CP patients. New treatment options are needed.