Dasatinib for Chronic Phase Chronic Myeloid Leukemia After Failure of Imatinib In Korean Patients.

Although imatinib could induce efficacious and stable responses in patients with chronic myeloid leukemia (CML), resistance is increasingly problematic. Dasatinib, a BCR-ABL inhibitor with 325-fold greater potency in vitro than imatinib, induced MCyR 59%, CCyR 48%, PFS 90% and OS 96% for patients who can not tolerate or are resistant to imatinib in START-C.

We assessed retrospectively the efficacy and safety of dasatinib in patients with chronic phase (CP)-CML, resistant or intolerant to imatinib who received dasatinib 70 mg to 140 mg per day. Dose was adjusted according to toxicity.

Between 21 June 2005 and 31 March 2010, medical records of 47 patients from 6 centers in Korea were reviewed: 22 with imatinib-resistant and 1 with imatinib-intolerant CP-CML. 8 Imatinib–resistant ABL kinase domain mutations were found including E255K, T315I, F317L. Median duration of dasatinib therapy was 20.6 months. CHR, MCyR, CCyR and MMR was attained in 91%, 79%, 56% and 44% of patients, respectively. 18 month MMR rate was 71%, 67% in imatinib-intolerant and 53% in imatinib-resistant group. There was no difference in PFS according to the Sokal score, to the best response of imatinib to the type of mutation. 3-year PFS was 71% and OS was 79% with a median follow up of 20.6 months. There was no disease progression or death in imatinib intolerant group. Grade 3/4 anemia, neutropenia and thrombocytopenia were reported in 36%, 49% and 45% of patients, respectively. Non-hematologic toxicity (grade 3/4) consisted of infection(15%), dyspnea(4%), pleural effusion(6%), abdominal pain(2%) and skin rash(2%).

Dasatinib showed promising efficacy and tolerability in imatinib-resistant or -intolerant CP-CML in Korean patients.

No relevant conflicts of interest to declare.