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

Abstract Abstract 4494 Background: 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. Method: 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. Result: 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%). Conclusion: Dasatinib showed promising efficacy and tolerability in imatinib-resistant or -intolerant CP-CML in Korean patients. Disclosures: No relevant conflicts of interest to declare.