(ChemotherapyAdvisor) – Long-term treatment with dasatinib is safe and efficacious in patients with imatinib-resistant, chronic phase chronic myeloid leukemia (CP-CML), according to an international team of researchers. This conclusion is based on an abstract entitled “Six-year Follow-up of Patients with Imatinib-resistant or Imatinib-intolerant Chronic-Phase Chronic Myeloid Leukemia (CP-CML) Receiving Dasatinib,” which was presented at the 17th Congress of the European Hematological Association in Amsterdam, The Netherlands.

Recommended dosing for dasatinib is 100mg once daily, based on the CA180-034 dose-optimization study. Six-year analysis of that study provides the longest follow-up of patients with CP-CML resistant or intolerant to imatinib, noted lead author Delphine Rea, MD, of Hôpital Saint-Louis, Paris, France. In this study, patients (N=670) were randomized to dasatinib 100mg once-daily (n=167), 50mg twice daily (n=167), 140mg once daily (n=168), or 70mg twice daily (n=168), and followed for up to six years.

At six months, 85% and 83% of patients achieved a major molecular response (MMR) and complete cytogenetic response (CCyR) at six months; 85% and 79% of patients achieving MMR and CCyR at 12 months were alive and progression-free at five years, respectively. For 100mg once daily, grade 3/4 hematologic adverse events (AEs) generally first occurred within 12 months of treatment and all-grade non-hematologic AEs generally first occurred within 24 months of treatment. Five-year rates of non-hematologic AEs (all-grades) for 100mg once daily vs other treatment arms include headache (33% vs. 28%), diarrhea (28% vs. 31%), fatigue (26% vs 23%), and pleural effusion (24% vs. 32%). Dose/schedule modifications were permitted to manage AEs.

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The investigators concluded that “the majority of patients receiving dasatinib after five years continue on once-daily dosing. Long-term follow-up of dasatinib 100mg once daily demonstrates durable efficacy and a generally well-tolerated safety profile for patients with CP-CML following prior imatinib therapy.”