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Medline ® Abstract for Reference 55

of 'Treatment of chronic myeloid leukemia in chronic phase after failure of initial therapy'

Dasatinib or high-dose imatinib for chronic-phase chronic myeloid leukemia resistant to imatinib at a dose of 400 to 600 milligrams daily: two-year follow-up of a randomized phase 2 study (START-R).
Kantarjian H, Pasquini R, Lévy V, Jootar S, Holowiecki J, Hamerschlak N, Hughes T, Bleickardt E, Dejardin D, Cortes J, Shah NP
Cancer. 2009;115(18):4136.
BACKGROUND: In patients with chronic-phase chronic myeloid leukemia (CP-CML), imatinib resistance is of increasing importance. Imatinib dose escalation was the main treatment option before dasatinib, which has 325-fold more potent inhibition than imatinib against unmutated Bcr-Abl in vitro. Data with a minimum of 2 years of follow-up were available for the current study of dasatinib and high-dose imatinib in CP-CML resistant to imatinib at daily doses from 400 mg to 600 mg.
METHODS: A phase 2, open-label study was initiated of 150 patients with imatinib-resistant CP-CML who were randomized (2:1) to receive either dasatinib 70 mg twice daily (n=101) or high-dose imatinib 800 mg (400 mg twice daily; n=49).
RESULTS: At a minimum follow-up of 2 years, dasatinib demonstrated higher rates of complete hematologic response (93% vs 82%; P=.034), major cytogenetic response (MCyR) (53% vs 33%; P=.017), and complete cytogenetic response (44% vs 18%; P=.0025). At 18 months, the MCyR was maintained in 90% of patients on the dasatinib arm and in 74% of patients on the high-dose imatinib arm. Major molecular response rates also were more frequent with dasatinib than with high-dose imatinib (29% vs 12%; P=.028). The estimated progression-free survival also favored dasatinib (unstratified log-rank test; P=.0012).
CONCLUSIONS: After 2 years of follow-up, dasatinib demonstrated durable responses and improved response and progression-free survival rates relative to high-dose imatinib.
Department of Leukemia, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77230-1402, USA. hkantarj@mdanderson.org