Deep Molecular Response Is Reached by the Majority of Patients Treated With Imatinib, Predicts Survival, and Is Achieved More Quickly by Optimized High-Dose Imatinib: Results From the Randomized CML-Study IV
Mené sur 1 524 patients atteints d'une leucémie myéloïde chronique (durée médiane de suivi : 67,5 mois), cet essai randomisé montre qu'une réponse moléculaire profonde MR4.5 est observée chez la plupart des patients traités par imatinib, peut être atteinte plus rapidement avec une forte dose d'imatinib et peut prédire la survie à long terme
Purpose : Deep molecular response (MR4.5) defines a subgroup of patients with chronic myeloid leukemia (CML) who may stay in unmaintained remission after treatment discontinuation. It is unclear how many patients achieve MR4.5 under different treatment modalities and whether MR4.5 predicts survival.
Patients and Methods : Patients from the randomized CML-Study IV were analyzed for confirmed MR4.5 which was defined as ≥ 4.5 log reduction of BCR-ABL on the international scale (IS) and determined by reverse transcriptase polymerase chain reaction in two consecutive analyses. Landmark analyses were performed to assess the impact of MR4.5 on survival.
Results : Of 1,551 randomly assigned patients, 1,524 were assessable. After a median observation time of 67.5 months, 5-year overall survival (OS) was 90%, 5-year progression-free-survival was 87.5%, and 8-year OS was 86%. The cumulative incidence of MR4.5 after 9 years was 70% (median, 4.9 years); confirmed MR4.5 was 54%. MR4.5 was reached more quickly with optimized high-dose imatinib than with imatinib 400 mg/day (P = .016). Independent of treatment approach, confirmed MR4.5 at 4 years predicted significantly higher survival probabilities than 0.1% to 1% IS, which corresponds to complete cytogenetic remission (8-year OS, 92% v 83%; P = .047). High-dose imatinib and early major molecular remission predicted MR4.5. No patient with confirmed MR4.5 has experienced progression.
Conclusion : MR4.5 is a new molecular predictor of long-term outcome, is reached by a majority of patients treated with imatinib, and is achieved more quickly with optimized high-dose imatinib, which may provide an improved therapeutic basis for treatment discontinuation in CML.
Journal of Clinical Oncology , résumé, 2013