Early molecular response and female sex strongly predict stable undetectable BCR-ABL1, the criteria for imatinib discontinuation in patients with CML

Abstract

Recent studies have demonstrated that some patients with chronicmyeloid leukemia (CML) can maintain remission after discontinuation of imatinib. A prerequisite is stable, undetectable BCR-ABL1. It is not known how many patients achieve this response or the factors associated with its achievement. We examined 423 de novo imatinib-treated patients to determine the cumulative incidence of achieving the discontinuation criteria as defined in the CML8 study (≥2 years of undetectable BCR-ABL1 [Stable MR4.5]), and predictive factors. After 8 years of imatinib, the cumulative incidence of Stable MR4.5 was 36.5%. Therefore, 9% to 15% of first-line imatinib-treated patients would maintain remission after discontinuation. The BCR-ABL1 level at 3 months and factors at diagnosis were examined for association with Stable MR4.5: Sokal risk, age, sex, and assigned imatinib dose. The only independent predictors were female sex (54.4% vs 27.2%; P = .018) and the 3-month BCR-ABL1 (P ≤ .001). The highest cumulative incidence of Stable MR4.5 after 8 years was 78.2% for patients with BCR-ABL1 ≤ 0.10%IS at 3 months (n = 38). Time to major molecular response (MMR) influenced the time to reach Stable MR4.5 (P