In this D-FREE study, treatment discontinuation was attempted in newly diagnosed CML-CP patients treated with the 2G-TKI dasatinib who achieved BCR-ABL1 levels of ≤ 0.0032% (MR4.5) on the international scale (BCR-ABL1IS) and maintained these levels for exactly 1 year. The gene discussed is BCR; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.