For patients with chronic myeloid leukemia in chronic phase (CML-CP) who have achieved a stable deep molecular response (DMR) using BCR-ABL1 tyrosine kinase inhibitors (TKIs), treatment-free remission (TFR) following TKI cessation is an emerging goal (Hughes and Ross 2016; Mahon et al. 2010; Etienne et al. 2017; Rousselot et al. 2014; Ross et al. 2013; Lee et al. 2016; Mori et al. 2015; Hochhaus et al. 2017a; Hughes et al. 2016; Imagawa et al. 2015; Nakamae et al. 2017; Saussele et al. 2017; Rea et al. 2017; Boquimpani et al. 2014; Villemagne Sanchez et al. 2018). The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.