Tyrosine kinase inhibitor (TKI) therapy discontinuation with the aim of achieving treatment-free remission (TFR) is becoming more frequent, as an increasing number of chronic myeloid leukemia (CML) patients are achieving stable deep molecular response (DMR; i.e. BCR::ABL1 transcript level ≤0.01% on the International Scale); however, many challenges remain unresolved [1]. The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.