Rousselot et al1 recently reported on the According to Stop Imatinib (A-STIM) study evaluating the persistence of major molecular response (MMR) in patients with chronic-phase chronic myeloid leukemia (CP CML) who had discontinued imatinib after prolonged deep molecular remission. They found that 61% of the patients were still in MMR and were treatment free after 36 months, whereas those who lost MMR and restarted tyrosine kinase inhibitor (TKI) therapy all regained MMR. They concluded that loss of MMR is a safe criterion for restarting therapy after TKI discontinuation.