Nilotinib versus imatinib with early switch from imatinib to nilotinib to obtain treatment-free remission in newly diagnosed chronic myeloid leukemia patients: the analysis of the first co-primary endpoint

: Treatment-free remission is one of the most important goals of CML treatment but so far, the best treatment to reach this aim is still undefined, even though it is widely accepted that a sustained DMR is the prerequisite to discontinue TKI. Here we report on the depth of the molecular response, the first co-primary end point of the SUSTRENIM study, in a cohort of newly diagnosed CP-CML patients randomized 1:1 to be treated with nilotinib or with imatinib followed by switching to nilotinib in absence of optimal response. Of the 448 enrolled patients, 228 and 220 were randomized to the nilotinib (NIL) and imatinib (IM) arms, respectively, and followed for a median of 45.9 months. Eighty-two (37.2%) of the 220 patients on the IMarm did not fulfill the ELN criteria for optimal response of treatment and switched to nilotinib therapy. At the 24 months of follow-up, 107 of the 448 patients reached an MR4.5 response with a significantly higher frequency within the patients on the nilotinib arm (65 vs 42; p = 0.02). The analysis of the first primary endpoint indicates that, despite the early switch in the IM-randomized patients, NIL therapy is more effective to induce DMR.