Deep molecular responses achieved in chronic myeloid leukemia in chronic phase patients with BCR-ABL1 >10% at 3 months who are early switched to nilotinib.

There are still controversies about whether or when to change therapy for those chronic myeloid leukemia in chronic phase (CML-CP) patients with BCR-ABL1 transcript level at 3 months higher than 10%. Here we studied the clinical significance of early switching to nilotinib in CML-CP patients with BCR-ABL1 >10% at 3 months.,We investigated 495 first-line imatinib-treated patients with CML-CP and identified 117 (23.6%) patients with BCR-ABL1 >10% at 3 months, including 46 patients with warning response defined according to ELN-2013 recommendations. In 46 patients with warning response, 26 of them continued imatinib therapy and 20 patients early switched to nilotinib therapy.,Compared to continued imatinib group, nilotinib group showed significantly higher percentage achieving BCR-ABL1 <1% at 6 months (85.0% vs. 19.2%, P = 0.0004), better cumulative rates of MR3.0 and MR4.0 of 4 years (82.1% vs. 41.2%, P = 0.0091; 61.5% vs. 18.6%, P = 0.035).,In summary, early switching to nilotinib enabled more CML-CP patients with warning molecular response at 3 months to achieve early and deeper molecular response vs. remaining on imatinib.