Objective: Treatment-free remission (TFR) after tyrosine kinase inhibitor (TKI) discontinuation at the first attempt is a therapeutic goal for patients with chronic phase chronic myeloid leukemia (CML-CP). However, it remains unclear whether discontinuation of TKIs at a second or subsequent attempt can be performed safely.
Patients and method: Here, we report a 72-year-old man diagnosed with CML-CP. He achieved TFR successfully after TKI discontinuation at the third attempt. Before discontinuation, the patient received imatinib, nilotinib, and finally nilotinib. His neutrophil count at the third attempt was higher than after the second attempt. We also performed a retrospective investigation of 53 patients who discontinued TKIs on the first or subsequent attempts.
Results: Overall, 64 TKI discontinuations were documented (first, 53; second, ten; third, one). We found that a higher neutrophil count at the time of TKI discontinuation (>2439/μL; hazard ratio, 0.325; 95% confidence interval, 0.137-0.772; p = 0.011) was associated independently with lower rates of molecular relapse.
Conclusion: We report a case of a patient who successfully achieved third attempt TKI discontinuation and, an increased neutrophil percentage may reflect stronger antitumor immune responses in patients with CML-CP.
Keywords: ABL1 tyrosine kinase inhibitor; Chronic myeloid leukemia; higher neutrophil counts; third attempt tyrosine kinase inhibitor discontinuation; tyrosine kinase inhibitor discontinuation.