Comparable Outcomes of Pre- Versus Post-Tyrosine Kinase Inhibitor Era Treatment in Chronic Myeloid Leukemia: A Retrospective Cohort Study With Long-term Follow-up

Imatinib, a selective BCR-ABL tyrosine kinase inhibitor (TKI), was introduced after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for patients with chronic myeloid leukemia (CML). However, the long-term effects of allo-HSCT in chronic phase CML patients are mostly unknown. We retrospectively analyzed the outcomes of 204 patients with sibling donors who received peripheral stem cells and underwent allo-HSCT of chronic phase I (CP1) in the pre- and post-TKI era at Shariati Hospital in Tehran, Iran, from 1998 to 2017 and followed up till the end of 2021. The median follow-up time for all patients was 8.7 (SD = 0.54) years. Fifteen-year overall survival (OS), disease-free survival (DFS), graft-versus-host disease-free relapse-free survival (GRFS), relapse, and non-relapse mortality (NRM) incidence were 65.70%, 57.83%, 17.56%, 13.17%, and 28.98%, respectively. Using multivariable analyses, the only risk factor increasing the hazard of death was the time between diagnosis to allo-HSCT greater than 1 year compared to this time less than 1 year by 74% [hazard ratio (HR) = 1.74, P = 0.039]. Also, age is a significant risk factor for DFS (HR = 1.03, P = 0.031). Our findings suggested that allo-HSCT is still an important treatment option for CP1 patients, especially those resistant to TKI treatment. TKI consumption can have a desirable effect on NRM after allo-HSCT for CP1 CML.