Marrow fibrosis is an independent predictor of hematological toxicity of tyrosine kinase inhibitors for the treatment of chronic myeloid leukemia.

Hematological toxicity is a common adverse effect of tyrosine kinase inhibitors (TKIs) for the treatment of chronic myeloid leukemia (CML). We retrospectively investigated the incidence of hematological toxicity after TKI administration in 143 CML patients and parameters associated with hematological toxicity. Severe hematological toxicity (grade 3-4) existed in 26 (18.2%) patients. Marrow fibrosis (MF), age, Sokal score, and spleen enlargement were associated with severe hematological toxicity. Further multivariate analysis showed that only MF was an independent predictor. Complete cytogenetic response(CCyR) rates and major molecular response (MMR) rates with grade 3-4 hematological toxicity were 42.3% and 26.9%, respectively, significantly lower than patients with grade 1-2 and without hematological toxicity ( = .032 for CCyR and  = .044 for MMR). Similar results were observed regarding progression-free survival (PFS) and overall survival (OS) ( = .011 for PFS and  = .037 for OS). This study indicated that MF was an independent predictor of severe hematological toxicity of TKIs.