Clinical characteristics and prognostic factors in myeloid blast-Phase chronic myeloid leukemia

Abstract Background The advent of the tyrosine kinase inhibitor (TKI) era has resulted in long-term survival for patients with chronic-phase chronic myeloid leukemia (CP-CML) approaching that of the general population.However,survival outcomes for patients in blast-phase chronic myeloid leukemia (BP-CML) remain poor.This is particularly evident in the myeloid blast phase (MBP) subtype,where the prognosis is especially dismal,with a 5-year overall survival (OS) rate of only 15%. Methods We retrospectively reviewed the clinical records of 141 MBP-CML patients treated at Henan Cancer Hospital between September 2009 and July 2024.Data collected included demographics, disease characteristics, treatment response, and survival.Prognostic factors were analyzed using Cox proportional hazards regression models. Results The median age of the 141 patients was 46 years (IQR35-53),with a male-to-female ratio of 1.47:1.At blast phase onset,111 patients (78.7%) had prior tyrosine kinase inhibitor (TKI) exposure,including 15 patients (13.5% of TKI-exposed) who had received a third-generation TKI.Extramedullary blast crisis (EMBC) occurred in 26 patients (18.4%), including 7 cases (5.0%) of isolated EMBC.Additional chromosomal abnormalities (ACAs) were present in 57.4% of patients,with 63% of these exhibiting complex karyotypes.ABL1 kinase domain mutations were detected in 58% of patients;the T315I mutation rate was 25%.Treatment included TKI plus chemotherapy for 98 patients (69.5%),TKI combined with venetoclax and azacitidine for 9 patients (6.4%),and single-agent TKI for 34 patients (24.1%).Response was evaluable in 132 patients:major hematologic response (MHR) rate was 53.8%,complete cytogenetic response (CCyR) rate 21.2%, major molecular response (MMR) rate 12.9%,and deep molecular response (DMR) rate 12.9%.With a median follow-up of 6.51 months,the median event-free survival (EFS) was 5.26 months and median overall survival (OS) was 7.72 months.Multivariate analysis identified:Prior third-generation TKI therapy as an independent adverse prognostic factor for EFS (HR2.772,95%CI:1.297-5.923,P=0.008).Lower peripheral blood blast percentage (HR0.563,95%CI:0.342-0.926,P=0.024) and isolated EMBC(HR0.211,95%CI:0.064-0.704,P=0.011) as favorable prognostic factors for EFS and OS,respectively.Achievement of MHR and/or DMR with treatment as a strong favorable prognostic factor for both EFS(MHR:HR0.317,95%CI:0.183-0.549,P<0.001;DMR:HR0.101,95%CI:0.030-0.343,P<0.001) and OS(MHR: HR 0.184,95%CI:0.102-0.330,P<0.001;DMR:(HR:0.119,95%CI:0.028-0.504,P<0.001).Conclusion:Most MBP-CML patients have prior TKI exposure,with high ratesof complex karyotypes and T315I mutations at blast phase.TKI plus chemotherapy remains the predominant treatment strategy,yet overall response rates and outcomes are poor.Key factors influencing survival include prior use of third-generation TKIs,peripheral blood blast percentage, the presence of isolated EMBC,and achieving MHR and/or DMR with first-line therapy. 【Keywords】 Leukemia,myeloid,chronic;Myeloid blast phase;Clinical features;Prognosis