Efficacy and Safety of Tyrosine Kinase Inhibitor Combined With Venetoclax-Based Regimen in Pediatric Patients With Chronic Myeloid Leukemia in the Blast Phase: A Single-Center Retrospective Study.

Pediatric chronic myeloid leukemia in the blast phase (CML-BP) is rare and high-risk, requiring early hematopoietic stem cell transplantation (HSCT). Tyrosine kinase inhibitor (TKI) combined with intensive chemotherapy prior to HSCT is associated with substantial toxicity, often causing complications that delay HSCT. Therefore, safer attenuated regimens are urgently needed. We retrospectively analyzed CML-BP pediatric patients treated with TKI plus venetoclax and assessed treatment safety via hematological and non-hematological adverse events. Six pediatric patients (five males and one female) treated with TKI and venetoclax were retrospectively collected from September 2022 to September 2025, with a median age of 13 years. Four patients presented with the lymphoid blast phase (CML-LBP), one with the myeloid blast phase (CML-MBP) and one with central nervous system leukemia (CNSL). After one cycle of TKI combined with venetoclax, four patients showed a decrease in BCR::ABL1 international scales (BCR::ABL1IS) transcript ratio in bone marrow fluid was >1 log, and five patients achieved minimal residual disease (MRD)-negative. With a median follow-up of 17 months, five of the six patients were alive. The safety profile was excellent, with Grade-2-3 hematological toxicities and Grade 1 nausea in six patients, Grade 2 fever in one patient, and Grade 1 hyperbilirubinemia in one patient. All the adverse reactions were alleviated with symptomatic therapy. The combination of TKI and venetoclax may be a viable strategy for treating pediatric patients with CML-BP.