Treatment of Chronic Myeloid Leukemia in Blast Phase with Blasts 20% or Greater
Blast phase (BP) chronic myeloid leukemia — defined by 20% or more blasts in the peripheral blood or bone marrow, or by extramedullary blast proliferation — represents an advanced, high-urgency disease state. Per the 2022 WHO revised classification, this threshold now directly defines blast phase, replacing the former accelerated phase concept.
This protocol applies to patients with CML in blast phase presenting with blasts 20% or greater in peripheral blood or bone marrow, or with extramedullary blast proliferation. Rapid assessment and prompt initiation of treatment are essential in this setting.
Management for eligible patients involves intensive combination chemotherapy in conjunction with a tyrosine kinase inhibitor. The specific agents, eligibility criteria, alternative pathways for patients who cannot tolerate intensive therapy, and the full treatment algorithm are covered in the complete protocol.
The primary objective is regain of a second chronic phase. Every possible effort toward this goal is prioritised, with allogeneic stem cell transplantation considered as a subsequent step.
References
DOI: 10.1038/s41375-025-02664-w
- In 2022 the WHO revised the classification of disease phase in CML, omitting the concept of AP, and defining BP as the presence of >20% blasts.
- Treatment for eligible patients in BP is by intensive combination chemotherapy with a TKI, ideally dasatinib or ponatinib, followed by alloSCT.
- Every possible effort should be made to regain a second chronic phase and offer alloSCT promptly thereafter.