ABSTRACT
Blast crisis is the terminal phase of chronic myeloid leukemia (CML), a clonal myeloproliferative disorder of the pluripotent hematopoietic stem cell, which typically evolves in three distinct clinical stages: chronic phase, accelerated phase, and blast crisis. The mechanisms responsible for transition of CML chronic phase to blast crisis remain poorly understood, although a reasonable assumption is that the unrestrained activity of breakpoint cluster region-Abelson in hematopoietic stem/progenitor cells is the primary determinant of disease progression. Cytogenetic and molecular changes occur in the vast majority of CML patients during transition to blast crisis; however, the mechanism(s) whereby each specific secondary genetic alteration contributes to disease progression is still largely unclear. Microsatellite instability, a feature associated with tumor progression, does not seem to be involved in CML disease progression. In this regard, CML disease progression is similar to the transition from a premalignant to a frank neoplastic state in solid tumors.
