Criteria for sudden blast crisis:
(1) patient with low or intermediate risk Philadelphia chromosome-positive CML
(2) favorable response to therapy with a complete cytogenetic response
(3) blast crisis (>= 30% blasts in peripheral blood OR >= 30% blasts in the bone marrow OR extramedullary blastic disease)
(4) sudden onset (abrupt transformation occurring within 3 months of a documented complete cytogenetic response)
Features of the sudden blast crisis:
(1) It may occur in a patient treated with imatinib mesylate or interferon-based regimens.
(2) The blasts may be lymphoid, myeloid or biclonal.
In the study of Alimena et al, sudden blast crisis occurred in around 4% of patients receiving imatinib and followed for a median period of 3 years.
