Predicting early blast transformation in chronic-phase chronic myeloid leukemia: is immunophenotyping the missing link?
BACKGROUND
Flow cytometry (FC) is a commonly requested test in the workup of leukocytosis in community practices. The role of FC in chronic-phase chronic myeloid leukemia (CP-CML) is unknown. We hypothesized that finding aberrant cells with FC in CP-CML may predict early blast-phase (BP) transformation.


METHODS
Results for FC performed at the time of diagnosis for adult and pediatric patients with CP-CML who were referred to our institution were reviewed, and they were correlated with outcomes.


RESULTS
FC was performed at the time of diagnosis for 110 of 233 patients (47%) with CP-CML. Aberrant populations, representing a median of 2% (range, 0.3%-15%), were detected with FC in 30% of patients (33 of 110): 2 of these 33 patients expressed lymphoid markers, and 31 expressed aberrant myeloid markers. Patients received imatinib (85%), dasatinib (12%), or nilotinib (3%) as their first-line treatment. With a median follow-up of 43 months (range, 2-113 months), chronic myeloid leukemia transformed to BP in 5 of the 33 patients. The 2 patients with lymphoid markers and the 3 of 31 patients with aberrant myeloid markers experienced a transformation to lymphoid BP at a median of 11 months (range, 4-72 months) after the initiation of tyrosine kinase inhibitor therapy. Although both cases with detectable lymphoid markers rapidly progressed to lymphoid BP, the positive predictive value of BP transformation by the detection of myeloid aberrant cells with FC was only 10% (3 of 31).


CONCLUSIONS
In contrast to aberrant myeloid markers, the detection of lymphoid markers by FC at the time of the diagnosis of CP-CML appears to be associated with early progression to lymphoid BP.
Division of Hematology, Department of Hematology and Medical Oncology, the Winship Cancer Institute of Emory University, Atlanta, Georgia.
Fuad
F
El Rassi
John D
JD
Bergsagel
Martha
M
Arellano
Manila
M
Gaddh
Anand
A
Jillella
Vamsi
V
Kota
Leonard T
LT
Heffner
Elliott F
EF
Winton
Hanna Jean
HJ
Khoury
D000328:Adult; D001752:Blast Crisis / Q000276:immunology* / Q000473:pathology*; D002648:Child; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D016130:Immunophenotyping / Q000379:methods*; D015466:Leukemia, Myeloid, Chronic-Phase / Q000276:immunology* / Q000473:pathology*; D008297:Male; D011237:Predictive Value of Tests
chronic myeloid leukemia (CML); chronic phase; early blast phase; flow cytometry