VARIOUS RESPONSE PATTERNS OF Ph’ CELLS TO IFN-a IN PATIENTS WITH CHRONIC MYELOCYTIC LEUKEMIA
Summary. It is well known fact that introduction of interferon alfa (IFN-a) can prolong the survival of CML patients, especially in cases of reduction in the percentage of Ph' metaphases. So far, the precise mechanism of IFN-a to kill the Ph’ cells is unknown and there is no useful marker(s) to predict good cytogenetic response at the time of diagnosis. We have examined the serial hematological findings, the proportion of Ph' metaphases and the products of reverse transcription/polymerase chain reaction (RT-PCR) in 29 patients to identify reduction patterns of Ph' cells. Six of 29 patients demonstrated a complete cytogenetic response (CCR) and 5 of 29 patients showed a partial cytogenetic response (PCR). Mean white blood cell (WBC) count during 3 to 12 months in a major cytogenetic response group (CCR plus PCR) was lower than in poor response group. No relationships between the cytogenetic response, previous therapy, the percentage of Ph' at diagnosis and the hematological findings at the initiation of IFN-a therapy have been found. 29 patients under study could be divided into five groups according to the patterns of Ph' clone fluctuations. We suggest that there are intrinsically unknown factors allowing us to categorize CML patients at diagnosis concerning response to IFN-a. Meanwhile, it is important to keep WBC count at low level to attain a major cytogenetic response.
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