Various response patterns of Ph ' cells to IFN-alpha in patients with chronic myelocytic leukemia

It is well known fact that introduction of interferon alfa (IFN-alpha) can prolong the survival of CML patients, especially in cases of reduction in t he percentage of Ph' metaphases. So far, the precise mechanism of IFN-alpha to kill the Ph' cells is unknown and there is no useful marker(s) to predi ct good cytogenetic response at the time of diagnosis. We have examined the serial hematological findings, the proportion of Ph' metaphases and the pr oducts of reverse transcription/polymerase chain reaction (RT-PCR) in 29 pa tients to identify reduction patterns of Ph' cells. Six of 29 patients demo nstrated a complete cytogenetic response (CCR) and 5 of 29 patients showed a partial cytogenetic response (PCR). Mean white blood cell (WBC) count dur ing 3 to 12 months in a major cytogenetic response group (CCR plus PCR) was lower than in poor response group. No relationships between the cytogeneti c response, previous therapy, the percentage of Ph' at diagnosis and the he matological findings at the initiation of IFN-alpha therapy have been found . 29 patients under study could be divided into five groups according to th e patterns of Ph' clone fluctuations. We suggest that there are intrinsical ly unknown factors allowing us to categorize CML patients at diagnosis conc erning response to IFN-alpha. Meanwhile, it is important to keep WBC count at low level to attain a major cytogenetic response.