[Molecular analysis of bcr-abl mRNA during long-term follow-up of cases of chronic myelogenous leukemia].

Forty cases of Ph1-positive CML patients, who were followed up for a long period, were evaluated for bcr-abl mRNA using RT-PCR. We analyzed the relation of the bcr-abl mRNA subtype to the duration of chronic phase and blast crisis lineage. The mean duration of the chronic phase was 2 years 3 months (2Y3M) in b2-a cases, 1Y11M in b3-a, and 1Y4M in both b2-a and b3-a cases. The myeloid/lymphoid ratio at the blastic phase was 1.0 in b2-a, 0.33 in b3-a, and 2.5 in both mRNA cases. No significant difference was observed in the mean duration of the chronic phase and the frequency of two kinds of blast crisis lineage among different bcr-abl mRNA cases. We also evaluated CML patients in clinical remission after BMT. Bcr-abl mRNA was detectable in 6 of 7 cases (6/7) within 6 months after BMT, all five cases from 6 months to 1 year (1Y), 2/8 at 1Y, 3/7 at 2Y, and 3/7 over 3Y. It suggested the longer time after BMT, the more patients were negative for RT-PCR. In one patient, RT-PCR signal became undetectable at 9Y. This demonstrated that bcr-abl mRNA-positive residual cells could be eradicated long after BMT.