Premature chromosome condensation studies in human leukemia: 5. Prediction of early relapse

Previous reports have suggested that the technique of premature chromosome condensation (PCC) is useful for predicting relapse in patients with acute leukemia. However, these studies involved patients had been in complete remission (CR) for various periods of time and had heterogeneous expectations for relapse. The purpose of this study was to further determine the value of PCC in predicting relapse by examining the PCC characteristics of bone marrow specimens from patients with acute leukemia on a common therapeutic regimen after similar periods in CR. The remission durations after the PCC determinations were compared between patients with high or low proliferative potential indices (PPI, or the fraction of G1 cells in late G1 phase). Of 60 patients studied between two and eight weeks after achieving CR, 14 of the 16 patients exhibiting high PPI values (greater than or equal to 35) have relapsed. The mean time from PCC measurement to relapse was 23 weeks. In contrast, only 19 of the 44 patients exhibiting low PPI values have relapsed, with an estimated mean time to relapse of 68+ weeks. Likewise, of 38 patients studied between nine and 15 weeks of CR, nine of the ten patients exhibiting high PPI values have relapsed (mean time to relapse, 23 weeks), while only 16 of 28 patients with low PPI values have relapsed (estimated mean time to relapse, 54+ weeks). The predictive value of the PCC technique was found to be independent of other prognostic factors for the duration of CR, and it identified those patients within the poor prognostic category with a high likelihood of imminent relapse. While similar trends were observed at later time intervals in CR, the differences in relapse rate between patients with high or low PPI values is not significant. These results confirm the usefulness of the PCC technique in predicting relapse in acute leukemia and could aid in the identification of patients who might benefit by an alteration of therapeutic strategy.