An abnormal CD34(+) myeloid/CD34(+) lymphoid ratio at the end of chemotherapy predicts relapse in patients with acute myeloid leukemia

During conventional follow-up of patients with acute myeloid leukemia (AML) , the emergence of cytopenias is considered to be a sign of impending relap se, and it represents an example of how leukemic hematopoiesis affects norm al hemopoietic differentiation. In the present study, we have explored the possible value of the analysis of the distribution of CD34(+) myeloid and C D34(+) lymphoid progenitor cells in follow-up complete remission bone marro w samples from de novo AML patients as a prognostic parameter for predictin g relapse. A total of 213 hone marrow samples from 36 AML patients in morph ological complete remission, obtained at the end of induction, consolidatio n, and intensification therapy and every six months thereafter were analyze d. The normal CD34(+) myeloid/CD34(+) lymphoid ratio ranged between 2.4 and 8.9. In contrast, in most AML cases an abnormally high ratio (greater than or equal to 10) was observed at the end of induction and consolidation the rapy: 96% and 75% of cases, respectively. On the other hand, at the end of intensification, 70% of the patients displayed a normal CD34(+) ratio. Pati ents with a myeloid/lymphoid CD34(+) ratio higher than 10 at the end of int ensification showed a significantly lower overall survival (median survival of 19 months versus median not reached, P = 0.05), as well as a lower dise ase-free survival (median of 7 months versus 30 months, P = 0.0001). Regard ing sequential studies, 67% of the relapses were preceded by the re-appeara nce of an abnormal CD34 ratio, whereas relapse was not predicted in four pa tient with leukemia classified as Mg undergoing maintenance therapy. From t he remaining 18 patients who are still in continuous complete remission, al l except 3 cases (17%) displayed a normal CD34 myeloid/lymphoid ratio. In s ummary, the present study shows that the persistence at the end of chemothe rapy of an abnormally high (greater than or equal to 10) ratio between CD34 (+) myeloid and CD34(+) lymphoid progenitors in the bone marrow of AML pati ents is associated with high risk of relapse and a shorter overall survival . Cytometry (Comm. Clin. Cytometry) 38: 70-75, 1999. (C) 1999 Wiley-Liss, I nc.