Monitoring of minimal residual disease in patients with acute promyelocytic leukemia

Aim. To study efficacy of different programs of maintenance therapy, to create the program of differential therapy of minimal residual disease (MRD) and molecular recurrences at all stages of acute promyelocytic leukemia (APL) basing on the results of monitoring. Material and methods. A total of 76 APL patients entered the trial. They received therapy by the protocols APL-97/98, APL-01, AIDA, 5D. Expression of chymeric oncogen PML/RARa in the disease onset was estimated by bone marrow and/or peripheral blood examination with RT-PCR. The study of chymeric oncogen PML/RARa was made once in two months. Results. The program of differential therapy of APL is proposed on the basis of molecular-biological monitoring of expression of chymeric oncogen PML/RARa. The results of molecular monitoring of MRD correlated with development of molecular and hematological recurrences. Therapeutic policy is determined after diagnosis of molecular recurrence. Further therapy of APL is determined which allows a rise in overall and recurrence-free survival of the patients. Conclusion. The efficacy of maintenance therapy only with cytostatic drugs or their combination with ATRA is similar. The response to biological therapy with ATRA plus interferon-alpha is not sufficient. Molecular recurrences - probable or documented - are detected in maintenance therapy 2 months earlier, on the average, than hematological ones. Changes in the treatment policy in registration of molecular recurrence significantly diminish probability of hematological recurrence (from 36 to 0%, p = 0.001).