Monitoring of minimal residual disease in acute promyelocytic leukemia.

Monitoring of minimal residual disease was performed in 35 patients with. acute promyelocytic leukemia. Blood and bone marrow samples were studied by RT-PCR assays according to the protocol BIOMED-1. Transcript of chimeric gene PML-RARalpha was a marker of leukemic cells. Follow-up varied from 4 to 40 months. The tests were made each 2-3 months. The results of our study agreed with the literature data. In consolidation, chimeric transcript was not detected on the treatment month 1-3 in 27 of 30 patients, i.e. 27 patients achieved molecular remission. Delayed conversion to PCR-negativity was found in three patients. It may be due to violation of the treatment protocol. Hematological recurrences followed conversion from PCR-negativity to PCR-positivity (a molecular recurrence). For a short time the transcript appeared in 5 patients during molecular remission (transitory PCR-positivity). The phenomenon of transitory PCR-positivity should be studied further for-establishment-of reliable criteria of its differentiation with the molecular recurrence.