[Molecular responses in acute promyelocytic leukemia patients monitored by real-time quantitative RT-PCR]

Previous clinical and experimental results have indicated a close relationship between residual leukemia cell clones and clinical outcome in acute promyelocytic leukemia (APL) patients. Real-time fluorescent quantitative reverse transcription-polymerase chain reaction (RQ-RT-PCR) is a sensitive and accurate method in detecting leukemia cell clones and monitoring minimal residual disease (MRD). This study was to evaluate the molecular responses and monitor the MRD in APL patients by RQ-RT-PCR.

All-trans retinoic acid (ATRA) and compound Huangdai tablets were used for remission induction in 100 newly diagnosed APL patients. Two isoforms of PML/RARalpha were detected by RQ-RT-PCR. The results known as normalized quotient (NQ) were calibrated by the transcripts of ABL control gene. NQ level of transcripts in 33 of these 100 patients were monitored consecutively, and molecular responses were assessed by log-reduction analysis.

The median NQ was 0.58 in these 100 APL patients: the median NQ of long isoform was 0.52, while that of short isoform was 0.74 (P>0.05). The NQ of fusion gene transcripts in 33 patients during follow-up decreased from 0.62 at diagnosis to 0.25 at clinical and hematologic remission (CHR) after induction, to 0.000 3 after consolidation chemotherapy and to 0 during maintenance. Of the 33 patients, 21 (63.64%) achieved minor molecular response at first CHR, 32 (96.97%) achieved partial molecular response after consolidation chemotherapy and all achieved major molecular response eventually.

RQ-RT-PCR combined log-reduction analysis is feasible for monitoring the molecular responses in APL patients.