PML RAR-ALPHA TRANSCRIPTS MONITORED BY POLYMERASE CHAIN-REACTION IN ACUTE PROMYELOCYTIC LEUKEMIA DURING COMPLETE REMISSION, RELAPSE AND AFTER BONE-MARROW TRANSPLANTATION/

The translocation t(15;17)(q24;q21), unique to acute promyelocytic leu kemia (APL), gives rise to PML/RAR alpha fusion transcripts detected b y the sensitive reverse transcriptase-polymerase chain reaction (PCR) technique, PCR may help in the diagnosis and in monitoring minimal res idual disease. Reversion of PCR to negative is obtained by chemotherap y (CT) alone or in combination with all-trans retinoic acid (ATRA). He re we show a serial PCR study of 10 APL cases. Five cases were studied at the time of diagnosis, and all were PCR positive for the rearrange d transcripts (three bcr1 type, two bcr3 type). Seven cases in complet e remission (CR) after one cycle of induction CT were persistently PCR negative, one case in CR after ATRA rescue was persistently PCR posit ive (bcr1 type), one patient (bcr3 type) relapsed 15 months after the PCR-negative CR and one patient died early. Seven patients underwent b one marrow transplantation (BMT) (five allogeneic, two autologous). On e of them died early after take of the allogeneic BMT, the other six c ases studied by serial PCR were persistently negative. At a median fol low-up of 31 months (range 9-39), none of these six cases had relapsed . PCR data characterize the CR at the molecular level and evaluate the efficacy of different treatments, including BMT. The data may help to define a standardized schedule for PCR follow-up, and are also potent ially useful to establish the time required before judging patients wi th persistently negative PCR to be cured, BMT as post-induction treatm ent in first CR is also discussed.