POLYMERASE CHAIN-REACTION IS HIGHLY PREDICTIVE OF RELAPSE IN PATIENTSFOLLOWING T-CELL-DEPLETED ALLOGENEIC BONE-MARROW TRANSPLANTATION FOR CHRONIC MYELOID-LEUKEMIA

In chronic myeloid leukemia (CML) the polymerase chain reaction (PCR) can be used to detect minimal residual disease after bone marrow trans plantation (BMT), Previous studies have shown that PCR positivity is c ommon following BMT, However, the clinical significance of this findin g for any given individual who is PCR positive remains unclear, as man y of these patients remain long-term disease-free survivors after allo geneic BMT, In the present study, we used PCR to detect BCR-ABL mRNA i n 144 blood or marrow samples from 36 patients who received a T cell-d epleted BMT for CML in first chronic phase, Six patients had no eviden ce of PCR-detectable residual disease at any time following transplant , The other 30 patients had at least one positive PCR result post-BMT, Once PCR positivity was found, it was usually sustained, with only fo ur patients having a subsequent PCR negative assay, No patient who had two consecutive PCR-positive assays had a return to PCR negativity, N one of the six patients with exclusively PCR-negative assays have deve loped either cytogenetic or hematologic relapse at a median followup o f 42 months, Of the 30 patients with at least one PCR-positive assay p ost-BMT, 28 were PCR positive at last follow-up, and 22 have progresse d to cytogenetic or hematologic relapse, If the PCR-positive assay occ urred within 24 months of the transplant then the estimated probabilit y of progression to cytogenetic or hematologic relapse was 65% at 24 m onths, Twenty of the 26 patients who were studied early (less than or equal to 6 months) after BMT had at least one positive PCR assay, Fift een of the 20 patients who were PCR positive less than or equal to 6 m onths following transplant have progressed to either cytogenetic or he matologic relapse resulting in an estimated probability of relapse of 84% at 24 months, These results indicate that following T cell-deplete d BMT for CML in first chronic phase, PCR is highly predictive of rela pse and may identify a cohort of patients in need of therapeutic inter vention before the onset of overt clinical relapse.