Comparative testing of peripheral blood and bone marrow for BCR-ABL transcripts in patients post allogeneic bone marrow transplantation and during interferon treatment for chronic myeloid leukemia

Patients with CML post allogeneic BMT or during treatment with Interferon w ere monitored in bone marrow and peripheral blood for BCR-ABL transcripts b y RT-PCR and in the majority of cases also by Southern blotting. Bone marro w and peripheral blood samples were obtained simultaneously and tested by R T-PCR with the objective to determine the usefulness to follow CML patients by testing peripheral blood rather than bone marrow samples. For the purpo se of this study we have considered the test results obtained from bone mar row samples as the standard. A total of 111 CML patients were examined who underwent either an allogeneic BMT (n = 91) or were treated with Interferon (n = 20) amounting to a total of 163 assessments for BCR-ABL. Concordance of results was observed in 153 samples (93.9%). 10 samples showed discordan ce. Seven of these were subjected to repeat testing by RT-PCR. The previous ly obtained discordant results were confirmed. The sensitivity of periphera l blood assays was calculated to be 96.2% with a specificity of 89.5%. RT-P CR results restricted to Southern blot negative patients showed concordance of bone marrow and peripheral blood in 91.1% of tested samples with a sens itivity of 92.7% and a specificity of 88.6%. The subset of patients in whic h Southern blot testing was not available showed concordance at a similar l evel. Complete concordance was seen in all patients that were found to be p ositive by Southern blotting. We conclude from this study that peripheral blood testing for BCR-ABL trans scripts by RT-PCR is a test with high sensitivity and specificity and may p otentially replace bone marrow testing. This approach will probably result in a high level of acceptance by patients and may permit more frequent moni toring.