An assessment of chimeric transcript detection in CML patients after bone marrow transplantation.

The Polymerase Chain Reaction (PCR) was used to evaluate minimal residual disease in 21 Ph+ CML patients at various intervals after allogeneic bone-marrow transplantation (ABMT) by amplification of bcr-abl cDNA. All patients were cytogenetically Ph- at the moment of molecular analysis. Of these 76% were PCR negative, 24% positive for bcr-abl transcripts. 100% of the Cyclosporine A/Methotrexate treated patients (7/7) were negative. Severe chronic GvHD was twice as frequent in PCR positive patients (60%) than in negative ones (31%). The only patient who relapsed during follow up was PCR positive. The two longest survivors were PCR negative. These data are still insufficient for assessing the predictive value of PCR analysis in CML. Patients. 25 patients with Ph+ CML at diagnosis were enrolled in this study. Two died soon after BMT because of infection for failure of engraftment/early relapse, two were Ph chromosome positive and PCR+, and were therefore dismissed from this study. All remaining 21 patients were cytogenetically Ph- at the time of molecular analysis and underwent ABMT from matched donors. All patients were conditioned with cyclophosphamide and TBI: 330 cGy the three days prior to transplantation (990 cGy total, treatment B), or 200 cGy two times daily for three days (1200 cGy total, treatment A). In 3 cases the marrow was treated for GvHD prophilaxis with Campath alone or Campath plus BT 5/9 monoclonal antibodies (1). All patients were treated with Cyclosporin A (CS) 5 mg/kg i.v. from the day prior to transplantation until 25-30 days after; 9 of these were treated with CS plus Methotrexate (MTX).