Molecular measurement of BCR-ABL transcript variations in chronic myeloid leukemia patients in cytogenetic remission

<p>Abstract</p> <p>Background</p> <p>The monitoring of <it>BCR-ABL </it>transcript levels by real-time quantitative polymerase chain reaction (RT-qPCR) has become important to assess minimal residual disease (MRD) and standard of care in the treatment of chronic myeloid leukemia (CML). In this study, we performed a prospective, sequential analysis using RT-qPCR monitoring of <it>BCR-ABL </it>gene rearrangements in blood samples from 91 CML patients in chronic phase (CP) who achieved complete cytogenetic remission (CCyR) and major molecular remission (MMR) throughout imatinib treatment.</p> <p>Methods</p> <p>The absolute level of <it>BCR-ABL </it>transcript from peripheral blood was serially measured every 4 to 12 weeks by RT-qPCR. Only level variations > 0.5%, according to the international scale, was considered positive. Sequential cytogenetic analysis was also performed in bone marrow samples from all patients using standard protocols.</p> <p>Results</p> <p>Based on sequential analysis of <it>BCR-ABL </it>transcripts, the 91 patients were divided into three categories: (A) 57 (62.6%) had no variation on sequential analysis; (B) 30 (32.9%) had a single positive variation result obtained in a single sample; and (C) 4 (4.39%) had variations of <it>BCR-ABL </it>transcripts in at least two consecutive samples. Of the 34 patients who had elevated levels of transcripts (group B and C), 19 (55.8%) had a < 1% of <it>BCR-ABL/BCR </it>ratio, 13 (38.2%) patients had a 1% to 10% increase and 2 patients had a >10% increase of RT-qPCR. The last two patients had lost a CCyR, and none of them showed mutations in the <it>ABL </it>gene. Transient cytogenetic alterations in Ph-negative cells were observed in five (5.5%) patients, and none of whom lost CCyR.</p> <p>Conclusions</p> <p>Despite an increase levels of <it>BCR-ABL/BCR </it>ratio variations by RT-qPCR, the majority of CML patients with MMR remained in CCyR. Thus, such single variations should neither be considered predictive of subsequent failure and nor an indication for altering imatinib dose or switching to second generation therapy. Changing of imatinib on the basis of <it>BCR-ABL/BCR</it>% sustained increase and mutational studies is a prudent approach for preserving other therapeutic options in imatinib-resistant patients.</p

Detection of abnormal pretransplant clones in progenitor cells of patients who developed myelodysplasia after autologous transplantation

Secondary myelodysplastic syndromes (MDS) have been reported after autologous transplantation. It is not known whether the MDS results from the pretransplant conventional-dose chemotherapy or from the high-dose chemotherapy (HDC) used for the transplant procedure. We performed a multicenter, retrospective analysis of morphologically normal pretransplant marrow or stem cell specimens from 12 patients who subsequently developed myelodysplasia after HDC. To determine if the abnormal clone was present before HDC, we used fluorescence in situ hybridization (FISH) to detect the cytogenetic markers observed at the onset of posttransplant MDS. Cryopreserved, pretransplant bone marrow, peripheral blood stem cell specimens, obtained at the time of harvest, or archival smears were used. Standard cytogenetic analysis had been performed pretransplant in four patients, showing a normal karyotype. In 9 of 12 cases, the same cytogenetic abnormality observed at the time of MDS diagnosis was detected by FISH in the pre-HDC specimens. Our findings support the hypothesis that, in many cases of posttransplant MDS, the stem cell damage results from prior conventional-dose chemotherapy and may be unrelated to HDC or the transplantation process itself. (C) 1999 by The American Society of Hematology

Detection of abnormal pretransplant clones in progenitor cells of patients who developed myelodysplasia after autologous transplantation

Secondary myelodysplastic syndromes (MDS) have been reported after autologous transplantation. It is not known whether the MDS results from the pretransplant conventional-dose chemotherapy or from the high-dose chemotherapy (HDC) used for the transplant procedure. We performed a multicenter, retrospective analysis of morphologically normal pretransplant marrow or stem cell specimens from 12 patients who subsequently developed myelodysplasia after HDC. To determine if the abnormal clone was present before HDC, we used fluorescence in situ hybridization (FISH) to detect the cytogenetic markers observed at the onset of posttransplant MDS. Cryopreserved, pretransplant bone marrow, peripheral blood stem cell specimens, obtained at the time of harvest, or archival smears were used. Standard cytogenetic analysis had been performed pretransplant in four patients, showing a normal karyotype. In 9 of 12 cases, the same cytogenetic abnormality observed at the time of MDS diagnosis was detected by FISH in the pre-HDC specimens. Our findings support the hypothesis that, in many cases of posttransplant MDS, the stem cell damage results from prior conventional-dose chemotherapy and may be unrelated to HDC or the transplantation process itself. (C) 1999 by The American Society of Hematology