Quantification of BCR-ABL transcripts in CML patients in cytogenetic remission after interferon-α-based therapy

Abstract

Summary:We measured using a competitive quantitative polymerase chain reaction-capillary electrophoresis (PCR-CE)-based assay, the levels of bcr-abl transcripts in 44 patients with chronic myeloid leukemia (CML) after interferon-␣ (IFN-␣) therapy, who achieved a major (10 patients, MCR group) or complete (34 patients, CCR group) cytogenetic response. All 34 CCR patients had molecular evidence of residual disease detected in bone marrow samples at the time of best karyotypic response. The median number of bcr-abl transcripts of 34 evaluable patients in the CCR group at the time of complete cytogenetic remission was 4/ g RNA (range 3-4600), while the median number of bcr-abl transcripts of 10 patients in the MCR group at the time of best cytogenetic response was 4490/ g RNA (range 600-23 900) (P = 0.000024). In nine CCR and five MCR patients we were able to quantify the amount of bcr-abl transcript both at diagnosis and after interferon therapy: no statistical difference (P = 0.18) was found between the two groups at diagnosis (median bcr-abl transcripts/ g RNA was 30 000 vs 39 650, respectively). During IFN-␣ therapy, the two groups were evaluable at the time of major karyotypic conversion: at this point, there was a statistical difference of expression of bcr-abl transcript between the CCR group (17 patients) (median 2700; range 76-40 000) and the MCR group (10 patients) (median 4490; range 600-23 900), respectively (P = 0.046). No differences of bcr-abl amount of transcript were found in patients with CCR obtained either by IFN-␣ therapy alone (20 patients) vs IFN-␣ plus ABMT (13 patients) (P = 0.47). We firstly demonstrated that although the CCR and MCR groups were clinically, cytogenetically and molecularly indistinguishable at diagnosis, the two groups could be recognized successfully during interferon therapy based on the level of bcr-abl transcript. Bone Marrow Transplantation (2000) 25, 729-736.

Molecular response to imatinib in late chronic-phase chronic myeloid leukemia

“…31,32 With IFN-␣, although several patients achieve a complete and stable CgR, a molecular negativity is rarely seen, but the greater the reduction of BCR/ABL transcripts the better the long-term outcome. 22,25,33,34 AlloHSCT induces a CHR and a CCgR in almost all cases. Longitudinal molecular studies after alloHSCT have shown that a small amount of transcript can be detected within 1 year from transplantation, but that once the transcript becomes undetectable, the disease is almost always cured.…”

Chronic myeloid leukemia and interferon-α: a study of complete cytogenetic responders

“…In many cases the BCR/ABL transcript was always detectable, in some cases it was occasionally undetectable, and in a few cases it was always undetectable, as has been reported by several investigators over the last 10 years. [24][25][26] These registry data are not presented in more detail because they have been produced over a long period of time, in many different laboratories, and with different techniques. These data cannot contribute more to the debate on the concept of the cure of CML.…”

“…It is widely recognized that the specificity of a conventional cytogenetic evaluation is relatively low and it has been reported that the leukemia-specific BCR/ABL transcript can be found in almost all the cases of CCgR. [24][25][26] However, those having a CCgR have less residual disease than other responders [24][25][26] and there is little doubt that CCgRs are a fascinating élite of patients who have the highest sensitivity to IFN-␣ and are the most likely candidates for prolonged survival and possibly cure. 5,17,23,27 For these reasons, better knowledge of more CCgRs is required and this is possible only through an international cooperative effort.…”

Applications of Short-Chain Polydimethylacrylamide as Sieving Medium for the Electrophoretic Separation of DNA Fragments and Mutation Analysis in Uncoated Capillaries

“…A major step forward was the introduction in recent years of replaceable polymer solutions as separation or sieving media, including linear polyacrylamide (6 -11), cellulose derivatives (8,12,13), and poly(ethylene oxide) (14,15). These advances in matrix preparation have promoted the application of CE in DNA analysis, such as mutation detection (16 -20), forensic genotyping (21,22), DNA sequencing (5,10,15), and measurement of gene expression (23)(24)(25).…”