FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W22172979> ?p ?o ?g. }

• W22172979 endingPage "10" @default.
• W22172979 startingPage "1" @default.
• W22172979 abstract "A variety of molecular-based targets are potentially amenable to analysis for the evaluation of minimal residual disease (MRD) following attempts at curative therapies in hematological malignancies. These can be broadly divided into one of three types: pathological rearrangements (translocations), physiological rearrangements (antigen receptor gene rearrangements), and others (for example the overexpression of the Wilm's tumor gene WT1). This review will focus on one specific and extensively studied example from the first group, namely the t(9;22) of chronic myeloid leukemia (CML). Any appreciation of MRD testing is contingent on an understanding of the biology of the disease being tested, as well as the therapeutic scenario in which it is being tested. Accordingly, this article will also briefly review both the biology and the therapy of CML. The reader is referred to a number of recent reviews that cover other molecular targets available for MRD testing,1Bagg A Minimal residual disease: how low do we go?.Mol Diagn. 2001; 6: 155-160PubMed Google Scholar, 2Foroni L Harrison CJ Hoffbrand AV Potter MN Investigation of minimal residual disease in childhood and adult acute lymphoblastic leukaemia by molecular analysis.Br J Haematol. 1999; 105: 7-24PubMed Google Scholar, 3Campana D Neale GA Coustan-Smith E Pui CH Detection of minimal residual disease in acute lymphoblastic leukemia: the St. Jude experience.Leukemia. 2001; 15: 278-279Crossref PubMed Scopus (40) Google Scholar as well as to other recent excellent reviews specifically addressing MRD in CML.4Faderl S Talpaz M Kantarjian HM Estrov Z Should polymerase chain reaction analysis to detect minimal residual disease in patients with chronic myelogenous leukemia be used in clinical decision making?.Blood. 1999; 93: 2755-2759PubMed Google Scholar, 5Roman J Alvarez MA Torres A Molecular basis for therapeutic decisions in chronic myeloid leukemia patients after allogeneic bone marrow transplantation.Haematologica. 2000; 85: 1072-1082PubMed Google Scholar, 6Hochhaus A Weisser A La Rosee P Emig M Muller MC Saussele S Reiter A Kuhn C Berger U Hehlmann R Cross NC Detection and quantification of residual disease in chronic myelogenous leukemia.Leukemia. 2000; 14: 998-1005Crossref PubMed Scopus (98) Google Scholar Chronic myeloid leukemia (CML) is a most intriguing disease that has become a challenging paradigm for clinical hematologist-oncologists, experimental biologists, and molecular pathologists. It is a true hematopoietic stem cell disorder that primarily manifests with expanding myelopoiesis. This accounts for the classic peripheral blood features, dominated by the presence of granulocytes in all phases of maturation. It was the first recognized type of leukemia,7Virchow R Weisses Blut.Floriep's Notizen. 1845; 36: 151-156Google Scholar and, over a century later, was the first malignancy shown to have an acquired and specific genetic abnormality, with the identification of an abnormally shortened chromosome 22, the Philadelphia (Ph) chromosome.8Nowell PC Hungerford DA A minute chromosome in human chronic granulocytic leukemia.Science. 1960; 132: 1497Google Scholar Following this seminal discovery, there was a 13 year hiatus before it was demonstrated that the Ph chromosome resulted from a reciprocal t(9;22) translocation.9Rowley JD A new consistent chromosomal abnormality in chronic myelogenous leukemia identified by quinacrine fluorescence and Giemsa staining.Nature. 1973; 243: 290-293Crossref PubMed Scopus (3310) Google Scholar The molecular correlates of this translocation were first identified 10 years later, with the subsequent recognition of the fusion of two distinct genes, BCR and ABL.10Heisterkamp N Stephenson JR Groffen J Hansen PF de Klein A Bartram CR Grosveld G Localization of the c-ab1 oncogene adjacent to a translocation break point in chronic myelocytic leukaemia.Nature. 1983; 306: 239-242Crossref PubMed Scopus (615) Google Scholar The ability of this chimeric gene and protein to cause CML was demonstrated by retrovirally-transfecting BCR-ABL into mice in 1990, which led to the induction of a CML-like syndrome.11Daley GQ Van Etten RA Baltimore D Induction of chronic myelogenous leukemia in mice by the P210bcr/abl gene of the Philadelphia chromosome.Science. 1990; 247: 824-830Crossref PubMed Scopus (1908) Google Scholar However, a definitive transgenic mouse model of CML has remained elusive, despite numerous attempts. There are a variety of mechanisms through which the heightened tyrosine kinase (TK) activity of BCR-ABL transforms cells. A multitude of cellular substrates are phosphorylated by this relocated (from nucleus to cytoplasm) TK, leading to proliferation, diminished growth factor dependence, apoptosis inhibition, and altered adhesion, among other effects.12Deininger MW Goldman JM Melo JV The molecular biology of chronic myeloid leukemia.Blood. 2000; 96: 3343-3356Crossref PubMed Google Scholar While the precise subcellular pathways through which these ultimate biological consequences are attained remain to be definitively dissected, the fact that BCR-ABL is indeed the cause of CML appears clear now, based on the clinical response to targeted TK inhibition with the drug imatinib mesylate (formerly known as STI571), trade-named Gleevec.13Druker BJ Talpaz M Resta DJ Peng B Buchdunger E Ford JM Lydon NB Kantarjian H Capdeville R Ohno-Jones S Sawyers CL Efficacy and safety of a specific inhibitor of the BCR-ABL tyrosine kinase in chronic myeloid leukemia.N Engl J Med. 2001; 344: 1031-1037Crossref PubMed Scopus (4388) Google Scholar CML is an at least biphasic disease, with the characteristic chronic phase of the myeloproliferation almost invariably metamorphosing into an acute blastic phase, often through an intermediate accelerated phase. This progression is likely related to the genetic instability induced by BCR-ABL, and is commonly associated with the acquisition of additional, and frequently characteristic, genetic changes.14Mintzer DA Bagg A Clinical syndromes of transformation in clonal hematologic disorders.Am J Med. 2001; 111: 480-488Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar The Ph chromosome and BCR-ABL fusion, however, persist through all phases. The t(9;22) translocation is not pathognomonic of CML, and may be seen in the context of other leukemias. Although indistinguishable at the traditional karyotypic level, the t(9;22) translocation comes in three predominant (and a variety of less common) molecular flavors, each with a characteristic (but not completely specific) clinicopathologic correlate (Figure 1). These differences are due to differences in the breakpoint within the BCR gene. By contrast, breakpoints involving ABL are relatively consistent, typically in the intron before exon 2 (a2). Almost invariably, the breakpoint in CML involves the Major breakpoint cluster region (M-bcr) of the BCR gene, occurring after exon 13 (e13 or b2) or exon 14 (e14 or b3). These two different breakpoints in the M-bcr are of no established clinical consequence, and although the latter includes an additional 75 bp, both give rise to the prototypic, CML-associated p210 protein. By contrast, the p190 protein, generated by a more 5′ breakpoint, beyond exon 1 (e1) is more tightly associated with Ph+ acute lymphoblastic leukemia (ALL), while the p230 protein, as a consequence of a more 3′ breakpoint beyond exon 19 (e19), is more characteristically seen in the context of chronic neutrophilic leukemia. Although the involvement of the M-bcr region alluded to above is quite consistently seen in CML, differential or alternative spicing may lead to heterogeneity at the level of the mRNA transcript. This may be minimal, with a single b3a2 DNA fusion yielding both a b3a2 and a b2a2 transcript, or rather more substantial, resulting in an e1a2 transcript. While the latter RNA transcript is characteristically associated with Ph+ ALL, it is commonly seen in CML too.15Lichty BD Keating A Callum J Yee K Croxford R Corpus G Nwachukwu B Kim P Guo J Kamel-Reid S Expression of p210 and p190 BCR-ABL due to alternative splicing in chronic myelogenous leukaemia.Br J Haematol. 1998; 103: 711-715Crossref PubMed Scopus (59) Google Scholar Importantly, however, it is not a consequence of the Ph+ ALL-associated DNA breakpoint, although it may have some clinicopathologic correlates (see Figure 1) and applications in MRD testing in CML (see below). An appreciation of the different therapeutic modalities available for CML is appropriate for those charged with gauging remission and tracking minimal residual disease post-therapy. CML therapy has undergone numerous changes, and standard therapeutic practice has evolved over the past few decades, most dramatically in the last 10 to 15 years. This has resulted in busulphan supplanting radiotherapy, hydroxyurea supplanting busulphan, and then interferon-α (IFN-α) supplanting hydroxyurea. However, none of these approaches has led to the eradication of the clone and cure of the disease. The only form of therapy that can currently cure patients of CML, perhaps without complete eradication of the clone, is allogeneic bone marrow or peripheral blood stem cell transplantation (collectively designated SCT in this review). SCT, although the treatment of choice for younger patients, is not trivial, being associated with significant morbidity and mortality, and is not an option for every patient and is not definitively recommended as the treatment of choice for all patients with CML.16Silver RT Woolf SH Hehlmann R Appelbaum FR Anderson J Bennett C Goldman JM Guilhot F Kantarjian HM Lichtin AE Talpaz M Tura S An evidence-based analysis of the effect of busulfan, hydroxyurea, interferon, and allogeneic bone marrow transplantation in treating the chronic phase of chronic myeloid leukemia: developed for the American Society of Hematology.Blood. 1999; 94: 1517-1536PubMed Google Scholar The current exciting data notwithstanding, it remains to be determined whether imatinib mesylate (STI571) will become the therapy of choice for this disease. Phase III clinical trials using this agent are currently underway, and other creative therapies, for example, those capable of trapping the BCR-ABL protein in the nucleus, are in the pipeline.17Vigneri P Wang JY Induction of apoptosis in chronic myelogenous leukemia cells through nuclear entrapment of BCR-ABL tyrosine kinase.Nat Med. 2001; 7: 228-234Crossref PubMed Scopus (283) Google Scholar However, even imatinib mesylate may disappoint as a panacea, since CML cells can be quite conniving; reports are emerging of the development of resistance to this form of therapy, with the reactivation of BCR-ABL signal transduction via gene amplification or mutation.18Gorre ME Mohammed M Ellwood K Hsu N Paquette R Rao PN Sawyers CL Clinical resistance to STI-571 cancer therapy caused by BCR-ABL gene mutation or amplification.Science. 2001; 293: 876-880Crossref PubMed Scopus (2706) Google Scholar Response to therapy is measured using three broad modalities: hematological, cytogenetic, and molecular. Hematological remission is designated once the blood counts and spleen size have returned to normal, while cytogenetic responses are determined by the percentage of residual Ph+ cells, classified as none (100%), minor (35 to 99%), major-partial (1 to 34%), and major-complete (0%).19Talpaz M Kantarjian H Kurzrock R Trujillo JM Gutterman JU Interferon-alpha produces sustained cytogenetic responses in chronic myelogenous leukemia: Philadelphia chromosome-positive patients.Ann Intern Med. 1991; 114: 532-538Crossref PubMed Scopus (404) Google Scholar While these two definitions are simple and reproducible, in the context of contemporary therapy, especially SCT, they have, in large part, been replaced by considerations of molecular remission. A variety of technologies may be included under those used to monitor disease at a molecular level. These include FISH, Southern blot, western blot, and reverse transcriptase polymerase chain reaction (RT-PCR). RT-PCR is performed in preference to DNA PCR, given the fact that the genomic breakpoints are almost invariably intronic and widely dispersed. For example, the breaks in the typically involved first intron of the ABL gene may occur anywhere within a greater than 300-kb span. While not impossible,20Waller CF Dennebaum G Feldmann C Lange W Long-template DNA polymerase chain reaction for the detection of the bcr/abl translocation in patients with chronic myelogenous leukemia.Clin Cancer Res. 1999; 5: 4146-4151PubMed Google Scholar this would render DNA-based analysis rather cumbersome; nature has solved this potential analytic problem for us through the process of mRNA splicing. FISH has some clear applications in certain monitoring scenarios, however none of the first three methods has sufficient analytic sensitivity to consistently detect less than 1% malignant cells, while RT-PCR is up to four orders of magnitude more sensitive. Accordingly, RT-PCR is the best method for tracking MRD and will be the focus of this review. Nevertheless, even though the discussion will be restricted to RT-PCR, the most powerful and sensitive modality for tracking disease, what will emerge is that this is clearly not straightforward, with much of the complexity a consequence of both rapidly evolving and non-standardized methodologies. This review will attempt to synthesize, reconcile and clarify the published data, and highlight the need for the development of international standards. The relative roles of the other modalities, including conventional karyotypic analysis, have recently been reviewed elsewhere.21Wang YL Bagg A Pear W Nowell PC Hess JL Chronic myelogenous leukemia: laboratory diagnosis and monitoring.Genes Chromosomes Cancer. 2001; 32: 97-111Crossref PubMed Scopus (47) Google Scholar As alluded to above, MRD testing has different connotations in different therapeutic scenarios. For example, in the context of SCT, approximately 50 to 80% of patients achieve complete cytogenetic remission, with the majority of those (∼ 80 to 85%) also attaining molecular (RT-PCR) remission. By contrast, while about 30 to 40% of patients treated with IFN-α reach complete cytogenetic remission, virtually none attain molecular remission. Hence, MRD testing will be considered separately for these two treatment options (as yet, there are no substantive data for imatinib mesylate). While complete eradication of the BCR-ABL clone may not be an absolute prerequisite to the attainment of cure, the degree to which the tumor load is reduced following therapy is a significant prognosticator. Even the most powerful RT-PCR assays are currently unable to exceed a 10−8 level of sensitivity. However, this level of sensitivity is neither required nor recommended, especially in light of the detection of BCR-ABL transcripts in normal individuals, when tested with this degree of sensitivity.22Biernaux C Loos M Sels A Huez G Stryckmans P Detection of major bcr-abl gene expression at a very low level in blood cells of some healthy individuals.Blood. 1995; 86: 3118-3122PubMed Google Scholar, 23Bose S Deininger M Gora-Tybor J Goldman JM Melo JV The presence of typical and atypical BCR-ABL fusion genes in leukocytes of normal individuals: biologic significance and implications for the assessment of minimal residual disease.Blood. 1998; 92: 3362-3367PubMed Google Scholar The purported presence of these very low numbers of BCR-ABL+ cells in normal individuals is, of course, biologically intriguing. Such findings may then support the notion that BCR-ABL is necessary, but not in isolation, sufficient, for the neoplastic phenotype. Importantly, given that CML at presentation accounts for ∼1012Deininger MW Goldman JM Melo JV The molecular biology of chronic myeloid leukemia.Blood. 2000; 96: 3343-3356Crossref PubMed Google Scholar cells, with these “over-sensitive” assays, this would still leave the order of at least 104 cells in the body at the time of “molecular remission”. This likely explains why patients in complete molecular remission may relapse. An additional explanation for this is that there are subpopulations, albeit rare, of transcriptionally quiescent cells,24Holyoake T Jiang X Eaves C Eaves A Isolation of a highly quiescent subpopulation of primitive leukemic cells in chronic myeloid leukemia.Blood. 1999; 94: 2056-2064PubMed Google Scholar that would be missed by even the most powerful RT-PCR assays. Furthermore, it should be noted that an increase or decrease in BCR-ABL levels does not necessarily correspond to alterations in cell number. In addition to the presence of transcriptionally silent cells noted above, the converse has also been described, wherein cells may up-regulate transcription.25Gaiger A Henn T Horth E Geissler K Mitterbauer G Maier-Dobers-berger T Greinix H Mannhalter C Haas OA Lechner K Increase of bcr-abl chimeric mRNA expression in tumor cells of patients with chronic myeloid leukemia precedes disease progression.Blood. 1995; 86: 2371-2378PubMed Google Scholar Although RT-PCR is used, and discussed here, primarily in the context of MRD, it may be used in at least three other scenarios. These are: as an up-front diagnostic tool in Ph chromosome-negative cases,21Wang YL Bagg A Pear W Nowell PC Hess JL Chronic myelogenous leukemia: laboratory diagnosis and monitoring.Genes Chromosomes Cancer. 2001; 32: 97-111Crossref PubMed Scopus (47) Google Scholar to predict disease progression,25Gaiger A Henn T Horth E Geissler K Mitterbauer G Maier-Dobers-berger T Greinix H Mannhalter C Haas OA Lechner K Increase of bcr-abl chimeric mRNA expression in tumor cells of patients with chronic myeloid leukemia precedes disease progression.Blood. 1995; 86: 2371-2378PubMed Google Scholar and in gauging the contamination of autografts.26Corsetti MT Lerma E Dejana A Basta P Ferrara R Benvenuto F Vassallo F Abate M Piaggio G Parodi C Sessarego M Li Pira G Manca F Carella AM Quantitative competitive reverse transcriptase-polymerase chain reaction for BCR-ABL on Philadelphia-negative leukaphereses allows the selection of low-contaminated peripheral blood progenitor cells for autografting in chronic myelogenous leukemia.Leukemia. 1999; 13: 999-1008Crossref PubMed Scopus (15) Google Scholar However, conventional cytogenetics remains the mainstay in the second scenario, and autologous transplantation is fraught with high relapse rates (given the absence of a graft versus leukemia effect), as well as some procedure-related toxicity. Much of the original literature on MRD testing in CML (published during most of the 1990s) was based on either qualitative PCR (initially) or quantitative, such as competitive PCR, methods (subsequently) that were based on end-point measurements. What has emerged is that a measurement at a single time-point, using a qualitative assay, is not of robust predictive value. Real-time methodology is likely to be associated with a lower variance in the results and a much higher reproducibility rate. Nevertheless, it is appropriate to review the history, albeit brief, of MRD testing to highlight the etiology of some of the apparent confusion and controversy, and set the stage for the grail of more standardized assays. Indeed, as recently as 1999, some noted authorities in this field4Faderl S Talpaz M Kantarjian HM Estrov Z Should polymerase chain reaction analysis to detect minimal residual disease in patients with chronic myelogenous leukemia be used in clinical decision making?.Blood. 1999; 93: 2755-2759PubMed Google Scholar proposed that it was difficult to make therapeutic recommendations on MRD studies published to date since there was methodologic heterogeneity at numerous levels. This included different PCR techniques, various levels of sensitivity, and variable and short follow-up. Additionally, it has been argued that there is biological heterogeneity that may confound the efforts to formulate predictive models. Such heterogeneity here includes different kinetics of the tumor in different patients, distinct host-disease interactions—for example, the presence of PR1 (a peptide derived from proteinase 3, an abundant myeloid-restricted enzyme) specific T-cells27Molldrem JJ Lee PP Wang C Felio K Kantarjian HM Champlin RE Davis MM Evidence that specific T lymphocytes may participate in the elimination of chronic myelogenous leukemia.Nat Med. 2000; 6: 1018-1023Crossref PubMed Scopus (590) Google Scholar—and diverse therapeutic/conditioning approaches. Furthermore, there is the issue (for some) of whether BCR-ABL alone is sufficient for leukemogenesis. However, these proposals were controversial, and spawned quite strong subsequent correspondence from other noted authorities.28Goldman JM Kaeda JS Cross NC Hochhaus A Hehlmann R Clinical decision making in chronic myeloid leukemia based on polymerase chain reaction analysis of minimal residual disease.Blood. 1999; 94: 1484-1486PubMed Google Scholar, 29Lion T Monitoring of residual disease in chronic myelogenous leukemia by quantitative polymerase chain reaction and clinical decision making.Blood. 1999; 94: 1486-1488PubMed Google Scholar, 30Moravcova J Nadvornikova S Lukasova M Klamova H Polymerase chain reaction analyses should be used as a basis for clinical decision making in patients with chronic myelogenous leukemia.Blood. 1999; 94: 3609-3611PubMed Google Scholar Similarly, an earlier review31Lion T Monitoring of residual disease in chronic myelogenous leukemia: methodological approaches and clinical aspects.Leukemia. 1996; 10 (901906): 896-900PubMed Google Scholar was also associated with a somewhat heterogeneous debate regarding the optimal manner in which to monitor MRD. Albeit historic, in the context of evolving technologies, the reader is referred to this, and the subsequent round table discussion, for some perception of the rather disparate approaches, usually dictated by personal (but substantial) individual experience. Since the first report of MRD testing in CML in 1989,32Morgan GJ Hughes T Janssen JW Gow J Guo AP Goldman JM Wiedemann LM Bartram CR Polymerase chain reaction for detection of residual leukaemia.Lancet. 1989; 1: 928-929Abstract PubMed Scopus (126) Google Scholar there have been numerous studies of various sizes, and with sometimes variable conclusions. This, in large part, reflects the evolution of testing modalities, from purely qualitative assays with parallel but separate dilutional sensitivity controls, through semiquantitative assays using incorporated competitive targets, to real time measurements. Some of the pertinent features from the larger of these studies are summarized in Table 1, specifically reflecting those in the context of the major curative therapeutic modality, SCT. There were concerns in some of the initial studies of the late 1980's and early 1990's regarding the high frequency of false-positive rates, and this prompted efforts at standardization and precautions to prevent contamination early on.33Hughes T Janssen JW Morgan G Martiat P Saglio G Pignon JM Pignatti FP Mills K Keating A Gluckman E False-positive results with PCR to detect leukaemia-specific transcript.Lancet. 1990; 335: 1037-1038Abstract PubMed Scopus (47) Google Scholar, 34Hughes T Goldman JM Improved results with PCR for chronic myeloid leukaemia.Lancet. 1990; 336: 812Abstract PubMed Scopus (17) Google Scholar Before the advent of real time technology, most attempts at quantitation used dilutional or competitive PCR strategies. Such technology may control for variability in amplification efficiency and reaction kinetics.Table 1Major Studies on MRD Testing in CML following Stem Cell Transplantation (SCT)PCR resultsReference no.n*n, number of patients enrolled in study.Method†Qual-N, qualitative, nested; Quant-N, quantitative (using a competitive template; see text for details), nested.Sensitivity/cut-off levelMedian follow-up‡Follow-up in months. This was measured differently in different studies (from SCT, from first positive PCR result), was sometimes not clearly stated and had to be derived.+Relapse−RelapsePredictive value of relapse for a positive PCR result36§All three of these studies were from the same center (Royal Postgraduate Medical School/Hammersmith Hospital, London).37Qual-N10−5∼33154 (27%)220 (0%)After 6 months Before 6 monthsYes No3764Qual-N10−6∼153713 (39%)270 (0%)Window 1 to 12 months >1 occasionYes Yes4030Qual-N10−6∼40155 (33%)150 (0%)Serial positive Transient positiveYes No3964Qual-N10−6∼24337 (21%)31¶The negative PCRs in this study were heterogeneous, being defined as one or more negative PCRs. Some of these negative cases were intermittently PCR positive.0 (0%)No predictive data38346Qual-N10−6∼1638|These PCR data are not for all 346 patients, only for those tested in the window 6 to 12 months post-SCT.16 (42%)112|These PCR data are not for all 346 patients, only for those tested in the window 6 to 12 months post-SCT.3 (3%)Window 6 to 12 months After 36 monthsYes**The relative risk for relapse was 26, as compared with patients who were PCR negative. No4452Qual-N5 cells∼242012 (60%)321 (3%)≥ One positive resultYes42§All three of these studies were from the same center (Royal Postgraduate Medical School/Hammersmith Hospital, London).98Quant-N50 transcripts/μg RNA∼162921 (72%)691 (1%)Anytime above cut-offYes43§All three of these studies were from the same center (Royal Postgraduate Medical School/Hammersmith Hospital, London). The overall relapse rate in this study is quite high, perhaps due to the use of in vivo monoclonal antibody T cell depletion and prolonged immunosuppression.138Quant-N0% =− <0.02%This percentage reflects the ratio of BCR-ABL/ABL. 0.02% BCR-ABL/ABL is equivalent to 100 BCR-ABL transcripts/μg RNA (see text for details). = low+ >0.02% = high +∼3663 (high) 14 (low)52 (83%) 8 (57%)6114 (23%)Window 3 to 5 monthsYes4155Qual-N10−5∼3014The positive and negative data pertain to p190 positivity only (see text for details).14 (100%)41The positive and negative data pertain to p190 positivity only (see text for details).0 (0%)p190 positiveYes* n, number of patients enrolled in study.† Qual-N, qualitative, nested; Quant-N, quantitative (using a competitive template; see text for details), nested.‡ Follow-up in months. This was measured differently in different studies (from SCT, from first positive PCR result), was sometimes not clearly stated and had to be derived.§ All three of these studies were from the same center (Royal Postgraduate Medical School/Hammersmith Hospital, London).¶ The negative PCRs in this study were heterogeneous, being defined as one or more negative PCRs. Some of these negative cases were intermittently PCR positive.‖ These PCR data are not for all 346 patients, only for those tested in the window 6 to 12 months post-SCT.** The relative risk for relapse was 26, as compared with patients who were PCR negative.†† The overall relapse rate in this study is quite high, perhaps due to the use of in vivo monoclonal antibody T cell depletion and prolonged immunosuppression.‡‡ This percentage reflects the ratio of BCR-ABL/ABL. 0.02% BCR-ABL/ABL is equivalent to 100 BCR-ABL transcripts/μg RNA (see text for details).§§ The positive and negative data pertain to p190 positivity only (see text for details). Open table in a new tab In competitive RT-PCR, serial dilutions of an artificially constructed BCR-ABL competitor are added to the patient cDNA, in what is, in essence, a titration assay.35Cross NC Feng L Chase A Bungey J Hughes TP Goldman JM Competitive polymerase chain reaction to estimate the number of BCR-ABL transcripts in chronic myeloid leukemia patients after bone marrow transplantation.Blood. 1993; 82: 1929-1936PubMed Google Scholar While the same primers that amplify the patient target also amplify this competitor template, the product sizes are different, so that they may be discriminated from one another in an appropriate electrophoretic system (gel or capillary). A correction factor is then applied to compensate for this size difference, to correct for the more efficient amplification of shorter targets. In the initial studies, visual inspection was used to evaluate the equivalence point at which the sample and competitor products are of equal intensity. More objective tools, such as densitometry or fluorescently- or radioactively-labeled primers, fortunately replaced this approach. A housekeeping transcript, for example ABL or GAPDH, is co-amplified to standardize the results and account for variation in the quantity and quality of the sample, the RNA and the cDNA. Ultimately, results are expressed as a percentage, such as BCR-ABL:ABL, or as numbers of chimeric transcripts per microgram of RNA. One potential pitfall of these assays is that there is no direct control for the RT step, since the competitor is DNA. However, using DNA does have the practical advantage of not needing to deal with RNA degradability. Six of the seven studies summarized in Table 1, using purely qualitative nested methodology, and with comparable sensitivities (10−5 to 10−6), were able to show, in general terms, the value of RT-PCR in predicting relapse post-SCT. Three of these studies36Hughes TP Morgan GJ Martiat P Goldman JM Detection of residual leukemia after bone marrow transplant for chronic myeloid leukemia: role of polymerase chain reaction in predicting relapse.Blood. 1991; 77: 874-878PubMed Google Scholar, 37Roth MS Antin JH Ash R Terry VH Gotlieb M Silver SM Ginsburg D Prognostic significance of Philadelphia chromosome-positive cells detected by the polymerase chain reaction after allogeneic bone marrow transplant for chronic myelogenous leukemia.Blood. 1992; 79: 276-282PubMed Google Scholar, 38Radich JP Gehly G Gooley T Bryant E Clift RA Collins S Edmands S Kirk J Lee A Kessler P Schoch G Buckner CD Sullivan KM Appelbaum FR Thomas ED Polymerase chain react" @default.
• W22172979 created "2016-06-24" @default.
• W22172979 creator A5089634995 @default.
• W22172979 date "2002-02-01" @default.
• W22172979 modified "2023-09-25" @default.
• W22172979 title "Chronic Myeloid Leukemia" @default.
• W22172979 cites W120597284 @default.
• W22172979 cites W126560450 @default.
• W22172979 cites W1430390330 @default.
• W22172979 cites W1482758361 @default.
• W22172979 cites W1483173437 @default.
• W22172979 cites W1489165903 @default.
• W22172979 cites W1497974883 @default.
• W22172979 cites W1511009642 @default.
• W22172979 cites W1520440593 @default.
• W22172979 cites W1540355515 @default.
• W22172979 cites W1569947224 @default.
• W22172979 cites W1582339002 @default.
• W22172979 cites W1599349966 @default.
• W22172979 cites W1604672566 @default.
• W22172979 cites W1924483703 @default.
• W22172979 cites W1926593386 @default.
• W22172979 cites W1964339633 @default.
• W22172979 cites W1967794707 @default.
• W22172979 cites W1986680315 @default.
• W22172979 cites W1998593414 @default.
• W22172979 cites W1999614615 @default.
• W22172979 cites W2002904896 @default.
• W22172979 cites W2003300990 @default.
• W22172979 cites W2016656445 @default.
• W22172979 cites W2022682658 @default.
• W22172979 cites W2031255542 @default.
• W22172979 cites W2034892057 @default.
• W22172979 cites W2036518057 @default.
• W22172979 cites W2042428466 @default.
• W22172979 cites W2049611823 @default.
• W22172979 cites W2050680849 @default.
• W22172979 cites W2063137898 @default.
• W22172979 cites W2070721758 @default.
• W22172979 cites W2075084712 @default.
• W22172979 cites W2076372887 @default.
• W22172979 cites W2080218581 @default.
• W22172979 cites W2082976903 @default.
• W22172979 cites W2089697181 @default.
• W22172979 cites W2092932956 @default.
• W22172979 cites W2111787644 @default.
• W22172979 cites W2117782490 @default.
• W22172979 cites W2130157398 @default.
• W22172979 cites W2130810825 @default.
• W22172979 cites W2133347844 @default.
• W22172979 cites W2139462813 @default.
• W22172979 cites W2144602285 @default.
• W22172979 cites W2153504834 @default.
• W22172979 cites W2156315441 @default.
• W22172979 cites W2156667202 @default.
• W22172979 cites W2172824259 @default.
• W22172979 cites W221736890 @default.
• W22172979 cites W2258838187 @default.
• W22172979 cites W2264905649 @default.
• W22172979 cites W2284253990 @default.
• W22172979 cites W2312283368 @default.
• W22172979 cites W2313524135 @default.
• W22172979 cites W2318278155 @default.
• W22172979 cites W2326419722 @default.
• W22172979 cites W2329648702 @default.
• W22172979 cites W2331184083 @default.
• W22172979 cites W2336477635 @default.
• W22172979 cites W2394816133 @default.
• W22172979 cites W2397749961 @default.
• W22172979 cites W2401025033 @default.
• W22172979 cites W2401486119 @default.
• W22172979 cites W2418751010 @default.
• W22172979 cites W2435356199 @default.
• W22172979 cites W2437312869 @default.
• W22172979 cites W2468135478 @default.
• W22172979 cites W271139275 @default.
• W22172979 cites W291163937 @default.
• W22172979 cites W4230181738 @default.
• W22172979 cites W4232775316 @default.
• W22172979 cites W4237653819 @default.
• W22172979 cites W4254800281 @default.
• W22172979 cites W68935899 @default.
• W22172979 doi "https://doi.org/10.1016/s1525-1578(10)60675-7" @default.
• W22172979 hasPubMedCentralId "https://www.ncbi.nlm.nih.gov/pmc/articles/1906972" @default.
• W22172979 hasPubMedId "https://pubmed.ncbi.nlm.nih.gov/11826183" @default.
• W22172979 hasPublicationYear "2002" @default.
• W22172979 type Work @default.
• W22172979 sameAs 22172979 @default.
• W22172979 citedByCount "22" @default.
• W22172979 countsByYear W221729792012 @default.
• W22172979 countsByYear W221729792013 @default.
• W22172979 countsByYear W221729792015 @default.
• W22172979 countsByYear W221729792019 @default.
• W22172979 countsByYear W221729792021 @default.
• W22172979 crossrefType "journal-article" @default.
• W22172979 hasAuthorship W22172979A5089634995 @default.
• W22172979 hasBestOaLocation W221729792 @default.
• W22172979 hasConcept C2778461978 @default.

• next