Publications by authors named "Bryone J Kuss"

18 Publications

  • Page 1 of 1

The future of laboratory testing in chronic lymphocytic leukaemia.

Pathology 2021 Apr 5;53(3):377-384. Epub 2021 Mar 5.

Molecular Medicine and Genetics, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia; Department of Haematology and Genetic Pathology, Flinders Medical Centre and SA Pathology, Bedford Park, SA, Australia. Electronic address:

Chronic lymphocytic leukaemia (CLL) is a malignant lymphoproliferative disorder characterised by the accumulation of dysfunctional B-lymphocytes in the blood and lymphoid tissues. It is a clonally complex disease with a high degree of both intra-tumoural and inter-patient heterogeneity. This variability leads to a wide range of clinical outcomes and highlights the critical need for accurate prognostic tests in CLL. With the advent of a range of new targeted agents for CLL in recent years, there is also a clinical need for improved predictive tests to therapy. This review of laboratory testing in CLL focuses on emerging technologies for prognostication including single nucleotide polymorphism microarray for karyotypic analysis, targeted next generation sequencing analysis of the immunoglobulin heavy chain variable region gene as well as genes recurrently mutated in the disease such as TP53, and detection of minimal residual disease.
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http://dx.doi.org/10.1016/j.pathol.2021.01.006DOI Listing
April 2021

A biclonal case of chronic lymphocytic leukaemia with discordant mutational status of the immunoglobulin heavy chain variable region and bimodal CD49d expression.

Br J Haematol 2021 02 5;192(3):e77-e81. Epub 2020 Dec 5.

Genetics and Molecular Medicine, Flinders Health and Medical Research Institute, Flinders University, Bedford Park, South Australia.

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http://dx.doi.org/10.1111/bjh.17257DOI Listing
February 2021

BTK inhibitor therapy is effective in patients with CLL resistant to venetoclax.

Blood 2020 06;135(25):2266-2270

Department of Clinical Haematology, Royal Melbourne Hospital and Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.

Highly active BTK inhibitors (BTKis) and the BCL2 inhibitor venetoclax have transformed the therapeutic landscape for chronic lymphocytic leukemia (CLL). Results of prospective clinical trials demonstrate the efficacy of venetoclax to salvage patients with disease progression on BTKis, but data on BTKi therapy after disease progression on venetoclax are limited, especially regarding durability of benefit. We retrospectively evaluated the records of 23 consecutive patients with relapsed/refractory CLL who received a BTKi (ibrutinib, n = 21; zanubrutinib, n = 2) after stopping venetoclax because of progressive disease. Median progression-free survival (PFS) and median overall survival after BTKi initiation were 34 months (range, <1 to 49) and 42 months (range, 2-49), respectively. Prior remission duration ≥24 months and attainment of complete remission or undetectable measurable residual disease on venetoclax were associated with longer PFS after BTKi salvage (P = .044 and P = .029, respectively). BTKi therapy achieved durable benefit for patients with the BCL2 Gly101Val venetoclax resistance mutation (estimated 24-month PFS, 69%). At a median survivor follow-up of 33 months (range, 2-53), 11 patients remained on BTKi and 12 had stopped therapy because of disease progression (n = 8) or toxicity (n = 4). Our findings indicate that BTKi therapy can provide durable CLL control after disease progression on venetoclax.
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http://dx.doi.org/10.1182/blood.2020004782DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7316215PMC
June 2020

Efficacy and Safety of Duvelisib Following Disease Progression on Ofatumumab in Patients with Relapsed/Refractory CLL or SLL in the DUO Crossover Extension Study.

Clin Cancer Res 2020 05 21;26(9):2096-2103. Epub 2020 Jan 21.

Department of Medicine I, Division of Hematology and Hemostaseology, and Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria.

Purpose: In the phase III DUO trial, duvelisib, an oral dual PI3K-δ,γ inhibitor, demonstrated significantly improved efficacy versus ofatumumab [median (m) progression-free survival (PFS), 13.3 vs. 9.9 months (HR, 0.52; < 0.0001); overall response rate [ORR], 74% vs. 45% ( < 0.0001)], with a manageable safety profile in patients with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). We report results from patients with progressive disease (PD) after ofatumumab who crossed over to duvelisib in the DUO trial.

Patients And Methods: Patients with radiographically confirmed PD after ofatumumab received duvelisib 25 mg twice daily in 28-day cycles until PD, intolerance, death, or study withdrawal. The primary endpoint was ORR per investigator. Secondary endpoints included duration of response (DOR), PFS, and safety.

Results: As of December 14, 2018, 90 ofatumumab-treated patients in the DUO trial prior to crossover had an ORR of 29%, mDOR of 10.4 months, and mPFS of 9.4 months. After crossover, 77% of patients (69/90) achieved a response, with an mDOR of 14.9 months and mPFS of 15.7 months. Patients with del(17p) and/or mutations had similar outcomes [ORR, 77% (20/26); mPFS, 14.7 months]. Notably, 73% of patients (47/64) with disease previously refractory to ofatumumab achieved a response. The most frequent any-grade/grade 3/4 treatment-emergent adverse events were diarrhea (47%/23%), neutropenia (26%/23%), pyrexia (24%/4%), cutaneous reactions (23%/4%), and thrombocytopenia (10%/6%).

Conclusions: Duvelisib demonstrated high response rates with good durability and a manageable safety profile in patients with R/R CLL/SLL who progressed on ofatumumab, including patients with high-risk disease and disease previously refractory to ofatumumab.
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http://dx.doi.org/10.1158/1078-0432.CCR-19-3061DOI Listing
May 2020

Altered expression of metabolic pathways in CLL detected by unlabelled quantitative mass spectrometry analysis.

Br J Haematol 2019 04 17;185(1):65-78. Epub 2019 Jan 17.

Discipline Molecular Medicine and Pathology, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.

Chronic lymphocytic leukaemia (CLL) remains the most common incurable malignancy of B cells in the western world. Patient outcomes are heterogeneous and can be difficult to predict with current prognostic markers. Here, we used a quantitative label-free proteomic technique to ascertain differences in the B-cell proteome from healthy donors and CLL patients with either mutated (M-CLL) or unmutated (UM-CLL) IGHV to identify new prognostic markers. In peripheral B-CLL cells, 349 (22%) proteins were differentially expressed between normal B cells and B-CLL cells and 189 (12%) were differentially expressed between M-CLL and UM-CLL. We also examined the proteome of proliferating CLL cells in the lymph nodes, and identified 76 (~8%) differentially expressed proteins between healthy and CLL lymph nodes. B-CLL cells show over-expression of proteins involved in lipid and cholesterol metabolism. A comprehensive lipidomic analysis highlighted large differences in glycolipids and sphingolipids. A shift was observed from the pro-apoptotic lipid ceramide towards the anti-apoptotic/chemoresistant lipid, glucosylceramide, which was more evident in patients with aggressive disease (UM-CLL). This study details a novel quantitative proteomic technique applied for the first time to primary patient samples in CLL and highlights that primary CLL lymphocytes display markers of a metabolic shift towards lipid synthesis and breakdown.
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http://dx.doi.org/10.1111/bjh.15751DOI Listing
April 2019

The phase 3 DUO trial: duvelisib vs ofatumumab in relapsed and refractory CLL/SLL.

Blood 2018 12 4;132(23):2446-2455. Epub 2018 Oct 4.

Department III of Internal Medicine, University Hospital Ulm, Ulm, Germany; and.

Duvelisib (also known as IPI-145) is an oral, dual inhibitor of phosphatidylinositol 3-kinase δ and γ (PI3K-δ,γ) being developed for treatment of hematologic malignancies. PI3K-δ,γ signaling can promote B-cell proliferation and survival in clonal B-cell malignancies, such as chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). In a phase 1 study, duvelisib showed clinically meaningful activity and acceptable safety in CLL/SLL patients. We report here the results of DUO, a global phase 3 randomized study of duvelisib vs ofatumumab monotherapy for patients with relapsed or refractory (RR) CLL/SLL. Patients were randomized 1:1 to oral duvelisib 25 mg twice daily (n = 160) or ofatumumab IV (n = 159). The study met the primary study end point by significantly improving progression-free survival per independent review committee assessment compared with ofatumumab for all patients (median, 13.3 months vs 9.9 months; hazard ratio [HR] = 0.52; < .0001), including those with high-risk chromosome 17p13.1 deletions [del(17p)] and/or mutations (HR = 0.40; = .0002). The overall response rate was significantly higher with duvelisib (74% vs 45%; < .0001) regardless of del(17p) status. The most common adverse events were diarrhea, neutropenia, pyrexia, nausea, anemia, and cough on the duvelisib arm, and neutropenia and infusion reactions on the ofatumumab arm. The DUO trial data support duvelisib as a potentially effective treatment option for patients with RR CLL/SLL. This trial was registered at www.clinicaltrials.gov as #NCT02004522.
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http://dx.doi.org/10.1182/blood-2018-05-850461DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6284216PMC
December 2018

Aberrant determination of phenotypic markers in chronic lymphocytic leukemia (CLL) lymphocytes after cryopreservation.

Exp Hematol 2018 07 26;63:28-32.e1. Epub 2018 Apr 26.

Discipline of Molecular Medicine and Pathology, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia; Hematology, Molecular Medicine and Pathology, SA Pathology, Flinders Medical Centre, Adelaide, South Australia, Australia.

The cryopreservation of peripheral blood mononuclear cells (PBMCs) is a routine research laboratory process, enabling long-term storage of primary patient blood samples. Retrospective analysis of these samples has the potential to identify markers that may be associated with prognosis and response to treatment. To draw valid biological conclusions from this type of analysis, it is essential to ensure that any observed changes are directly related to the pathology of the disease rather than the preservation process itself. Therefore, we have investigated 15 cell surface markers that are relevant to chronic lymphocytic leukemia (CLL) on matched fresh and thawed samples to determine the effect of cryopreservation on their detection. We found that the number of CLL cells positive for the markers CD22, CD40, CD49d, CD54, CD69, and CXCR3 was decreased significantly after cryopreservation. In addition, the mean fluorescence intensity of 10 of the 15 markers changed significantly after cryopreservation. These findings demonstrate that care must be taken when interpreting this type of analysis on thawed samples.
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http://dx.doi.org/10.1016/j.exphem.2018.04.003DOI Listing
July 2018

Resistance to proteasome inhibitors and other targeted therapies in myeloma.

Br J Haematol 2018 07 20;182(1):11-28. Epub 2018 Apr 20.

Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, Australia.

The number of novel therapies for the treatment of myeloma is rapidly increasing, as are the clinical trials evaluating them in combination with other novel and established therapies. Proteasome inhibitors, immunomodulatory agents and monoclonal antibodies are the most well known and studied classes of novel agents targeting myeloma, with histone deacetylase inhibitors, nuclear export inhibitors and several other approaches also being actively investigated. However, in parallel with the development and clinical use of these novel myeloma therapies is the emergence of novel mechanisms of resistance, many of which remain elusive, particularly for more recently developed agents. Whilst resistance mechanisms have been best studied for proteasome inhibitors, particularly bortezomib, class effects do not universally apply to all class members, and within-class differences in efficacy, toxicity and resistance mechanisms have been observed. Although immunomodulatory agents share the common cellular target cereblon and thus resistance patterns relate to cereblon expression, the unique cell surface antigens to which monoclonal antibodies are directed means these agents frequently exhibit unique within-class differences in clinical efficacy and resistance patterns. This review describes the major classes of novel therapies for myeloma, highlights the major clinical trials within each class and discusses known resistance mechanisms.
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http://dx.doi.org/10.1111/bjh.15210DOI Listing
July 2018

Management of high risk chronic lymphocytic leukaemia (CLL) patients in Australia.

Intern Med J 2017 Dec;47 Suppl 6:5-10

Department of Haematology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.

Background: Chronic lymphocytic leukaemia (CLL) frequently responds to chemoimmunotherapy combining cytotoxic chemotherapy and monoclonal antibodies. However, CLL is associated with significant genetic heterogeneity, and some high-risk forms are known to be chemo-resistant and associated with early relapse.

Aims: To review the current treatment paradigm of patients with high-risk disease, in particular those with del(17p) and TP53 variants.

Results: A 'watch and wait' approach is recommended for all patients who are asymptomatic. When symptomatic, fluorescence in situ hybridisation testing should be performed and gene sequencing considered subsequently to identify del(17p) and TP53 variants respectively. In the front-line setting, treatment within a clinical trial is the preferred option. In the relapsed or refractory setting, patients with del(17p) or TP53 aberrations should be offered treatment with a novel agent, such as ibrutinib, idelalisib-rituximab or venetoclax. However, of note, at the date of this publication venetoclax is not PBS reimbursed, and ibrutinib will not be reimbursed until 1 December 2017.

Conclusion: Testing for del(17p) and TP53 variants identifies high-risk CLL that requires specialist management.
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http://dx.doi.org/10.1111/imj.13680DOI Listing
December 2017

Trisomy 12 assessment by conventional fluorescence in-situ hybridization (FISH), FISH in suspension (FISH-IS) and laser scanning cytometry (LSC) in chronic lymphocytic leukemia.

Cancer Genet 2017 Oct 4;216-217:142-149. Epub 2017 Aug 4.

College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia; Hematology, Molecular Medicine and Pathology, Bedford Park, SA Australia. Electronic address:

Chronic lymphocytic leukemia (CLL) has an extremely heterogeneous clinical course, and prognostication is based on common genetic abnormalities which are detected by standard cytogenetic methods. However, current methods are restricted by the low number of cells able to be analyzed, resulting in the potential to miss clinically relevant sub-clonal populations of cells. A novel high throughput methodology called fluorescence in situ hybridization in suspension (FISH-IS) incorporates a flow cytometry-based imaging approach with automated analysis of thousands of cells. Here we have demonstrated that the FISH-IS technique is applicable to aneuploidy detection in CLL samples for a range of chromosomes using appropriate centromere probes. This method is able to accurately differentiate between monosomy, disomy and trisomy with a sensitivity of 1% in CLL. An analysis comparing conventional FISH, FISH-IS and laser scanning cytometry (LSC) is presented.
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http://dx.doi.org/10.1016/j.cancergen.2017.07.009DOI Listing
October 2017

Development of locus specific sub-clone separation by fluorescence in situ hybridization in suspension in chronic lymphocytic leukemia.

Cytometry A 2017 11 11;91(11):1088-1095. Epub 2017 Oct 11.

Discipline Molecular Medicine and Pathology College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.

Intra-tumor genetic heterogeneity is a hallmark of cancer. The ability to monitor and analyze these sub-clonal cell populations can be considered key to successful treatment, particularly in the modern era of targeted therapies. Although advances in sequencing technologies have significantly improved our ability to analyze the mutational landscape of tumors, this utility is reduced when considering small, but clinically significant sub-clones, that is, those representing <10% of the tumor burden. We have developed a high-throughput method that utilizes a 17-probe labeled bacterial artificial chromosome contig to quantify sub-clonal populations of cells based on deletion of a single locus. Chronic lymphocytic leukemia (CLL) cells harboring deletion of the short arm of chromosome 17 (del17p), an important prognostic marker for CLL were used to demonstrate the technique. Sub-clones of del17p cells were quantified and isolated from heterogeneous CLL populations using fluorescence in situ hybridization in suspension (FISH-IS) and the locus specific probe set. Using the combination of FISH-IS with the locus-specific probe set enables automated analysis of tens of thousands of cells, accurately quantifying and isolating cells carrying a del17p. Based on the fluorescence intensity of 17p probes, 17p (TP53) deleted cells were identified and sorted using flow cytometric techniques, and enrichment was demonstrated using single nucleotide polymorphism analysis. The ability to separate sub-clones of cells based on genetic heterogeneity, independent of the clone size, highlights the potential application of this method not only in the diagnostic and prognostic setting, but also as an unbiased approach to enable further detailed genetic analysis of the sub-clone with deep sequencing approaches. © 2017 International Society for Advancement of Cytometry.
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http://dx.doi.org/10.1002/cyto.a.23264DOI Listing
November 2017

From genome to proteome: Looking beyond DNA and RNA in chronic lymphocytic leukemia.

J Proteomics 2017 02 6;155:73-84. Epub 2017 Jan 6.

Department of Haematology and Genetic Pathology, Flinders University, Adelaide, South Australia, Australia.

Chronic lymphocytic leukemia (CLL) remains the most common leukemia in the Western world. Whilst its disease course is extremely heterogeneous (ranging from indolent to aggressive), current methods are unable to accurately predict the clinical journey of each patient. There is clearly a pressing need for both improved prognostication and treatment options for patients with this disease. Whilst molecular studies have analyzed both genetic mutations and gene expression profiles of these malignant B-cells, and as a result have shed light on the pathogenesis of CLL, proteomic studies have been largely overlooked to date. This review summarizes our current knowledge of the proteomics of CLL, and discusses some of the issues in CLL proteomic research, such as reproducibility and data interpretation. In addition, we look ahead to how proteomics may significantly help in the development of a successful treatment for this currently incurable disease.
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http://dx.doi.org/10.1016/j.jprot.2017.01.001DOI Listing
February 2017

Minimal change disease associated with newly diagnosed mantle cell lymphoma.

Ren Fail 2014 May 6;36(4):634-7. Epub 2014 Feb 6.

Department of General Medicine, Flinders Medical Centre, Flinders University , Adelaide, South Australia , Australia .

Mantle cell lymphoma (MCL) is a rare but aggressive form of non-Hodgkin's lymphoma. Involvement of the kidney is an infrequent occurrence in patients with MCL and can be the result of direct infiltration or paraneoplastic glomerulopathy. Proliferative glomerulonephritis, membranoproliferative glomerulonephritis and focal segmental glomerulosclerosis have previously been reported in association with MCL. We report a 55-year-old woman who developed nephrotic syndrome due to biopsy proven minimal change disease (MCD) in association with MCL. Proteinuria decreased with prednisolone treatment and MCD remains in remission without any immunosuppressant after the treatment of the underlying MCL.
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http://dx.doi.org/10.3109/0886022X.2014.883905DOI Listing
May 2014

Malignant pleural mesothelioma with associated minimal change disease and acute renal failure.

Ren Fail 2010 ;32(8):1012-5

Department of Renal Medicine, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia.

Paraneoplastic manifestations in malignant pleural mesothelioma are rare. We report a case of malignant pleural mesothelioma associated with minimal change disease (MCD). A 58-year-old man with occupational exposure to asbestos presented with severe peripheral edema, heavy proteinuria, and acute renal failure shortly after the diagnosis of mesothelioma had been confirmed. The renal biopsy demonstrated MCD. The underlying pathogenesis of this association remains unknown.
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http://dx.doi.org/10.3109/0886022X.2010.502275DOI Listing
February 2011

Expression and prognostic assessment of dipeptidyl peptidase IV and related enzymes in B-cell chronic lymphocytic leukemia.

Cancer Biol Ther 2010 Jul 26;10(2):180-9. Epub 2010 Jul 26.

School of Biological Sciences, Flinders University, Adelaide, SA, Australia.

Recent observations of the deregulated expression of several dipeptidyl peptidase (DP) IV-like enzymes in human cancers have led to presumptions of their pathogenic role in cancer. To further explore this concept we have characterized the expression of all DPIV-like enzymes in chronic lymphocytic leukemia (CLL). We have demonstrated the constitutive expression of DPIV, DP8, DP9, DPII and PEP mRNA and DPIV, DP8 and DP9 protein in CLL. FAP mRNA was not detected in CLL or normal B-lymphocytes. This correlated with an absence of FAP protein on the cell surface. This study also shows that DP8 mRNA expression is significantly upregulated in CLL compared to normal tonsil B-lymphocytes (p < 0.05) which may suggest biological importance in this disease. DP expression could not be correlated with any molecular or clinical prognostic markers for CLL in this cohort including IgVH mutational status, CD38, ZAP-70 or CD49d expression (n = 58). However, the constitutive expression of the DPIV-like enzymes in CLL and their emergence as potent immune regulators makes them candidate therapeutic targets in this disease.
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http://dx.doi.org/10.4161/cbt.10.2.12168DOI Listing
July 2010

Determining the repertoire of IGH gene rearrangements to develop molecular markers for minimal residual disease in B-lineage acute lymphoblastic leukemia.

J Mol Diagn 2009 May 26;11(3):194-200. Epub 2009 Mar 26.

Department of Hematology and Genetic Pathology, Flinders University and Medical Centre, Adelaide, Australia.

Molecular markers for minimal residual disease in B-lineage acute lymphoblastic leukemia were identified by determining, at the time of diagnosis, the repertoire of rearrangements of the immunoglobulin heavy chain (IGH) gene using segment-specific variable (V), diversity (D), and junctional (J) primers in two different studies that involved a total study population of 75 children and 18 adults. This strategy, termed repertoire analysis, was compared with the conventional strategy of identifying markers using family-specific V, D, and J primers for a variety of antigen receptor genes. Repertoire analysis detected significantly more markers for the major leukemic clone than did the conventional strategy, and one or more IgH rearrangements that were suitable for monitoring the major clone were detected in 96% of children and 94% of adults. Repertoire analysis also detected significantly more IGH markers for minor clones. Some minor clones were quite large and a proportion of them would not be able to be detected by a minimal residual disease test directed to the marker for the major clone. IGH repertoire analysis at diagnosis has potential advantages for the identification of molecular markers for the quantification of minimal residual disease in acute lymphoblastic leukemia cases. An IGH marker enables very sensitive quantification of the major leukemic clone, and the detection of minor clones may enable early identification of additional patients who are prone to relapse.
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http://dx.doi.org/10.2353/jmoldx.2009.080047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671336PMC
May 2009

Sensitive and specific measurement of minimal residual disease in acute lymphoblastic leukemia.

J Mol Diagn 2009 May 26;11(3):201-10. Epub 2009 Mar 26.

Department of Haematology and Genetic Pathology, Flinders University and Medical Centre, Adelaide, Australia.

A sensitive and specific quantitative real-time polymerase chain reaction method, involving three rounds of amplification with two allele-specific oligonucleotide primers directed against an rearrangement, was developed to quantify minimal residual disease (MRD) in B-lineage acute lymphoblastic leukemia (ALL). For a single sample containing 10 microg of good quality DNA, MRD was quantifiable down to approximately 10(-6), which is at least 1 log more sensitive than current methods. Nonspecific amplification was rarely observed. The standard deviation of laboratory estimations was 0.32 log units at moderate or high levels of MRD, but increased markedly as the level of MRD and the number of intact marker gene rearrangements in the sample fell. In 23 children with ALL studied after induction therapy, the mean MRD level was 1.6 x 10(-5) and levels ranged from 1.5 x 10(-2) to less than 10(-7). Comparisons with the conventional one-round quantitative polymerase chain reaction method on 29 samples from another 24 children who received treatment resulted in concordant results for 22 samples and discordant results for seven samples. The sensitivity and specificity of the method are due to the use of nested polymerase chain reaction, one segment-specific and two allele-specific oligonucleotide primers, and the use of a large amount of good quality DNA. This method may improve MRD-based decisions on treatment for ALL patients, and the principles should be applicable to DNA-based MRD measurements in other disorders.
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http://dx.doi.org/10.2353/jmoldx.2009.080048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671337PMC
May 2009

In vitro and in vivo downregulation of MRP1 by antisense oligonucleotides: a potential role in neuroblastoma therapy.

Int J Cancer 2002 Mar;98(1):128-33

Institute of Child Health, University College London, London, United Kingdom.

The expression of MRP1 (multidrug resistance protein-1) is associated with chemoresistance and poor prognosis in neuroblastoma. MRP1 antisense oligonucleotides were used in an in vivo mouse-human xenograft model of neuroblastoma to downregulate MRP1. The MRP1 ASO reduced protein levels of MRP1 to an average of 40% of the nil treated controls (p = 0.007). There was significant chemosensitisation to single-agent chemotherapy, VP16 (etoposide), at 1 microg/mL (p = 0.035) and 10 microg/mL (p = 0.02) in comparison to tumours not receiving oligonucleotides. In contrast, MDR1-ASO produced significant chemosensitisation only at 10 microg/mL of VP16 (p = 0.029). No significant chemosensitisation was seen following nonsense oligonucleotides. The downregulation of MRP1 was also associated with an increase in tumour cell death (79% increase in apoptosis index p = 0.0313) and a reduction in cell turnover (42% reduction in mitotic index p = 0.0313), which was not seen with any other oligonucleotide. This new and novel perspective of MRP1 function, which is an apparent involvement in apoptosis and cell cycle progression in neuroblasts, presents a fresh avenue for investigation of the biologic consequences of MRP1 expression that occurs in many tumour cell types. Our work is the first to concurrently explore the effects of downregulation of MRP1 and MDR1 by antisense oligonucleotides in a neuroblastoma xenograft model. It provides rationale for the investigation of therapy adjuvants such as antisense oligonucleotides in the treatment of this malignancy.
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http://dx.doi.org/10.1002/ijc.10159DOI Listing
March 2002
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