EndoPredict (EP) is a clinically validated multianalyte gene expression test to predict distant metastasis in ER-positive, HER2-negative breast cancer treated with endocrine therapy alone. The test is based on the combined analysis of 12 genes in formalin-fixed, paraffin-embedded (FFPE) tissue by reverse transcription-quantitative real-time PCR (RT-qPCR). Recently, it was shown that EP is feasible for reliable decentralized assessment of gene expression. The aim of this study was the analytical validation of the performance characteristics of the assay and its verification in a molecular-pathological routine laboratory.
Gene expression values to calculate the EP score were assayed by one-step RT-qPCR using RNA from FFPE tumor tissue. Limit of blank, limit of detection, linear range, and PCR efficiency were assessed for each of the 12 PCR assays using serial samples dilutions. Different breast cancer samples were used to evaluate RNA input range, precision and inter-laboratory variability.
PCR assays were linear up to Cq values between 35.1 and 37.2. Amplification efficiencies ranged from 75% to 101%. The RNA input range without considerable change of the EP score was between 0.16 and 18.5 ng/μl. Analysis of precision (variation of day, day time, instrument, operator, reagent lots) resulted in a total noise (standard deviation) of 0.16 EP score units on a scale from 0 to 15. The major part of the total noise (SD 0.14) was caused by the replicate-to-replicate noise of the PCR assays (repeatability) and was not associated with different operating conditions (reproducibility). Performance characteristics established in the manufacturer’s laboratory were verified in a routine molecular pathology laboratory. Comparison of 10 tumor samples analyzed in two different laboratories showed a Pearson coefficient of 0.995 and a mean deviation of 0.15 score units.
The EP test showed reproducible performance characteristics with good precision and negligible laboratory-to-laboratory variation. This study provides further evidence that the EP test is suitable for decentralized testing in specialized molecular pathological laboratories instead of a reference laboratory. This is a unique feature and a technical advance in comparison with existing RNA-based prognostic multigene expression tests.
Breast cancer; Prognostic multigene expression test; Analytical validation; PCR; Pathology
The validated EndoPredict assay is a novel tool to predict the risk of metastases of patients with estrogen receptor positive, HER2 negative breast cancer treated with endocrine therapy alone. It has been designed to integrate genomic and clinical information and includes clinico-pathological factors such as tumor size and nodal status. The test is feasible in a decentral setting in molecular pathology laboratories. In this project, we investigated the performance of this test in clinical practice, and performed a retrospective evaluation of its impact on treatment decisions in breast cancer. During one year, EndoPredict assays from 167 patients could be successfully performed. For retrospective evaluation of treatment decisions, a questionnaire was sent to the clinical partner. Regarding the molecular EP class, samples from 56 patients (33.5%) had a low-risk, whereas 111 patients (66.5%) showed a high-risk gene profile. After integration of the clinicopathological factors the combined clinical and molecular score (EPclin) resulted in a low-risk group of 77 patients (46.4%), while 89 (53.6%) had a high risk EPclin score. The EPclin-based estimated median 10-year-risk for metastases with endocrine therapy alone was 11% for the whole cohort. The median handling time averaged three days (range: 0 to 11 days), 59.3% of the tests could be performed in three or less than three days. Comparison of pre- and post-test therapy decisions showed a change of therapy in 37.7% of patients. 16 patients (12.3%) had a change to an additional chemotherapy while 25.4% of patients (n = 33) changed to an endocrine therapy alone. In 73 patients (56.2%) no change of therapy resulted. In 6.1% of patients (n = 8), the patients did not agree to the recommendation of the tumor board. Our results show that the EndoPredict assay could be routinely performed in decentral molecular pathology laboratories and the results markedly change treatment decisions.
Several multigene expression-based tests offering prognostic and predictive information in hormone-receptor positive early breast cancer were established during the last years. These tests provide prognostic information on distant recurrences and can serve as an aid in therapy decisions. We analyzed the recently validated reverse-transcription-quantitative-real-time PCR-based multigene-expression Endopredict (EP)-test on 34 hormone-receptor positive breast-cancer cases and compared the EP scores with the Oncotype DX Recurrence-scores (RS) obtained from the same cancer samples.
Formalin-fixed, paraffin-embedded invasive breast-cancer tissues from 34 patients were analyzed by the EP-test. Representative tumor blocks were analyzed with Oncotype DX prior to this study. Tumor tissue was removed from unstained slides, total-RNA was isolated and EP-analysis was performed blinded to Oncotype DX results.
Extraction of sufficient amounts of RNA and generation of valid EP-scores were possible for all 34 samples. EP classified 11 patients as low-risk and 23 patients as high-risk. RS Score defined 15 patients as low-risk, 10 patients as intermediate-risk in and 9 patients as high-risk. Major-discrepancy occurred in 6 of 34 cases (18%): Low-risk RS was classified as high-risk by EP in 6 cases. Combining the RS intermediate-risk and high-risk groups to a common group, the concordance between both tests was 76%. Correlation between continuous EP and RS-scores was moderate (Pearson-coefficient: 0.65 (p<0.01).
We observed a significant but moderate concordance (76%) and moderate correlation (0.65) between RS and EP Score. Differences in results can be explained by different weighting of biological motives covered by the two tests. Further studies are needed to explore the clinical relevance of discrepant test results with respect of outcome.
This study compared the perfomance of the RNA-based EndoPredict multigene test on core biopsies and surgical breast cancer specimens and analysed the influence of biopsy-induced tissue injuries on the test result.
80 formalin-fixed paraffin-embedded samples comprising paired biopsies and surgical specimens from 40 ER-positive, HER2-negative patients were evaluated. Total RNA was extracted and the EndoPredict score was determined.
RNA yield was considerably lower in core biopsies, but sufficient to measure the assay in all samples. The EndoPredict score was highly correlated between paired samples (Pearson r=0.92), with an excellent concordance of classification into a low or high risk of metastasis (overall agreement 95%).
The measurements are comparable between core biopsies and surgical sections, which suggest that the EndoPredict assay can be performed on core biopsy tissue. Inflammatory changes induced by presurgical biopsies had no significant effect on the RNA-based risk assessment in surgical specimens.
Breast; breast cancer; breast pathology; cancer; cancer genetics; cancer research; EGFR; endocrine pathology; gynaecological pathology; molecular oncology; molecular pathology; oncology; ovary; statistics; tumour markers
EndoPredict (EP) is an RNA-based multigene test that predicts the likelihood of distant recurrence in patients with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2–negative (HER2−) breast cancer (BC) who are being treated with adjuvant endocrine therapy. Herein we report the prospective-retrospective clinical validation of EP in the node-positive, chemotherapy-treated, ER+/HER2− BC patients in the GEICAM 9906 trial.
The patients (N = 1,246) were treated either with six cycles of fluorouracil, epirubicin and cyclophosphamide (FEC) or with four cycles of FEC followed by eight weekly courses of paclitaxel (FEC-P), as well as with endocrine therapy if they had hormone receptor–positive disease. The patients were assigned to EP risk categories (low or high) according to prespecified cutoff levels. The primary endpoint in the clinical validation of EP was distant metastasis-free survival (MFS). Metastasis rates were estimated using the Kaplan-Meier method, and multivariate analysis was performed using Cox regression.
The molecular EP score and the combined molecular and clinical EPclin score were successfully determined in 555 ER+/HER2− tumors from the 800 available samples in the GEICAM 9906 trial. On the basis of the EP, 25% of patients (n = 141) were classified as low risk. MFS was 93% in the low-risk group and 70% in the high-risk group (absolute risk reduction = 23%, hazard ratio (HR) = 4.8, 95% confidence interval (CI) = 2.5 to 9.5; P < 0.0001). Multivariate analysis showed that, in this ER+/HER2− cohort, EP results are an independent prognostic parameter after adjustment for age, grade, lymph node status, tumor size, treatment arm, ER and progesterone receptor (PR) status and proliferation index (Ki67). Using the predefined EPclin score, 13% of patients (n = 74) were assigned to the low-risk group, who had excellent outcomes and no distant recurrence events (absolute risk reduction vs high-risk group = 28%; P < 0.0001). Furthermore, EP was prognostic in premenopausal patients (HR = 6.7, 95% CI = 2.4 to 18.3; P = 0.0002) and postmenopausal patients (HR = 3.3, 95% CI = 1.3 to 8.5; P = 0.0109). There were no statistically significant differences in MFS between treatment arms (FEC vs FEC-P) in either the high- or low-risk groups. The interaction test results between the chemotherapy arm and the EP score were not significant.
EP is an independent prognostic parameter in node-positive, ER+/HER2− BC patients treated with adjuvant chemotherapy followed by hormone therapy. EP did not predict a greater efficacy of FEC-P compared to FEC alone.
ER+/HER2− breast cancers have a proclivity for late recurrence. A personalised estimate of relapse risk after 5 years of endocrine treatment can improve patient selection for extended hormonal therapy.
A total of 1702 postmenopausal ER+/HER2− breast cancer patients from two adjuvant phase III trials (ABCSG6, ABCSG8) treated with 5 years of endocrine therapy participated in this study. The multigene test EndoPredict (EP) and the EPclin score (which combines EP with tumour size and nodal status) were predefined in independent training cohorts. All patients were retrospectively assigned to risk categories based on gene expression and on clinical parameters. The primary end point was distant metastasis (DM). Kaplan–Meier method and Cox regression analysis were used in an early (0–5 years) and late time interval (>5 years post diagnosis).
EP is a significant, independent, prognostic parameter in the early and late time interval. The expression levels of proliferative and ER signalling genes contribute differentially to the underlying biology of early and late DM. The EPclin stratified 64% of patients at risk after 5 years into a low-risk subgroup with an absolute 1.8% of late DM at 10 years of follow-up.
The EP test provides additional prognostic information for the identification of early and late DM beyond what can be achieved by combining the commonly used clinical parameters. The EPclin reliably identified a subgroup of patients who have an excellent long-term prognosis after 5 years of endocrine therapy. The side effects of extended therapy should be weighed against this projected outcome.
EndoPredict; endocrine therapy; late relapse
In early estrogen receptor (ER)-positive/HER2-negative breast cancer, the decision to administer chemotherapy is largely based on prognostic criteria. The combined molecular/clinical EndoPredict test (EPclin) has been validated to accurately assess prognosis in this population. In this study, the clinical relevance of EPclin in relation to well-established clinical guidelines is assessed.
Patients and methods
We assigned risk groups to 1702 ER-positive/HER2-negative postmenopausal women from two large phase III trials treated only with endocrine therapy. Prognosis was assigned according to National Comprehensive Cancer Center Network-, German S3-, St Gallen guidelines and the EPclin. Prognostic groups were compared using the Kaplan–Meier survival analysis.
After 10 years, absolute risk reductions (ARR) between the high- and low-risk groups ranged from 6.9% to 11.2% if assigned according to guidelines. It was at 18.7% for EPclin. EPclin reassigned 58%–61% of women classified as high-/intermediate-risk (according to clinical guidelines) to low risk. Women reclassified to low risk showed a 5% rate of distant metastasis at 10 years.
The EPclin score is able to predict favorable prognosis in a majority of patients that clinical guidelines would assign to intermediate or high risk. EPclin may reduce the indications for chemotherapy in ER-positive postmenopausal women with a limited number of clinical risk factors.
adjuvant treatment; breast cancer; endocrine therapy; EndoPredict gene; expression
Current immunohistochemical (IHC)-based definitions of luminal A and B breast cancers are imperfect when compared with multigene expression-based assays. In this study, we sought to improve the IHC subtyping by examining the pathologic and gene expression characteristics of genomically defined luminal A and B subtypes.
Patients and Methods
Gene expression and pathologic features were collected from primary tumors across five independent cohorts: British Columbia Cancer Agency (BCCA) tamoxifen-treated only, Grupo Español de Investigación en Cáncer de Mama 9906 trial, BCCA no systemic treatment cohort, PAM50 microarray training data set, and a combined publicly available microarray data set. Optimal cutoffs of percentage of progesterone receptor (PR) –positive tumor cells to predict survival were derived and independently tested. Multivariable Cox models were used to test the prognostic significance.
Clinicopathologic comparisons among luminal A and B subtypes consistently identified higher rates of PR positivity, human epidermal growth factor receptor 2 (HER2) negativity, and histologic grade 1 in luminal A tumors. Quantitative PR gene and protein expression were also found to be significantly higher in luminal A tumors. An empiric cutoff of more than 20% of PR-positive tumor cells was statistically chosen and proved significant for predicting survival differences within IHC-defined luminal A tumors independently of endocrine therapy administration. Finally, no additional prognostic value within hormonal receptor (HR) –positive/HER2-negative disease was observed with the use of the IHC4 score when intrinsic IHC-based subtypes were used that included the more than 20% PR-positive tumor cells and vice versa.
Semiquantitative IHC expression of PR adds prognostic value within the current IHC-based luminal A definition by improving the identification of good outcome breast cancers. The new proposed IHC-based definition of luminal A tumors is HR positive/HER2 negative/Ki-67 less than 14%, and PR more than 20%.
We report here the results of the analytical validation of assays that measure HER2 total protein (H2T) and HER2 homodimer (H2D) expression in Formalin Fixed Paraffin Embedded (FFPE) breast cancer tumors as well as cell line controls. The assays are based on the VeraTag technology platform and are commercially available through a central CAP-accredited clinical reference laboratory. The accuracy of H2T measurements spans a broad dynamic range (2-3 logs) as evaluated by comparison with cross-validating technologies. The measurement of H2T expression demonstrates a sensitivity that is approximately 7–10 times greater than conventional immunohistochemistry (IHC) (HercepTest). The HERmark assay is a quantitative assay that sensitively and reproducibly measures continuous H2T and H2D protein expression levels and therefore may have the potential to stratify patients more accurately with respect to response to HER2-targeted therapies than current methods which rely on semiquantitative protein measurements (IHC) or on indirect assessments of gene amplification (FISH).
Selecting the appropriate treatment for breast cancer requires accurately determining the estrogen receptor (ER) status of the tumor. However, the standard for determining this status, immunohistochemical analysis of formalin-fixed paraffin embedded samples, suffers from numerous technical and reproducibility issues. Assessment of ER-status based on RNA expression can provide more objective, quantitative and reproducible test results.
To learn a parsimonious RNA-based classifier of hormone receptor status, we applied a machine learning tool to a training dataset of gene expression microarray data obtained from 176 frozen breast tumors, whose ER-status was determined by applying ASCO-CAP guidelines to standardized immunohistochemical testing of formalin fixed tumor.
This produced a three-gene classifier that can predict the ER-status of a novel tumor, with a cross-validation accuracy of 93.17±2.44%. When applied to an independent validation set and to four other public databases, some on different platforms, this classifier obtained over 90% accuracy in each. In addition, we found that this prediction rule separated the patients' recurrence-free survival curves with a hazard ratio lower than the one based on the IHC analysis of ER-status.
Our efficient and parsimonious classifier lends itself to high throughput, highly accurate and low-cost RNA-based assessments of ER-status, suitable for routine high-throughput clinical use. This analytic method provides a proof-of-principle that may be applicable to developing effective RNA-based tests for other biomarkers and conditions.
The secreted enzyme EndoS, an endoglycosidase from Streptococcus pyogenes, hydrolyzes the N-linked glycan of the constant region of immunoglobulin G (IgG) heavy chain and renders the antibody unable to interact with Fc receptors and elicit effector functions. In this study we couple targeted allelic replacement mutagenesis and heterologous expression to elucidate the contribution of EndoS to group A Streptococcus (GAS) phagocyte resistance and pathogenicity in vitro and in vivo.
Knocking out the EndoS gene in GAS M1T1 background revealed no significant differences in bacterial survival in immune cell killing assays or in a systemic mouse model of infection. However, exogenous addition and heterologous expression of EndoS was found to increase GAS resistance to killing by neutrophils and monocytes in vitro. Additionally, heterologous expression of EndoS in M49 GAS increased mouse virulence in vivo.
We conclude that in a highly virulent M1T1 background, EndoS has no significant impact on GAS phagocyte resistance and pathogenicity. However, local accumulation or high levels of expression of EndoS in certain GAS strains may contribute to virulence.
Molecular genetic studies on rare tumour entities, such as bone tumours, often require the use of decalcified, formalin-fixed, paraffin-embedded tissue (dFFPE) samples. Regardless of which decalcification procedure is used, this introduces a vast breakdown of DNA that precludes the possibility of further molecular genetic testing. We set out to establish a robust protocol that would overcome these intrinsic hurdles for bone tumour research.
The goal of our study was to establish a protocol, using a modified DNA isolation procedure and quality controls, to select decalcified samples suitable for array-CGH testing. Archival paraffin blocks were obtained from 9 different pathology departments throughout Europe, using different fixation, embedding and decalcification procedures, in order to preclude a bias for certain lab protocols. Isolated DNA samples were subjected to direct chemical labelling and enzymatic labelling systems and were hybridised on a high resolution oligonucleotide chip containing 44,000 reporter elements.
Genomic alterations (gains and losses) were readily detected in most of the samples analysed. For example, both homozygous deletions of 0.6 Mb and high level of amplifications of 0.7 Mb were identified.
We established a robust protocol for molecular genetic testing of dFFPE derived DNA, irrespective of fixation, decalcification or sample type used. This approach may greatly facilitate further genetic testing on rare tumour entities where archival decalcified, formalin fixed samples are the only source.
Whole genome microarray gene expression profiling is the ‘gold standard’ for the discovery of prognostic and predictive genetic markers for human cancers. However, suitable research material is lacking as most diagnostic samples are preserved as formalin-fixed, paraffin-embedded tissue (FFPET). We tested a new workflow and data analysis method optimized for use with FFPET samples.
Sixteen breast tumor samples were split into matched pairs and preserved as FFPET or fresh-frozen (FF). Total RNA was extracted and tested for yield and purity. RNA from FFPET samples was amplified using three different commercially available kits in parallel, and hybridized to Affymetrix GeneChip® Human Genome U133 Plus 2.0 Arrays. The array probe set was optimized in silico to exclude misdesigned and misannotated probes.
FFPET samples processed using the WT-Ovation™ FFPE System V2 (NuGEN) provided 80% specificity and 97% sensitivity compared with FF samples (assuming values of 100%). In addition, in silico probe set redesign improved sequence detection sensitivity and, thus, may rescue potentially significant small-magnitude gene expression changes that could otherwise be diluted by the overall probe set background.
In conclusion, our FFPET-optimized workflow enables the detection of more genes than previous, nonoptimized approaches, opening new possibilities for the discovery, validation, and clinical application of mRNA biomarkers in human diseases.
Biomarker; Breast cancer; Gene; HER2; Microarray
Clinical specimens undergoing diagnostic molecular pathology testing are fixed in formalin due to the necessity for detailed morphological assessment. However, formalin fixation can cause major issues with molecular testing, as it causes DNA damage such as fragmentation and non-reproducible sequencing artefacts after PCR amplification. In the context of massively parallel sequencing (MPS), distinguishing true low frequency variants from sequencing artefacts remains challenging. The prevalence of formalin-induced DNA damage and its impact on molecular testing and clinical genomics remains poorly understood.
The Cancer 2015 study is a population-based cancer cohort used to assess the feasibility of mutational screening using MPS in cancer patients from Victoria, Australia. While blocks were formalin-fixed and paraffin-embedded in different anatomical pathology laboratories, they were centrally extracted for DNA utilising the same protocol, and run through the same MPS platform (Illumina TruSeq Amplicon Cancer Panel). The sequencing artefacts in the 1-10% and the 10-25% allele frequency ranges were assessed in 488 formalin-fixed tumours from the pilot phase of the Cancer 2015 cohort. All blocks were less than 2.5 years of age (mean 93 days).
Consistent with the signature of DNA damage due to formalin fixation, many formalin-fixed samples displayed disproportionate levels of C>T/G>A changes in the 1-10% allele frequency range. Artefacts were less apparent in the 10-25% allele frequency range. Significantly, changes were inversely correlated with coverage indicating high levels of sequencing artefacts were associated with samples with low amounts of available amplifiable template due to fragmentation. The degree of fragmentation and sequencing artefacts differed between blocks sourced from different anatomical pathology laboratories. In a limited validation of potentially actionable low frequency mutations, a NRAS G12D mutation in a melanoma was shown to be a false positive.
These findings indicate that DNA damage following formalin fixation remains a major challenge in laboratories working with MPS. Methodologies that assess, minimise or remove formalin-induced DNA damaged templates as part of MPS protocols will aid in the interpretation of genomic results leading to better patient outcomes.
The Oncotype DX® assay is a validated genomic test that predicts the likelihood of breast cancer recurrence, patient survival within ten years of diagnosis and the benefit of chemotherapy in early-stage, node-negative, estrogen receptor-positive breast cancer. Further markers of recurrence include disseminated tumor cells (DTCs) in the bone marrow (BM) and circulating tumor cells (CTCs) in the blood, particularly stemness-like tumor cells (slCTCs). In this study, Oncotype DX, DTCs, CTCs and slCTCs were used to evaluate the risk of recurrence in 68 patients with human epidermal growth factor receptor 2-negative, early-stage breast cancer. Formalin-fixed, paraffin-embedded tissue sections were analyzed for the expression of 16 cancer genes and 5 reference genes by Oncotype DX, yielding a recurrence score (RS). G2 tumors were evaluated for urokinase-type plasminogen activator (uPA)/plasminogen activator inhibitor type 1 (PAI1) and Ki-67. Two BM aspirates were analyzed by immunocytochemistry for DTCs using the pan-cytokeratin antibody A45-B/B3. CTCs and slCTCs in the blood were detected using the AdnaTest BreastCancer, AdnaTest EMT and the AdnaTest TumorStemCell. Oncotype DX was performed in 68 cases, yielding a low RS in 30/68 patients (44%), an intermediate RS in 29/68 patients (43%) and a high RS in 9/68 patients (13%). DTCs were detected in 19/68 patients (28%), CTCs in 13/68 patients (19%) and slCTCs in 26/68 (38%) patients. Moreover, 8/68 patients (12%) with G2 tumors were positive for uPA, 6/68 (9%) for PAI1 and 21/68 (31%) for Ki-67. Ki-67, progesterone receptor (PR) and G3 tumors were significantly correlated with RS (P<0.001; P=0.006; and P=0,002, respectively), whereas no correlation was identified between DTCs, CTCs, slCTCs and RS. Ki-67 may support therapeutic decisions in cases where Oncotype DX is not feasible. Larger patient cohorts are required to estimate the additional detection of DTCs and CTCs for the determination of risk recurrence.
early breast cancer; risk of recurrence; Ki-67; urokinase-type plasminogen activator/plasminogen activator inhibitor type 1; circulating tumor cells; disseminated tumor cells; Oncotype DX
Breast cancer is the most frequently diagnosed cancer in women. Intraepithelial lesions (IELs), such as usual ductal hyperplasia (UH), atypical ductal hyperplasia (ADH), and ductal carcinoma in situ (DCIS) are risk factors that predict a woman's chance of developing invasive breast cancer. Therefore, a comparative study that establishes an animal model of pre-invasive lesions is needed for the development of preventative measures and effective treatment for both mammary IELs and tumors. The purpose of this study was to characterize the histologic and molecular features of feline mammary IELs and compare them with those in women.
Formalin-fixed, paraffin-embedded specimens (n = 205) from 203 female cats with clinical mammary disease were retrieved from the archives of the Purdue University Animal Disease Diagnostic Laboratory and Veterinary Teaching Hospital (West Lafayette, IN), and the Department of Pathology and Veterinary Clinic, School of Veterinary Medicine (Sassari, Italy). Histologic sections, stained with hematoxylin and eosin (HE), were evaluated for the presence of IELs in tissue adjacent to excised mammary tumors. Lesions were compared to those of humans. Immunohistochemistry for estrogen receptor (ER-alpha), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2/neu) and Ki-67 was performed in IELs and adjacent tumor tissues.
Intraepithelial lesions were found in 57 of 203 (28%) feline mammary specimens and were categorized as UH (27%), ADH (29%), and DCIS (44%). Most IELs with atypia (ADH and DCIS) were associated with mammary cancer (91%), whereas UH was associated with benign lesions in 53% of cases. Feline IELs were remarkably similar to human IELs. No ER or PR immunoreactivity was detected in intermediate-grade or high-grade DCIS or their associated malignant tumors. HER-2 protein overexpression was found in 27% of IELs.
The remarkable similarity of feline mammary IELs to those of humans, with the tendency to lose hormone receptor expression in atypical IELs, supports the cat as a possible model to study ER- and PR-negative breast lesions.
NSCLC exhibits considerable heterogeneity in its sensitivity to chemotherapy and similar heterogeneity is noted in vitro in a variety of model systems. This study has tested the hypothesis that the molecular basis of the observed in vitro chemosensitivity of NSCLC lies within the known resistance mechanisms inherent to these patients' tumors.
The chemosensitivity of a series of 49 NSCLC tumors was assessed using the ATP-based tumor chemosensitivity assay (ATP-TCA) and compared with quantitative expression of resistance genes measured by RT-PCR in a Taqman Array™ following extraction of RNA from formalin-fixed paraffin-embedded (FFPE) tissue.
There was considerable heterogeneity between tumors within the ATP-TCA, and while this showed no direct correlation with individual gene expression, there was strong correlation of multi-gene signatures for many of the single agents and combinations tested. For instance, docetaxel activity showed some dependence on the expression of drug pumps, while cisplatin activity showed some dependence on DNA repair enzyme expression. Activity of both drugs was influenced more strongly still by the expression of anti- and pro-apoptotic genes by the tumor for both docetaxel and cisplatin. The doublet combinations of cisplatin with gemcitabine and cisplatin with docetaxel showed gene expression signatures incorporating resistance mechanisms for both agents.
Genes predicted to be involved in known mechanisms drug sensitivity and resistance correlate well with in vitro chemosensitivity and may allow the definition of predictive signatures to guide individualized chemotherapy in lung cancer.
Ovarian cancer shows considerable heterogeneity in its sensitivity to chemotherapy both clinically and in vitro. This study tested the hypothesis that the molecular basis of this difference lies within the known resistance mechanisms inherent to these patients' tumours.
The chemosensitivity of a series of 31 ovarian tumours, all previously treated with platinum-based chemotherapy, was assessed using the ATP-based tumour chemosensitivity assay (ATP-TCA) and correlated with resistance gene expression measured by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) in a TaqMan Array following extraction of mRNA from formalin-fixed paraffin-embedded tissue. The results were standardised against a housekeeping gene (PBGD), and assessed by multiple linear regression.
Predictive multiple linear regression models were derived for four single agents (cisplatin, gemcitabine, topotecan, and treosulfan), and for the combinations of cisplatin+gemcitabine and treosulfan+gemcitabine. Particularly strong correlations were obtained for cisplatin, gemcitabine, topotecan, and treosulfan+gemcitabine. No individual gene expression showed direct correlation with activity in the ATP-TCA. Genes involved in DNA repair and apoptosis were strongly represented, with some drug pumps also involved.
The chemosensitivity of ovarian cancer to drugs is related to the expression of genes involved in sensitivity and resistance mechanisms.
ovarian cancer; chemosensitivity; chemoresistance; gene expression; ATP; RT–PCR
In most pathology laboratories worldwide, formalin-fixed paraffin embedded (FFPE) samples are the only tissue specimens available for routine diagnostics. Although commercial kits for diagnostic molecular pathology testing are becoming available, most of the current diagnostic tests are laboratory-based assays. Thus, there is a need for standardized procedures in molecular pathology, starting from the extraction of nucleic acids. To evaluate the current methods for extracting nucleic acids from FFPE tissues, 13 European laboratories, participating to the European FP6 program IMPACTS (www.impactsnetwork.eu), isolated nucleic acids from four diagnostic FFPE tissues using their routine methods, followed by quality assessment. The DNA-extraction protocols ranged from homemade protocols to commercial kits. Except for one homemade protocol, the majority gave comparable results in terms of the quality of the extracted DNA measured by the ability to amplify differently sized control gene fragments by PCR. For array-applications or tests that require an accurately determined DNA-input, we recommend using silica based adsorption columns for DNA recovery. For RNA extractions, the best results were obtained using chromatography column based commercial kits, which resulted in the highest quantity and best assayable RNA. Quality testing using RT-PCR gave successful amplification of 200 bp–250 bp PCR products from most tested tissues. Modifications of the proteinase-K digestion time led to better results, even when commercial kits were applied. The results of the study emphasize the need for quality control of the nucleic acid extracts with standardised methods to prevent false negative results and to allow data comparison among different diagnostic laboratories.
Electronic supplementary material
The online version of this article (doi:10.1007/s00428-010-0917-5) contains supplementary material, which is available to authorized users.
FFPE; Multicentre study; Molecular analyses standardisation; PCR; DNA; RNA; Isolation
The invasiveness of breast cancer cells was shown to be associated with the suppressed ability to develop apoptosis. The role of cell death DNases/endonucleases has not been previously examined in relation with the invasiveness of breast cancer cells. We have compared the activity of the endonucleases in seven human breast cancer cell lines different in the level of invasiveness and differentiation. The invasiveness of cell lines was confirmed by an in vitro Matrigel-based assay. The total endonuclease activity in the differentiated non-invasive (WDNI) cell lines was higher than that in the poorly differentiated invasive (PDI) cells. The expression of EndoG strongly correlated with the degree of estrogen receptor expression and showed an inverse correlation with vimentin and matrix metalloproteinase-13. The EndoG-positive WDNI cells were more sensitive to etoposide- or camptothecin-induced cell death than EndoG-negative PDI cells. Silencing of EndoG caused inhibited of SK-BR-3 WDNI cell death induced by etoposide. Human ductal carcinomas in situ expressed high levels of EndoG, while invasive medullar and ductal carcinomas had significantly decreased expression of EndoG. This correlated with decreased apoptosis as measured by TUNEL assay. Our findings suggest that the presence of EndoG in non-invasive breast cancer cells determines their sensitivity to apoptosis, which may be taken into consideration for developing the chemotherapeutic strategy for cancer treatment.
endonuclease G; DNase I; breast cancer; invasiveness; differentiation; chemotherapy; apoptosis
Epigenetics acts as an interface between environmental / exogenous factors, cellular responses and pathological processes. Aberrant epigenetic signatures are a hallmark of complex multifactorial diseases, including non-neoplastic disorders (e.g., cardiovascular diseases, hypertension, diabetes mellitus, autoimmune diseases, and some infectious diseases) and neoplasms (e.g., leukemias, lymphomas, sarcomas, and breast, lung, prostate, liver and colorectal cancers). Epigenetic signatures (DNA methylation, mRNA and microRNA expression, etc.) may serve as biomarkers for risk stratification, early detection, and disease classification, as well as targets for therapy and chemoprevention. DNA methylation assays are widely applied to formalin-fixed paraffin-embedded archival tissue specimens as clinical pathology tests. To better understand the interplay between etiologic factors, cellular molecular characteristics, and disease evolution, the field of “Molecular Pathological Epidemiology (MPE)” has emerged as an interdisciplinary integration of “molecular pathology” and “epidemiology”, with a similar conceptual framework to systems biology and network medicine. In contrast to traditional epidemiologic research including genome-wide association studies (GWAS), MPE is founded on the unique disease principle; that is, each disease process results from unique profiles of exposomes, epigenomes, transcriptomes, proteomes, metabolomes, microbiomes, and interactomes in relation to the macro-environment and tissue microenvironment. The widespread application of epigenomics (e.g., methylome) analyses will enhance our understanding of disease heterogeneity, epigenotypes (CpG island methylator phenotype, LINE-1 hypomethylation, etc.), and host-disease interactions. MPE may represent a logical evolution of GWAS, termed “GWAS-MPE approach”. Though epigenome-wide association study attracts increasing attention, currently, it has a fundamental problem in that each cell within one individual has a unique, time-varying epigenome. This article will illustrate increasing contribution of modern pathology to broader public health sciences, which attests pivotal roles of pathologists in the new integrated MPE science towards our ultimate goal of personalized medicine and prevention.
molecular pathologic epidemiology; genetics; omics; hypermethylation; hypomethylation; personalized therapy; unique tumor principle; CIMP; long interspersed nucleotide element
Gene expression profiling of human breast tumors has uncovered several molecular signatures that can divide breast cancer patients into good and poor outcome groups. However, these signatures typically comprise many genes (~50-100), and the prognostic tests associated with identifying these signatures in patient tumor specimens require complicated methods, which are not routinely available in most hospital pathology laboratories, thus limiting their use. Hence, there is a need for more practical methods to predict patient survival.
We modified a feature selection algorithm and used survival analysis to derive a 2-gene signature that accurately predicts breast cancer patient survival.
We developed a tree based decision method that segregated patients into various risk groups using KIAA0191 expression in the context of E2F1 expression levels. This approach led to highly accurate survival predictions in a large cohort of breast cancer patients using only a 2-gene signature.
Our observations suggest a possible relationship between E2F1 and KIAA0191 expression that is relevant to the pathogenesis of breast cancer. Furthermore, our findings raise the prospect that the practicality of patient prognosis methods may be improved by reducing the number of genes required for analysis. Indeed, our E2F1/KIAA0191 2-gene signature would be highly amenable for an immunohistochemistry based test, which is commonly used in hospital laboratories.
Besides typing and grading of breast cancer, Pathologists are involved in the determination of biomarkers, such as steroid hormone receptors and HER2, which are of utmost importance in adjuvant therapy. There have been concerns with regard to security and reproducibility of the biomarker assays done on tissue sections applying either immunohistochemistry or in-situ hybridisation. In order to assure the quality of these biomarker assays, a number of measures are required, among them external proficiency testing. Therefore, external quality assurance trials have been implemented in Germany. In the period of 2002-2007, 5 consecutive trials were conducted with up to 180 participating laboratories. Tissue microarrays with 20–24 different breast cancer samples including cell lines enabled that a huge number of pathologists were challenged with identical samples which provides the prerequisite for comparability. Because there is no legal duress to undergo external proficiency testing in histopathology, all laboratories that took part volunteered to do so. These innovative quality assurance trials (Qualitätsinitiative Pathologie, QuIP) will be continued in the future on an annual or bi-annual basis. Participation is recommended for pathology departments involved in the service for breast units. The organisational frame work of the trials is described here.
Steroid receptor; HER2; Immunohistochemistry; Quality assurance
Apurinic/apyrimidinic endonuclease (Ap endo) is a key DNA repair activity that confers radiation resistance in human cells. Here we examined the association between Ap endo activity and response to radiotherapy in pediatric ependymomas, tumors for which treatment options are limited and survival rates are only about 50%. We assayed Ap endo activity in 36 ependymomas and expression of Ape1/Ref-1, the predominant Ap endo activity in humans, in 44 tumors by immunostaining. Cox proportional hazards regression models were used to analyze the association of activity or expression with progression-free survival or with overall survival. Activity varied 13-fold and was not associated with tumor or patient characteristics. In univariate models with Ap endo activity entered as a continuous variable, the hazard ratio for progression increased by a factor of 2.18 for every 0.01 unit increase in activity (P ≤ 0.003) in 24 grade II ependymomas. Risk for death increased by a factor of 1.89 (P ≤ 0.02) in the same population. The fraction of Ape1/Ref-1 immunopositive cells varied widely within individual tumors and was not associated with either progression-free or with overall survival. Suppressing Ap endo activity in pediatric ependymoma cells significantly increased radiation sensitivity, suggesting that the association of activity with radiation response reflected, at least in part, repair of radiation-induced DNA lesions. Our data indicate that Ap endo activity is predictive of outcome following radiotherapy, and suggest that Ape1/Ref-1 promotes radiation resistance in pediatric ependymomas. Our findings support the use of inhibitors of Ap endo activity to overcome resistance.
Ape1/Ref-1; brain tumor; DNA repair; γ-ray resistance