Prognostic significance of circulating tumor cells and tumor related transcripts in small cell lung cancer: A step further to clinical implementation

Small-cell lung cancer (SCLC) is a fatal disease with limited treatment options. Circulating tumor cells (CTCs) in liquid biopsy samples may serve as predictive and prognostic biomarkers; but the analysis of CTCs is still challenging. By using microfluidic or density gradient CTC enrichment in combination with immunofluorescent (IF) staining or qPCR of CTC-related transcripts, we achieved a 60.8% to 88.0% positivity in SCLC blood samples. Epithelial and neuroendocrine transcripts including the druggable target DLL3 were associated with shorter overall survival (OS), indicating the clinical value of these markers in terms of differential diagnosis and treatment decisions. High CTC counts and the presence of CTC duplets detected by IF staining were prognostic for OS, and thus may serve as indicators of disease progression or therapy failure. In patient samples with high CTC load detected by IF staining, a concordance of the transcripts positivity in circulating free plasma RNA and CTCs was observed. Our data emphasize the role of CTCs and CTC-related transcripts and underline the clinical value of liquid biopsy analysis in SCLC.

Gene expression markers in peripheral blood and outcome in patients with platinum-resistant ovarian cancer: A study of the European GANNET53 consortium

Disease progression is a major problem in ovarian cancer. There are very few treatment options for patients with platinum-resistant ovarian cancer (PROC), and therefore, these patients have a particularly poor prognosis. The aim of the present study was to identify markers for monitoring the response of 123 PROC patients enrolled in the Phase I/II GANNET53 clinical trial, which evaluated the efficacy of Ganetespib in combination with standard chemotherapy versus standard chemotherapy alone. In total, 474 blood samples were collected, comprising baseline samples taken before the first administration of the study drugs and serial samples taken during treatment until further disease progression (PD). After microfluidic enrichment, 27 gene transcripts were analyzed using quantitative polymerase chain reaction and their utility for disease monitoring was evaluated. At baseline, ERCC1 was associated with an increased risk of PD (hazard ratio [HR] 1.75, 95% confidence interval [CI]: 1.20-2.55; p = 0.005), while baseline CDH1 and ESR1 may have a risk-reducing effect (CDH1 HR 0.66, 95% CI: 0.46-0.96; p = 0.024; ESR1 HR 0.58, 95% CI: 0.39-0.86; p = 0.002). ERCC1 was observed significantly more often (72.7% vs. 53.9%; p = 0.032) and ESR1 significantly less frequently (59.1% vs. 78.3%; p = 0.018) in blood samples taken at radiologically confirmed PD than at controlled disease. At any time during treatment, ERCC1-presence and ESR1-absence were associated with short PFS and with higher odds of PD within 6 months (odds ratio 12.77, 95% CI: 4.08-39.97; p < 0.001). Our study demonstrates the clinical relevance of ESR1 and ERCC1 and may encourage the analysis of liquid biopsy samples for the management of PROC patients.

Association of Four Interleukin-8 Polymorphisms (-251 A>T, +781 C>T, +1633 C>T, +2767 A>T) with Ovarian Cancer Risk: Focus on Menopausal Status and Endometriosis-Related Subtypes

Interleukin-8 (IL-8) is involved in the regulation of inflammatory processes and carcinogenesis. Single-nucleotide polymorphisms (SNPs) within the IL-8 gene have been shown to alter the risks of lung, gastric, or hepatocellular carcinomas. To date, only one study examined the role of IL-8 SNPs in ovarian cancer (OC), suggesting an association between two IL-8 SNPs and OC risk. In this study, we investigated four common IL-8 SNPs, rs4073 (-251 A>T), rs2227306 (+781 C>T), rs2227543 (+1633 C>T), and rs1126647 (+2767 A>T), using the restriction fragment length polymorphism (PCR-RFLP) technique. Our study included a cohort of 413 women of Central European descent, consisting of 200 OC patients and 213 healthy controls. The most common (73.5%) histological type was high-grade serous OC (HGSOC), whereas 28/200 (14%) patients had endometriosis-related (clear cell or endometrioid) OC subtypes (EROC). In postmenopausal women, three of the four investigated SNPs, rs4073 (-251 A>T), rs2227306 (+781 C>T), and rs2227543 (+1633 C>T), were associated with OC risk. Furthermore, we are the first to report a significant relationship between the T allele or TT genotype of SNP rs1126647 (+2767 A>T) and the EROC subtype (p = 0.02 in the co-dominant model). The TT homozygotes were found more than twice as often in EROC compared to other OC subtypes (39% vs. 19%, p = 0.015). None of the examined SNPs appeared to influence OC risk in premenopausal women, nor were they associated with the aggressive HGSOC subtype or the stage of disease at the initial diagnosis.

Amyloid-like p53 as prognostic biomarker in serous ovarian cancer-a study of the OVCAD consortium

TP53 is the most commonly mutated gene in cancer and has been shown to form amyloid-like aggregates, similar to key proteins in neurodegenerative diseases. Nonetheless, the clinical implications of p53 aggregation remain unclear. Here, we investigated the presence and clinical relevance of p53 aggregates in serous ovarian cancer (OC). Using the p53-Seprion-ELISA, p53 aggregates were detected in 46 out of 81 patients, with a detection rate of 84.3% in patients with missense mutations. High p53 aggregation was associated with prolonged progression-free survival. We found associations of overall survival with p53 aggregates, but they did not reach statistical significance. Interestingly, p53 aggregation was significantly associated with elevated levels of p53 autoantibodies and increased apoptosis, suggesting that high levels of p53 aggregates may trigger an immune response and/or exert a cytotoxic effect. To conclude, for the first time, we demonstrated that p53 aggregates are an independent prognostic marker in serous OC. P53-targeted therapies based on the amount of these aggregates may improve the patient's prognosis.

tRNA-derived small RNA 3'U-tRFValCAC promotes tumour migration and early progression in ovarian cancer

INTRODUCTION

Despite recent advances in epithelial ovarian cancer (EOC) management, the highly heterogenous histological/molecular tumour background and patients' treatment response obstructs personalised prognosis and therapeutics. Herein, we have studied the role and clinical utility of the novel subclass of tRNA-derived small RNA fragments emerging via 3'-trailer processing of pre-tRNAs (3'U-tRFs) in EOC.

METHODS

SK-OV-3 and OVCAR-3 cells were used for in vitro study. Following transfection, cell growth and migration were assessed by CCK8 and wound healing assays, respectively. 3'U-tRFs levels were assessed by reverse transcription quantitative PCR (RT-qPCR), following 3'-end RNA polyadenylation. A screening (OVCAD, n = 100) and institutionally independent validation (TU Munich, n = 103) cohorts were employed for survival analysis using disease progression and patients' death as clinical end-points. Bootstrap analysis was performed for internal validation, and decision curve analysis was used to evaluate clinical benefit on disease prognosis.

RESULTS

Following primary clinical assessment, target prediction and gene ontology analyses, the 3'U-tRF^ValCAC (derived from pre-tRNA^ValCAC) was highlighted to regulate cell proliferation and adhesion, and to correlate with inferior patients' outcome. 3'U-tRF^ValCAC transfection of SK-OV-3 and OVCAR-3 cells resulted in significantly increased cell growth and migration, in a dose-dependent manner. Elevated tumour 3'U-tRF^ValCAC levels were associated with significantly higher risk for early progression and worse survival following first-line platinum-based chemotherapy, independently of patients' clinicopathological data, chemotherapy response, and residual tumour. Interestingly, 3'U-tRF^ValCAC-fitted multivariate models improved risk stratification and provided superior clinical net benefit in prediction of treatment outcome compared to disease established markers.

CONCLUSIONS

3'U-tRF^ValCAC promotes tumour cell growth and migration and supports modern risk stratification and prognosis in EOC.

Effect of short-term storage of blood samples on gene expression in lung cancer patients

OBJECTIVES

The stability of gene transcripts associated with the presence of circulating tumor cells (CTCs) has been predominantly studied in cultured cancer cell lines added to blood samples under artificial conditions. In the present study the effect of storage on CTC-related transcripts was assessed in blood samples taken from patients with non-small lung cancer (n=58).

METHODS

The blood samples were split in two equal parts to compare the gene expression with and without storage for 24 h at ambient temperature without preservative added. After enrichment using the microfluidic Parsortix^® technology, the expression levels of selected genes were assessed using quantitative PCR following a gene-specific pre-amplification. The prognostic relevance of each gene in fresh and stored blood samples was evaluated using the R-package Survminer.

RESULTS

Some genes were either not affected (TWIST1, CDH5, CK19) or upregulated upon storage (NANOG, MET, UCHL1) but still associated with poor prognosis. In contrast, ERBB3, PTHLH, EpCAM, and TERT were no longer associated with the overall survival of the patients.

CONCLUSIONS

The study demonstrates the surprising stability of CTC-related transcripts, which makes overnight shipping of native blood samples possible. Careful verification is required when using model systems - such as normal blood spiked with tumor cells - or other CTC-related markers, as individual transcripts may respond differently to storage.

Biomarker-Based Models for Preoperative Assessment of Adnexal Mass: A Multicenter Validation Study

Ovarian cancer (OC) is the most lethal genital malignancy in women. We aimed to develop and validate new proteomic-based models for non-invasive diagnosis of OC. We also compared them to the modified Risk of Ovarian Malignancy Algorithm (ROMA-50), the Copenhagen Index (CPH-I) and our earlier Proteomic Model 2017. Biomarkers were assessed using bead-based multiplex technology (Luminex®) in 356 women (250 with malignant and 106 with benign ovarian tumors) from five European centers. The training cohort included 279 women from three centers, and the validation cohort 77 women from two other centers. Of six previously studied serum proteins (CA125, HE4, osteopontin [OPN], prolactin, leptin, and macrophage migration inhibitory factor [MIF]), four contributed significantly to the Proteomic Model 2021 (CA125, OPN, prolactin, MIF), while leptin and HE4 were omitted by the algorithm. The Proteomic Model 2021 revealed a c-index of 0.98 (95% CI 0.96, 0.99) in the training cohort; however, in the validation cohort it only achieved a c-index of 0.82 (95% CI 0.72, 0.91). Adding patient age to the Proteomic Model 2021 constituted the Combined Model 2021, with a c-index of 0.99 (95% CI 0.97, 1) in the training cohort and a c-index of 0.86 (95% CI 0.78, 0.95) in the validation cohort. The Full Combined Model 2021 (all six proteins with age) yielded a c-index of 0.98 (95% CI 0.97, 0.99) in the training cohort and a c-index of 0.89 (95% CI 0.81, 0.97) in the validation cohort. The validation of our previous Proteomic Model 2017, as well as the ROMA-50 and CPH-I revealed a c-index of 0.9 (95% CI 0.82, 0.97), 0.54 (95% CI 0.38, 0.69) and 0.92 (95% CI 0.85, 0.98), respectively. In postmenopausal women, the three newly developed models all achieved a specificity of 1.00, a positive predictive value (PPV) of 1.00, and a sensitivity of >0.9. Performance in women under 50 years of age (c-index below 0.6) or with normal CA125 (c-index close to 0.5) was poor. CA125 and OPN had the best discriminating power as single markers. In summary, the CPH-I, the two combined 2021 Models, and the Proteomic Model 2017 showed satisfactory diagnostic accuracies, with no clear superiority of either model. Notably, although combining values of only four proteins with age, the Combined Model 2021 performed comparably to the Full Combined Model 2021. The models confirmed their exceptional diagnostic performance in women aged ≥50. All models outperformed the ROMA-50.

MUC1 and CD147 Are Promising Markers for the Detection of Circulating Tumor Cells in Small Cell Lung Cancer

BACKGROUND/AIM

Lung cancer is the most prevalent type of cancer globally and small cell lung cancer (SCLC) accounts for only 15% of all cases but exhibits a dismal prognosis. The standard of care of SCLC has not changed for decades and novel biomarkers and novel strategies for patient's care are urgently needed.

MATERIALS AND METHODS

The expression of the two potential markers MUC1 and CD147 was evaluated in circulating tumor cells (CTCs) and CTC-derived SCLC cell lines using qRT PCR, western blotting, immunohistochemistry, and ELISA assays.

RESULTS

Both CTCs enriched from patient blood samples by Parsortix isolation technology and SCLC/CTC cell lines exhibited significant expression of MUC1 and CD147. Silencing of MUC1 increased chemosensitivity of an SCLC line to topotecan.

CONCLUSION

Both markers, MUC1 and CD147, are highly expressed in patient-derived SCLC and SCLC CTC cell lines and show promise as potential biomarkers in SCLC.

Prognostic Significance of SLFN11 Methylation in Plasma Cell-Free DNA in Advanced High-Grade Serous Ovarian Cancer

Background: Epigenetic alterations in ctDNA are highly promising as a source of novel potential liquid biopsy biomarkers and comprise a very promising liquid biopsy approach in ovarian cancer, for early diagnosis, prognosis and response to treatment. Methods: In the present study, we examined the methylation status of six gene promoters (BRCA1, CST6, MGMT, RASSF10, SLFN11 and USP44) in high-grade serous ovarian cancer (HGSOC). We evaluated the prognostic significance of DNA methylation of these six gene promoters in primary tumors (FFPEs) and plasma cfDNA samples from patients with early, advanced and metastatic HGSOC. Results: We report for the first time that the DNA methylation of SLFN11 in plasma cfDNA was significantly correlated with worse PFS (p = 0.045) in advanced stage HGSOC. Conclusions: Our results strongly indicate that SLFN11 epigenetic inactivation could be a predictor of resistance to platinum drugs in ovarian cancer. Our results should be further validated in studies based on a larger cohort of patients, in order to further explore whether the DNA methylation of SLFN11 promoter could serve as a potential prognostic DNA methylation biomarker and a predictor of resistance to platinum-based chemotherapy in ovarian cancer.

Association of a Combined Cancer Exhaustion Score with Circulating Tumor Cells and Outcome in Ovarian Cancer-A Study of the OVCAD Consortium

We investigated the prognostic role of systemic characteristics for cancer exhaustion and the presence of circulating tumor cells (CTCs) in primary epithelial ovarian cancer (EOC) patients. We included 185 patients in this multicenter study with a median follow-up time of 10.25 years. Albumin, c-reactive protein (CRP) and the kynurenine to tryptophan ratio (Kyn/Trp) as well as the CTC-related marker cyclophilin C (PPIC) were obtained before primary therapy and were correlated to the respective clinical and outcome data. The information provided by albumin and Kyn/Trp was integrated in a combined score for cancer exhaustion (CCES). A high CCES characterized by hypoalbuminemia and a high Kyn/Trp was associated with both decreased overall and progression-free survival, independent from other known prognostic factors in a multivariable analysis. The presence of PPIC-positive CTCs was significantly associated with a high CCES, highlighting that the interplay between the systemic microenvironment and CTCs should be considered in "liquid biopsy" biomarker assessment.

Cancer Stem Cell-Like Circulating Tumor Cells Are Prognostic in Non-Small Cell Lung Cancer

Despite recent advances in the treatment of non-small cell lung cancer (NSCLC), less than 10% of patients survive the first five years when the disease has already spread at primary diagnosis. Methods: Blood samples were taken from 118 NSCLC patients at primary diagnosis or at progression of the disease before the start of a new treatment line and enriched for circulating tumor cells (CTCs) by microfluidic Parsortix™ (Angle plc, Guildford GU2 7AF, UK) technology. The gene expression of epithelial cancer stem cell (CSC), epithelial to mesenchymal (EMT), and lung-related markers was assessed by qPCR, and the association of each marker with overall survival (OS) was evaluated using log-rank tests. Results: EpCAM was the most prevalent transcript, with 53.7% positive samples at primary diagnosis and 25.6% at recurrence. EpCAM and CK19, as well as NANOG, PROM1, TERT, CDH5, FAM83A, and PTHLH transcripts, were associated with worse OS. However, only the CSC-specific NANOG and PROM1 were related to the outcome both at primary diagnosis (NANOG: HR 3.21, 95%CI 1.02–10.14, p = 0.016; PROM1: HR 4.23, 95% CI 0.65–27.56, p = 0.007) and disease progression (NANOG: HR 4.17, 95%CI 0.72–24.14, p = 0.025; PROM1: HR 4.77, 95% CI 0.29–78.94, p = 0.032). Conclusions: The present study further underlines the relevance of the molecular characterization of CTCs. Our multi-marker analysis highlighted the prognostic value of cancer stem cell-related transcripts at primary diagnosis and disease progression.

Biomarker-based early detection of epithelial ovarian cancer based on a five-protein signature in patient's plasma - a prospective trial

BACKGROUND

Trial on five plasma biomarkers (CA125, HE4, OPN, leptin, prolactin) and their possible role in differentiating benign from malignant ovarian tumors.

METHODS

In this unicentric prospective trial preoperative blood samples of 43 women with ovarian masses determined for ovarian surgery were analyzed. 25 patients had pathologically confirmed benign, 18 malignant ovarian tumors. Blood plasma was analyzed for CA125, HE4, OPN, leptin, prolactin and MIF by multiplex immunoassay analysis. Each single protein and a logistical regression model including all the listed proteins were tested as preoperative predictive marker for suspect ovarian masses.

RESULTS

Plasma CA125 was confirmed as a highly accurate tumor marker in ovarian cancer. HE4, OPN, leptin and prolactin plasma levels differed significantly between benign and malignant ovarian masses. With a logistical regression model a formula including CA125, HE4, OPN, leptin and prolactin was developed to predict malignant ovarian tumors. With a discriminatory AUC of 0.96 it showed to be a highly sensitive and specific diagnostic test for a malignant ovarian tumor.

CONCLUSIONS

The calculated formula with the combination of CA125, HE4, OPN, leptin and prolactin plasma levels surpasses each single marker in its diagnostic value to discriminate between benign and malignant ovarian tumors. The formula, applied to our patient population was highly accurate but should be validated in a larger cohort.

TRIAL REGISTRATION

Clinical Trials.gov under NCT01763125 , registered Jan. 8, 2013.

The Long-Term Prognostic Significance of Circulating Tumor Cells in Ovarian Cancer-A Study of the OVCAD Consortium

INTRODUCTION

We previously reported the prognostic impact of circulating tumor cells (CTCs) in a multicenter study on minimal residual disease in primary ovarian cancer. With additional follow-up data, we evaluated the combined CTC approach (CTCs^combo), in particular for the patients who had survived more than five years.

MATERIAL AND METHODS

Blood samples taken at baseline and six months after adjuvant treatment (follow-up) were assessed by quantitative PCR (qPCR) measuring PPIC transcripts and immunofluorescent staining (IF). A positive result with either IF or qPCR was classified as CTC^combo-positive. Further, PPIC was assessed in the primary tumor tissue.

RESULTS

The concordance of IF and qPCR was 65% at baseline and 83% after treatment. Results showed that 50.5% of the baseline and 29.5% of the follow-up samples were CTC^combo-positive. CTCs^combo after treatment were associated with increased mortality after adjusting for FIGO stage (HR 2.574, 95% CI: 1.227-5.398, p = 0.012), a higher risk of recurrence after adjusting for peritoneal carcinosis (HR 4.068, 95% CI: 1.948-8.498, p < 0.001), and increased mortality after five survived years.

DISCUSSION

The two-sided analytical approach revealed CTC subpopulations associated with ovarian cancer progression and may illuminate a potential treatment-related shift in molecular phenotypes. That approach can identify patients who have elevated risk of recurrence and death due to ovarian cancer and who may require risk-adapted treatment strategies.

miR-181a overexpression predicts the poor treatment response and early-progression of serous ovarian cancer patients

Ovarian cancer (OC) remains a leading cause of gynecological cancer-related death worldwide, characterized by poor 5-year survival. Molecular markers could serve as crucial tools of personalized prognosis and therapy. Herein, we present miR-181a as novel predictor of OC prognosis, using five independent OC cohorts. In particular, a screening (n = 81) and an institutionally independent validation (n = 100, OVCAD multicenter study) serous OC (SOC) cohorts were analyzed. Bagnoli et al (2016) OC179 (n = 124) to OC133 (n = 100) and TCGA (n = 489) served as external validation cohorts. Patients' survival and disease progression were assessed as clinical endpoint events. Bootstrap analysis was performed for internal validation and decision curve analysis was utilized to evaluate clinical benefit. miR-181a overexpression was unveiled as powerful and independent molecular predictor of patients' poor survival and higher risk for disease progression after debulking surgery and platinum-based chemotherapy. Analysis of the OVCAD institutionally independent cohort, as well as of Bagnoli et al. and TCGA external cohorts further confirmed the unfavorable prognostic nature of miR-181a overexpression in SOC. Strikingly, multivariate prognostic models incorporating miR-181a with established disease markers clearly improved patients' risk-stratification and offered superior clinical benefit in OC prognostication. Conclusively, miR-181a evaluation could augment prognostic accuracy and support precision medicine decisions in OC.

miR-203 is an independent molecular predictor of prognosis and treatment outcome in ovarian cancer: a multi-institutional study

Ovarian cancer (OC) accounts for the most gynecological cancer-related deaths in developed countries. Unfortunately, the lack of both evident early symptoms and effective asymptomatic population screening results in late diagnosis and inevitably poor prognosis. Hence, it is urgent to identify novel molecular markers to support personalized prognosis. In the present study, we have analyzed the clinical significance of miR-203 in OC using two institutionally independent cohorts. miR-203 levels were quantified in a screening (n = 125) and a validation cohort (n = 100, OVCAD multicenter study). Survival analysis was performed using progression and death as clinical endpoint events. Internal validation was conducted by bootstrap analysis, and decision curve analysis was used to evaluate the clinical benefit. Increased miR-203 levels in OC patients were correlated with unfavorable prognosis and higher risk for disease progression, independently of FIGO stage, tumor grade, residual tumor after surgery, chemotherapy response and age. The analysis of the institutionally independent validation cohort (OVCAD study) clearly confirmed the shorter survival outcome of the patients overexpressing miR-203. Additionally, integration of miR-203 levels with the established disease prognostic markers led to a superior stratification of OC patients that can ameliorate prognosis and benefit patient clinical management. In this regard, miR-203 expression constitutes a novel independent molecular marker to improve patients' prognosis in OC.

Gene Expression of Kallikreins in Breast Cancer Cell Lines

BACKGROUND/AIM

This study analyzed the gene expression of the "classic" KLK1 and "new" kallikreins KLK4-KLK15, in relation to the molecular characteristics and in vitro invasiveness of 21 breast cancer (BC) and three normal breast-derived cell lines (CLs).

MATERIALS AND METHODS

Gene expression of KLKs was determined by using real-time polymerase chain reaction (PCR). The invasiveness of the CLs was examined using a fibroblast-collagen-based in vitro cell culture assay.

RESULTS

KLK5 and KLK7-KLK11 were down-regulated in several BCCLs. In contrast, KLK4, KLK8, KLK12 and KLK15 demonstrated strikingly high expression in two BCCLs, UACC 812 and MDA-MB 330. The KLK expression differed frequently according to the presence of androgen receptor (KLK1 and KLK5-KLK9), and occasionally according to estrogen receptor (KLK9) and EGFR (KLK7). Two KLK clusters were detected (first: KLK1, 4, 12, 15; second: all other KLKs), with two subclasses within the second cluster (KLK5-9 and KLK10, 11, 13, and 14). The CLs that expressed at least six KLKs belonged predominantly to basal or HER2 intrinsic subtypes. No KLK predicted the in vitro invasiveness of CLs.

CONCLUSION

Gene expression of KLKs was altered in BCCLs. This change was mostly down-regulation and often related to the presence of androgen receptor. The observed clusters point to a possible functional interplay of selected KLKs in BCCLs.

Abstract AP15: IDENTIFICATION OF P53 PRIONS AS AN INDEPENDENT PROGNOSTIC MARKER FOR SURVIVAL IN HIGH-GRADE SEROUS OVARIAN CANCER

PURPOSE: Although the discovery of prions was rewarded with a Nobel Prize, their existence was only attributed to a limited number of diseases. Recent evidence suggests that their role has been underestimated and several other proteins carry prion-like properties, like ß-amyloid, and most recently p53. High-grade serous ovarian cancers (HGSOC) harbor TP53 mutations in about 96% of cases. These mutations promote p53 aggregation, which might be responsible for complete abrogation of tumor suppressor functions, resulting in dominant-negative activity and oncogenic gain-of-function. Here, we describe the use of an ELISA-based technology for p53 prion detection in fresh-frozen tumor tissue and their clinical relevance in ovarian cancer.

EXPERIMENTAL PROCEDURES: Fresh-frozen tumor tissue specimens of 81 HGSOC patients, who previously had been included in the EU-funded OVCAD study, were analyzed. For each of these patients at least 5-year follow-up data were available. For the detection of p53 prions the Seprion-ELISA, previously designed for the detection of BSE and scrapie was adapted and optimized. To investigate the impact of p53 aggregation on clinical outcomes (overall survival and progression-free survival), we performed a complete-case analysis. In a subset of patients the Ki67 proliferation index and a homologous recombination deficiency (HRD) score, based on the Myriad score, were available. Correlations were analyzed using ANOVA and t-test.

RESULTS: In 39 of 46 (84.8%) patients with missense mutated cancers a p53 prion specific signal was observed. The aggregation propensity varied considerably within samples carrying the same mutations. Multivariable Cox regression models, with respect to other prognostic factors significantly associated with overall survival in patients with late-stage serous epithelial ovarian cancer (age, FIGO stage and presence of a residual tumor), show superiority of the group with extensive p53 aggregation in overall survival and in progression-free survival. No and moderate p53 aggregation are associated with a worse overall survival in contrast to high p53 aggregation (P values 0.025 and 0.011). Similar results in these groups are assessed for progression-free survival (P values 0.030 and 0.008). Interestingly, the group with extensive p53 aggregation was associated with a non-significant trend toward higher HR deficiency. Furthermore, this group had a significantly higher Ki67 index compared to patients with moderate p53 aggregation (P value 0.033).

CONCLUSIONS: This study reports the first specific and quantitative screening for p53 prions in patient material. We were able to demonstrate that the p53-Seprion-ELISA is a robust and highly sensitive detection tool for p53 prions. Our data show that the aggregation propensity is not only depending on the TP53 mutation and that other cofactors may be involved. Moreover, we show that p53 aggregation is an independent prognostic marker for survival. The higher Ki67 proliferation index and the trend towards higher genomic instability in patients with extensive p53 aggregation suggest that these tumors have an increased likelihood of response to platinum-containing therapy. To conclude, we demonstrated the high potential of p53 aggregation as a biomarker for patients' survival, suggesting that classification of patients based on the amount of aggregated p53 could allow therapy decisions.

Citation Format: Nicole Heinzl, Elisabeth Maritschnegg, Katarzyna Koziel, Stuart Wilson, Georg Heinze, Christine Wallisch, Reinhard Horvat, Jalid Sehouli, Ioana Braicu, Ignace Vergote, Els van Nieuwenhuysen, Sven Mahner, Eva Obermayr, Eva Schuster, Barbara Holzer, Nicole Concin, Robert Zeillinger. IDENTIFICATION OF P53 PRIONS AS AN INDEPENDENT PROGNOSTIC MARKER FOR SURVIVAL IN HIGH-GRADE SEROUS OVARIAN CANCER [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr AP15.

Molecular Characterization of Circulating Tumor Cells Enriched by A Microfluidic Platform in Patients with Small-Cell Lung Cancer

At initial diagnosis, most patients with small-cell lung cancer (SCLC) present with metastatic disease with a high number of tumor cells (CTCs) circulating in the blood. We analyzed RNA transcripts specific for neuroendocrine and for epithelial cell lineages, and Notch pathway delta-like 3 ligand (DLL3), the actionable target of rovalpituzumab tesirine (Rova-T) in CTC samples. Peripheral blood samples from 48 SCLC patients were processed using the microfluidic Parsortix™ technology to enrich the CTCs. Blood samples from 26 healthy donors processed in the same way served as negative controls. The isolated cells were analyzed for the presence of above-mentioned transcripts using quantitative PCR. In total, 16/51 (31.4%) samples were CTC-positive as determined by the expression of epithelial cell adhesion molecule 1 (EpCAM), cytokeratin 19 (CK19), chromogranin A (CHGA), and/or synaptophysis (SYP). The epithelial cell lineage-specific EpCAM and/or CK19 gene expression was observed in 11 (21.6%) samples, and positivity was not associated with impaired survival. The neuroendocrine cell lineage-specific CHGA and/or SYP were positive in 13 (25.5%) samples, and positivity was associated with poor overall survival. DLL3 transcripts were observed in four (7.8%) SCLC blood samples and DLL3-positivity was similarly associated with poor overall survival (OS). CTCs in SCLC patients can be assessed using epithelial and neuroendocrine cell lineage markers at the molecular level. Thus, the implementation of liquid biopsy may improve the management of lung cancer patients, in terms of a faster diagnosis, patient stratification, and on-treatment therapy monitoring.

Abstract AP04: THE MOLECULAR DETECTION OF CIRCULATING TUMOR CELLS IN THE BLOOD OF OVARIAN CANCER PATIENTS

PURPOSE OF THE STUDY: The detection of circulating tumor cells (CTCs) in the blood of cancer patients has raised considerable interest over the last decade as a promising biomarker of minimal residual disease in various solid tumors. Although hematogenous spread has not been deemed a major issue for ovarian cancer, there are several studies demonstrating the presence and prognostic impact of CTCs in ovarian cancer patients. Recently, we developed a protocol for the enrichment of CTCs from ovarian cancer blood samples, achieving a high purity of the target cells and enabling high specificity.

EXPERIMENTAL PROCEDURES: Blood samples were enriched using a density gradient centrifugation (OncoQuick, Greiner Bio–One) followed by a micro–fluidic based isolation of the target cells using the Parsortix™ system (Angle plc.). The captured target cells were lysed, RNA was extracted (RNeasy Micro Kit, Qiagen) and transcribed into cDNA (ssVILO, Life Technologies). After a pre–amplification step (PreAmp Master Mix, Life Technologies), the transcript levels of selected genes (EpCAM, PPIC, TUSC3, EMP2, LAMB1, MAL2, FN1) were measured using RT–qPCR. Additionally, density gradient enriched cells were immuno–fluorescently stained targeting CK8/18/19, PPIC, TP53 and CD45.

SUMMARY: By combining a density gradient based pre–enrichment and the micro–fluidic Parsortix™ technology we achieved an up to 106–fold depletion of blood cell contamination. The analysis of CTC–related transcripts in the enriched samples indicated the presence of CTCs in 78% of the ovarian cancer blood samples taken at primary diagnosis (N=15) and in 80% of the samples taken at relapse (N=9). Concordant results of immuno–fluorescent staining and RT–qPCR were obtained in just 30% of ovarian cancer samples. By adding further 22 RT–qPCR markers, 92% of all cancer patients (n=13) and 100% of the ovarian cancer patients (n=7) were classified as being CTC–positive by RT–qPCR.

CONCLUSIONS: In conclusion, we developed a protocol which enabled the detection of CTC–related transcripts in the majority of ovarian cancer blood samples, which is a clear improvement in sensitivity as compared to earlier studies employing density gradient centrifugation as the only enrichment step. Our results are currently validated in the large cohort of platinum resistant ovarian cancer patients provided by a multi–center Gannet53 study.

Citation Format: Eva Obermayr, Elisabeth Maritschnegg, Paul Speiser, Eva Schuster, Barbara Holzer, Nina Pecha, Robert Zeillinger. THE MOLECULAR DETECTION OF CIRCULATING TUMOR CELLS IN THE BLOOD OF OVARIAN CANCER PATIENTS [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr AP04.

Abstract DPOC-009: DETECTION OF A CLINICALLY OCCULT OVARIAN CARCINOMA BY NEW DIAGNOSTIC TOOLS – A CASE REPORT

75% of ovarian cancer (OC) cases are detected at an advanced stage. State–of–the–art diagnostic tools don't show sufficient sensitivity, especially in diagnosing early–stage disease. Still, due to lack in alternatives, these methods are used for monitoring BRCA mutation carriers, who face a high penetrance of OC.

A 41–year old BRCA1 mutation carrier decided to undergo risk–reducing bilateral salpingo–oophorectomy (rrBSO), currently the only effective way of reducing the OC risk. The day before surgery, 20ml of peripheral blood were drawn to test for the presence of circulating tumor cells (CTCs) by applying a microfluidic device (Parsortix system) and subsequent qPCR. Furthermore, a lavage of the uterine cavity was performed as previously described. According to state–of–the–art techniques, no signs of cancer were present. However, microscopic malignant lesions at both ovaries and the right diaphragm were observed, and final histopathology revealed FIGO IIIB serous OC. Multiple precursor lesions (STICs) were observed in the fallopian tube. qPCR of preoperative enriched cell fraction indicated the presence of CTCs. Analysis of the lavage sample using TP53 mutation analysis revealed 17% mutant allelic fraction. The same mutation was identified in different STIC and invasive lesions.

This case shows that early detection of high–grade serous OC does not necessarily translate into a stage shift, but easier to resect disease. Considering the lag–time between STIC to clinically–overt OC development, both described methods present an opportunity for monitoring high–risk patients to delay rrBSO. Both methods proved to be able to diagnose occult OC, and even carry the potential of detecting STICs.

Citation Format: Elisabeth Maritschnegg, Eva Obermayr, Barbara Holzer, Noreen Gleeson, Florian Heitz, Leon Massuger, Gunda Pristauz Telsnigg, Adam Rosenthal, Fabian Trillsch, Els Van Nieuwenhuysen, Michael Zikan, Paul Speiser, Robert Zeillinger. DETECTION OF A CLINICALLY OCCULT OVARIAN CARCINOMA BY NEW DIAGNOSTIC TOOLS – A CASE REPORT [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr DPOC-009.

Biclustering strategies for genetic marker selection in gynecologic tumor cell lines

Over the past few decades great interest has been focused on cell lines derived from tumors, because of their usability as models to understand the biology of cancer. At the same time, advanced technologies such as DNA-microarrays have been broadly used to study the expression level of thousands of genes in primary tumors or cancer cell lines in a single experiment. Results from microarray analysis approaches have provided valuable insights into the underlying biology and proven useful for tumor classification, prognostication and prediction. Our approach utilizes biclustering methods for the discovery of genes with coherent expression across a subset of conditions (cell lines of a tumor type). More specifically, we present a novel modification on Cheng & Church's algorithm that searches for differences across the studied conditions, but also enforces consistent intensity characteristics of each cluster within each condition. The application of this approach on a gynecologic panel of cell lines succeeds to derive discriminant groups of compact bi-clusters across four types of tumor cell lines. In this form, the proposed approach is proven efficient for the derivation of tumor-specific markers.

Skeletal Muscle Depletion and Markers for Cancer Cachexia Are Strong Prognostic Factors in Epithelial Ovarian Cancer

Objective

Tumor cachexia is an important prognostic parameter in epithelial ovarian cancer (EOC). Tumor cachexia is characterized by metabolic and inflammatory disturbances. These conditions might be reflected by body composition measurements (BCMs) ascertained by pre-operative computed tomography (CT). Thus, we aimed to identify the prognostically most relevant BCMs assessed by pre-operative CT in EOC patients.

Methods

We evaluated muscle BCMs and well established markers of nutritional and inflammatory status, as well as clinical-pathological parameters in 140 consecutive patients with EOC. Furthermore, a multiplexed inflammatory marker panel of 25 cytokines was used to determine the relationship of BCMs with inflammatory markers and patient’s outcome. All relevant parameters were evaluated in uni- and multivariate survival analysis.

Results

Muscle attenuation (MA)—a well established BCM parameter—is an independent prognostic factor for survival in multivariate analysis (HR 2.25; p = 0.028). Low MA—reflecting a state of cachexia—is also associated with residual tumor after cytoreductive surgery (p = 0.046) and with an unfavorable performance status (p = 0.015). Moreover, MA is associated with Eotaxin and IL-10 out of the 25 cytokine multiplex marker panel in multivariate linear regression analysis (p = 0.021 and p = 0.047, respectively).

Conclusion

MA—ascertained by routine pre-operative CT—is an independent prognostic parameter in EOC patients. Low MA is associated with the inflammatory, as well as the nutritional component of cachexia. Therefore, the clinical value of pre-operative CT could be enhanced by the assessment of MA.

Abstract LB-197: Circulating rare cells enable highly efficient cancer detection

Objectives of the study

We intended to develop a protocol combining a novel micro-fluidic enrichment technology and RT-qPCR for the molecular analysis of CTCs. Recently we identified CTC-specific mRNA markers allowing CTC detection in 29% of breast cancer patients and in 24.5% of ovarian cancer patients at diagnosis. However, the detection of cancer cells was hampered by the large number of contaminating leukocytes. The necessary use of cut-off values for positivity reduced the specificity of the down-stream PCR assay. By improving the purity of cancer cells and PCR analysis we sought to increase both sensitivity and specificity of the diagnostic procedure.

Methodology

For reducing the blood sample volume (up to 20ml) density gradient centrifugation was used when needed. The samples were passed through a micro-fluidic disposable cassette, which captures tumor cells based on their less deformable nature and larger size compared to blood cells. Lysis of the captured cells was done directly in the cassette and total RNA was extracted. After a cDNA pre-amplification step gene expression levels of leukocyte-specific and CTC-related markers were measured using RT-qPCR. The efficiency of the combined protocol was assessed in blood samples taken from patients with primary and recurrent malignant diseases.

Results

7 out of 13 pre-selected RNA markers were not detectable in blood samples from 11 healthy volunteers. In cancer patients we observed measurable gene expression of at least one out of these 7 RNA markers. 5 out of 5 breast cancer (primary disease: N = 1; metastatic: N = 4), 9 out of 10 primary and 4 out of 8 relapsed ovarian cancer patients were classified correctly by the test. The most striking finding is the detection rate of 90% for primary ovarian cancer at a specificity of 100%.

Conclusions

The enrichment of rare cells from blood samples using micro-fluidics results in a highly pure cell population. This enables the application of extremely sensitive methods, like RT-qPCR to specifically detect rare events. By combining a novel micro-fluidic cell enrichment and molecular analysis we have taken a major step forward, which allows the implementation of ′liquid biopsies′ in cancer detection studies and as a companion diagnostic in clinical trials.

Citation Format: Eva Obermayr, Elisabeth Maritschnegg, Paul Speiser, Christian Singer, Eva M. Schuster, Sabine Danzinger, Nina Pecha, Robert Zeillinger. Circulating rare cells enable highly efficient cancer detection. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-197. doi:10.1158/1538-7445.AM2015-LB-197

A combined blood based gene expression and plasma protein abundance signature for diagnosis of epithelial ovarian cancer--a study of the OVCAD consortium

BACKGROUND

The immune system is a key player in fighting cancer. Thus, we sought to identify a molecular 'immune response signature' indicating the presence of epithelial ovarian cancer (EOC) and to combine this with a serum protein biomarker panel to increase the specificity and sensitivity for earlier detection of EOC.

METHODS

Comparing the expression of 32,000 genes in a leukocytes fraction from 44 EOC patients and 19 controls, three uncorrelated shrunken centroid models were selected, comprised of 7, 14, and 6 genes. A second selection step using RT-qPCR data and significance analysis of microarrays yielded 13 genes (AP2A1, B4GALT1, C1orf63, CCR2, CFP, DIS3, NEAT1, NOXA1, OSM, PAPOLG, PRIC285, ZNF419, and BC037918) which were finally used in 343 samples (90 healthy, six cystadenoma, eight low malignant potential tumor, 19 FIGO I/II, and 220 FIGO III/IV EOC patients). Using new 65 controls and 224 EOC patients (thereof 14 FIGO I/II) the abundances of six plasma proteins (MIF, prolactin, CA125, leptin, osteopondin, and IGF2) was determined and used in combination with the expression values from the 13 genes for diagnosis of EOC.

RESULTS

Combined diagnostic models using either each five gene expression and plasma protein abundance values or 13 gene expression and six plasma protein abundance values can discriminate controls from patients with EOC with Receiver Operator Characteristics Area Under the Curve values of 0.998 and bootstrap .632+ validated classification errors of 3.1% and 2.8%, respectively. The sensitivities were 97.8% and 95.6%, respectively, at a set specificity of 99.6%.

CONCLUSIONS

The combination of gene expression and plasma protein based blood derived biomarkers in one diagnostic model increases the sensitivity and the specificity significantly. Such a diagnostic test may allow earlier diagnosis of epithelial ovarian cancer.

Relaxin and gonadal steroid receptors in uterosacral ligaments of women with and without pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

This study evaluates the expression of estrogen receptor isoforms alpha (ERα) and beta (ERβ), progesterone receptor (PR), and relaxin receptor isoforms 1 and 2 (LGR7, LGR8) in uterosacral ligament (USL) tissue of women with pelvic organ prolapse and controls.

METHODS

Tissue samples of USL from women with and without pelvic organ prolapse (POP) were subjected to immunohistochemistry against ERα, ERβ, PR, and LGR7 proteins. The respective mRNA expression as well as of LGR8 was assessed by quantitative real-time polymerase chain reaction.

RESULTS

The cellular distribution of the receptor proteins was different due to cell types, independent of POP: ERα and PR were found in smooth muscle cells, but not in endothelial cells, whereas ERβ was found in endothelial cells, but not in connective tissue. ERα, ERβ, PR, and LGR7 mRNAs could be detected in all patients of both groups. ERα mRNA expression was significantly and ERβ mRNA borderline significantly higher in USL of patients with POP: ERα: p < 0.001, ERβ: p = 0.057.

CONCLUSIONS

Enhanced effects of estrogen via altered mRNA expression patterns of ERα and ERβ--but not those of progesterone--may exist in USL of patients affected by POP. A local effect of relaxin needs to be further clarified because of this first report of prevalent ligamental expression of LGR7.

Molecular markers for circulating tumor cells in breast cancer

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Background: Recently, we identified a six gene panel (CCNE2, DKFZp762E1312, EMP2, MAL2, PPIC, and SLC6A8) for the RT-qPCR based detection of circulating tumor cells (CTC) in breast cancer patients. The aim of the present study was to evaluate the gene panel in further blood samples.

Methods: Blood samples were taken from breast cancer patients with metastatic disease (MBC, N=10) or with no evidence of disease (NED, N=30). Putative CTC were enriched by Oncoquick density gradient centrifugation. Total RNA was isolated with RNeasy Micro Kit (QIAgen). Template cDNA was generated with M-MLV Reverse Transcriptase, RNase H Minus (Promega) and random nonamers as primers. RT-qPCR was performed in duplicate reactions using TaqMan Assays (Applied Biosystems) with default thermal cycling parameters. Raw data were analyzed with the AB7900 Sequence Detection Software version 2.2.2 using automatic baseline correction and manual cycle threshold setting. Gene expression was normalized to GAPDH expression. A threshold value TX for each gene X was set at two standard deviations above the mean dCtX value in the healthy control group. A patient was defined as CTC-positive, if at least one gene marker was over-expressed compared to the defined threshold.

Results: The gene panel consisting of CCNE2, DKFZp762E1312, EMP2, MAL2, PPIC, and SLC6A8 identified 4/11 MBC but only 5/27 NED patients as CTC positive (p=0.163). By adding known CTC markers (SCGB2A2, TFF1, FXYD3, AGR2, S100A18, and EPCAM) to the panel, 7/11 MBC but only 6/27 NED patients were CTC positive (p=0.018). The presence of CTC in NED patients correlated with pN staging (p=0.026). Only one out of the six CTC positive NED patients relapsed within the observation period (median 35 months, range 25-39 months from blood sampling). We observed no correlation of CTC positivity and recurrence in NED patients.

Conclusions: The sensitivity of the RT-qPCR based CTC detection in breast cancer patients may be enhanced by adding known CTC markers (SCGB2A2, TFF1, FXYD3, AGR2, S100A18, and EPCAM) to the six gene panel (CCNE2, DKFZp762E1312, EMP2, MAL2, PPIC, and SLC6A8). Longer follow-up times are needed to evaluate the predictive value of the gene markers on survival.

Detection of EpCAM positive and negative circulating tumor cells in metastatic breast cancer patients

BACKGROUND

Immunomagnetic EpCAM based methods are used to enrich circulating tumor cells (CTCs) in metastatic breast cancer (mBC) patients. EpCAM negative CTCs may be missed. We addressed the question of the reliability of an EpCAM dependent assay to enrich CTCs.

METHODS

To elucidate this issue, our study has been designed to assess two different CTC enrichment technologies (i) in EpCAM positive (+) and EpCAM negative cell lines and (ii) in mBC patients in dependency on their respective EpCAM expression. These two technologies encompass one anti-EpCAM immunomagnetic enrichment technology, MACS HEA MicroBeads(®) (MACS), and one EpCAM independent density centrifugation method, OncoQuick(®) plus (OQ+). Furthermore, the coherence between EpCAM expression in the primary tumor tissue of mBC patients and the CTC detection rates in the corresponding patients is analyzed.

RESULTS

(i) MACS recovered significantly more EpCAM (+) than EpCAM (-) tumor cells (p < 0.001) in spiked blood samples. With OQ+ no significantly different recovery rates between EpCAM (+) and EpCAM (-) tumor cells (p = 0.796) were detected. (ii) In mBC patients MACS yielded a significantly higher (p = 0.024) detection rate of EpCAM (+) CTCs. No statistically significant difference (p = 0.070) was found concerning the EpCAM status-based detection rate of CTCs by OQ+. (iii) CTC detection rates are independent of the primary tumors' EpCAM expression.

CONCLUSIONS

EpCAM (-) CTCs can not be detected by immunomagnetic EpCAM dependent enrichment methods. EpCAM independent enrichment technologies seem to be superior to detect the entire CTC population. Evaluation of CTCs as prognostic marker should compromise EpCAM (+) and (-) subpopulations.

Assessment of a six gene panel for the molecular detection of circulating tumor cells in the blood of female cancer patients

Background

The presence of circulating tumor cells (CTC) in the peripheral blood of cancer patients has been described for various solid tumors and their clinical relevance has been shown. CTC detection based on the analysis of epithelial antigens might be hampered by the genetic heterogeneity of the primary tumor and loss of epithelial antigens. Therefore, we aimed to identify new gene markers for the PCR-based detection of CTC in female cancer patients.

Methods

Gene expression of 38 cancer cell lines (breast, ovarian, cervical and endometrial) and of 10 peripheral blood mononuclear cell (PBMC) samples from healthy female donors was measured using microarray technology (Applied Biosystems). Differentially expressed genes were identified using the maxT test and the 50% one-sided trimmed maxT-test. Confirmatory RT-qPCR was performed for 380 gene targets using the AB TaqMan^® Low Density Arrays. Then, 93 gene targets were analyzed using the same RT-qPCR platform in tumor tissues of 126 patients with primary breast, ovarian or endometrial cancer. Finally, blood samples from 26 healthy women and from 125 patients (primary breast, ovarian, cervical, or endometrial cancer, and advanced breast cancer) were analyzed following OncoQuick enrichment and RNA pre-amplification. Likewise, hMAM and EpCAM gene expression was analyzed in the blood of breast and ovarian cancer patients. For each gene, a cut-off threshold value was set at three standard deviations from the mean expression level of the healthy controls to identify potential markers for CTC detection.

Results

Six genes were over-expressed in blood samples from 81% of patients with advanced and 29% of patients with primary breast cancer. EpCAM gene expression was detected in 19% and 5% of patients, respectively, whereas hMAM gene expression was observed in the advanced group (39%) only. Multimarker analysis using the new six gene panel positively identified 44% of the cervical, 64% of the endometrial and 19% of the ovarian cancer patients.

Conclusions

The panel of six genes was found superior to EpCAM and hMAM for the detection of circulating tumor cells in the blood of breast cancer, and they may serve as potential markers for CTC derived from endometrial, cervical, and ovarian cancers.

An ELISA for the detection of TIMP-1 based on recombinant single chain Fv fusion proteins

BACKGROUND

Altered serum levels of TIMP-1 are an indicator of various pathological states. To quantitate TIMP-1 in biological samples, we have previously isolated TIMP-1 specific single-chain Fv fragments (scFvs) using phage-display. In the work presented here, we have used these scFvs to establish a TIMP-1 ELISA based exclusively on recombinant scFv fusion proteins.

METHODS

Two distinct TIMP-1 specific scFvs were used as the antigen binding components after being genetically fused to the N-termini of two different fusion protein constructs. One fusion protein, comprising a CL domain, serves as a coating reagent, while the second fusion protein with a modified form of bacterial alkaline phosphatase is used as a detection reagent. A double antibody sandwich-ELISA was then established and optimized.

RESULTS

An ELISA for the quantitation of tissue inhibitor of metalloproteinase (TIMP)-1, based entirely on recombinant antibody fragments, was developed as an alternative to assays using polyclonal antisera or monoclonal antibodies. Its performance was shown to compare well with a conventional ELISA. Finally, TIMP-1 concentrations in the sera of sixty healthy individuals were determined.

CONCLUSION

The assay described here provides a standardized, reliable and readily available means of quantitation of TIMP-1 in a large number of blood samples.

Expression of TIMP-1 in Pichia pastoris. Selection of an anti-TIMP-1 specific single-chain Fv antibody from a large non-immune library

To quantitate tissue inhibitor of metalloproteinase (TIMP)-1 in biological samples, a strategy for isolation of monoclonal antibodies was applied that employs a phage-displayed single-chain Fv (scFv). In order to obtain sufficient amounts of TIMP-1 to use as an antigen, high-level expression in Pichia pastoris was achieved under the control of the AOX-1 promotor. Purified protein antigen was then used for panning to achieve enrichment of specific phage from naive scFv library. In five subsequent panning rounds, antibody fragments that display specificity to TIMP-1 were selected. Regions encoding scFv were subcloned into a vector allowing production of scFv-alkaline phosphatase (AP) fusion proteins. Two such conjugates displaying dose-dependent reactivity with TIMP-1 were isolated and characterised, providing the basis for the construction of a TIMP-1 quantitation assay based entirely on recombinant proteins.