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Introduction: Leptomeningeal metastases (LM) occur in approximately 5% of patients with breast cancer, negatively impacting their prognosis. Reliable diagnosis of LM is challenging, but timely diagnosis could lead to more treatment options and consequently a better prognosis. Circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs) in cerebrospinal fluid (CSF) are potential methods to improve the diagnosis of LM. In this prospective study we compared cytology (current gold standard for CSF analysis in diagnosing LM) with CTC enumeration and ctDNA detection in CSF for diagnosing LM in patients with breast cancer. Methods: In a prospective study in patients with clinical suspicion of LM who were planned to undergo a diagnostic lumbar puncture (LP) for CSF cytology the presence of CTCs/ctDNA in CSF was compared to the presence of tumor cells in CSF by cytology. CTC enumeration was performed using the FDA approved CellSearch System (Menarini). The detection of ctDNA was performed using the mFAST-Seqs method, which detects aneuploidy throughout the genome by selective amplification of long interspaced nuclear element sequences (LINE-1 elements). In a control group consisting of 15 patients with a hematologic malignancy with suspicion of LM, 2 cases had 1 CTC in their CSF, therefore the cutoff for a positive CTC test was set at 2 CTCs. Results: In total 80 patients with breast cancer were included from January 2016 till January 2022. In 16 out of 80 patients CSF cytology was positive of whom 14 (87.5%) had a positive CTC test. From the 2 patients in which the CTC test was negative, one patient had 1 CTC detected in CSF and for both patients a lower volume of CSF was available for the CTC test compared to the volume used for cytology. In 2 of the 16 cytology positive patients, who underwent a second LP, CTCs were positive in the CSF from the first LP, while cytology was only positive in the CSF of the second LP. Of the 64 patients with a negative cytology, 7 (10.9%) patients had a positive CTC test. Two of these 7 patients had typical symptoms of LM, a suspicious MRI and a course of disease matching with LM according to the neuro-oncologist. Overall survival (OS) was shorter in patients with a positive CTC test compared to patients with a negative test (median OS: 19.2 months vs. 3.4 months, log-rank test, p=0.007). When only patients with a negative cytology were included in this analysis, OS remains significantly shorter in the group with a positive CTC test (n=7) compared to the group with the negative CTCs (n=57) (median OS 19.3 months vs. 3.5 months, long-rank test, p=0.003). Additionally, ctDNA detection in CSF was compared to CSF cytology in 51 patients, of which 11 had a positive CSF cytology result. For 8 of these 11 patients ctDNA was detected (72.2%) while 1 of the 40 patients with a negative cytology had ctDNA. Discussion: Both CTC enumeration and ctDNA detection can be used to detect LM in CSF. CTC detection could even improve timely diagnosis of LM in patients with breast cancer. However, the added value of ctDNA seems less evident. Citation Format: Elisabeth M Jongbloed, Lindsay Angus, Martin J van den Bent, Joost LM Jongen, John WM Martens, Ngoc M Van, Vanja de Weerd, Carolien HM van Deurzen, Jaco Kraan, Saskia M Wilting, Agnes Jager. OPTIMIZING THE DIAGNOSIS OF LEPTOMENINGEAL METASTASES IN BREAST CANCER PATIENTS BY CIRCULATING TUMOR CELLS AND CIRCULATING TUMOR DNA [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-05-23.

Elisabeth M Jongbloed,1 Hedwig M Blommestein,2 Hannah M van Schoubroeck,2 John WM Martens,1 Saskia M Wilting,1 Carin A Uyl-de Groot,2 Agnes Jager1 1Department of Medical Oncology; Erasmus MC Cancer Institute, Rotterdam, the Netherlands; 2Erasmus School of Health Policy and Management, Erasmus University, Rotterdam, the NetherlandsCorrespondence: Elisabeth M Jongbloed, Department of Medical Oncology; Erasmus MC Cancer Institute, Dr. Molenwaterplein 40, Rotterdam, 3014 GD, the Netherlands, Tel +31 107044375, Email e.jongbloed@erasmusmc.nlPurpose: The addition of two years of abemaciclib treatment to standard adjuvant endocrine therapy in all patients with high risk ER+, HER2- early breast cancer (EBC) has been approved by the US Food and Drug Administration (FDA). Pre-selection of patients with an immediate risk of recurrence within the group of clinically high risk patients using detection of minimal residual disease (MRD) using patient-informed circulating tumor DNA assays during follow-up could enhance efficacy. Here, we investigate the cost-effectiveness of the addition of two years abemaciclib in all high risk HR+, HER2- patients and in MRD-guided high risk patients only.Methods: Two semi-Markov models were developed to evaluate the cost-effectiveness of adding two years of abemaciclib compared to “standard treatment”: 1) “abemaciclib all” and 2) “MRD-guided abemaciclib” using MRD-guidance. Data of the MonarchE trial were used to model the invasive disease-free survival (iDFS). Since iDFS and overall survival (OS) data of abemaciclib were currently limited, abemaciclib effects were extrapolated using a favorable, intermediate and unfavorable effect scenario.Results: The addition of abemaciclib in all high-risk EBC patients prolonged iDFS slightly (0.04 additional quality adjusted life years (QALYs)) and led to higher costs compared to standard ET, leading to a high incremental cost effectiveness ratio (ICER) of € 1,551,876/QALY. Neither the favorable effect scenario (additional 1.09 QALYs) was cost-effective (ICER € 62,935/QALY), using a willingness-to-pay threshold of € 50,000/QALY. The “MRD-guided abemaciclib” strategy resulted in lower costs and an increase in QALYs (1.27) compared to “standard treatment” in the unfavorable effect scenario.Conclusion: The addition of abemaciclib to adjuvant endocrine therapy in all high-risk ER+, HER2- EBC patients is not cost-effective. However, using MRD detection to justify the addition of abemaciclib treatment dominates standard treatment in this cost-effectiveness analysis. Further evaluation of MRD detection in EBC by means of prospective clinical trials assessing clinical utility is recommended and promising in terms of cost-effectiveness.Keywords: breast cancer, minimal residual disease, circulating tumor DNA, cost-effectiveness, abemaciclib

Multiple prognostic biomarkers, including circulating tumor cell (CTC) counts, exist in metastatic castration-resistant prostate cancer (mCRPC) patients, but none of them have been implemented into daily clinical care. The modified fast aneuploidy screening test-sequencing system (mFast-SeqS), which yields a genome-wide aneuploidy score, is able to reflect the fraction of cell-free tumor DNA (ctDNA) within cell-free DNA (cfDNA) and may be a promising biomarker in mCRPC. In this study, we investigated the prognostic value of dichotomized aneuploidy scores (

Introduction: Inflammatory breast cancer (IBC) is a rare ( Citation Format: Jasper JL van Geel, Gonneke van der Schoor, Elise van Leeuwen-Stok, John WM Martens, Saskia M Wilting, Jelle Wesseling, Gabe S Sonke, Carolien P Schröder. Clinicopathological characterization of inflammatory breast cancer in the Netherlands: First results of the prospective INFLAME registry [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-24-03.

Purpose: Epigenetic host cell changes involved in cervical cancer development following a persistent high-risk human papillomavirus (hrHPV) infection, provide promising markers for the management of hrHPV-positive women. In particular, markers based on DNA methylation of tumor suppressor gene promoters are valuable. These markers ideally identify hrHPV-positive women with precancer (CIN2/3) in need of treatment. Here, we set out to identify biologically relevant methylation markers by genome-wide methylation analysis of both hrHPV-transformed cell lines and cervical tissue specimens.Experimental Design and Results: Genome-wide discovery by next-generation sequencing (NGS) of methyl-binding domain–enriched DNA (MBD-Seq) yielded 20 candidate methylation target genes. Further verification and validation by multiplex-targeted bisulfite NGS and (quantitative) methylation-specific PCR (MSP) resulted in 3 genes (GHSR, SST, and ZIC1) that showed a significant increase in methylation with severity of disease in both tissue specimens and cervical scrapes (P < 0.005). The area under the ROC curve for CIN3 or worse varied between 0.86 and 0.89. Within the group of CIN2/3, methylation levels of all 3 genes increased with duration of lesion existence (P < 0.0005), characterized by duration of preceding hrHPV infection, and were significantly higher in the presence of a 3q gain (P < 0.05) in the corresponding tissue biopsy.Conclusions: By unbiased genome-wide DNA methylation profiling and comprehensive stepwise verification and validation studies using in vitro and patient-derived samples, we identified 3 promising methylation markers (GHSR, SST, and ZIC1) associated with a 3q gain for the detection of cervical (pre)cancer. Clin Cancer Res; 23(14); 3813–22. ©2017 AACR.

Purpose:Detection of leptomeningeal metastasis is hampered by limited sensitivities of currently used techniques: MRI and cytology of cerebrospinal fluid (CSF). Detection of cell-free tumor DNA in CSF has been proposed as a tumor-specific candidate to detect leptomeningeal metastasis at an earlier stage. The aim of this study was to investigate mutation and aneuploidy status in CSF-derived cell-free DNA (cfDNA) of patients with breast cancer with a clinical suspicion of leptomeningeal metastasis.Experimental Design:cfDNA was isolated from stored remnant CSF and analyzed by targeted next-generation sequencing (NGS; n = 30) and the modified fast aneuploidy screening test-sequencing system (mFAST-SeqS; n = 121). The latter method employs selective amplification of long interspaced nuclear elements sequences that are present throughout the genome and allow for fast and cheap detection of aneuploidy. We compared these results with the gold standard to diagnose leptomeningeal metastasis: cytology.Results:Leptomeningeal metastasis was cytology proven in 13 of 121 patients. Low DNA yields resulted in insufficient molecular coverage of NGS for the majority of samples (success rate, 8/30). The mFAST-SeqS method, successful in 112 of 121 (93%) samples, detected genome-wide aneuploidy in 24 patients. Ten of these patients had cytology-proven leptomeningeal metastasis; 8 additional patients were either concurrently diagnosed with central nervous system metastases by radiological means or developed these soon after the lumbar puncture. The remaining six cases were suspected of leptomeningeal metastasis, but could not be confirmed by cytology or imaging. Aneuploidy was associated with development of leptomeningeal metastasis and significantly worse overall survival.Conclusions:Aneuploidy in CSF-derived cfDNA may provide a promising biomarker to improve timely detection of leptomeningeal metastasis.

Further detailed description of methods

Correlation between input ng cfDNA in the Oncomine Breast V2 breast panel and the median molecular coverage (i.e., the median number of uniquely

Supplementary Figure S1: Overview of study populations. Supplementary Figure S2: Correlation heatmap of all 72 hrHPV-positive self-samples analyzed by Infinium Methylation 450K Array. Supplementary Figure S3: The effect of informative co-data. Supplementary Figure S4: Approach to build a 3-gene methylation classifier applicable to both lavage and brush self-samples. Supplementary Figure S5: DNA methylation levels of all 28 methylation targets in hrHPV-positive lavage self-samples. Supplementary Figure S6: DNA methylation-positivity determined by the 3-gene methylation classifier. Supplementary Figure S7: Classification tree model for lavage self-samples. Supplementary Figure S8: Classification tree model for brush self-samples. Supplementary Figure S9: DNA methylation-positivity in hrHPV-positive self-samples from women with glandular lesions and cancer. Supplementary Figure S10: Predicted probabilities in self-samples from women with and without CIN3. Supplementary Figure S11: DNA methylation levels of ASCL1, LHX8 and ST6GALNAC5 in self-samples from women with HPV16 or with other hrHPV types (non-HPV16). Supplementary Table S1: Primers and probes used in multiplex qMSP. Supplementary Table S2: Logistic regression analysis results of the 3-gene methylation classifier for CIN3 detection in hrHPV-positive self-samples. Supplementary Table S3: The comparison of the performance of logistic regression and CART models.

Supplementary Tables

Purpose: Offering self-sampling of cervico-vaginal material for high-risk human papillomavirus (hrHPV) testing is an effective method to increase the coverage in cervical screening programs. Molecular triage directly on hrHPV-positive self-samples for colposcopy referral opens the way to full molecular cervical screening. Here, we set out to identify a DNA methylation classifier for detection of cervical precancer (CIN3) and cancer, applicable to lavage and brush self-samples.Experimental Design: We determined genome-wide DNA methylation profiles of 72 hrHPV-positive self-samples, using the Infinium Methylation 450K Array. The selected DNA methylation markers were evaluated by multiplex quantitative methylation-specific PCR (qMSP) in both hrHPV-positive lavage (n = 245) and brush (n = 246) self-samples from screening cohorts. Subsequently, logistic regression analysis was performed to build a DNA methylation classifier for CIN3 detection applicable to self-samples of both devices. For validation, an independent set of hrHPV-positive lavage (n = 199) and brush (n = 287) self-samples was analyzed.Results: Genome-wide DNA methylation profiling revealed 12 DNA methylation markers for CIN3 detection. Multiplex qMSP analysis of these markers in large series of lavage and brush self-samples yielded a 3-gene methylation classifier (ASCL1, LHX8, and ST6GALNAC5). This classifier showed a very good clinical performance for CIN3 detection in both lavage (AUC = 0.88; sensitivity = 74%; specificity = 79%) and brush (AUC = 0.90; sensitivity = 88%; specificity = 81%) self-samples in the validation set. Importantly, all self-samples from women with cervical cancer scored DNA methylation–positive.Conclusions: By genome-wide DNA methylation profiling on self-samples, we identified a highly effective 3-gene methylation classifier for direct triage on hrHPV-positive self-samples, which is superior to currently available methods. Clin Cancer Res; 24(14); 3456–64. ©2018 AACR.

Figure S1: Overview of MSP results in Verification II. Figure S2: Representative MSP results in cervical tissue specimens. Figure S3: Validation of GHSR, SST and ZIC1 by qMSP in hrHPV-positive cervical scrapes. Figure S4: No association of FAM19A4, CADM1, MAL and miR124-2 methylation levels with 3q gain. Table S1: Number of samples used per study item.

According to the current guidelines, watchful waiting (WW) is a feasible option for patients with good or intermediate prognosis renal-cell carcinoma (RCC). However, some patients rapidly progress during WW, requiring the initiation of treatment. Here, we explore whether we can identify those patients using circulating cell-free DNA (cfDNA) methylation. We first defined a panel of RCC-specific circulating methylation markers by intersecting differentially methylated regions from a publicly available dataset with known RCC methylation markers from the literature. The resulting RCC-specific methylation marker panel of 22 markers was subsequently evaluated for an association with rapid progression by methylated DNA sequencing (MeD-seq) in serum from 10 HBDs and 34 RCC patients with a good or intermediate prognosis starting WW in the IMPACT-RCC study. Patients with an elevated RCC-specific methylation score compared to HBDs had a shorter progression-free survival (PFS, p = 0.018), but not a shorter WW-time (p = 0.15). Cox proportional hazards regression showed that only the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) criteria were significantly associated with WW time (HR 2.01, p = 0.01), whereas only our RCC-specific methylation score (HR 4.45, p = 0.02) was significantly associated with PFS. The results of this study suggest that cfDNA methylation is predictive of PFS but not WW.

INTRODUCTION: Circulating tumor cell (CTC) count and levels of circulating tumor DNA (ctDNA) have proven their individual prognostic value in metastatic breast cancer (MBC). Whereas CTCs can be quantified by enumeration, levels of ctDNA are often expressed as the variant allele frequency of the dominant mutation. The modified fast aneuploidy screening test-sequencing system (mFAST-SeqS) estimates ctDNA-load by measuring chromosomal aneuploidy instead of mutations. The mFAST-SeqS method is cheap and provides a comprehensive overview of the tumor genome without prior knowledge on genomic tumor aberrations. Previously, we showed in a small MBC cohort (n=50), heterogeneous with regard to subtype and line of treatment, that the mFAST-SeqS-derived genome-wide aneuploidy score (GWA-score) was an independent prognostic biomarker (1). Our current aim was to provide evidence for the prognostic value of GWA-score in a homogeneous cohort of estrogen receptor positive (ER+), HER2 negative (HER2-) MBC patients, starting first line treatment with an aromatase inhibitor. MATERIALS & METHODS: CTCs were enumerated using the CellSearch-system (Menarini) and screened for ctDNA fraction using mFAST-SeqS in ER+, HER2- MBC patients, starting with first line aromatase inhibitors. CTC-count was divided into high (CTChigh) and low (CTClow) using the validated cut-off of 5 CTCs/7.5 ml blood; similarly GWA-score was divided in high (GWAhigh)and low (GWAlow) based on the previously described cut-off of 5 (2). PFS and OS were estimated using Kaplan-Meier. Cox regression was used for uni- and multivariable analysis. RESULTS: One hundred and thirty-four patients were included in this analysis. Mean age was 68 (range 40-90). Median follow up was 26 months. Sixty-five samples had both scores low and 30 both high, 25 samples were CTChigh/GWAlow and 14 were CTClow/GWAhigh. PFS and OS were not significantly different between CTChigh versus CTClow groups (p=0.07 and p=0.26, median PFS 15 vs 24 months, median OS 45 vs 49 months). However, PFS and OS were significantly different between GWAhigh versus GWAlow groups (p < 0.01 for both, median PFS 11 vs 24 months, median OS 31 vs 51 months). In multivariate analysis, GWA-score was a significant prognostic factor for both PFS and OS while presence of visceral disease was also prognostic for OS (table 1). CONCLUSIONS: In patients treated with aromatase inhibitors in the first line of treatment, GWA-score was an independent prognostic marker for a worse PFS and OS and may have added value beyond CTC-count. 1. Verschoor, N., et al., Abstract P2-01-17: Circulating tumor cell count and levels of circulating tumor DNA are complementary prognostic biomarkers in metastatic breast cancer - A pilot study. Cancer Research, 2022. 82(4_Supplement): p. P2-01-17-P2-01-17. 2. Belic, J., et al., mFast-SeqS as a Monitoring and Pre-screening Tool for Tumor-Specific Aneuploidy in Plasma DNA. Adv Exp Med Biol, 2016. 924: p. 147-155. Table 1: Uni- and multivariate Cox regression for PFS and OS Citation Format: Noortje Verschoor, Jaco Kraan, Vanja de Weerd, Ngoc M Van, Agnes Jager, Stefan Sleijfer, John WM Martens, Saskia M Wilting. Tumor-agnostic measurement of ctDNA levels in first line ER+, HER2- metastatic breast cancer patients as a marker for survival [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-03-14.

Introduction: Recurrence risk after curative surgery for colorectal liver metastases (CRLM) remains high, underlining the need for novel prognostic markers. Liquid biopsies provide promising biomarkers to detect minimal residual disease (MRD) after local treatment. The aim of this study was to determine and compare the characteristics of cell-free DNA (cfDNA) and circulating tumor DNA (ctDNA) in liquid biopsies taken before and after surgical treatment of CRLM. Materials & Methods: Patients with isolated CRLM were recruited before undergoing potentially curative hepatic resection. Only patients who did not receive per-operative chemotherapy were selected. Peripheral blood samples were collected in CellSave preservative tubes at four different time points and processed into plasma within 96 hours after withdrawal. Subsequently, cfDNA was isolated from 4mL plasma, in which the total cfDNA concentration was measured. Mutations characterizing ctDNA were determined before surgery by next generation sequencing (NGS) using a colon-specific targeted panel (Oncomine Colon cfDNA assay, 14 genes). Samples were sequenced at >20.000 average reads depth and variants were called mutations when the variant allele frequency was above their predefined limit of detection. Longitudinal blood samples of ctDNA-positive patients were evaluated by digital PCR (dPCR) using mutation-specific assays, in which samples were considered ctDNA positive when >5 mutant copies were detected. Results: Blood samples of 231 patients were collected one day before surgery (T0), and were repeated one day (T1), one week (T2), and three weeks (T3) after surgery. The cfDNA yields per mL plasma were higher at T1 and T2 (median 93 ng and 64 ng, respectively) compared to T0 (6 ng, p Discussion/Conclusion: ctDNA is a potential biomarker to detect MRD after curative treatment for CRLM. Our results demonstrate that out of all patients with detectable ctDNA at baseline (before surgery), ctDNA is still present in 36% of patients three weeks after resection. Citation Format: Lissa Wullaert, Maurice P. Jansen, Jaco Kraan, Jan M. van Rees, Corine M. Beaufort, Yannick M. Meyer, Boris Galjart, Pieter M. Nierop, Florian E. Buisman, Diederik J. Höppener, Erik P. van der Stok, Gianmarco Motta, Dirk J. Grünhagen, Henk M. Verheul, Stefan Sleijfer, Saskia M. Wilting, Cornelis Verhoef, John W. Martens. Circulating tumor DNA in colorectal cancer patients with resectable liver metastases: Preliminary results of the MIRACLE study. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5715.

ESR1 methylation was proposed as mechanism for endocrine resistance in metastatic breast cancer patients. To evaluate its potential as a minimally invasive biomarker, we investigated the feasibility of measuring ESR1 methylation in cell-free DNA (cfDNA) and its association with endocrine resistance. First, we provided evidence that demethylation in vitro restores ER expression. Subsequently, we found that ESR1 methylation in cfDNA was not enriched in endocrine-resistant versus endocrine-sensitive patients. Interestingly, we found a correlation between ESR1 methylation and age. Publicly available data confirm an age-related increase in ESR1 methylation in leukocytes, confounding the determination of the ESR1 methylation status of tumors using cfDNA.

The progression of anchorage-dependent epithelial cells to anchorage-independent growth represents a critical hallmark of malignant transformation. Using an in vitro model of human papillomavirus (HPV)-induced transformation, we previously showed that acquisition of anchorage-independent growth is associated with marked (epi)genetic changes, including altered expression of microRNAs. However, the laborious nature of the conventional growth method in soft agar to measure this phenotype hampers a high-throughput analysis. We developed alternative functional screening methods using 96- and 384-well ultra-low attachment plates to systematically investigate microRNAs regulating anchorage-independent growth. SiHa cervical cancer cells were transfected with a microRNA mimic library (n = 2019) and evaluated for cell viability. We identified 84 microRNAs that consistently suppressed growth in three independent experiments. Further validation in three cell lines and comparison of growth in adherent and ultra-low attachment plates yielded 40 microRNAs that specifically reduced anchorage-independent growth. In conclusion, ultra-low attachment plates are a promising alternative for soft-agar assays to study anchorage-independent growth and are suitable for high-throughput functional screening. Anchorage independence suppressing microRNAs identified through our screen were successfully validated in three cell lines. These microRNAs may provide specific biomarkers for detecting and treating HPV-induced precancerous lesions progressing to invasive cancer, the most critical stage during cervical cancer development.

Among the structural variants observed in metastatic colorectal cancer (mCRC), deletions (DELs) show a size preference of ~10 kb–1 Mb and are often found in common fragile sites (CFSs). To gain more insight into the biology behind the occurrence of these specific DELs in mCRC, and their possible association with outcome, we here studied them in detail in metastatic lesions of 429 CRC patients using available whole-genome sequencing and corresponding RNA-seq data. Breakpoints of DELs within CFSs are significantly more often located between two consecutive replication origins compared to DELs outside CFSs. DELs are more frequently located at the midpoint of genes inside CFSs with duplications (DUPs) at the flanks of the genes. The median expression of genes inside CFSs was significantly higher than those of similarly-sized genes outside CFSs. Patients with high numbers of these specific DELs showed a shorter progression-free survival time on platinum-containing therapy. Taken together, we propose that the observed DEL/DUP patterns in expressed genes located in CFSs are consistent with a model of transcription-dependent double-fork failure, and, importantly, that the ability to overcome the resulting stalled replication forks decreases sensitivity to platinum-containing treatment, known to induce stalled replication forks as well. Therefore, we propose that our DEL score can be used as predictive biomarker for decreased sensitivity to platinum-containing treatment, which, upon validation, may augment future therapeutic choices.

Cellular senescence is a state of stable growth arrest and a desired outcome of tumor suppressive interventions. Treatment with many anti-cancer drugs can cause premature senescence of non-malignant cells. These therapy-induced senescent cells can have pro-tumorigenic and pro-disease functions via activation of an inflammatory secretory phenotype (SASP). Inhibitors of cyclin-dependent kinases 4/6 (CDK4/6i) have recently proven to restrain tumor growth by activating a senescence-like program in cancer cells. However, the physiological consequence of exposing the whole organism to pharmacological CDK4/6i remains poorly characterized. Here, we show that exposure to CDK4/6i induces non-malignant cells to enter a premature state of senescence dependent on p53. We observe in mice and breast cancer patients that the CDK4/6i-induced senescent program activates only a partial SASP enriched in p53 targets but lacking pro-inflammatory and NF-κB-driven components. We find that CDK4/6i-induced senescent cells do not acquire pro-tumorigenic and detrimental properties but retain the ability to promote paracrine senescence and undergo clearance. Our results demonstrate that SASP composition is exquisitely stress-dependent and a predictor for the biological functions of different senescence subsets.

Background DNA methylation detection in liquid biopsies provides a highly promising and much needed means for real-time monitoring of disease load in advanced cancer patient care. Compared to the often-used somatic mutations, tissue- and cancer-type specific epigenetic marks affect a larger part of the cancer genome and generally have a high penetrance throughout the tumour. Here, we describe the successful application of the recently described MeD-seq assay for genome-wide DNA methylation profiling on cell-free DNA (cfDNA). The compatibility of the MeD-seq assay with different types of blood collection tubes, cfDNA input amounts, cfDNA isolation methods, and vacuum concentration of samples was evaluated using plasma from both metastatic cancer patients and healthy blood donors (HBDs). To investigate the potential value of cfDNA methylation profiling for tumour load monitoring, we profiled paired samples from 8 patients with resectable colorectal liver metastases (CRLM) before and after surgery. Results The MeD-seq assay worked on plasma-derived cfDNA from both EDTA and CellSave blood collection tubes when at least 10 ng of cfDNA was used. From the 3 evaluated cfDNA isolation methods, both the manual QIAamp Circulating Nucleic Acid Kit (Qiagen) and the semi-automated Maxwell® RSC ccfDNA Plasma Kit (Promega) were compatible with MeD-seq analysis, whereas the QiaSymphony DSP Circulating DNA Kit (Qiagen) yielded significantly fewer reads when compared to the QIAamp kit (p Conclusions The MeD-seq assay provides a promising new method for cfDNA methylation profiling. Potential future applications of the assay include marker discovery specifically for liquid biopsy analysis as well as direct use as a disease load monitoring tool in advanced cancer patients.

Background: In depth sequencing of primary breast cancer (BC) has identified a heterogeneous repertoire of disease drivers, evidence of clonal evolution and underlying mutational processes. As cancer evolves over time and under treatment pressure, whole genome sequencing (WGS) of metastatic BC (MBC) tissue is crucial to gain further insight into its genetic make-up and driving forces, thereby allowing improved patient management. Methods: Metastatic tissue and matched germline DNA of patients with MBC (N=501) were prospectively recruited under the biopsy protocol of the Center of Personalized Cancer Treatment (CPCT-02; NCT01855477) and analyzed by WGS. Sequence reads were mapped to the reference genome to call somatic single nucleotide variants (SNV), small insertions and deletions (InDels) and copy number variations from which mutational signatures and tumor mutational burden (TMB; the number of SNV and InDels relative to the genome) were derived. The incidence of called aberrations in our cohort was compared to previously reported WGS data of 560 primary BC (BASIS cohort, Nik-Zainal et al. Nature 2016) (Table 1). Results: According to routine diagnostics 303 patients (60.5%) were ER+/HER2-, 70 (14%) triple negative (TNBC), 95 (19%) HER2+ and the remaining 33 (6.6%) had as of yet an unknown subtype. Top 5 recurrently affected genes were TP53 (47%), ATM (33%), MAP2K4 (32%), NCOR1 (31%), ERBB2 (30%). In the metastatic lesions, median TMB was 2.9 per million base pairs (IQR: 1.7-5.3). Interestingly, 53 (11%) patients had a high TMB (≥10). Compared to primary BC (BASIS cohort), we found (subtype-specific) enrichment of alterations in multiple genes such as ATM (0.4% to 33%), GPS2 (1.3% to 29%), MAP2K4 (6.4% to 32%), CBFB (2.7% to 25%), and, as previously reported, ESR1 (1.3% to 20%). APOBEC signature mutations appeared to be enriched in MBC while HRD signature mutations seemed less prevalent. Analyses to reveal additional genomic features is ongoing as well as the association of genomic alterations with uniquely collected information on prior treatments and response to treatment received directly after biopsy (i.e. endocrine therapy alone or combined with CDK4/6 inhibitors and chemotherapy). Also, to exclude methodological bias the raw data of the BASIS cohort will be processed through our pipeline. Table 1:Comparison of ER+/HER2- and TNBC subtypes: BASIS versus CPCT-02 MBC BASISCPCT-02 MBC ER+/HER2-(%)TNBC(%)ER+/HER2-(%)TNBC(%)Number of samples32615530370Median TMB0.962.632.732.91SNV burden/Mbp0.892.52.412.64InDel burden/Mbp0.060.120.210.3Top 5 affected genesPIK3CA (37)TP53 (83)TP53 (43)TP53 (61) TP53 (20)PTEN (37)ATM (43)MYC (37) CCND1 (20)MYC (26)MAP2K4 (37)CDKN2A (33) GATA3 (15)RB1 (24)NCOR1 (35)CDKN2B (33) MYC (14)PIK3CA (17)CDH1 (34)RB1 (33)Mutational signatures (median relative contribution) Age23.27.213.711.8APOBEC6.97.814.68.3Homologous-recombinant deficiency4.439.94.919.8DNA mismatch Repair Deficiency0.600.30 Conclusion: WGS of this unique cohort of patients with MBC shows a genetic make-up roughly similar to primary BC, but does show subtype-specific enrichment of selected driver mutations in metastatic disease. This study provides better insight into the tumor biology of MBC potentially improving management of these patients. Citation Format: Angus L, Wilting SM, van Riet J, Smid M, Steenbruggen TG, Tjan-Heijnen VC, Labots M, van Riel JM, Bloemendal HJ, Steeghs N, van de Werken HJ, Lolkema MP, Voest EE, Jager A, Cuppen E, Sleijfer S, Martens JW. The genomic landscape of 501 metastatic breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS1-07.

Publisher's version (útgefin grein), Circular RNAs (circRNAs) are a class of RNAs that is under increasing scrutiny, although their functional roles are debated. We analyzed RNA-seq data of 348 primary breast cancers and developed a method to identify circRNAs that does not rely on unmapped reads or known splice junctions. We identified 95,843 circRNAs, of which 20,441 were found recurrently. Of the circRNAs that match exon boundaries of the same gene, 668 showed a poor or even negative (R < 0.2) correlation with the expression level of the linear gene. In silico analysis showed only a minority (8.5%) of circRNAs could be explained by known splicing events. Both these observations suggest that specific regulatory processes for circRNAs exist. We confirmed the presence of circRNAs of CNOT2, CREBBP, and RERE in an independent pool of primary breast cancers. We identified circRNA profiles associated with subgroups of breast cancers and with biological and clinical features, such as amount of tumor lymphocytic infiltrate and proliferation index. siRNA-mediated knockdown of circCNOT2 was shown to significantly reduce viability of the breast cancer cell lines MCF-7 and BT-474, further underlining the biological relevance of circRNAs. Furthermore, we found that circular, and not linear, CNOT2 levels are predictive for progression-free survival time to aromatase inhibitor (AI) therapy in advanced breast cancer patients, and found that circCNOT2 is detectable in cell-free RNA from plasma. We showed that circRNAs are abundantly present, show characteristics of being specifically regulated, are associated with clinical and biological properties, and thus are relevant in breast cancer., We thank the Erasmus MC Cancer Computational Biology Center for giving access to their IT infrastructure and the software that was used for the computations and data analysis in this study. We thank Sandra Albassam for her help with the first versions of the script to identify circular regions. We thank Maurice P.H.M. Jansen, Jean C. Helmijr, Inge de Kruijff, and Manouk K. Bos for their help in evaluating plasma samples that were gathered in the EU-FP7 CareMore (nr 601760) project. We thank for technical support Miriam Ragle Aure and Anita Langerød of the Oslo University Hospital, Norway; Ewan Birney of the European Bioinformatics Institute, UK; and Stefania Tommasi of the IRCCS Istituto Tumori “Giovanni Paolo II,” Bari, Italy. We thank the Oslo Breast Cancer Research Consortium (OSBREAC), Norway (https://www.ous-research.no/home/kgjebsen/home/14105) for contributing patient samples and Sabine Linn and Marleen Kok of The Netherlands Cancer Institute for contributing samples for the AI cohort. Finally, we thank all members of the ICGC Breast Cancer Working Group. This work has been funded through the ICGC Breast Cancer Working group by the Breast Cancer Somatic Genetics Study (a European research project funded by the European Community’s Seventh Framework Programme (FP7/2010-2014) under the grant agreement number 242006) and the Triple Negative project funded by the Wellcome Trust (grant reference 077012/Z/05/Z). F.G.R.-G. and S.M. were funded by BASIS. J.A.F. was funded through an ERC Advanced Grant (ERC-2012-AdG-322737) and ERC Proof-of-Concept Grant (ERC-2017-PoC-767854). K.U. was funded by the Daniel den Hoed Foundation. S.N.-Z. is a Wellcome Beit Fellow and personally funded by a Wellcome Trust Intermediate Fellowship (WT100183MA). A.L.R. is partially supported by the Dana-Farber/Harvard Cancer Center SPORE in Breast Cancer (NIH/NCI 5 P50 CA16 8504-02). A.M.S. was supported by Cancer Genomics Netherlands (CGC.nl) through a grant from the Netherlands Organization of Scientific research (NWO). M. Smid was supported by the EU-FP7-DDR response project. C.D. was supported by a grant from the Breast Cancer Research Foundation. J.E. was funded by The Icelandic Centre for Research (RANNIS).

The emerging interest in circulating tumor DNA (ctDNA) analyses for clinical trials has necessitated the development of a high-throughput method for fast, reproducible, and efficient isolation of ctDNA. Currently, the majority of ctDNA studies use the manual QIAamp (QA) platform to isolate DNA from blood. The purpose of this study was to compare two competing automated DNA isolation platforms [Maxwell (MX) and QIAsymphony (QS)] to the current ‘gold standard’ QA to facilitate high-throughput processing of samples in prospective trials. We obtained blood samples from healthy blood donors and metastatic cancer patients for plasma isolation. Total cell-free DNA (cfDNA) quantity was assessed by TERT quantitative PCR. Recovery efficiency was investigated by quantitative PCR analysis of spiked-in synthetic plant DNA. In addition, a b-actin fragmentation assay was performed to determine the amount of contamination by genomic DNA from lysed leukocytes. ctDNA quality was assessed by digital PCR for somatic variant detection. cfDNA quantity and recovery efficiency were lowest using the MX platform, whereas QA and QS showed a comparable performance. All platforms preferentially isolated small (136 bp) DNA fragments over large (420 and 2000 bp) DNA fragments. Detection of the number variant and wild-type molecules was most comparable between QA and QS. However, there was no significant difference in variant allele frequency comparing QS and MX to QA. In summary, we show that the QS platform has comparable performance to QA, the ‘gold standard’, and outperformed the MX platform depending on the readout used. We conclude that the QS can replace the more laborious QA platform, especially when high-throughput cfDNA isolation is needed.

Purpose: Detection of leptomeningeal metastasis is hampered by limited sensitivities of currently used techniques: MRI and cytology of cerebrospinal fluid (CSF). Detection of cell-free tumor DNA in CSF has been proposed as a tumor-specific candidate to detect leptomeningeal metastasis at an earlier stage. The aim of this study was to investigate mutation and aneuploidy status in CSF-derived cell-free DNA (cfDNA) of patients with breast cancer with a clinical suspicion of leptomeningeal metastasis. Experimental Design: cfDNA was isolated from stored remnant CSF and analyzed by targeted next-generation sequencing (NGS; n = 30) and the modified fast aneuploidy screening test-sequencing system (mFAST-SeqS; n = 121). The latter method employs selective amplification of long interspaced nuclear elements sequences that are present throughout the genome and allow for fast and cheap detection of aneuploidy. We compared these results with the gold standard to diagnose leptomeningeal metastasis: cytology. Results: Leptomeningeal metastasis was cytology proven in 13 of 121 patients. Low DNA yields resulted in insufficient molecular coverage of NGS for the majority of samples (success rate, 8/30). The mFAST-SeqS method, successful in 112 of 121 (93%) samples, detected genome-wide aneuploidy in 24 patients. Ten of these patients had cytology-proven leptomeningeal metastasis; 8 additional patients were either concurrently diagnosed with central nervous system metastases by radiological means or developed these soon after the lumbar puncture. The remaining six cases were suspected of leptomeningeal metastasis, but could not be confirmed by cytology or imaging. Aneuploidy was associated with development of leptomeningeal metastasis and significantly worse overall survival. Conclusions: Aneuploidy in CSF-derived cfDNA may provide a promising biomarker to improve timely detection of leptomeningeal metastasis.

Simple Summary Currently, the most commonly used method to monitor response to treatment in metastatic breast cancer patients is by radiological imaging. However, these imaging techniques are relatively insensitive and give little to no insight into biological tumor characteristics that might be relevant for the choice of treatment. Circulating tumor DNA (ctDNA), released by tumor cells into the blood of cancer patients, can be used to overcome these shortcomings. Besides the fact that specific alterations are known to predict response to treatment and development of resistance, the total amount of ctDNA is believed to reflect the proliferation rate of the tumor, suggesting ctDNA levels can be used as a general tool to evaluate treatment response. Different methods are available to measure ctDNA primarily based on detection of cancer-specific somatic mutations, DNA methylation, and copy number variations. In this review we have critically analyzed recently published studies using blood-derived ctDNA of metastatic breast cancer patients on multiple time points to monitor disease response in respect to analytical validity and clinical utility. Abstract Monitoring treatment response in metastatic breast cancer currently consists mainly of radiological and clinical assessments. These methods have high inter-observer variation, suboptimal sensitivity to determine response to treatment and give little insight into the biological characteristics of the tumor. Assessing circulating tumor DNA (ctDNA) over time could be employed to address these limitations. Several ways to quantify and characterize ctDNA exist, based on somatic mutations, copy number variations, methylation, and global circulating cell-free DNA (cfDNA) fragment sizes and concentrations. These methods are being explored and technically validated, but to date none of these methods are applied clinically. We systematically reviewed the literature on the use of quantitative ctDNA measurements over time to monitor response to systemic therapy in patients with metastatic breast cancer. Cochrane, Embase, PubMed and Google Scholar databases were searched to find studies focusing on the use of cfDNA to longitudinally monitor treatment response in advanced breast cancer patients until October 2020. This resulted in a total of 33 studies which met the inclusion criteria. These studies were heterogeneous in (pre-)processing procedures, applied techniques and design. An association between ctDNA and treatment response was found in most of the included studies, independent of the applied assay. To implement ctDNA-based response monitoring into daily clinical practice for metastatic breast cancer patients, sample (pre-) processing procedures need to be standardized and large prospectively collected sample cohorts with well annotated clinical follow-up are required to establish its clinical validity.

In contrast to primary colorectal cancer (CRC) little is known about the genomic landscape of metastasized CRC. Here we present whole genome sequencing data of metastases of 429 CRC patients participating in the pan-cancer CPCT-02 study (NCT01855477). Unsupervised clustering using mutational signature patterns highlights three major patient groups characterized by signatures known from primary CRC, signatures associated with received prior treatments, and metastasis-specific signatures. Compared to primary CRC, we identify additional putative (non-coding) driver genes and increased frequencies in driver gene mutations. In addition, we identify specific genes preferentially affected by microsatellite instability. CRC-specific 1kb-10Mb deletions, enriched for common fragile sites, and LINC00672 mutations are associated with response to treatment in general, whereas FBXW7 mutations predict poor response specifically to EGFR-targeted treatment. In conclusion, the genomic landscape of mCRC shows defined changes compared to primary CRC, is affected by prior treatments and contains features with potential clinical relevance., Molecular landscapes of metastatic colorectal cancers (mCRC) have often been restricted to coding regions or low numbers of patients. Here the authors present a whole-genome landscape of 429 mCRC patients, revealing the mutational impact of prior therapies and potential actionable targets.