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Approximately 25% of the patients with muscle-invasive bladder cancer (MIBC) who are clinically node negative have occult lymph node metastases at radical cystectomy (RC) and pelvic lymph node dissection. The aim of this study was to evaluate preoperative CT-based radiomics to differentiate between pN+ and pN0 disease in patients with clinical stage cT2-T4aN0-N1M0 MIBC. Patients with cT2-T4aN0-N1M0 MIBC, of whom preoperative CT scans and pathology reports were available, were included from the prospective, multicenter CirGuidance trial. After manual segmentation of the lymph nodes, 564 radiomics features were extracted. A combination of different machine-learning methods was used to develop various decision models to differentiate between patients with pN+ and pN0 disease. A total of 209 patients (159 pN0; 50 pN+) were included, with a total of 3153 segmented lymph nodes. None of the individual radiomics features showed significant differences between pN+ and pN0 disease, and none of the radiomics models performed substantially better than random guessing. Hence, CT-based radiomics does not contribute to differentiation between pN+ and pN0 disease in patients with cT2-T4aN0-N1M0 MIBC.

Circulating tumor cells (CTCs) and cell-free DNA (cfDNA) together with newer emerging liquid biopsies have a unique potential to deal with key issues in oncology. For example, they can be used to assess prognosis, direct treatment with certain kinds of drug, or provide information about response to treatment. However, despite an overflow of literature on the subject, clinical implementation of these liquid biopsies has been scarce. This is mainly because there is a lack of preanalytical standardization, multiple different techniques or platforms are being used, and a lack of prospective studies investigating a meaningful clinical question are performed. Here, we provide an overview of the current state of liquid biopsies and make suggestions for how liquid biopsies can reach the tipping point.

Background Extracellular vesicles (EVs) are actively secreted by cells into body fluids and contain nucleic acids of the cells they originate from. The goal of this study was to detect circulating tumor-derived EVs (ctEVs) by mutant mRNA transcripts (EV-RNA) in plasma of patients with solid cancers and compare the occurrence of ctEVs with circulating tumor DNA (ctDNA) in cell-free DNA (cfDNA). Methods For this purpose, blood from 20 patients and 15 healthy blood donors (HBDs) was collected in different preservation tubes (EDTA, BCT, CellSave) and processed into plasma within 24 h from venipuncture. EVs were isolated with the ExoEasy protocol from this plasma and from conditioned medium of 6 cancer cell lines and characterized according to MISEV2018-guidelines. RNA from EVs was isolated with the ExoRNeasy protocol and evaluated for transcript expression levels of 96 genes by RT-qPCR and genotyped by digital PCR. Results Our workflow applied on cell lines revealed a high concordance between cellular mRNA and EV-RNA in expression levels as well as variant allele frequencies for PIK3CA, KRAS and BRAF. Plasma CD9-positive EV and GAPDH EV-RNA levels were significantly different between the preservation tubes. The workflow detected only ctEVs with mutant transcripts in plasma of patients with high amounts (> 20%) of circulating tumor DNA (ctDNA). Expression profiling showed that the EVs from patients resemble healthy donors more than tumor cell lines supporting that most EVs are derived from healthy tissue. Conclusions We provide a workflow for ctEV detection by spin column-based generic isolation of EVs and PCR-based measurement of gene expression and mutant transcripts in EV-RNA derived from cancer patients’ blood plasma. This workflow, however, detected tumor-specific mutations in blood less often in EV-RNA than in cfDNA.

BACKGROUND The outcome to treatment administered to patients with metastatic castration-resistant prostate cancer (mCRPC) greatly differs between individuals, underlining the need for biomarkers guiding treatment decision making. OBJECTIVE To investigate the prognostic value of circulating tumor cell (CTC) enumeration and dynamics, in the context of second-line endocrine therapies (ie, abiraterone acetate or enzalutamide), irrespective of prior systemic therapies. DESIGN, SETTINGS, AND PARTICIPANTS In a prospective, multicentre study blood samples for CTC enumeration were collected from patients with mCRPC at baseline (n = 174). In patients who responded for minimally 10-12 weeks a follow-up sample was collected. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS For baseline analysis, patients were stratified in

Mutations and splice variants in the estrogen receptor (ER) gene, ESR1, may yield endocrine resistance in metastatic breast cancer (MBC) patients. These putative endocrine resistance markers are likely to emerge during treatment, and therefore, its detection in liquid biopsies, such as circulating tumor cells (CTCs) and cell-free DNA (cfDNA), is of great interest. This research aimed to determine whether ESR1 mutations and splice variants occur more frequently in CTCs of MBC patients progressing on endocrine treatment. In addition, the presence of ESR1 mutations was evaluated in matched cfDNA and compared to CTCs. CellSearch-enriched CTC fractions (≥5/7.5 mL) of two MBC cohorts were evaluated, namely (a) patients starting first-line endocrine therapy (n = 43, baseline cohort) and (b) patients progressing on any line of endocrine therapy (n = 40, progressing cohort). ESR1 hotspot mutations (D538G and Y537S/N/C) were evaluated in CTC-enriched DNA using digital PCR and compared with matched cfDNA (n = 18 baseline cohort; n = 26 progressing cohort). Expression of ESR1 full-length and 4 of its splice variants ((increment)5, (increment)7, 36 kDa, and 46 kDa) was evaluated in CTC-enriched mRNA. It was observed that in the CTCs, the ESR1 mutations were not enriched in the progressing cohort (8%), when compared with the baseline cohort (5%) (P = 0.66). In the cfDNA, however, ESR1 mutations were more prevalent in the progressing cohort (42%) than in the baseline cohort (11%) (P = 0.04). Three of the same mutations were observed in both CTCs and cfDNA, 1 mutation in CTCs only, and 11 in cfDNA only. Only the (increment)5 ESR1 splice variant was CTC-specific expressed, but was not enriched in the progressing cohort. In conclusion, sensitivity for detecting ESR1 mutations in CTC-enriched fractions was lower than for cfDNA. ESR1 mutations detected in cfDNA, rarely present at the start of first-line endocrine therapy, were enriched at progression, strongly suggesting a role in conferring endocrine resistance in MBC.

4523 Background: International guidelines for the treatment of non-metastatic muscle-invasive bladder cancer (MIBC) recommend neoadjuvant chemotherapy (NAC), which, however, is underutilized in practice. We hypothesized that the absence of circulating tumour cells (CTCs), an established prognostic marker in MIBC, may identify patients with such a favourable prognosis that NAC may be withheld. Methods: The CirGuidance study included adults with clinical stage T2-T4aN0-N1M0 muscle-invasive urothelial carcinoma of the bladder who were fit to undergo radical cystectomy. CTCs were enumerated using the CellSearch system. CTC-negative patients (no CTCs detectable) underwent radical surgery without NAC; CTC-positive patients (≥1 detectable CTCs) were advised to receive NAC followed by radical surgery, but NAC could be withheld at the discretion of the treating physician. The primary endpoint was the two-year overall survival (OS) in the CTC-negative group, analysed in the intention-to-treat population. The prespecified criterion for trial success was a two-year OS of minimally 75% (95% confidence interval (CI) ±5%) in the CTC-negative group. Results: Of 315 patients screened for eligibility, 273 were enrolled in the study. The median age was 69 years; the median follow-up was 36 months. The two-year OS in the CTC-negative group was 69.5% (n = 203; 95% CI 62.6%-75.5%); in the CTC-positive group it was 58.2% (n = 70; 95% CI 45.5%-68.9%). CTC-positive patients had a higher rate of cancer-related mortality (hazard ratio (HR) 1.61, 95% CI 1.05-2.45, p = 0.03) and disease relapse (HR 1.87, 95% CI 1.28-2.73, p = 0.001) than CTC-negative patients. Explorative analyses suggested that CTC-positive patients who had received NAC (n = 22) survived longer than CTC-positive patients who had not (n = 48), with a two-year OS of 74.8% (95%CI 49.5%-88.8%) versus 52.0% (95% CI 37.2%-65.0%), respectively. Conclusions: The two-year OS in the CTC-negative group did not meet the prespecified criterion for trial success. However, given the trial population’s advanced age and high rate of non-cancer related mortality, the benefit of NAC is likely to be limited in CTC-negative MIBC patients. CTC enumeration at the moment of diagnosis could aid in the decision to prescribe neoadjuvant chemotherapy for a muscle-invasive bladder cancer patient as a criterion in addition to clinical characteristics. Clinical trial information: NL3954.

Purpose There is a lack of robust and clinically utilizable markers for the diagnosis and prognostication of malignant pleural mesothelioma (MPM). This research was aimed at optimizing and exploring novel approaches to improve the diagnosis and prognostication of MPM in pleural effusions and peripheral blood samples. Methods CellSearch-based and flow cytometry-based assays using melanoma cell adhesion molecule (MCAM) to identify circulating tumor cells (CTCs) in pleural effusions and peripheral blood samples of MPM patients were optimized, validated, explored clinically and, in case of pleural effusions, compared with cytological analyses. Additionally, tumor-associated circulating endothelial cells (CECs) were measured in peripheral blood samples. The assays were performed on a MPM cohort encompassing patients with histology-confirmed MPM (n=27) and in a control cohort of patients with alternative diagnoses (n=22). Exploratory analyses on the prognostic value of all assays were also performed. Results The malignancy of MCAM-positive cells in pleural effusions from MPM patients was confirmed. The detection of MPM CTCs in pleural effusions by CellSearch showed a poor specificity. The detection of MPM CTCs in pleural effusions by flow cytometry showed a superior sensitivity (48%) to standard cytological analysis (15%) (p = 0.03). In peripheral blood, CTCs were detected in 26% of the MPN patients, whereas in 42% of the MPM patients tumor-associated CECs were detected above the upper limit of normal (ULN). In exploratory analyses the absence of CTCs in pleural effusions, and tumor-associated CECs in peripheral blood samples above the ULN, appeared to be associated with a worse overall survival. Conclusion MCAM-based flow cytometric analysis of pleural effusions is more sensitive than routine cytological analysis. Flow cytometric analysis of pleural effusions and tumor-associated CECs in peripheral blood may serve as a promising approach for the prognostication of MPM patients and, therefore, warrants further study. Electronic supplementary material The online version of this article (doi:10.1007/s13402-017-0327-7) contains supplementary material, which is available to authorized users.

Background In metastatic breast cancer (MBC) patients ESR1 mutations (mESR1) in cell-free DNA (cfDNA) have been related to endocrine therapy (ET) resistance. Such mutations might also be detectable in circulating tumor cells (CTCs). Mutation detection in small amounts of cfDNA and in CTCs in a background of leukocytes is highly challenging. The current study evaluated how to reliably investigate mESR1 status in such minute amounts of cfDNA and in DNA from CellSearch-enriched CTCs. Materials & Methods Plasma (200 µL) and matched CellSearch-enriched CTC fractions of 7 healthy blood donors (HBD) and 29 MBC patients at baseline and after ET (≥ 5 CTC/7.5 mL) were evaluated. cfDNA was isolated from plasma with the QIAamp CNA kit and CTC-enriched DNA with the AllPrep kit (Qiagen). mESR1 status in both cfDNA and CTC-enriched DNA fractions was compared with or without whole genome amplification (repli-g WGA, Qiagen) or ESR1 target specific amplification. Quantitative PCR (qPCR) for wild type (WT) ESR1 was used to control the number of WT copies loaded into the chips for digital PCR (dPCR) analysis. The variant allele frequencies (VAF) of hotspot mutations for ESR1 (D538G, Y537S, Y537C and Y537N) were evaluated with mutation-specific Taqman assays by chip-based dPCR (QuantStudio 3D, Thermo Fischer Scientific). Results To allow inclusion of as many samples as possible, we successfully downscaled the volume of required plasma from 1 mL to 200 µL as this resulted in the same VAF. Sample-type specific thresholds for mESR1 presence were established (2% for the cell-free plasma samples, at which percentage all HBDs were negative, and 0.5% for the CTCs to allow identification of one mutated CTC-specific copy in a background of ~1,000 leukocytes). WGA was unable to adequately amplify fragmented cfDNA, resulting in a too low DNA yield. However, locus-specific target pre-amplification of a 136 bp fragment covering all 4 different mutations followed by mutant specific dPCR performed well for both cfDNA and CTC DNA, but only if the loading of the pre-amplified product into the dPCR chips was optimized by qPCR for the number of WT ESR1 copies. The most optimal results for dPCR data interpretation were obtained after: 1. including at least one positive sample in each dPCR session; 2. using a “safe loading window”, 3. loading and reading chips at least twice in QuantStudio 3D ; 4. critically evaluating the contribution by a non-specific “comet effect”; and 5. after loading the data in the software, performing at least two independent data analyses to exclude intra-observer variations. Summary Here we describe our workflow to assess mESR1 in a limited amount of plasma cfDNA or CellSearch enriched CTC DNA. This workflow has been successfully used to investigate the mESR1 VAF status in DNA from matched CTC DNA and cfDNA of MBC patients before start of 1st line endocrine therapy and at progression (see also abstract number 851017). Citation Format: Vitale SR, Sieuwerts AM, Helmijr J, Beije N, van der Vlugt – Daane M, Foekens JA, Sleijfer S, Jansen MPHM, Martens JWM. An optimized workflow to analyze ESR1 mutations in both circulating cell-free and circulating tumor cell DNA by digital PCR [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-09-20.

Circulating tumor DNA (ctDNA) has emerged as a potential new biomarker with diagnostic, predictive, and prognostic applications for various solid tumor types. Before beginning large prospective clinical trials to prove the added value of utilizing ctDNA in clinical practice, it is essential to investigate the effects of various preanalytical conditions on the quality of cell-free DNA (cfDNA) in general and of ctDNA in particular in order to optimize and standardize these conditions. Whole blood samples were collected from patients with metastatic cancer bearing a known somatic variant. The following preanalytical conditions were investigated: (a) different time intervals to plasma isolation (1, 24, and 96 h) and (b) different preservatives in blood collection tubes (EDTA, CellSave, and BCT). The quality of cfDNA/ctDNA was assessed by DNA quantification, digital polymerase chain reaction (dPCR) for somatic variant detection and a β-actin fragmentation assay for DNA contamination from lysed leukocytes. In 11 (69%) of our 16 patients, we were able to detect the known somatic variant in ctDNA. We observed a time-dependent increase in cfDNA concentrations in EDTA tubes, which was positively correlated with an increase in wild-type copy numbers and large DNA fragments (> 420 bp). Using different preservatives did not affect somatic variant detection ability, but did stabilize cfDNA concentrations over time. Variant allele frequency was affected by fluctuations in cfDNA concentration only in EDTA tubes at 96 h. Both CellSave and BCT tubes ensured optimal ctDNA quality in plasma processed within 96 h after blood collection for downstream somatic variant detection by dPCR.

Purpose: To infer the prognostic value of simultaneous androgen receptor (AR) and TP53 profiling in liquid biopsies from patients with metastatic castration-resistant prostate cancer (mCRPC) starting a new line of AR signaling inhibitors (ARSi). Experimental Design: Between March 2014 and April 2017, we recruited patients with mCRPC (n = 168) prior to ARSi in a cohort study encompassing 10 European centers. Blood samples were collected for comprehensive profiling of CellSearch-enriched circulating tumor cells (CTC) and circulating tumor DNA (ctDNA). Targeted CTC RNA sequencing (RNA-seq) allowed the detection of eight AR splice variants (ARV). Low-pass whole-genome and targeted gene-body sequencing of AR and TP53 was applied to identify amplifications, loss of heterozygosity, mutations, and structural rearrangements in ctDNA. Clinical or radiologic progression-free survival (PFS) was estimated by Kaplan–Meier analysis, and independent associations were determined using multivariable Cox regression models. Results: Overall, no single AR perturbation remained associated with adverse prognosis after multivariable analysis. Instead, tumor burden estimates (CTC counts, ctDNA fraction, and visceral metastases) were significantly associated with PFS. TP53 inactivation harbored independent prognostic value [HR 1.88; 95% confidence interval (CI), 1.18–3.00; P = 0.008], and outperformed ARV expression and detection of genomic AR alterations. Using Cox coefficient analysis of clinical parameters and TP53 status, we identified three prognostic groups with differing PFS estimates (median, 14.7 vs. 7.51 vs. 2.62 months; P < 0.0001), which was validated in an independent mCRPC cohort (n = 202) starting first-line ARSi (median, 14.3 vs. 6.39 vs. 2.23 months; P < 0.0001). Conclusions: In an all-comer cohort, tumor burden estimates and TP53 outperform any AR perturbation to infer prognosis. See related commentary by Rebello et al., p. 1699

Assessing circulating tumor DNA (ctDNA) is a promising method to evaluate somatic mutations from solid tumors in a minimally‐invasive way. In a group of twelve metastatic colorectal cancer (mCRC) patients undergoing liver metastasectomy, from each patient DNA from cell‐free DNA (cfDNA), the primary tumor, metastatic liver tissue, normal tumor‐adjacent colon or liver tissue, and whole blood were obtained. Investigated was the feasibility of a targeted NGS approach to identify somatic mutations in ctDNA. This targeted NGS approach was also compared with NGS preceded by mutant allele enrichment using synchronous coefficient of drag alteration technology embodied in the OnTarget assay, and for selected mutations with digital PCR (dPCR). All tissue and cfDNA samples underwent IonPGM sequencing for a CRC‐specific 21‐gene panel, which was analyzed using a standard and a modified calling pipeline. In addition, cfDNA, whole blood and normal tissue DNA were analyzed with the OnTarget assay and with dPCR for specific mutations in cfDNA as detected in the corresponding primary and/or metastatic tumor tissue. NGS with modified calling was superior to standard calling and detected ctDNA in the cfDNA of 10 patients harboring mutations in APC, ATM, CREBBP, FBXW7, KRAS, KMT2D, PIK3CA and TP53. Using this approach, variant allele frequencies in plasma ranged predominantly from 1 to 10%, resulting in limited concordance between ctDNA and the primary tumor (39%) and the metastases (55%). Concordance between ctDNA and tissue markedly improved when ctDNA was evaluated for KRAS, PIK3CA and TP53 mutations by the OnTarget assay (80%) and digital PCR (93%). Additionally, using these techniques mutations were observed in tumor‐adjacent tissue with normal morphology in the majority of patients, which were not observed in whole blood. In conclusion, in these mCRC patients with oligometastatic disease NGS on cfDNA was feasible, but had limited sensitivity to detect all somatic mutations present in tissue. Digital PCR and mutant allele enrichment before NGS appeared to be more sensitive to detect somatic mutations.

Background: The European Pooled Analysis of CTC (EPAC) in metastatic breast cancer, based on 1,944 individual data from patients with various tumor types and clinical settings (Bidard et al, Lancet Oncol 2014), has established CTC count (CellSearch) at baseline and during therapy as a level of evidence 1 independent prognostic biomarker and demonstrated its superiority over serum blood markers. As part of the study pre-planned objectives, we sought to establish nomograms allowing accurate individual survival predictions. Methods: Using individual data from 17 centers, we built simplified multivariate prognostic models taking into account the independent prognostic clinico-pathological (CP) characteristics including CTC count, dichotomized using the 5CTC/7.5ml threshold, at baseline and at 3-5 weeks after the start of a new treatment regimen, and derived nomograms for progression-free survival (PFS) and overall survival (OS) prediction at baseline and after 3-5 weeks of treatment. We report here the internal validation of these nomograms. Discrimination of the models was assessed using the c-index estimated by a jackknife procedure and the calibration was visually assessed through 10-fold crossvalidated calibration plots at 1,2,3 years for OS and 1,2 years for PFS. Results: Multivariate models at baseline for PFS and OS were fitted on 1501 and 568 individual patient data with CTC count at baseline and CTC count at baseline and after 3-5 weeks, respectively. Models include tumor subtype, the number of previous chemotherapy lines (0/1/≥2), PS, age (50-65/>65 years), metastasis-free intervals (0/>0-3/>3 years), metastatic sites (liver and CNS) and CTC count at baseline and eventually at 3-5 weeks of treatment. The C-index increased from 0.722 to 0.755 (increase in C-index:0.033, 95% CI [0.019;0.045]) when adding baseline CTC to the CP only model for OS (n=1501). For those patients with CTC values at 3-5 weeks (n=568), there was an additional increase in the C-index when adding CTC at 3-5 weeks to a model with already CP and baseline CTC from 0.731 to 0.743 (increase in C-index 0.013, 95% CI [-0.004;0.025]). The model with CP and baseline CTC counts showed a good calibration for OS at 1,2,3 years and the model with CP, baseline CTC and CTC count at 3-5 weeks a moderately good calibration. Similar results were obtained for PFS. Conclusion: From the largest database with individual CTC data, we were able to build PFS and OS survival nomograms, with satisfactory discrimination and calibration. Our planned next step is to validate the nomogram in an additional cohort. Citation Format: Bidard F-C, Peeters D, Fehm T, Nole F, Gisbert-Criado R, Mavroudis D, Grisanti S, Generali D, Garcia-Saenz JA, Stebbing J, Caldas C, Gazzaniga P, Manso L, Zamarchi R, Fernandez de Lascoiti A, de Mattos-Arruda L, Ignatiadis M, van Laere SJ, Meier-Stiegen F, Sandri M-T, Vidal-Martinez J, Politaki E, Consoli F, Bottini A, Diaz-Rubio E, Krell J, Dawson S-J, Raimondi C, Rutten A, Janni W, Munzone E, Carañana V, Agelaki S, Almici C, Dirix L, Solomayer E, Zorzino L, Reis-Filho JS, Squifflet P, Pantel K, Beije N, Sleijfers S, Pierga J-Y, Michiels S. Circulating tumor cells count-based nomograms to predict survival of metastatic breast cancer patients: Results from the European pooled analysis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-08-08.

The detection of mutated genes in cell-free DNA (cfDNA) in plasma has emerged as an important minimally invasive way to obtain detailed information regarding tumor biology. Reliable determination of circulating tumor–derived DNA, often present at a low quantity amidst an excess of normal DNA in plasma, would be of added value for screening and monitoring of cancer patients and for hypothesis-generating studies in valuable retrospective cohorts. Our aim was to establish a workflow to simultaneously assess four hotspot estrogen receptor mutations (mESR1) in cfDNA isolated from only 200 μL of plasma by means of uniplex or multiplex pre-amplification combined with digital PCR. This workflow was then applied in metastatic breast cancer (MBC) patients receiving systemic therapies for MBC. In accordance with previous studies, estrogen receptor mutations were more frequently detected in endocrine-treated MBC patients at progressive disease [34.1% (15/44)] than before the start of endocrine therapy [3.9% (2/51); P = 0.001]. For a subset of samples, results were compared with analysis of these mutations by Oncomine-targeted next-generation sequencing, which, although requiring a higher cfDNA input, yielded concordant results. The data establish development and validation of a digital PCR workflow for the simultaneous detection of several tumor-derived mutations in minute amounts of cfDNA and show the potential of this workflow for use on archived volume-limited blood samples.

Recent reports have emphasized the clinical relevance of detecting AR-V7 in circulating tumor cells (CTCs). Our aim was to set up a validated multicenter pipeline to measure AR-V7 by quantitative RT-PCR (RT-qPCR) in RNA isolated from CellSearch-enriched CTCs to provide an AR-V7–positive or AR-V7–negative score in a clinically acceptable time range. CellSearch-enirched CTCs from patients with metastatic castration–resistant prostate cancer were characterized by RT-qPCR. After optimization, it was prospectively tested whether it was possible to report the AR-V7 status within 11 days (PRELUDE study). In the range of the RNA equivalent of 0.2 to 12 VCaP cells, the CV for AR-V7 was 9% (n = 37). The limit of detection was 0.3, and the limit of quantitation was 3 cells in the final RT-qPCR. No differences were observed between AR-V7 data generated by five technicians or in two different laboratories. For the 45 patients in PRELUDE, 13 patients were ineligible, 22 patients were AR-V7 negative, and 10 were AR-V7 positive. The median time to inform the physician of the test result was 7 days (range, 2 to 11 days). This assay can establish the AR-V7 status in CTCs from patients with metastatic castration–resistant prostate cancer. Furthermore, it was possible to provide an AR-V7 outcome within 11 days, indicating that it may be used to choose between an anti–androgen receptor or taxane-based cabazitaxel treatment.

Circulating tumor cells (CTCs) are cancer cells that are present in the blood of patients with solid cancers and are shed from existing tumor lesions into the blood stream. The enumeration of CTCs has long been considered to hold great promise in guiding treatment decision-making in breast cancer patients. However, guidelines on how to use CTC enumeration in clinical decision-making in primary breast cancer and metastatic breast cancer are lacking. Here, we set out to review the most relevant literature to date, to ultimately come to general recommendations regarding the use of CTC enumeration in primary breast cancer and metastatic breast cancer. (C) 2014 Elsevier Ltd. All rights reserved.

Background: Angiogenesis is crucial for glioblastoma growth, and anti-vascular endothelial growth factor agents are widely used in recurrent glioblastoma patients. The number of circulating endothelial cells (CECs) is a surrogate marker for endothelial damage. We assessed their kinetics and explored their prognostic value in patients with recurrent glioblastoma.Methods: In this side study of the BELOB trial, 141 patients with recurrent glioblastoma were randomised to receive single-agent bevacizumab or lomustine, or bevacizumab plus lomustine. Before treatment, after 4 weeks and after 6 weeks of treatment, CECs were enumerated.Results: The number of CECs increased during treatment with bevacizumab plus lomustine, but not during treatment in the single-agent arms. In patients treated with lomustine single agent, higher absolute CEC numbers after 4 weeks (log(10)CEC hazard ratio (HR) 0.41, 95% CI 0.18-0.91) and 6 weeks (log(10)CEC HR 0.16, 95% CI 0.05-0.56) of treatment were associated with improved overall survival (OS). Absolute CEC numbers in patients receiving bevacizumab plus lomustine or bevacizumab single agent were not associated with OS.Conclusion: CEC numbers increased during treatment with bevacizumab plus lomustine but not during treatment with either agent alone, suggesting that this combination induced the greatest vascular damage. Although the absolute number of CECs was not associated with OS in patients treated with bevacizumab either alone or in combination, they could serve as a marker in glioblastoma patients receiving lomustine single agent.

Umbilical cord blood stem cell transplantation (UCBT) is associated with retarded hematopoietic recovery and immune reconstitution and a high infection-related morbidity and mortality, especially after conditioning including anti-thymocyte globulin (ATG). However, data on immune recovery, incidence of infections, and outcome in double UCBT (dUCBT) recipients receiving an ATG-free reduced intensity conditioning (RIC) are lacking. In this study, recovery of lymphocyte subsets, thymopoiesis, and its association with severe infections and clinical outcome was assessed in a group of 55 recipients of a dUCBT ATG-free RIC regimen. T cell recovery was severely protracted in the majority of patients. However, T cell receptor excision circle TREC+ T cells were detectable in 62% of patients at 3 months post-transplantation. A total of 128 common toxicity criteria grade 3-4 infections were observed in the first year post-transplantation. Non-relapse mortality at 12 months post-transplant was 16%, of which 78% infectious mortality. One-year overall survival was 73%. Patients who failed to recover thymopoiesis at 3 months post-transplantation were at a 3.3-fold higher risk of subsequent severe grade 3-4 infections.

Mutations in the gene coding for the estrogen receptor (ER), ESR1, have been associated with acquired endocrine resistance in patients with ER-positive metastatic breast cancer (MBC). Functional studies revealed that these ESR1 mutations lead to constitutive activity of the ER, meaning that the receptor is active in absence of its ligand estrogen, conferring resistance against several endocrine agents. While recent clinical studies reported that the occurrence of ESR1 mutations is rare in primary breast cancer tumors, these mutations are more frequently observed in metastatic tissue and circulating cell-free DNA of MBC patients pretreated with endocrine therapy. Given the assumed impact that the presence of ESR1 mutations has on outcome to endocrine therapy, assessing ESR1 mutations in MBC patients is likely to be of significant interest to further individualize treatment for MBC patients. Here, ESR1 mutation detection methods and the most relevant pre-clinical and clinical studies on ESR1 mutations regarding endocrine resistance are reviewed, with particular interest in the ultimate goal of guiding treatment decision-making based on ESR1 mutations.

BACKGROUND: Preclinical and clinical studies have reported that human epidermal growth factor receptor 2 (HER2) overexpression yields resistance to endocrine therapies. Here the prevalence and prognostic impact of HER2-positive circulating tumor cells (CTCs) were investigated retrospectively in metastatic breast cancer (MBC) patients with a HER2-negative primary tumor receiving endocrine therapy. Additionally, the prevalence and prognostic significance of HER2-positive CTCs were explored in a chemotherapy cohort, as well as the prognostic impact of the estrogen receptor (ER) CTC status in both cohorts. METHODS: Included were MBC patients with a HER2-negative primary tumor, with ≥1 detectable CTC, starting a new line of treatment. CTCs were enumerated using the CellSearch system, characterized for HER2 with the CellSearch anti-HER2 phenotyping reagent, and characterized for ER mRNA expression. Primary end point was progression-free rate after 6 months (PFR6months) of endocrine treatment in HER2-positive versus HER2-negative CTC patients. RESULTS: HER2-positive CTCs were present in 29% of all patients. In the endocrine cohort (n=72), the PFR6months was 53% for HER2-positive versus 68% for HER2-negative CTC patients (P=.23). In the chemotherapy cohort (n=82), no prognostic value of HER2-positive CTCs on PFR6months was observed either. Discordances in ER status between the primary tumor and CTCs occurred in 25% of all patients but had no prognostic value in exploratory survival analyses. CONCLUSION: Discordances regarding HER2 status and ER status between CTCs and the primary tumor occurred frequently but had no prognostic impact in our MBC patient cohorts.

Background Mutations in ESR1, the gene encoding the estrogen receptor, have been linked to endocrine resistance in metastatic breast cancer (MBC). It is thought that these mutations are selected during endocrine treatment (ET), but direct evidence that these ESR1 mutations (mESR1) emerge during treatment with endocrine agents is scant. We set out to evaluate mESR1 in circulating tumor cells (CTCs) and matched plasma cell-free DNA (cfDNA) of MBC patients before start of 1st line ET and at progression. Materials & Methods CellSearch-enriched CTCs (≥ 5 CTC/7.5 mL) of 37 MBC patients before start of 1st line ET (baseline cohort; BL) and 38 MBC patients who had progressed on any line of ET for metastatic disease (progressive disease cohort; PD) were evaluated. 52% of the PD patients received one line of ET and 48% more lines, of which 92% contained an aromatase inhibitor. In addition, 10 CellSearch-enriched fractions from healthy blood donors (HBDs) and 46 matched plasma samples (7xHBD, 15xBL, 24xPD) were included. DNA was isolated using the AllPrep kit and cfDNA with the QIAamp CNA kit (Qiagen). Hotspot mutations for ESR1 (D538G, Y537S, Y537C and Y537N) were evaluated with mutation-specific Taqman assays by chip-based digital PCR (QuantStudio 3D). mESR1 status was assessed after target-specific ESR1 amplification capturing all 4 mutations, with thresholds for positivity based on the highest variant allele frequencies in HBDs. Results Of all the CTC samples in the BL cohort, 1 patient had mutated Y537N copies, while this mutation was not detected in the matched cfDNA. This patient had received adjuvant treatment with tamoxifen. Also none of the other 14 BL cfDNA samples analyzed harbored mESR1. Three PD patients (8%) were positive for mESR1 in their CTCs (2x D538G and 1x Y537S). These D538G variants identified in CTCs were also detected in the corresponding cfDNA of these patients; for the Y537S mutation no matched cfDNA was available. Seven additional mESR1 carriers were identified in the other 22 matched cfDNA PD samples, resulting in 38% mESR1 positivity of the PD plasma samples (7x D538G, 1x Y537C and 1x Y537C). Conclusion Sensitivity for detecting mESR1 in CTC fractions (identified in 8% of the PD patients) was lower than for cfDNA samples. Using cfDNA for mESR1 detection, we found an higher prevalence of mESR1 variants in samples obtained at progression to ET (38%) compared to baseline (0%). These findings further substantiate the role of mESR1 in endocrine resistance. Citation Format: Sieuwerts AM, Beije N, Kraan J, Van M, Onstenk W, Vitale SR, van der Vlugt – Daane M, Hamberg P, Dirix LY, Brouwers A, de Jongh FE, Jager A, Seynaeve CM, Jansen MPHM, Foekens JA, Martens JWM, Sleijfer S. ESR1 mutations in circulating tumor cell versus circulating cell-free DNA of metastatic breast cancer patients before first-line endocrine therapy and at progression [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-02-02.

Introduction: The presence of the androgen receptor splice variant 7 (AR-V7) in circulating tumor cells (CTCs) has shown to be associated with resistance to anti-AR treatment with abiraterone or enzalutamide, but not to chemotherapy containing taxanes such as cabazitaxel in patients with metastatic castration-resistant prostate cancer (mCRPC). The primary objective of this project was to set up a validated multi-center pipeline to measure AR-V7 by RT-qPCR in RNA isolated from CellSearch-enriched CTCs. This pipeline included a) the pre-analytical phase (appropriate anonymized sample collection and sample preservation), b) the analytical phase (assay performance with high analytical sensitivity, precision and specificity and c) the post-analytical phase (data evaluation and reporting). Materials and Methods: CellSearch-enirched CTCs from metastatic castration-resistant prostate cancer (mCRPC) patients were characterized by RT-qPCR. To validate the pipeline, we determined the proportion of blood samples from mCRPC patients having three or more CTCs per 7.5 mL of blood for whom an AR-V7 status can be assayed and returned to the clinician within 11 days (design PRELUDE study protocol). Results: In the range of the RNA equivalent of 0.2-12 AR-V7 positive VCaP cells the coefficient of variation (CV) for AR-V7 was 9% (n=37). The limit of detection (LOD) was 0.3 and the limit of quantification (LOQ) 3 cells in the final RT-qPCR. In none of 17 healthy blood donors an AR-V7 signal was detected, showing high diagnostic specificity (100%). No differences were observed between AR-V7 data generated by four different technicians or in two different laboratories. For the 45 patients in the PRELUDE study, thirteen patients were not eligible due to poor RNA quality (n=1) or because the blood sample did not contain enough epithelial signal (n=12). Twenty-two patients were AR-V7 negative and ten AR-V7 positive. The median, 75th and 90th percentile reporting times from blood draw to dissemination of the test results were 7, 8 and 9 days, respectively. Conclusion: This AR-V7 test with validated cut-offs, a strong intra- and inter-laboratory performance and the ability to report the outcome within a clinically acceptable time frame for the large majority of patients, met our pre-specified objectives. The AR-V7 test is now ready to be used in prospective studies (including randomized controlled trials) to test its predictive value for outcome on post-docetaxel (anti-AR of cabazitaxel) treatment. Citation Format: Anieta M. Sieuwerts, Bianca Mostert, Michelle van der Vlugt-Daane, Jaco Kraan, Corine Beaufort, Mai Van, Wendy J. Prager, Bram De Laere, Nick Beije, Paul Hamberg, Hans M. Westgeest, Metin Tascilar, Luc Y. Dirix, Wendy Onstenk, Ronald de Wit, Martijn P. Lolkema, Ron H. Mathijssen, John W. Martens, Stefan Sleijfer. A multicenter project to test the validity and logistics surrounding the testing of AR-V7 mRNA expression in circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2617.

Allogeneic stem cell transplantation (allo-SCT) has the potential to cure patients with various hematologic malignancies. Significant morbidity and mortality, however, occurs following allo-SCT due to complications such as graft-versus-host disease (GvHD), infections and conditioning-related toxicity. In addition to early morbidity, it is increasingly appreciated that long-term allo-SCT survivors have an increased incidence of cardiovascular risk factors and have a greater burden of cardiovascular morbidity1,2 with odds ratios ranging from 2.3 to 3.0 in recipients of allo-SCT compared to a matched general population.2

Ondanks curatieve lokale behandeling ontwikkelt 50 % van de patienten met een spierinvasief urotheelcarcinoom van de blaas metastasen op afstand. Betrouwbare markers die de kans op metastasering na curatieve behandeling voorspellen en die gebruikt kunnen worden voor indicatiestelling voor perioperatieve systemische therapie ontbreken. Circulerende tumorcellen (CTC’s) zijn kankercellen die aanwezig zijn in het bloed van patienten met solide tumoren en zijn afkomstig van tumorlaesies in het lichaam. CTC’s zijn in verschillende tumoren prognostisch van belang gebleken bij het voorspellen van de kans op metastasen bij individuele patienten. Deze review gaat in op de meest relevante literatuur omtrent de klinische waarde van CTC’s bij blaaskanker. Bovendien wordt de CirGuidance-studie gepresenteerd. Dit is de eerste interventiestudie waarin, aan de hand van CTC’s, de beslissing wordt getest omtrent het wel of niet geven van neoadjuvante chemotherapie aan patienten met een spierinvasief blaascarcinoom.