Circulating DNA in the neoadjuvant setting of early stage colon cancer

BACKGROUND

While circulating tumour (ct)DNA is an indicator of minimal residual disease and negative prognostic factor in stage II-III colon cancer, no study has ever analysed the value of this biomarker in colon cancer patients treated with neoadjuvant chemotherapy. We sought to fill this gap by using prospectively collected plasma samples from 80 stage III colon cancer patients, receiving one cycle of neoadjuvant FOLFOX followed by surgery +/- adjuvant FOLFOX in the PePiTA trial.

MATERIAL AND METHODS

Samples were collected at baseline, 2 weeks and surgery. NPY and WIF1 were selected as universal methylation markers for ctDNA, and analysed with ddPCR technology. ROC curves were applied for cut-off points, and outcome measures included 5-year disease-free survival (DFS) and 6-year overall survival (OS).

RESULTS

After a median follow-up of 52.5 months, baseline circulating-free (cf) DNA was an independent prognostic factor for DFS (HR 3.35, 95% CI: 1.15-9.77, p = .03), and a trend towards a similar association was observed for relative cfDNA changes between baseline and surgery (HR 2.57, 95% CI: 0.94-7.05, p = .07). Among 60 ctDNA assessable patients, 25 (42%) had detectable ctDNA at baseline. While detection of ctDNA at any pre-operative timepoint was not associated with outcome, patients with ctDNA increase (change of the worst trending methylation marker ≥11%, or mean ctDNA change of NPY and WIF1 ≥ 0%) between baseline and surgery showed a trend towards worse 5-year DFS (HR 3.66, 95% CI: 0.81-16.44, p = .09).

CONCLUSION

This is the first study of ctDNA in the neoadjuvant setting of early-stage colon cancer. Results are hypothesis-generating and should be confirmed in larger series.

Sex and Regorafenib Toxicity in Refractory Colorectal Cancer: Safety Analysis of the RegARd-C Trial

BACKGROUND

Regorafenib is a standard treatment for refractory metastatic colorectal cancer (mCRC). In view of the toxicity burden, significant research efforts have been made to increase the therapeutic ratio of this multikinase inhibitor. Predictive factors for treatment-related adverse events (TRAEs), however, are still lacking.

MATERIALS AND METHODS

We assessed the association between a number of baseline clinical, laboratory and imaging parameters and the occurrence of TRAEs in 136 patients who had received regorafenib (160 mg/day, 3-weeks-on/1-week-off) in a prospective phase II clinical trial.

RESULTS

Grade ≥ 2 TRAEs during the first cycle of treatment (84% vs. 60%, P = .002) and grade ≥ 3 TRAEs throughout the whole treatment (71% vs. 53%, P = .035) occurred more frequently in females, with sex being the only independent predictive factor of early and any-time toxicity (OR 3.4; 95% CI: 1.2-11.1, P = .02 and OR 2.1; 95% CI: 1.0-4.4, P = .045, respectively). Fatigue, anorexia, hypertension, and rash were reported significantly more frequently by females than males (P < .04). Females were also more likely to suffer early (19% vs. 5%, P = .014) and any-time serious AEs (28% vs. 9%, P = .005), and to require early dose modifications (55% vs. 37%, P = .055).

CONCLUSION

This is the first study showing an association between sex and TRAEs during regorafenib treatment for mCRC. If confirmed in larger, independent series, these results could pave the way for the implementation of personalized regorafenib dosing strategies with the potential to optimize oncological outcomes while reducing toxicity and preserving quality of life.

Abstract 28: Prognostic value of baseline and early changes of circulating cell-free (cf)DNA in the neoadjuvant setting of early stage colon cancer (CC)

Introduction Circulating tumour (ct)DNA is an indicator of minimal residual disease and negative prognostic factor in stage II-III CC treated with surgery +/- adjuvant chemotherapy. No study, however, has ever analysed the prognostic value of this biomarker in CC patients (pts) treated with neoadjuvant chemotherapy. We sought to evaluate the prognostic value of baseline and early, on-treatment changes of cfDNA and ctDNA in stage II-III CC pts who were treated with one cycle of neoadjuvant FOLFOX chemotherapy followed by surgery +/- adjuvant FOLFOX chemotherapy in the PePiTA trial.

Methods PePITA was a multicentre, single-arm, prospective phase II trial aiming to test in vivo tumour chemosensitivity as assessd by metabolic response using 18F-FDG PET/CT scan of early stage CC and to evaluate its association with survival outcome (NCT00994864). Plasma samples were prospectively collected at baseline and 2 weeks (ie, after one cycle of neoadjuvant FOLFOX chemotherapy). cfDNA was isolated with the QIAmp circulating nucleic acid kit (Qiagen), and quantified with the Qubit fluorometer (Life-Technologies). cfDNA samples were bisulfite converted using the EZ DNA Methylation-Gold™ Kit (Zymo Research), with NPY and WIF1 being selected as universal methylation markers for ctDNA and analysed with digital droplet (dd)PCR technology. Data from ddPCR were processed with the QuantaSoft V1.6 software (BioRad). The primary outcome measure was 3-year disease-free survival (DFS). Receiver operating characteristics curve analyses, Kaplan-Meier method, cox proportional hazards models and log-rank tests were used. Statistical analyses were carried out with the SPSS for MacOS version 25.0 (SPSS Inc).

Results 80 pts were included (ypStage I-II 56%, ypStage III 44%). After a median follow-up of 52.5 months, 3-year DFS was 80% (95%CI 71.2-90.8) and 5-year OS 84% (95%CI 75.2-94.9). Pts with high (≥1.2 ng/µl) baseline cfDNA level had worse 3-year DFS (48% vs 80%; HR 2.72, 95%CI 1.02-7.25; p=0.036) and 5-year OS (71% vs 90%; HR 5.36, 95%CI 1.14-25.28; p=0.017) than those with low baseline cfDNA level. In a multivariable analysis (including sex, ypStage and CEA), baseline cfDNA was the only factor showing a trend towards statistical significance (HR DFS 2.6, 95%CI 0.96-7.01; p=0.059; HR OS 4.65, 95%CI 0.97-22.32; p=0.055). Early changes of cfDNA (Δ ≥11%) after one cycle of neoadjuvant FOLFOX chemotherapy failed to predict survival (HR DFS 1.08, 95%CI 0.42-2.81; p=0.873; HR OS 0.68, 95%CI 0.19-2.39; p=0.543). ctDNA analyses are ongoing and will be presented at the meeting.

Conclusions For the first time, we have shown that baseline cfDNA may predict survival outcome in early stage CC pts treated with neoadjuvant chemotherapy. Pending confirmation in larger series, testing for cfDNA at baseline could help select high-risk pts who may benefit from neoadjuvant, FOXTROT-like, treatment strategies.

Citation Format: Giacomo Bregni, Elena Trevisi, Chiara Senti, Andrea Pretta, Caroline Vandeputte, Pashalina Kehagias, Elena Acedo Reina, Amélie Deleporte, Paraskevas Gkolfakis, Jean-Luc Van Laethem, Philippe Vergauwe, Marc Van den Eynde, Guido Deboever, Jos Janssens, Gauthier Demolin, Stephane Holbrechts, Marylene Clausse, Thierry De Grez, Marc Peeters, Lionel D'Hondt, Karen Geboes, Tatiana Besse-Hammer, Alexis Buggenhout, Françoise Rothé, Patrick Flamen, Alain Hendlisz, Francesco Sclafani. Prognostic value of baseline and early changes of circulating cell-free (cf)DNA in the neoadjuvant setting of early stage colon cancer (CC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 28.

Abstract 1082: Regorafenib resistance is associated with senescence-like phenotype and EMT in colorectal cancer (CRC)

The introduction of the multi-targeted tyrosine kinase inhibitor (TKI) regorafenib in clinical routine improve patients' survival with metastatic CRC who failed to respond to standard therapies, however at the cost of significant toxicities. Moreover, patients' tumor exhibit heterogeneous responses and become resistant. Its mechanism of action remains largely unknown, challenging the selection of patients through the identification of clinically useful predictive biomarkers. This study aimed to explore the effects on human CRC cell lines of short- and long-term exposure to regorafenib and investigate resistance-related mechanisms. Two representative CRC cell lines were used, HCT-116 and SW480. Short-term (3 days) and long-term exposure to IC50 values (HCT-116, 3µM and 6µM; SW480, 5µM and 6µM respectively) were intended to explore intrinsic and acquired resistance. The observation of early morphological changes (increased cell volume) in SW480 cells after regorafenib exposure led us to investigate a drug-initiated senescence-like phenotype commonly associated with resistance to treatment allowing cell death escape. These cells acquired stable senescent-like properties (slow-cycling cells, high β-galactosidase activity) and the majority of them were arrested in the G2/M cell cycle phase after long treatment exposure. A specific senescence-associated secretome (high sIL6Rα in cell supernatants) was also observed. In contrast, HCT-116 cells exposed to regorafenib presented early senescent features (high β-galactosidase activity) but developed over time an acquired resistance triggering EMT (high migration activity, upregulation of EMT-related factors) also known to contribute to TKI resistance. Moreover, the investigation of MAPK and PI3K/AKT pathways pointed to the latter as a significant player in acquired resistance of HCT-116 cells (increase of AKT phosphorylation) possibly related to the presence of a PI3KCA mutation in this cell line. Our findings provide new insights into the phenotypic plasticity of CRC cells under treatment pressure able to (1) either acquire stable senescent-like properties or (2) use early senescence state to undergo EMT. Our findings need further investigations of the major determinants involved in regorafenib-induced phenotype-switching and may help to develop new therapeutic strategies to overcome related resistances.

Citation Format: Pashalina Kehagias, Mohammad Krayem, Nadège Kindt, Ahmad Najem, Caroline Vandeputte, Fabrice Journé, Ahmad Awada, Ghanem E. Ghanem, Alain Hendlisz. Regorafenib resistance is associated with senescence-like phenotype and EMT in colorectal cancer (CRC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1082.

Infiltrative tumour growth pattern correlates with poor outcome in oesophageal cancer

Objective

Oesophageal cancer (OEC) is an aggressive disease with a poor survival rate. Prognostic markers are thus urgently needed. Due to the demonstrated prognostic value of histopathological growth pattern (HGP) in other cancers, we performed a retrospective assessment of HGP in patients suffering from invasive OEC.

Design

A first cohort composed of 89 treatment-naïve operated patients with OEC from The Cancer Genome Atlas (TCGA) public database was constituted, from which H&E images and RNA-sequencing data were retrieved. Next, a second cohort composed of 99 patients with OEC treated and operated in a Belgian hospital was established. H&E-stained sections and extracted tumorous RNA were obtained from the samples. HGP were assessed on H&E slides as infiltrative (IGP) or expansive (EGP). TCGA RNA-sequencing data were analysed through the gene set enrichment analysis and Cytoscape softwares. Real-time quantitative PCR (qPCR) experiments were performed to assess gene expression in the Belgian cohort.

Results

IGP patients displayed a grim prognosis compared with EGP patients, while IGP was found as associated with numerous lymphovascular emboli and perinervous infiltrations. Analyses of the TCGA expression data showed that angiogenesis, epithelial-to-mesenchymal transition (EMT) and inflammation were significantly upregulated in IGP compared with EGP samples. qPCR experiments of three genes appearing as highly upregulated in each pathway showed no difference in expression according to the HGP.

Conclusion

The current study demonstrates the poor prognostic value carried by IGP in OC and suggests angiogenesis, EMT and inflammation as key carcinogenetic pathways upregulated in this pattern.

Prognostic value of baseline and early changes of circulating-free (cf) and circulating tumor (ct) DNA in the neoadjuvant (NA) setting of early stage colon cancer (CC)

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Background: ctDNA is an indicator of minimal residual disease and negative prognostic factor in stage II-III CC treated with surgery +/- adjuvant chemotherapy (CT). No study, however, has ever analysed the prognostic value of this biomarker in CC patients (pts) treated with NACT. We sought to evaluate the prognostic value of baseline and early changes of cf/ctDNA in stage II-III CC pts who were treated with one cycle of NA FOLFOX CT followed by surgery +/- adjuvant FOLFOX CT in the PePiTA trial. Methods: PePiTA was a multicentre, single-arm, prospective phase II trial testing in vivo tumour chemosensitivity of early stage CC (as assessed by 18F-FDG PET/CT-based metabolic response to one cycle of NA FOLFOX) and its association with long-term outcome (NCT00994864). Plasma samples were prospectively collected at baseline, 2 weeks after one cycle of NA FOLFOX CT, and before surgery. NPY and WIF1 were selected as universal methylation markers for ctDNA and analysed with digital droplet (dd)PCR technology. Data from ddPCR were processed with the QuantaSoft v1.6 software (Bio-Rad). Survival outcome measures were 5-year disease-free survival (DFS) and 6-year overall survival (OS). ROC curve analyses, Kaplan-Meier method, cox proportional hazards models and log-rank tests were used. Statistical analyses were carried out with SPSS v25.0 (SPSS Inc.). Results: 80 pts were included (44 ypStage I-II and 36 ypStage III). After a median follow-up of 52.5 months, 5-year DFS and 6-year OS were 68% (95%CI 52-84) and 84% (95%CI 74-94), respectively. Pts with high (≥1600 ng/ml) baseline cfDNA had worse 6-year OS (HR 6.45, 95%CI 1.61-25.84; p = 0.008). Early changes of cfDNA after one cycle of NA FOLFOX CT failed to predict survival (HR DFS 0.96, 95%CI 0.38-2.43; p = 0.92; HR OS 0.62, 95%CI 0.16-2.50; p = 0.50). At baseline, 25 out of 60 (42%) ctDNA-assessable patients were positive. Detectable ctDNA at baseline (HR DFS 2.06, 95%CI 0.65-6.49; p = 0.22; HR OS 3.11, 95%CI 0.57-16.99; p = 0.19) or at any timepoint before surgery (HR DFS 1.65, 95%CI 0.54-5.04; p = 0.38; HR OS 2.80, 95%CI 0.54-14.44; p = 0.22) was not significantly associated with survival. A trend toward a significant association between ctDNA increase at surgery and 5-year DFS was found (HR 3.66, 95%CI 0.81-16.44; p = 0.09). Data on the correlation between early changes of cf/ctDNA and 18F-FDG PET/CT-based metabolic response will be presented at the meeting. Conclusions: For the first time, we have shown that baseline cfDNA may predict survival outcome in early stage CC pts treated with NACT. Pending confirmation in larger series, testing for cfDNA at baseline could help select high-risk pts who may benefit from FOxTROT-like, NACT treatment strategies. While analysis of ctDNA in this setting did not appear useful to predict prognosis, these results might be secondary to the small sample size.

Feasibility and clinical impact of routine molecular testing of gastrointestinal cancers at a tertiary centre with a multi-gene, tumor-agnostic, next generation sequencing panel

BACKGROUND

High-throughput sequencing technologies are increasingly used in research but limited data are available on the feasibility and value of these when routinely adopted in clinical practice.

MATERIAL AND METHODS

We analyzed all consecutive cancer patients for whom genomic testing by a 48-gene next-generation sequencing (NGS) panel (Truseq Amplicon Cancer Panel, Illumina) was requested as part of standard care in one of the largest Belgian cancer networks between 2014 and 2019. Feasibility of NGS was assessed in all study patients, while the impact of NGS on the decision making was analyzed in the group of gastrointestinal cancer patients.

RESULTS

Tumor samples from 1064 patients with varying tumor types were tested, the number of NGS requests increasing over time (p < .0001). Success rate and median turnaround time were 91.4% and 12.5 days, respectively, both significantly decreasing over time (p ≤ .0002). Non-surgical sampling procedure (OR 7.97, p < .0001), tissue from metastatic site (OR 2.35, p = .0006) and more recent year of testing (OR 1.79, p = .0258) were independently associated with NGS failure. Excluding well-known actionable or clinically relevant mutations which are recommended by international guidelines and commonly tested by targeted sequencing, 57/279 (20.4%) assessable gastrointestinal cancer patients were found to have tumors harboring at least one actionable altered gene according to the OncoKB database. NGS results, however, had a direct impact on management decisions by the treating physician in only 3 cases (1.1%).

CONCLUSIONS

Our findings confirm that NGS is feasible in the clinical setting with acceptably low failure rates and rapid turnaround time. In gastrointestinal cancers, however, NGS-based multiple-gene testing adds very little to standard targeted sequencing, and in routine practice the clinical impact of NGS panels including genes which are not routinely recommended by international guidelines remains limited.

Prognostic Value of the Pace of Tumor Progression as Assessed by Serial 18F-FDG PET/CT Scan and Liquid Biopsy in Refractory Colorectal Cancer: The CORIOLAN Trial

Simple Summary

Management of chemorefractory colorectal cancer patient is challenging, and reliable tools which can predict individual patient prognosis and help the decision making are needed. In this study, we hypothesized that the natural pace of cancer growth and progression, as assessed by early changes of a number of imaging and circulating biomarkers which are surrogates of tumor burden (i.e., metabolically active tumor volume, carcinoembryonic antigen, circulating tumor cells and circulating tumor DNA), could predict patient prognosis. By prospectively recruiting 47 eligible patients who had measurements of these biomarkers taken two weeks apart in the absence of any active anti-cancer treatment, we failed to demonstrate our hypothesis. On the other hand, we found that baseline assessment of the same biomarkers was associated with survival outcomes. Larger studies are needed to confirm these findings and translate them into applications for clinical practice.

Abstract

Introduction: Decision making in refractory colorectal cancer (rCRC) is challenging, with limited data available to predict patient outcome. We conducted a study to assess the pace of cancer progression as a potential prognostic and decision tool. Methods: CORIOLAN was a prospective, single-center, single-arm trial recruiting refractory CRC patients with an ECOG performance status of ≤1 and an estimated life expectancy of ≥12 weeks. 18 fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) scan and blood sample collection were carried out at baseline and after 2 weeks with no cancer treatment given between these timepoints. The primary objective was to evaluate the association between pace of cancer progression as defined by changes of the whole-body metabolically active tumor volume (WB-MATV) and overall survival (OS). Exploratory objectives included evaluation of the prognostic value of circulating cell-free DNA (cfDNA), circulating tumor cells (CTCs) and carcinoembryonic antigen (CEA). Results: 47 eligible patients who had received a median number of 5 (range 2–8) prior treatments were enrolled. At the time of analysis, 45 deaths had occurred, with 26% of patients dying within 12 weeks. The median OS was 6.3 months (range 0.4–14.3). The median relative delta between WB-MATV at baseline and 2 weeks was +21%. Changes of WB-MATV, however, failed to predict OS (hazard ratio (HR) 1.3, p = 0.383). Similarly, no association was observed between changes of any of the circulating biomarkers investigated and prognosis. By contrast, high WB-MATV (4.2 versus 9.4 months; HR 3.1, p = 0.003), high CEA (4.4 versus 7.0 months; HR 1.9, p = 0.053), high cfDNA (4.7 versus 7.0 months; HR 2.2, p = 0.015) and high CTC count (3.3 versus 7.5 months; HR 6.5, p < 0.001) at baseline were associated with worse OS. Conclusions: In this study, approximately 1 out of 4 refractory CRC patients who were judged to have a life expectancy >12 weeks actually died within 12 weeks. Baseline assessment of WB-MATV, cfDNA, CTCs and CEA, but not early change evaluation of the same, may help to refine patient prognostication and guide management decisions.

18F-FDG PET scan and liquid biopsy as tools to assess the pace of tumor progression and to predict overall survival (OS) in refractory colorectal cancer (rCRC): The CORIOLAN trial

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Background: Decision making in rCRC patients (pts) who have exhausted all available therapies is challenging. Clinical trials, treatment re-challenge and best supportive care are possible options. There are limited data, however, to predict pt outcome and guide treatment choices. Methods: CORIOLAN was a prospective, single-centre, single-arm trial. Eligible pts had to have an ECOG PS of ≤1, a life expectancy of ≥12 weeks (wks) and had to have received prior standard chemotherapy and targeted agents. No cancer treatment was allowed within 4 wks prior to study entry. 18F-FDG PET scan and blood sample collection were carried out at baseline and after 2 wks. No treatment was given between these timepoints, while further management was left to the treating physician. The primary objective was to evaluate the association between tumour metabolic progression index as defined by changes of the whole-body metabolically active tumour volume (WB-MATV) and OS. Exploratory objectives included evaluation of the prognostic value of circulating biomarkers such as cell-free DNA (cfDNA), circulating tumour cells (CTCs, CellTracks Analyzer II, CellSearch) and CEA. Validated cut-off values, Kaplan-Meier method, Cox proportional hazards model and logrank tests were used (R version 3.5.1). Results: From 2012 to 2018, 47 eligible pts were enrolled. Median age: 65 years (38-82). ECOG PS 1: 64%. Males: 53%. Left-sided tumours: 71%. Metastases: lung (83%), liver (66%), lymph-nodes (45%), peritoneum (30%), bone (21%). Known RAS/BRAF mutations: 57%/0%. Median number of prior treatments: 5 (2-8). At the time of analysis, 45 deaths had occurred, with 26% of pts dying within 12 wks. The median relative delta between WB-MATV at baseline and after 2 wks was +21%. Changes of WB-MATV, however, failed to predict OS (p≥0.383). Similarly, no association was observed between changes of any of the circulating biomarkers investigated and prognosis. By contrast, low WB-MATV (9.4 vs 4.2 months, HR 0.65, p = 0.003), low cfDNA (7.0 vs 4.7 months, HR 0.58, p = 0.015), low CTC count (7.5 vs 3.3 months, HR 0.67, p < 0.001) and low CEA (7.0 vs 4.4 months, HR 0.58, p = 0.053) at baseline were associated with longer OS. Conclusions: This study confirms the inaccuracy of life expectancy estimation for rCRC pts based on a physician judgement largely relying on conventional criteria. Baseline assessment of WB-MATV, cfDNA, CTCs and CEA, but not early change evaluation of the same, may help to refine pt prognostication and guide management decisions. Clinical trial information: NCT01591590 .

Computed tomography-based analyses of baseline body composition parameters and changes in breast cancer patients under treatment with CDK 4/6 inhibitors

PURPOSE

Body composition parameters including muscle and adipose tissue measurements have emerged as prognostic factors in cancer patients. Besides cell cycle regulation, CDK 4 and 6 also control metabolic processes (lipid synthesis, glycolysis, and mitochondrial function). We studied the impact of baseline body composition parameters on response to CDK 4/6 inhibition and changes on body composition during treatment.

METHODS

Retrospective study of 50 patients treated at Institut Jules Bordet between December 2016 and August 2019 with endocrine therapy and CDK 4/6 inhibitor as first or second-line treatment for metastatic breast cancer (BC). CT-based body composition analysis was performed at 3 time points. Cox regression and Kaplan-Meier method were used for the association with Progression-free survival (PFS). Changes in body composition parameters were described in means and compared using paired sampled T test.

RESULTS

Baseline sarcopenia was present in 40% of patients and associated with a significantly worse PFS compared to patients without sarcopenia (20.8 vs 9.6 months, HR 2.52; 95% CI 1.02-6.19, p = 0.037). Patients with higher visceral fat index and higher visceral fat density had better PFS (20.8 vs 10.4 months, HR 0.40; 95% CI 0.16-0.99 p = 0.041-stratified for treatment line). No significant alterations in body composition parameters during treatment were observed.

CONCLUSION

Sarcopenia is a potential early marker of poor prognosis among patients with metastatic BC treated with CDK 4/6 inhibitors. CT scan evaluation of sarcopenia and adiposity revealed significant prognostic information. Visceral fat could also play an important role in response to CDK 4/6 inhibitors, deserving further investigation.

Feasibility and clinical impact of routine molecular testing of gastrointestinal (GI) cancers at a tertiary center with a multigene, next generation sequencing (NGS) panel

216

Background: High-throughput technologies have been increasingly used in research. Nevertheless, limited data are available on the feasibility and clinical value of these technologies in routine practice. Methods: All consecutive GI cancer patients (pts) who were tested with the 48-gene Truseq Amplicon Cancer Panel (Illumina) as part of routine practice at our Institution were identified from a prospectively maintained pathology database. Feasibility, results and impact on management decisions were analysed. Associations were tested with Fisher’s test. Results: From Apr 2014 to Jun 2019, 314 pts were tested. Sequencing was successful in 290 cases (92.4%; 234 colorectal (CRC), 21 gastro-esophageal, 17 bilio-pancreatic, 9 GIST, 4 appendix, 3 small intestine, 2 hepatocellular). In successful and failed cases, respectively, analyses were attempted on core biopsy (37.0% vs 66.7%), surgery (62.6% vs 16.7%), and fine needle aspiration (0.4% vs 12.4%) tumour samples (p < 0.001). Median turnaround time (TAT) was 12.5 days, reducing from 13 days in 2014 to 10 days in 2019. The majority of successfully tested pts (85.6%) had stage IV disease. TP53 was the most frequent mutation (45.9%), followed by APC (42.1%), KRAS (39.7%), PIK3CA (12.1%), SMAD4 (7.6%), BRAF (6.2%), and NRAS (5.5%). All other mutations were found in < 5% of cases. Excluding RAS/BRAF and KIT/PDGFR mutations, sequencing results impacted on the management of 4 (1.4%) pts. In 199 stage IV CRC pts, KRAS mutations were associated with lung (p = 0.020) and bone metastases (mts) (p = 0.008), NRAS mutations with liver mts (p = 0.021), BRAF mutations with peritoneal mts (p = 0.001), and APC mutations with lymph node mts (p = 0.006). Assuming a median of 25 samples per run, the estimated cost of NGS analysis per pt was €186. Conclusions: Low failure rate, short TAT and fair costs support feasibility of multi-gene NGS in routine practice. The clinical impact of this technology, however, is still limited but it could raise with the identification of new biologically relevant genetic alterations and the increased availability of novel therapeutics.

Abstract 1610: Getting under the skin: Fat quality in esophageal cancer prognosis

INTRODUCTION

The last few years have seen an increased interest in the role of body mass composition parameters in cancer survival. this study sought to assess the impact of the body mass composition (BMC) on prognosis of locally advanced esophageal cancer (EC) patients beyond the usual quantitative weight loss associated with this condition.

METHODS

Diagnostic CT scans were assessed for BMC in 155 all-stage EC patients at diagnosis. The index (area/height2) of skeletal muscle (SMI), subcutaneous (SFI) and visceral fat (VFI) were delineated on two adjacent slides at the third lumbar vertebra level by two independent investigators using PLANET ONCO® software (DOSIsoft, France). Mean attenuation (or density) of fat tissue was measuring to assess the quality of adipose compartments. Survival and relapse free survival (RFS) were calculated from date of baseline CT-scan.

RESULTS

Interobserver correlations were excellent for all BMC parameters measured (r = 0.94 to 0.99). Remarkably, low subcutaneous fat density (SFD) was associated to better outcome, as were low disease stages. Low C-reactive protein (CRP) levels were also associated with better overall survival (OS). In contrast, low BMI did not affect the patients’ outcome. Relapse free survival (RFS) analysis showed that only high disease stages and SFD remained associated with poor RFS. Stepwise regression showed that the combination of SFD, stage and CRP was an effective model for OS prediction. No parameter was retained for RFS in the multivariate analysis. Detailed results are shown in Table 1.

CONCLUSION

SFD, stages and CRP appeared as robust prognostic factors of OS in EC patients, in contrast with BMI. While SFD and stages were significant in RFS univariate analysis, none of these two parameters were retained in multivariate analyses. These results confirm the validity of BMC assessment for evaluating patient prognosis and show for the first time that adipose tissues and inflammation may have a preponderant impact on cancer prognosis.

ParametersThresholdOSmalefemalep valueHR (95 CI)Low SFD&lt; -95,7&lt; -99,40,000282,2 (1,4-3,5)Low disease stages1+2A vs 2B+3+40,00472,2 (1,2-3,7)Low CRP&lt; 3,200,00532,2 (1,2-3,8)Low BMI&lt;250,130,71 (0,46-1,1)ParametersThresholdRFSmalefemalep valueHR (95 CI)Low SFD&lt; -95,7&lt; -99,40,041,6 (1-2,6)Low disease stages1+2A vs 2B+3+40,0441,8 (1-3,1)N.B. Thresholds for SFD are the sex-specific medians. Thresholds for CRP is the median

Citation Format: Maelle Anciaux, Lieveke Ameye, Thomas Guiot, Patrick Flamen, Serge Goldman, Pieter Demetter, Amélie Deleporte, André Van Gossum, Marianne Paesmans, Vincent Donckier, Alain Hendlisz, Caroline Vandeputte. Getting under the skin: Fat quality in esophageal cancer prognosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1610.

Abstract 2293: Is a single driver gene mutation sufficient for monitoring early response in advanced colorectal cancer

Purpose: Circulating tumor DNA (ctDNA) monitoring based on an individual mutation profile during therapy is under intense investigation in modern oncology. We previously reported that the increase of ≥50% of at least one somatic mutation among multiple monitored mutations per patient is associated with a significantly worse outcome1. This study investigates whether the ctDNA monitoring of one driver gene mutation, provides enough information as compared to multiple mutations to assess response to regorafenib in advanced chemorefractory colorectal cancer (aCRC) at an early timepoint.

Experimental procedures: Archival tumor tissue and plasma samples (PL) at baseline (BL) and 14 days (D14) after treatment initiation in aCRC pts (n=141) were prospectively collected in the RegARd-C multicenter clinical trial (NCT01929616). Somatic mutations were identified based on a CRC-oriented targeted gene sequencing of tumor tissue. All available (median 2 (1-4)) driver gene mutations were monitored per patient in PL at BL and D14 via droplet digital PCR (Bio-Rad QX200 ddPCR system) to assess ctDNA dynamics.

Results: In 96 evaluable patients, the most frequently monitored mutated genes were APC (73%), TP53 (72%), KRAS (66%), and PI3KCA (23%). Among patients with ≥2 monitored mutations (73/96), one was selected at random and compared to previous methodology taking in account dynamics of all followed mutations. Optimal cutoff (CO) evaluation (Contal & O’Quigley method) separated patients (n=96) according to a ctDNA increase of ≥50% versus an increase of &lt;50% or a decrease. The concordance of ctDNA dynamics based on one randomly selected mutation and multiple monitored mutations was 91%. Our data demonstrated that a ctDNA increase based on one single mutation taken at random is significantly associated with a worse clinical outcome in terms of progression-free survival (HR 2.42, 95% CI (1.56-3.74), P&lt;0.001) and overall-survival (HR 2.17, 95% CI (1.41-3.34), P&lt;0.001). In addition, when combining patients’ ctDNA dynamics to BL ctDNA levels (≥ or &lt; 5 ng/mL optimal CO) or BL cell-free DNA (cfDNA) levels (≥ or &lt; 50 ng/mL optimal CO), we could distinguish 4 patients’ subgroups with different prognosis. However, when performing a multivariate analysis including clinical parameters, BL ctDNA and BL cfDNA levels, BL ctDNA was not relevant in the presence of BL cfDNA.

Conclusion: The monitoring of ctDNA dynamics based on only one randomly selected driver gene mutation versus multiple is equally informative to describe adequately aCRC patients’ outcome under regorafenib after 14 days of treatment onset. Especially, combined with pre-treatment ctDNA levels, this simplifies a personalized patient monitoring. 1 P. Kehagias, et al. Circulating tumor DNA detects early response to regorafenib in advanced colorectal cancer [abstract]. AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-221

Citation Format: Pashalina Kehagias, Caroline Vandeputte, Lieveke Ameye, Hakim El Housni, Amélie Deleporte, Karen Geboes, Thierry Delaunoit, Gauthier Demolin, Marc Peeters, Lionel D'Hondt, Jos Janssens, Javier Carrasco, Maria Gomez Galdon, Pierre Heimann, Marianne Paesmans, Patrick Flamen, Alain Hendlisz. Is a single driver gene mutation sufficient for monitoring early response in advanced colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2293.

CTCs as a prognostic and predictive biomarker for stage II/III Colon Cancer: a companion study to the PePiTA trial

BACKGROUND

Adjuvant therapy improves the prognosis of stage II & III colon cancer patients. Unfortunately, most patients do not benefit from this treatment. PePITA (NCT00994864) is a prospective, multicenter, non-randomized study whose primary objective is to predict the outcome of adjuvant therapy in colon cancer.

METHODS

The primary objective was to determine the prognostic and predictive value of circulating tumor cell (CTC) detection before therapy and after one course of preoperative FOLFOX.

RESULTS

Out of the 58 first patients accrued in PePiTA trial, 36 patients participated in the CTC companion study, of whom 32 had at least one evaluable sample. Only 5 patients (14, 95% CI = 5-30%) had ≥1 CTC/22.5 ml blood in at least one of the two timepoints with 2 patients having ≥1 CTC/22.5 ml at baseline (6, 95% CI: 1-19%). The detection rate of patients with CTCs at baseline being lower than expected, the inclusion of patients in the PePiTA CTC substudy was stopped. The limited sample size did not allow us to investigate the prognostic and predictive value of CTCs in locally advanced colon cancer.

CONCLUSIONS

Our data illustrate the need for further standardized studies in order to find the most reliable prognostic/predictive biomarker in early-stage colon cancer.

TRIAL REGISTRATION

This trial was prospectively registered at Jules Bordet institute ( NCT00994864 ) on the October 14, 2009.

Combining 18F-FDG PET/CT-Based Metabolically Active Tumor Volume and Circulating Cell-Free DNA Significantly Improves Outcome Prediction in Chemorefractory Metastatic Colorectal Cancer

Baseline whole-body metabolically active tumor volume (WB-MATV) measured by ¹⁸F-FDG PET/CT and circulating cell-free DNA (cfDNA) have been separately validated as predictors of overall and progression-free survival (OS/PFS) in chemorefractory metastatic colorectal cancer (mCRC) patients. This study assessed the correlation between WB-MATV and cfDNA, evaluating the added prognostic value of these in combination, along with clinical parameters. Methods: Of 141 mCRC patients included in a prospective multicenter trial, 132 were evaluable for OS/PFS. cfDNA was extracted from 3 mL of plasma and quantified using a fluorometer. All target lesions were delineated on ¹⁸F-FDG PET/CT, and their metabolic volumes were summed to obtain the WB-MATV. Results: Baseline WB-MATV and cfDNA were strongly correlated (r = 0.70; P < 0.001) but showed discordance in 23 of 132 (17%) patients. A multivariate analysis identified 3 independent negative predictors of PFS (high cfDNA, short time since diagnosis, and body mass index < 30) and 5 of OS (high cfDNA, high WB-MATV, body mass index < 30, poor performance status, and short time since diagnosis). Combining WB-MATV and cfDNA increased the overall prognostic value and allowed identification of a subgroup of patients with low cfDNA and high WB-MATV who were associated with intermediate survival (median OS of 8.1 for low-cfDNA/high-MATV patients vs. 12.7 mo for low-cfDNA/low-MATV patients; hazard ratio, 2.04; P = 0.02). Conclusion: This study confirms the added prognostic value of combined circulating cfDNA and PET-based WB-MATV in chemorefractory mCRC patients. The combination of these two biomarkers should provide a firm basis for risk stratification, both in clinical practice and in research trials.

Prognostic value of adipose tissue and muscle mass in advanced colorectal cancer: a post hoc analysis of two non-randomized phase II trials

Background

The prognostic value of body composition in cancer patients has been widely studied during the last decade. The main finding of these studies is that sarcopenia, or skeletal muscle depletion, assessed by CT imaging correlates with a reduced overall survival (OS). By contrast, the prognostic value of fat mass remains ill-defined. This study aims to analyze the influence of body composition including both muscle mass and adipose tissue on OS in a homogeneous population of advanced colorectal cancer (CRC) patients.

Methods

Among 235 patients with chemorefractory advanced CRC included in the SoMore and RegARd-C trials, body composition was assessed in 217 patients on baseline CT images. The relationship between body composition (sarcopenia, muscle density, subcutaneous and visceral fat index and density), body mass index (BMI) and OS were evaluated.

Results

Patients with a higher BMI had a better OS (≥30 versus < 30, HR: 0.50; 0.33–0.76). Those with low muscle index and muscle density had an increased mortality (HR: 2.06; 1.45–2.93 and HR: 1.54; 1.09–2.18, respectively). Likewise, low subcutaneous and visceral fat index were associated with an increased risk of dying (HR: 1.63; 1.23–2.17 and 1.48; 1.09–2.02 respectively), as were a high subcutaneous and visceral adipose tissue density (HR: 1.93; 1.44–2.57 and 2.40; 1.79–3.20 respectively). In multivariate analysis, a high visceral fat density was the main predictor of poor survival.

Conclusions

Our results confirm the protective role of obesity in CRC patients at an advanced stage, as well as the negative prognostic impact of muscle depletion on survival. More importantly, our data show for the first time that visceral adipose tissue density is an important prognostic factor in metastatic CRC.

Trial registration

NCT01290926, 07/02/2011 and NCT01929616, 28/08/2013.

Abstract LB-221: Circulating tumor DNA detects early response to regorafenib in advanced colorectal cancer

Purpose: To demonstrate that an early increase in ctDNA plasmatic levels after 14 days may identify patients (pts) with advanced chemorefractory colorectal cancer (aCRC) unlikely to benefit from regorafenib. Experimental procedures: The RegARd-C prospective multicentric clinical trial (NCT01929616) collected archival tumor tissue and plasma samples at baseline (BL), 14 days (D14) and every 2 months after treatment initiation in aCRC pts (n=141). A targeted gene sequencing was performed on pts' tumor tissue to identify tumor-specific mutations using a panel of 47 genes commonly mutated in CRC. To monitor circulating tumor DNA (ctDNA) levels in plasma samples collected at BL and D14 via droplet digital PCR (Bio-Rad QX200 ddPCR system), we selected tumor-specific mutations based on their allelic frequency.

Results: As foreseen, in 96 pts the most common mutated genes were APC (73%), TP53 (72%), KRAS (66%), and PI3KCA (23%). Among these pts, 24 (25%), 49 (51%), 18 (19%) and 5 (5%) had respectively one, two, three and four tumor-specific mutations followed via ddPCR. On average 2 (range 1-4) tumor-specific mutations were followed per patient. In total, 65 specific paired PrimePCRTM ddPCRTM Mutation Detection Assays were optimized following digital MIQE guidelines to assess ctDNA levels. As previously described1, ctDNA levels were assessed in terms of absolute values of mutated copies per mL of plasma to avoid bias in the mutated/mutated + wild-type copies ratio. We considered an increase in ctDNA level of at least 12% as significant2. Pts were separated according to the presence (n=53) or absence (n=43) of at least one increasing mutation between BL and D14. An increase of at least one tumor-specific mutation as compared to none is associated with a significantly worse clinical outcome with a median PFS of 1.3 months versus 3.0 months (HR 1.88, P=0.002, 95% CI 1.24-2.85) and a median OS of 3.9 months versus 8.5 months (HR 2.04, P&lt;0.001, 95% CI 1.33-3.12).

Conclusion: Early (14 days) change in ctDNA levels under regorafenib therapy describes adequately the outcome of patients and may be used as a reliable tool for treatment personalization. Additionally, we confirmed the importance of using the absolute value of ctDNA instead of the mutated/total copies ratio usually reported in the literature for monitoring the outcome of a toxic treatment such as regorafenib. 1Kehagias P. et al. Oral presentation. LKI symposium, 2017; Leuven 2Whale AS. et al. Anal Chem. 2017

Citation Format: Pashalina Kehagias, Caroline Vandeputte, Lieveke Ameye, Hakim El Housni, Jean-François Laes, Amélie Deleporte, Karen Geboes, Thierry Delaunoit, Gauthier Demolin, Marc Peeters, Lionel D'Hondt, Jos Janssens, Javier Carrasco, Maria Gomez Galdon, Ghanem Ghanem, Pierre Heimann, Marianne Paesmans, Patrick Flamen, Alain Hendlisz. Circulating tumor DNA detects early response to regorafenib in advanced colorectal cancer [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 LB-221.

Circulating tumor DNA in early response assessment and monitoring of advanced colorectal cancer treated with a multi-kinase inhibitor

Predictive biomarkers are eagerly awaited in advanced colorectal cancer (aCRC). Targeted sequencing performed on tumor and baseline plasma samples in 20 patients with aCRC treated with regorafenib identified 89 tumor-specific mutations of which ≥50% are also present in baseline plasma. Droplet digital PCR (ddPCR) assays were optimized to monitor circulating tumor DNA (ctDNA) levels in plasmatic samples collected throughout the treatment course and showed the importance of using the absolute value for ctDNA rather than the mutant/wild type ratio in monitoring the therapy outcome. High baseline cell free DNA (cfDNA) levels are associated with shorter overall survival (OS) (HR 7.38, P=0.001). An early increase (D14) in mutated copies/mL is associated with a significantly worse PFS (HR 6.12, P=0.008) and OS (HR 8.02, P=0.004). These data suggest a high prognostic value for early ctDNA level changes and support the use of blood-born genomic markers as a tool for treatment.

Baseline cell-free DNA (cfDNA) and metabolic tumor volume (MTV) independently predict outcome in metastatic chemorefractory colorectal cancer (mCRC)

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Background: No validated prognostic biomarker is currently available for mCRC. This trial assessed cfDNA and MTV before treatment with regorafenib as prognostic biomarkers for progression-free survival (PFS) and overall survival (OS) in mCRC. Methods: After signed informed consent, mCRC patients were enrolled in a prospective non-randomized trial aiming to define unlikelihood to benefit from regorafenib (EudraCT number: 2012-005655-16) and assessed for cfDNA and FDG PET/CT MTV at baseline. cfDNA was extracted from 3mL of plasma and quantified using the Qubit 2.0 fluorometer. All target lesions were delineated on FDG PET/CT using a PERCIST-based threshold and their volumes were summed to obtain total MTV. MTV and cfDNA optimal cutoffs for OS and PFS prediction were determined by the Contal and O’Quigley’s method. MTV, cfDNA, age, gender, Body Mass Index (low, normal, high, obese), ECOG PS, number of chemotherapy lines (NCL), previous use of bevacizumab and presence of a KRAS mutation were included in a multivariate analysis. Results: MTV and cfDNA of 132 evaluable/141 eligible patients were well correlated (Spearman’s correlation coefficient = 0.70; p < 0.001) and risk groups for both PFS and OS were identified on the basis of cfDNA (cfDNA < 1 µg/mL; cfDNA≥1 µg/mL) and MTV (MTV < 100 cm³; 100-300 cm³; > 300 cm³). The multivariate analysis retained cfDNA, MTV, NCL, and obesity as independent parameters for PFS prediction, and cfDNA, MTV, NCL, BMI, and previous use of bevacizumab as independent parameters for OS prediction. Prognostic scores for PFS and OS were developed based on regression coefficients from the final Cox proportional hazards models. Prognostic scores for PFS (1.8 vs 5.3 months, HR: 3.15 for score ≥-3 vs < -3, (95% CI, 2.08-4.76); p < 0.001) and for OS (4.2 vs 13.9 months, HR: 4.59 for score ≥-6 vs < -6: (95% CI, 2.92-7.21); p < 0.001) both identified patients with much contrasted outcomes. Conclusions: Baseline cfDNA and MTV along with BMI parameters predict outcome in patients with mCRC before regorafenib onset. These parameters not related to treatment should be considered, if validated in further studies, as stratification factors in future clinical trials. Clinical trial information: 2012-005655-16.

Preclinical Evaluation of a P2X7 Receptor-Selective Radiotracer: PET Studies in a Rat Model with Local Overexpression of the Human P2X7 Receptor and in Nonhuman Primates

The P2X7 receptor (P2X7R) orchestrates neuroinflammation, and this is the basis for an increased interest in the development of antagonists inhibiting P2X7R function in the brain. This study provides the preclinical evaluation of (11)C-JNJ-54173717, a PET tracer for P2X7R in both rats and nonhuman primates.

METHODS

(11)C-JNJ-54173717 is a high-affinity radiotracer for the human P2X7R (hP2X7R). Biodistribution and radiometabolite studies were performed. Viral vectors encoding either enhanced green fluorescent protein-hP2X7R or 3flag-hP2X7R were engineered and validated in cell culture. hP2X7R was regionally overexpressed in the rat striatum after stereotactic injection of viral vectors. Dynamic small-animal PET studies were performed in vector-injected rats and in healthy monkeys using (11)C-JNJ-54173717.

RESULTS

The affinity of JNJ-54173717 was 1.6 ± 0.1 nM in a rat cortex P2X7R membrane binding assay. In a functional assay at the recombinant human and rat P2X7R orthologs, the half maximal inhibitory concentration (IC50) of JNJ-54173717 was 4.2 ± 0.01 nM and 7.6 ± 0.01 nM, respectively. The rat biodistribution study showed that (11)C-JNJ-54173717 crossed the blood-brain barrier and was cleared from plasma mainly via the hepatobiliary pathway. A polar radiometabolite was found in rat plasma. No radiometabolites were detected in rat brain. Dynamic small-animal PET showed binding of (11)C-JNJ-54173717 in the striatum expressing hP2X7R, with rapid washout from the noninjected control striatum and other brain regions. Likewise, (11)C-JNJ-54173717 PET signal was blocked by a chemically distinct P2X7R ligand, indicating specific binding to P2X7R in the monkey brain.

CONCLUSION

JNJ-54173717 is a high-affinity P2X7R antagonist. An animal rat model stably expressing hP2X7R was developed and validated, identifying favorable characteristics for (11)C-JNJ-54173717 as a PET radioligand for in vivo visualization of hP2X7R. (11)C-JNJ-54173717 selectively visualized P2X7R in the monkey brain, and this radioligand will be further evaluated in a clinical setting to study P2X7R expression levels in neurodegenerative disorders.

Regorafenib assessment in refractory advanced colorectal cancer: RegARd-C study protocol

INTRODUCTION

Regorafenib was recently approved for patients with pretreated advanced colorectal cancer (aCRC), despite a moderate improvement of the patients' outcome, and significant toxicities. Based on previous studies showing that early fluorodeoxyglucose-positron emission tomography (FDG-PET)-based metabolic response assessment (MRA) might adequately select patients unlikely to benefit from treatment, the RegARd-C trial uses early MRA to identify likely non-responders to regorafenib in a population of patients with aCRC and guide a comprehensive evaluation of genomic and epigenetic determinants of resistance to treatment.

METHODS AND ANALYSIS

RegARd-C is a multicentric prospective study. Its primary objective is to identify non-benefitters from regorafenib given at 160 mg/day, 3 weeks out of 4 in a population of patients with pretreated aCRC. Baseline PET is repeated at day 14 of the first treatment course. MRA is blinded for the investigators. Overall survival (OS) is the primary end point and will be correlated with metabolic parameters and (epi)genetic alterations assessed from tumour and serial blood samples. A target sample size of 105 evaluable patients (70 as derivation set and 35 as validation set), is considered as sufficient to validate an expected HR for OS of metabolic responders compared to metabolic non-responders significantly <1 (with 80% power and 1-sided 5% α in case of a true HR≤0.59 and a responders rate of 47%).

ETHICS AND DISSEMINATION

The study was approved by the Institut Jules Bordet's competent ethics committee and complies with the Helsinki declaration or the Belgian laws and regulations, whichever provides the greatest protection for the patient, and follows the International Conference on Harmonisation E 6 (R1) Guideline for Good Clinical Practice, reference number CPMP/ICH/135/95. The protocol and the trials results, even inconclusive, will be presented at international oncology congresses, and published in peer-reviewed journals. Genomic and epigenetic data will be made available in public open data sets.

TRIAL REGISTRATION NUMBERS

EudraCT number: 2012-005655-16; ClinicalTrials.gov number: NCT01929616.

Correlating tumor metabolic progression index measured by serial FDG PET-CT, apparent diffusion coefficient measured by magnetic resonance imaging (MRI) and blood genomics to patient's outcome in advanced colorectal cancer: the CORIOLAN study

Background

Metastatic colorectal cancer (mCRC) may present various behaviours that define different courses of tumor evolution. There is presently no available tool designed to assess tumor aggressiveness, despite the fact that this is considered to have a major impact on patient outcome.

Methods/Design

CORIOLAN is a single-arm prospective interventional non-therapeutic study aiming mainly to assess the natural tumor metabolic progression index (TMPI) measured by serial FDG PET-CT without any intercurrent antitumor therapy as a prognostic factor for overall survival (OS) in patients with mCRC.

Secondary objectives of the study aim to test the TMPI as a prognostic marker for progression-free survival (PFS), to assess the prognostic value of baseline tumor FDG uptake on PFS and OS, to compare TMPI to classical clinico-biological assessment of prognosis, and to test the prognostic value on OS and PFS of MRI-based apparent diffusion coefficient (ADC) and variation of vADC using voxel-based diffusion maps.

Additionally, this study intends to identify genomic and epigenetic factors that correlate with progression of tumors and the OS of patients with mCRC. Consequently, this analysis will provide information about the signaling pathways that determine the natural and therapy-free course of the disease. Finally, it would be of great interest to investigate whether in a population of patients with mCRC, for which at present no known effective therapy is available, tumor aggressiveness is related to elevated levels of circulating tumor cells (CTCs) and to patient outcome.

Discussion

Tumor aggressiveness is one of the major determinants of patient outcome in advanced disease. Despite its importance, supported by findings reported in the literature of extreme outcomes for patients with mCRC treated with chemotherapy, no objective tool allows clinicians to base treatment decisions on this factor. The CORIOLAN study will characterize TMPI using FDG-PET-based metabolic imaging of patients with chemorefractory mCRC during a period of time without treatment. Results will be correlated to other assessment tools like DW-MRI, CTCs and circulating DNA, with the aim to provide usable tools in daily practice and in clinical studies in the future.

Clinical trials.gov number

NCT01591590.

Bioluminescence imaging of stroke-induced endogenous neural stem cell response

Brain injury following stroke affects neurogenesis in the adult mammalian brain. However, a complete understanding of the origin and fate of the endogenous neural stem cells (eNSCs) in vivo is missing. Tools and technology that allow non-invasive imaging and tracking of eNSCs in living animals will help to overcome this hurdle. In this study, we aimed to monitor eNSCs in a photothrombotic (PT) stroke model using in vivo bioluminescence imaging (BLI). In a first strategy, inducible transgenic mice expressing firefly luciferase (Fluc) in the eNSCs were generated. In animals that received stroke, an increased BLI signal originating from the infarct region was observed. However, due to histological limitations, the identity and exact origin of cells contributing to the increased BLI signal could not be revealed. To overcome this limitation, we developed an alternative strategy employing stereotactic injection of conditional lentiviral vectors (Cre-Flex LVs) encoding Fluc and eGFP in the subventricular zone (SVZ) of Nestin-Cre transgenic mice, thereby specifically labeling the eNSCs. Upon induction of stroke, increased eNSC proliferation resulted in a significant increase in BLI signal between 2days and 2weeks after stroke, decreasing after 3months. Additionally, the BLI signal relocalized from the SVZ towards the infarct region during the 2weeks following stroke. Histological analysis at 90days post stroke showed that in the peri-infarct area, 36% of labeled eNSC progeny differentiated into astrocytes, while 21% differentiated into mature neurons. In conclusion, we developed and validated a novel imaging technique that unequivocally demonstrates that nestin(+) eNSCs originating from the SVZ respond to stroke injury by increased proliferation, migration towards the infarct region and differentiation into both astrocytes and neurons. In addition, this new approach allows non-invasive and specific monitoring of eNSCs over time, opening perspectives for preclinical evaluation of candidate stroke therapeutics.

In vitro and in vivo comparison of 18F and 123I-labeled ML10 with 68Ga-Cys2-AnxA5 for molecular imaging of apoptosis

AIM

Recently, 18F-labeled 2-(5-fluoropentyl)-2-methylmalonic acid or ML10 has been proposed as a promising PET tracer for imaging of apoptosis. In this study we compared 18F-ML10, the 123I labeled 5-iodo derivative (123I-ML10) and a 68Ga-labeled Annexin A5 (AnxA5) and evaluated them as apoptosis tracers in several distinct models.

METHODS

In vivo stability and biodistribution were studied in healthy mice. Apoptosis imaging was evaluated in anti-Fas treated mice and mice with muscular apoptosis. Furthermore, 18F-ML10 and 68Ga-Cys2-AnxA5 were evaluated in a rat model with reperfused liver infarct and a rat model with cerebral infarct as well as in Daudi tumor bearing mice, before and after treatment with cyclophosphamide and/or radiotherapy.

RESULTS

18F-ML10 and 68Ga-Cys2-AnxA5 were both stable, while 123I-ML10 metabolized very quickly in vivo. All tracers showed a 3-4 times higher uptake in apoptotic muscular tissue in comparison to that in healthy muscular tissue. Animals with anti-Fas induced hepatic apoptosis showed an increased liver uptake which was most pronounced for 18F-ML10. The uptake of both 18F-ML10 and 68Ga-Cys2-AnxA5 increased in the apoptotic region surrounding the cerebral infarction and the reperfused liver infarction. Tumor uptake of 68Ga-Cys2-AnxA5, but not of 18F-ML10, was statistically significantly higher after therapy as measured with PET/MRI.

CONCLUSION

All radiotracers were able to detect apoptosis in vitro and in vivo in each of the studied animal models of apoptosis. 68Ga-Cys2-AnxA5, but not 18F-ML10, allowed to visualize the effect of tumor therapy in a statistically significant way.

Preoperative chemosensitivity testing as Predictor of Treatment benefit in Adjuvant stage III colon cancer (PePiTA): protocol of a prospective BGDO (Belgian Group for Digestive Oncology) multicentric study

Background

Surgery is a curative treatment for patients with locally advanced colon cancer, but recurrences are frequent for those with stage III disease. FOLFOX adjuvant chemotherapy has been shown to improve recurrence-free survival and overall survival by more than 20% and is nowadays considered a standard of care. However, the vast majority of patients will not benefit from receiving cytotoxic drugs because they have either already been cured by surgery or because their tumor cells are resistant to the chemotherapy, for which predictive factors are still not available.

Identifying which patients are unlikely to respond to adjuvant chemotherapy from among those who are eligible for such treatment would be a major step towards treatment personalization. It would spare such patients from unnecessary toxicities and would improve the allocation of societal healthcare resources.

Methods/design

PePiTA is a prospective, multicenter, non-randomised trial built on the hypothesis that preoperative chemosensitivity testing using FDG-PET/CT before and after one course of FOLFOX can identify the patients who are unlikely to benefit from 6 months of adjuvant FOLFOX treatment for stage III colon cancer.

The study’s primary objective is to examine the ability of PET/CT-assessed tumor FDG uptake after one course of preoperative chemotherapy to predict the outcome of adjuvant therapy, as measured by 3-year disease-free survival.

Secondary objectives are to examine the predictive value of changes in PET/CT-assessed tumor FDG uptake on overall survival, to define the best cut-off value of FDG uptake for predicting treatment outcome, and to analyse the cost-effectiveness of such preoperative chemo-sensitivity testing.

At study planning, exploratory translational research objectives were 1) to assess the predictive value of circulating tumor cells for disease-free survival, 2) to examine the predictive value of single nucleotide polymorphisms for disease-free survival with respect to genes related either to toxicity or to drug targets, 3) to assess genomic rearrangements associated with response or resistance to FOLFOX treatment, 4) to identify an immunologic signature associated with metabolic tumor response to FOLFOX therapy and, finally, 5) to create a bank of frozen tumor samples for future studies.

Discussion

PePiTA is the first study to use the primitive tumor chemosensitivity assessed by metabolic imaging as a guidance for adjuvant therapy in colon cancer. It could pave the way for tailoring the treatment and avoiding useless toxicities for the patients and inadequate expenses for the society. It could also give an interesting insight into tumoral heterogeneity, resistance to chemotherapy, genetic predisposants to oxaliplatin toxicity and immune response to cancer.

EudraCT number

2009-011445-13

Trial registration

ClinicalTrials.gov number, NCT00994864

Preclinical evaluation of [11C]NE40, a type 2 cannabinoid receptor PET tracer

INTRODUCTION

Up-regulation of the type 2 cannabinoid receptor (CB(2)R) has been reported in (neuro)inflammatory diseases. In this study, we report the preclinical evaluation of [(11)C]NE40 as positron emission tomography (PET) radioligand for visualization of the CB(2)R.

METHODS

The selectivity of NE40 for CB(2)R and its toxicity and mutagenicity were determined. [(11)C]NE40 was evaluated by biodistribution and autoradiography studies in normal rats and a microPET study in normal mice, rats and a rhesus monkey. Specific in vivo binding of [(11)C]NE40 to human CB(2)R (hCB(2)R) was studied in a rat model with hCB(2)R overexpression.

RESULTS

[(11)C]NE40 shows specific CB(2)R binding in the spleen and blood of normal rats and high brain uptake in rhesus monkey. [(11)C]NE40 showed specific and reversible binding to hCB(2)R in vivo in a rat model with local hCB(2)R overexpression.

CONCLUSIONS

[(11)C]NE40 shows favorable characteristics as radioligand for in vivo visualization of the CB(2)R and is a promising candidate for hCB(2)R PET imaging.

Characterization of the inflammatory response in a photothrombotic stroke model by MRI: implications for stem cell transplantation

PURPOSE

The aim of this study was to evaluate the specificity of magnetic resonance imaging (MRI) contrast in a photothrombotic (PT) stroke model with and without engraftment of superparamagnetic iron oxide (SPIO)-labeled stem cells.

PROCEDURES

We monitored animals with PT stroke versus animals with PT stroke and stem cell engraftment by T(2)/T(2)*w MRI 4-8 h and 2, 4, 6/7 and 14 days after PT induction. Results were correlated with immunohistochemistry.

RESULTS

T(2)*w MRI images showed hypointense contrast due to the accumulation of inflammatory cells and corresponding iron accumulation and glial scar formation in the border zone of the lesion, similar as what was observed for SPIO-labeled cells. Histological analysis was thus indispensable to distinguish between labeled transplanted cells and immune cells.

CONCLUSION

These results raise caution regarding the non-invasive monitoring of SPIO-labeled transplanted stem cells by MRI in models that result in a strong inflammatory response.

Synthesis, in vitro and in vivo evaluation of fluorine-18 labelled FE-GW405833 as a PET tracer for type 2 cannabinoid receptor imaging

The type 2 cannabinoid receptor (CB₂R) is part of the endocannabinoid system and is expressed in tissues related to the immune system. As the CB₂R has a very low brain expression in non-pathological conditions, but is upregulated in activated microglia, it is an interesting target for visualization of neuroinflammation using positron emission tomography with a suitable radiolabeled CB₂R ligand. In this study, we radiolabelled a fluoroethyl derivative of GW405833, a well known CB₂R partial agonist, with fluorine-18 (half-life 109.8 min) by alkylation of the phenol precursor with 1-bromo-2-[¹⁸F]fluoroethane. In vitro studies showed that FE-GW405833 behaved as a selective high affinity (27 nM) inverse agonist for hCB₂R. [¹⁸F]FE-GW405833 showed moderate initial brain uptake in mice and rats, but a slow washout from brain and plasma due to retention of a radiometabolite. Specific binding of the tracer to human CB₂R was demonstrated in vivo in a rat model with local CB₂R overexpression in the brain. Optimized derivatives of GW405833 that are less susceptible to metabolism will need to be developed in order to provide a useful tracer for CB₂R quantification with PET.

A PET brain reporter gene system based on type 2 cannabinoid receptors

PET of gene expression in the brain may greatly facilitate neuroscience research and potential clinical implementation of gene or cell therapy of central nervous system diseases. To date, no adequate PET reporter system is available for the central nervous system because available tracers either do not cross the intact blood-brain barrier or have high background signals. Here we report the first, to our knowledge, PET reporter system for imaging gene expression in the intact brain.

METHODS

We selected the human type 2 cannabinoid receptor (hCB(2)) as a reporter because of its low basal expression in the brain. An inactive mutant (D80N) was chosen so as not to interfere with signal transduction. As a reporter probe we used the (11)C-labeled CB(2) ligand, (11)C-GW405833, which readily crosses the blood-brain barrier. Dual-modality imaging lentiviral and adeno-associated viral vectors encoding both hCB(2)(D80N) and firefly luciferase or enhanced green fluorescent protein were engineered and validated in cell culture. Next, hCB(2)(D80N) was locoregionally overexpressed in rat striatum by stereotactic injection of lentiviral and adeno-associated viral vectors.

RESULTS

Kinetic PET revealed specific and reversible CB(2) binding of (11)C-GW405833 in the transduced rat striatum. hCB(2) and firefly luciferase expression was followed until 9 mo and showed similar kinetics. Both hCB(2) expression and enhanced green fluorescent protein expression were confirmed by immunohistochemistry.

CONCLUSION

Dual-modality imaging viral vectors encoding hCB(2)(D80N) were engineered, and the reporter system was validated in different animal species. The results support the potential future clinical use of CB(2) as a PET reporter in the intact brain.

Metabolic and type 1 cannabinoid receptor imaging of a transgenic rat model in the early phase of Huntington disease

Several lines of evidence imply early alterations in metabolic and endocannabinoid neurotransmission in Huntington disease (HD). Using [(18)F]MK-9470 and small animal PET, we investigated for the first time cerebral changes in type 1 cannabinoid (CB1) receptor binding in vivo in pre-symptomatic and early symptomatic rats of HD (tgHD), in relation to glucose metabolism, morphology and behavioral testing for motor and cognitive function. Twenty-three Sprague-Dawley rats (14 tgHD and 9 wild-types) were investigated between the age of 2 and 11 months. Relative glucose metabolism and parametric CB1 receptor images were anatomically standardized to Paxinos space and analyzed voxel-wise. Volumetric microMRI imaging was performed to assess HD neuropathology. Within the first 10 months, bilateral volumes of caudate-putamen and lateral ventricles did not significantly differ between genotypes. Longitudinal- and genotype evolution showed that relative [(18)F]MK-9470 binding progressively decreased in the caudate-putamen and lateral globus pallidus of tgHD rats (-8.3%, p≤1.1×10(-5) at 5 months vs. -10.9%, p<1.5×10(-5) at 10 months). In addition, relative glucose metabolism increased in the bilateral sensorimotor cortex of 2-month-old tgHD rats (+8.1%, p≤1.5×10(-5)), where it was positively correlated to motor function at that time point. TgHD rats developed cognitive deficits at 6 and 11 months of age. Our findings point to early regional dysfunctions in endocannabinoid signalling, involving the lateral globus pallidus and caudate-putamen. In vivo CB1 receptor measurements using [(18)F]MK-9470 may thus be a useful early biomarker for HD. Our results also provide evidence of subtle motor and cognitive deficits at earlier stages than previously described.

Automated quantitative gait analysis in animal models of movement disorders

BACKGROUND

Accurate and reproducible behavioral tests in animal models are of major importance in the development and evaluation of new therapies for central nervous system disease. In this study we investigated for the first time gait parameters of rat models for Parkinson's disease (PD), Huntington's disease (HD) and stroke using the Catwalk method, a novel automated gait analysis test. Static and dynamic gait parameters were measured in all animal models, and these data were compared to readouts of established behavioral tests, such as the cylinder test in the PD and stroke rats and the rotarod tests for the HD group.

RESULTS

Hemiparkinsonian rats were generated by unilateral injection of the neurotoxin 6-hydroxydopamine in the striatum or in the medial forebrain bundle. For Huntington's disease, a transgenic rat model expressing a truncated huntingtin fragment with multiple CAG repeats was used. Thirdly, a stroke model was generated by a photothrombotic induced infarct in the right sensorimotor cortex. We found that multiple gait parameters were significantly altered in all three disease models compared to their respective controls. Behavioural deficits could be efficiently measured using the cylinder test in the PD and stroke animals, and in the case of the PD model, the deficits in gait essentially confirmed results obtained by the cylinder test. However, in the HD model and the stroke model the Catwalk analysis proved more sensitive than the rotarod test and also added new and more detailed information on specific gait parameters.

CONCLUSION

The automated quantitative gait analysis test may be a useful tool to study both motor impairment and recovery associated with various neurological motor disorders.

Effects of MRI contrast agents on the stem cell phenotype

The ultimate therapy for ischemic stroke is restoration of blood supply in the ischemic region and regeneration of lost neural cells. This might be achieved by transplanting cells that differentiate into vascular or neuronal cell types, or secrete trophic factors that enhance self-renewal, recruitment, long-term survival, and functional integration of endogenous stem/progenitor cells. Experimental stroke models have been developed to determine potential beneficial effect of stem/progenitor cell-based therapies. To follow the fate of grafted cells in vivo, a number of noninvasive imaging approaches have been developed. Magnetic resonance imaging (MRI) is a high-resolution, clinically relevant method allowing in vivo monitoring of cells labeled with contrast agents. In this study, labeling efficiency of three different stem cell populations [mouse embryonic stem cells (mESC), rat multipotent adult progenitor cells (rMAPC), and mouse mesenchymal stem cells (mMSC)] with three different (ultra)small superparamagnetic iron oxide [(U)SPIO] particles (Resovist, Endorem, Sinerem) was compared. Labeling efficiency with Resovist and Endorem differed significantly between the different stem cells. Labeling with (U)SPIOs in the range that allows detection of cells by in vivo MRI did not affect differentiation of stem cells when labeled with concentrations of particles needed for MRI-based visualization. Finally, we demonstrated that labeled rMAPC could be detected in vivo and that labeling did not interfere with their migration. We conclude that successful use of (U)SPIOs for MRI-based visualization will require assessment of the optimal (U)SPIO for each individual (stem) cell population to ensure the most sensitive detection without associated toxicity.

Actions of R- and S-verapamil and nifedipine on rat vascular and intestinal smooth muscle

1 We have investigated the actions of the calcium entry blockers nifedipine, R-verapamil and S-verapamil in rat aorta, colon and vas deferens. 2 In aorta and colon, these agents produced concentration-dependent relaxations of KCl (80 mM)-induced contractions. In both tissues, the order of potency was nifedipine > S-verapamil > R-verapamil. However, nifedipine showed selectivity for aorta (potency ratio, colon/aorta: 4.36), S-verapamil showed no selectivity (0.62), but R-verapamil showed selectivity for colon (0.19). 3 In prostatic portions of rat vas deferens, nifedipine (10 microM) abolished the contraction to a single electrical stimulus, but R- and S-verapamil were without effect. In epididymal portions of rat vas deferens, R- and S-verapamil inhibited alpha1-adrenoceptor-mediated contractions to a single electrical stimulus at concentrations of 10 microM and above. 4 In conclusion, R-verapamil may prove useful as an intestinal selective calcium entry blocker in the treatment of intestinal disease with a hypermotility component, e.g. irritable bowel syndrome.

Lack of involvement of pertussis toxin-sensitive G-proteins in norepinephrine-induced vasoconstriction of rat aorta smooth muscle

Several studies have shown that stimulation of pertussis toxin (PTX)-sensitive G-proteins amplified alpha-adrenoceptor (alpha-AR) agonist-induced vasoconstriction in small muscular and resistance arteries. The aim of this study was to assess the potential involvement of PTX-sensitive G-proteins in norepinephrine (NE)-induced constriction in a large diameter artery, the rat aorta. PTX (1 microg/mL, 2 hr; 3 microg/mL, 4 hr) did not modify concentration-response curves to NE in endothelium-denuded aortic rings. However, several lines of evidence suggested that aortic smooth muscle cells (SMC) had a PTX-sensitive G-protein pathway. [alpha-(32)P]ADP-ribosylation of G(i/o)-proteins by PTX (3 microg/mL, 4 hr) was demonstrated in situ in the intact aorta without endothelium. alpha(i/o) subunits were identified in vitro by both immunoblotting and ADP-ribosylation experiments in rat aorta SMC membranes. The measurement of G(i/o)-specific GTPase activity evidenced an effective coupling between NE receptors and G(i/o)-proteins, as NE induced an increase in basal G(i/o)-specific GTPase activity (20.7 +/- 2.8 vs 7.2 +/- 2.2 pmol P(i)/mg protein at 5 min; P < 0.05 vs basal). Co-immunoprecipitation revealed the in vitro coupling between alpha(1D)-ARs and G(i)-protein in rat aorta SMC membranes. In conclusion, we identified a PTX-sensitive G(i/o)-protein pathway in rat endothelium-denuded aorta. We showed an effective coupling between NE receptors and G(i)-proteins via alpha(1D)-ARs. Since PTX has no effect on NE-induced vasoconstriction, the PTX-sensitive G(i)-protein pathway does not play a predominant role in NE-induced responses in rat aorta SMC in contrast to small diameter muscular and resistance arteries.

Melatonin potentiates NE-induced vasoconstriction without augmenting cytosolic calcium concentration

Because little is known of the intracellular mechanisms involved in the vasoconstrictor effect of melatonin (Mel), we examined the in vitro effects of Mel by using perfused cylindrical segments of the rat tail artery loaded with the intracellular Ca(2+) concentration ([Ca(2+)](i))-sensitive fluorescent dye, fura 2. Mel (10(-14) to 10(-4) M) had no effect on baseline perfusion pressure or [Ca(2+)](i) but increased, at submicromolar concentrations, the vasoconstrictor effect of norepinephrine (NE) (P = 0.0029). Mel did not modify NE-induced [Ca(2+)](i) mobilization, and thus the [Ca(2+)](i) sensitivity of NE-induced contraction increased in the presence of Mel. Mel consistently increased KCl-induced vasoconstriction and [Ca(2+)](i) sensitivity of contraction, but differences were not statistically significant. In conclusion, Mel increases the [Ca(2+)](i) sensitivity of vasoconstriction evoked by NE suggesting that Mel may amplify endogenous vasoconstrictor responses to sympathetic outflow.

A microtiter plate assay for total glutathione and glutathione disulfide contents in cultured/isolated cells: performance study of a new miniaturized protocol

The microtiter plate technique reported by Baker and colleagues for the glutathione reductase-DTNB recycling assay of total glutathione (GSx) and glutathione disulfide (GSSG) has been modified according to Anderson's recommendations, in order to improve the reliability and accuracy of this miniaturized method for the measurement of glutathione status in cultured/isolated cells. Dilute HCl (10 mmol/L) has been used to lyse cells, before protein removal by centrifugation in the presence of 1.3% sulfosalicylic acid. The final DTNB, GSSG-reductase and NADPH concentrations in the reaction mixture have been increased to 0.7 mmol/L, 1.2 IU/ml and 0.24 mmol/L, respectively. The procedure specificity has been tested by spiking and dilution assays, showing that about 90% of the expected GSx amounts could actually be recovered, while no changes of GSSG concentrations were caused in the cells. Accuracy has been assessed by analysis of within-series precision as well as of intra- and interassay reproducibility, showing coefficient variation of < 10%. Glutathione changes measured either in control rat hepatocytes or in primary cultures treated with paracetamol or menadione were in good agreement with well-known literature data. These data suggest that the experimental conditions reported in this paper are suitable for the analysis of total glutathione and glutathione disulfide concentrations in cultured/isolated cells.