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Background: Gastric cancer (GC) is clinically heterogenous according to location (cardia/non-cardia) and histopathology (diffuse/intestinal). We aimed to characterize the genetic risk architecture of GC according to its subtypes. Another aim was to examine whether cardia GC and oesophageal adenocarcinoma (OAC) and its precursor lesion Barrett's oesophagus (BO), which are all located at the gastro-oesophageal junction (GOJ), share polygenic risk architecture. Methods: We did a meta-analysis of ten European genome-wide association studies (GWAS) of GC and its subtypes. All patients had a histopathologically confirmed diagnosis of gastric adenocarcinoma. For the identification of risk genes among GWAS loci we did a transcriptome-wide association study (TWAS) and expression quantitative trait locus (eQTL) study from gastric corpus and antrum mucosa. To test whether cardia GC and OAC/BO share genetic aetiology we also used a European GWAS sample with OAC/BO. Findings: Our GWAS consisting of 5816 patients and 10,999 controls highlights the genetic heterogeneity of GC according to its subtypes. We newly identified two and replicated five GC risk loci, all of them with subtype-specific association. The gastric transcriptome data consisting of 361 corpus and 342 antrum mucosa samples revealed that an upregulated expression of MUC1, ANKRD50, PTGER4, and PSCA are plausible GC-pathomechanisms at four GWAS loci. At another risk locus, we found that the blood-group 0 exerts protective effects for non-cardia and diffuse GC, while blood-group A increases risk for both GC subtypes. Furthermore, our GWAS on cardia GC and OAC/BO (10,279 patients, 16,527 controls) showed that both cancer entities share genetic aetiology at the polygenic level and identified two new risk loci on the single-marker level. Interpretation: Our findings show that the pathophysiology of GC is genetically heterogenous according to location and histopathology. Moreover, our findings point to common molecular mechanisms underlying cardia GC and OAC/BO. Funding: German Research Foundation (DFG).

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.

175 Background: The potential of monitoring circulating tumor DNA (ctDNA) dynamics to guide clinical decisions in metastatic colorectal cancer (mCRC) patients (pts) treated with I and II line systemic anti-cancer therapy (SACT) has not been widely tested. Methods: 862 serial plasmas were collected 4-weekly from baseline (BL) until disease progression in 75 mCRC pts undergoing SACT. ctDNA was tested using a custom (RMH GI; 20 genes) or a commercial (Roche Avenio; 77 genes) ctDNA next generation sequencing (NGS) panel. White blood cells were sequenced to rule out clonal hematopoiesis. Whole exome sequencing (WES) was performed on tissue biopsies. ctDNA normalization was defined as ≥99% clearance after 1 month of therapy (Mo1) in the 3 variants with the highest allele frequency in BL ctDNA. Results: 83 paired samples from 75 pts were available for analysis (for 8 pts, I and II line bloods were available). 12 pairs (14.4%) showed no variants in either BL or Mo1. In the remaining 71 comparisons (65 pts), 37 (52.1%) showed ctDNA normalization at Mo1. Among normalized pts there was a higher proportion of cases with a baseline ECOG performance status (PS) 0-1 (97.3% vs 82.4%, p = 0.0362) in comparison to non-normalized pts, whilst no other clinic-pathologic characteristics, including age, sex, prior primary tumor resection, sidedness, RAS/RAF genotype, type of regimen and number of metastatic sites were significantly associated with ctDNA dynamics. Pts with normalized ctDNA had significantly longer overall survival (OS), 45.6 months (95% confidence interval [CI]: 30.0 - not reached, 14 events) and progression-free survival (PFS), 13.9 months (95%CI: 11.2-18.3; 30 events) compared to non-normalized pts [OS = 22.6 months (95%CI: 16.6-31.2, 24 events) (Log-rank p = 0.01) and PFS = 10.7 months (95%CI: 7.53-13.8; 32 events) (Log-rank p = 0.036) respectively]. In addition, pts with normalized ctDNA had higher overall response rate (ORR) of 72.9% (27/37 responses; 95%CI: 53.0-84.1) compared to 38.2% (13/34 responses; 95%CI: 22.1 – 56.4) in non-normalized pts. In a multivariate model, ctDNA normalization was confirmed as an independent predictor of decreased risk of death (hazard ratio [HR] 0.47, 95%CI: 0.23-0.96; p = 0.04) and higher probability of achieving an objective response from front-line treatment (odds ratio [OR] 3.03, 95%CI: 1.08-8.49; p = 0.0351). Only 23/50 (46%) of variants detected in ctDNA were detected by WES in paired tissues in 12 pts for whom liquid/solid biopsy was available. Conclusions: ctDNA monitoring represents an early indicator of benefit from systemic therapy in mCRC pts. A significant fraction of variants detected in ctDNA was not detected in paired tissues.

Human hepatocellular carcinoma (HCC) is the most frequent primary tumor of the liver and the third cause of cancer-related deaths. The multikinase inhibitor sorafenib is a systemic drug for unresectable HCC. The identification of molecular biomarkers for the early diagnosis of HCC and responsiveness to treatment are needed. In this work, we performed an exploratory study to investigate the longitudinal levels of cell-free long ncRNA GAS5 and microRNAs miR-126-3p and -23b-3p in a cohort of 7 patients during the period of treatment with sorafenib. We used qPCR to measure the amounts of GAS5 and miR-126-3p and droplet digital PCR (ddPCR) to measure the levels of miR-23b-3p. Patients treated with sorafenib displayed variable levels of GAS5, miR-126-3p and miR-23b-3p at different time-points of follow-up. miR-23b-3p was further measured by ddPCR in 37 healthy individuals and 25 untreated HCC patients. The amount of miR-23b-3p in the plasma of untreated HCC patients was significantly downregulated if compared to healthy individuals. The ROC curve analysis underlined its diagnostic relevance. In conclusion, our results highlight a potential clinical significance of circulating miR-23b-3p and an exploratory observation on the longitudinal plasmatic levels of GAS5, miR-126-3p and miR-23b-3p during sorafenib treatment.

Predictive factors for adverse events in metastatic colorectal cancer patients treated with regorafenib are currently lacking. In this safety analysis of a prospective phase II clinical trial, we assess the association between several clinical, laboratory, and imaging parameters and the occurrence of adverse events. Our results show that female sex is an independent risk factor for increased toxicity. 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

SCOPUS: le.j, info:eu-repo/semantics/published

Background Despite recent improvements, management of locally advanced rectal cancer (LARC) remains challenging, and many patients (pts) still experience recurrence. In preclinical models, combining Rego with an anti-PD-1 inhibitor led to superior tumour growth suppression as compared with either treatment alone. In a phase I clinical trial, remarkable results were reported for the combination of Rego and Nivo in advanced MSS colorectal cancer. This synergistic effect is thought to be secondary to the anti-angiogenic effects of Rego and its potential to reduce TAMs, promote M1 macrophage conversion, and downregulate expression of immunosuppressive factors. Building on these data, we designed a trial of Rego-Nivo with standard SCRT in the neoadjuvant setting of RC. Trial design REGINA is an academic, multicentre, single-arm, phase II trial sponsored by Institut Jules Bordet. Eligible patients are treated according to the following plan: induction phase (Nivo 240 mg IV D1&15, and Rego 80 mg PO D1-14), SCRT (D22-26), consolidation phase (Nivo 240 mg IV D29,43&57, and Rego 80 mg PO D29-49), and surgery (7-8 weeks after SCRT). Key eligibility criteria include age ≥18 years, ECOG PS ≤1, adenocarcinomas below the peritoneal reflection, intermediate-risk, stage II-III tumour (ie, cT3/T4aNany or cT1-2N+, no involvement/threatening of the mesorectal fascia, no involvement of lateral pelvic lymph nodes). The primary endpoint is pathological complete response (pCR). Secondary endpoints include, among others, toxicity, compliance to treatment, pTRG, event-free survival, and overall survival. The study follows a Simon’s two-stage design (null hypothesis pCR=12%, alternative hypothesis pCR=24%; α=5%, β=20%) with a maximum of 60 pts to be enrolled. A safety interim analysis is planned after the first 6 pts have completed treatment. Serial collection of tumour, blood, and stool samples is mandatory at pre-specified time points for exploratory correlative biomarker analyses. The trial is planned to be run at 8-10 centres across Belgium. Study recruitment started in Q1 2021 and is anticipated to complete in Q3 2023. Clinical trial information: NCT04503694.

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 &le, 1 and an estimated life expectancy of &ge, 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&ndash, 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&ndash, 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 &lt, 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 &gt, 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.

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.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.Tumor samples from 1064 patients with varying tumor types were tested, the number of NGS requests increasing over time (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.

TPS226 Background: Despite recent improvements, management of locally advanced rectal cancer (LARC) remains challenging, and many patients (pts) still experience recurrence. In preclinical models, combining Rego with an anti-PD-1 inhibitor led to superior tumour growth suppression as compared with either treatment alone. In a phase I clinical trial, remarkable results were reported for the combination of Rego and Nivo in advanced MSS colorectal cancer. This synergistic effect is thought to be secondary to the anti-angiogenic effects of Rego and its potential to reduce TAMs, promote M1 macrophage conversion, and down-regulate expression of immunosuppressive factors. Building on these data, we designed a trial of Rego-Nivo with standard SCRT in the neoadjuvant setting of RC. Methods: REGINA is an academic, multicentre, single-arm, phase II trial sponsored by Institut Jules Bordet. Eligible patients are treated according to the following plan: induction phase (Nivo 240 mg IV D1&15, and Rego 80 mg PO D1-14), SCRT (D22-26), consolidation phase (Nivo 240 mg IV D29,43&57, and Rego 80 mg PO D29-49), and surgery (7-8 weeks after SCRT). Key eligibility criteria include age ≥18 years, ECOG PS ≤1, adenocarcinomas below the peritoneal reflection, intermediate-risk, stage II-III tumour (ie, cT3/T4aNany or cT1-2N+, no involvement/threatening of the mesorectal fascia, no involvement of lateral pelvic lymph nodes) irrespective of microsatellite instability status. The primary endpoint is pathological complete response (pCR). Secondary endpoints include, among others, toxicity, compliance to treatment, pathological tumour regression grade, event-free survival, and overall survival. Subjects will be followed for recurrence and survival for 5 years after end of treatment visit. The study follows a Simon’s two-stage design (null hypothesis pCR = 12%, alternative hypothesis pCR = 24%; α= 5%, β= 20%) with a maximum of 60 pts to be enrolled. A safety interim analysis is planned after the first 6 pts have completed treatment. Serial collection of tumour, blood, and stool samples is mandatory at pre-specified time points for exploratory correlative biomarker analyses. The trial is planned to be run at 8-10 centres across Belgium. Study recruitment started in Q1 2021 and is anticipated to complete in Q3 2023. The study is funded by Bayer. Clinical trial information: NCT04503694.

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.

Introduction: Monoclonal antibodies against the Epidermal Growth Factor Receptor (EGFR) such as cetuximab or panitumumab are used for the treatment of metastatic colorectal cancer (mCRC) patients. Unfortunately, most patients develop resistance against these therapies within months. Several studies have shown that aberrations in the RAS pathway are responsible for resistance. However, even in metastases that are refractory to anti-EGFR treatment a significant fraction of RAS wild-type (wt) cells remain. These findings suggest a cross-talk between RAS mutant and wt cells in mediating resistance in the wt compartment. Methods: Mouse and patient-derived organoids from mCRC as well as CRC cell lines were used to test the contribution of extracellular vesicles in mediating resistance in RAS wt cells. Using conditioned media, transfection experiments and liquid biopsies (plasma and urine) from patients differential expression of the let-7g microRNA was demonstrated in microvesicles from cetuximab sensitive and resistant cells. Changes in expression of let-7g were further analyzed by in-situ hybridization in tissues. Results: Conditioned media from RAS mutant organoids rendered RAS wt organoids resistant against cetuximab treatment. Basal let-7g expression from pre-treatment plasma and urine samples of RAS wt patients correlated with clinical outcome and changes in let-7g circulating levels mirrored clinical behavior. In-situ hybridization in tissues confirmed changes in expression of the let-7g microRNA observed in plasma and urine samples. Conclusions: Our data suggest that let-7g microRNA might function as a paracrine mediator of anti-EGFR resistance and might be exploited as a non-invasive biomarker of resistance to cetuximab treatment. Further work is ongoing to characterize the molecular mechanisms underpinning let-7g mediated effect on anti-EGFR sensitivity in RAS wt CRC cells. Citation Format: Jens C. Hahne, Andrea Lampis, Michele Ghidini, Margherita Ratti, Chiara Senti, Rodolfo Passalacqua, Luciano Cascione, Chiara Braconi, Owen Sansom, Matteo Fassan, Nicola Valeri. Expression of exosomal let-7g in biofluids and outcome in colon cancer patient treated with anti-EGFR therapy [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 2373.

3600 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.

Background Monoclonal antibodies against the Epidermal Growth Factor Receptor (EGFR) such as cetuximab or panitumumab are used for the treatment of metastatic colorectal cancer (mCRC) patients. Unfortunately, most patients develop resistance against these therapies within months. Several studies have shown that aberrations in the RAS pathway are responsible for resistance. However, even in metastases that are refractory to anti-EGFR treatment a significant fraction of RAS wild-type (wt) cells remain. These findings suggest a cross-talk between RAS mutant and wt cells in mediating resistance in the wt compartment. Methods We used mouse and patient-derived organoids from mCRC as well as CRC cell lines to test the contribution of extracellular vesicles in mediating resistance in RAS wt cells. Using conditioned media, transfection experiments and liquid biopsies (plasma and urine) from patients differential expression of the let-7g microRNA was demonstrated in microvesicles from cetuximab sensitive and resistant cells. Changes in expression of the let-7g microRNA were further analysed by in-situ hybridization in tissues. Results Basal let-7g expression from pre-treatment plasma and urine samples of RAS wt patients correlated with clinical outcome and changes in let-7g circulating levels mirrored clinical behaviour. In-situ hybridization in tissues confirmed changes in expression of the let-7g microRNA observed in plasma and urine samples. Conclusions Our data suggest that let-7g microRNA might function as a paracrine mediator of anti-EGFR resistance and might be exploited as a non-invasive biomarker of resistance to cetuximab treatment. Further work is ongoing to characterize the molecular mechanisms underpinning let-7g mediated effect on anti-EGFR sensitivity in RAS wt CRC cells. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure N. Valeri: Speaker Bureau / Expert testimony: Bayer; Speaker Bureau / Expert testimony: Eli Lilly; Speaker Bureau / Expert testimony: Pfizer; Speaker Bureau / Expert testimony: Merck. All other authors have declared no conflicts of interest.

e14545 Background: Liquid biopsies (LB) allow monitoring of genetically different and co-occurring cancer cell clones present in primary tumor and all metastatic sites in parallel. In metastatic colorectal cancer (mCRC), circulating-free DNA (cfDNA) can be relevant for monitoring treatment and identification of molecular alterations resulting in disease relapse often earlier than radiological examinations. Methods: Patients with mCRC at diagnosis and treated with chemotherapy (CT) in combination with antibodies (bevacizumab, cetuximab or panitumumab) before undergoing surgery for resectable disease were included in this study. LB were collected before therapy start, every four weeks during treatment, within ten days of radiological disease evaluation, at radiological relapse and until two months after relapse. Next generation sequencing based on plasma samples was performed (testing for mutations and copy number variations covering 77 genes). Results: From February 2016 to October 2018, 14 patients having surgery after first line treatment were included herein; median follow-up was 21.5 months. Five of them had RAS wild-type disease and received CT plus anti-EGFR treatment, while nine RAS mutated mCRC patients received bevacizumab. Surgery was radical in 10 cases, with no further treatment. In four cases, surgery was not radical and required further treatment. Disease relapse happened in seven cases, with subsequent death in three cases. In six out of seven cases, gene alterations were already detected in the pre-operative cfDNA. In the seven cases without disease relapse, gene variants were detected even after the surgery in two patients despite receiving radical resection. Median number of gene variants was two. Beside the well-established mutations in TP53 gene, both APC and ROS1 gene mutations were frequent, while further evaluations are required for the other variants detected. Conclusions: Evaluation of cfDNA mutations in LB from mCRC may be a useful tool for monitoring clinical response and predict treatment outcome. Moreover, this molecular analysis can help to subgroup patients with regard to risk of relapse after radical surgery. Indeed, cfDNA mutations present before surgery seem to be an indication for a higher risk of post-surgery disease relapse.

e15566 Background: Identification of prognostic biomarkers for gastric cancer (GC) patient selection is compelling to improve survival outcomes. Microsatellite instability (MSI) is related with a positive prognostic effect in GC, whereas perioperative chemotherapy resulted detrimental in this subgroup. In metastatic GC, immunotherapy with anti-PD1/PD-L1 drugs has shown promising results. Nevertheless, in early stages, data on the relation between MSI, clinic-pathological features, PD-L1 expression and overall survival (OS) remains sparse, especially in Western population. In our study, the prognostic role of MSI, clinic-pathological features and PD-L1 expression in a cohort of Italian GC patients was examined. Methods: CP data of 148 consecutive stage I-III GC pts resected in Cremona Institute between 2010 and 2014 (mostly chemo and/or radio-naive) were collected. MSI analysis was performed on tissue samples for all cases by polymerase chain reaction. PDL-1 expression, evaluated by immunohistochemistry, was assessed in MSI group. Differences between subgroups were evaluated with Chi-square test; Kaplan-Meier method and Long Rank test were used to calculate OS. Results: Female sex (p=0.012), earlier TNM stages (p=0.011) and limited nodal involvement (p=0.29) significantly correlated with MSI status. MSI is significantly associated with better prognosis, exhibiting an advantage of 28.6 months in OS compared with microsatellite stable subgroup (p

Introduction: Apatinib, a small-molecule inhibitor of vascular endothelial growth factor receptor 2, has demonstrated encouraging anti-cancer activity in gastric cancer within both in vitro and in vivo models.Areas covered: Apatinib's efficacy, tolerability and safety have been evaluated in one Phase II and one Phase III study in metastatic/advanced gastric cancer. In this review, we focus on the mechanism of action of apatinib, its pharmacokinetic profile and its clinical activity in the treatment of advanced/metastatic gastric cancer.Expert commentary: Unfortunately, as yet, there is no definitive biomarker data for apatinib in gastric cancer.

The OLTRE trial (ClinicalTrials.gov number: NCT02681562) is an open-label, ‘window of opportunity’ Phase II controlled trial to evaluate the biological activity of olaparib in locally advanced triple-negative breast cancer compared with other subtypes of locally advanced breast cancer patients carrying germinal BRCA mutation receiving olaparib with the same treatment approach. The primary end point is to investigate the correlation between baseline gene and protein expression profile in order to identify possible predictive markers of response to olaparib. The OLTRE trial is expected to identify the surrogate markers of the biological activity of olaparib in the treatment of patients with triple-negative breast cancer.

e16079Background: Surgical resection remains the only curative treatment option for non-metastatic gastric cancer (GC). A large cohort of GCs from a high-volume Italian center was analyzed to descr...

Small cell lung cancer (SCLC) is a lethal disease with a very restricted armamentarium of active treatments. In the new era of targeted therapies, several attempts based on the combination of chemotherapy with new compounds has been made but with a low rate of success. The idea of using the new targeted therapies as maintenance treatment after their combination with chemotherapy has been pursued. The aim of the present study was to analyze the available clinical data regarding the effect of the targeted agents as maintenance therapy on survival in patients with SCLC. A literature-based meta-analysis of randomized controlled trials, in accordance with the preferences for reported items in systematic reviews and meta-analyses guidelines, was performed. PubMed, the Cochrane Library, and a search of abstracts presented at American Society of Clinical Oncology meetings were searched for relevant studies. The primary outcome was overall survival (OS). Nine studies, with a total of 1385 patients, were included. The pooled analysis revealed that the new targeted therapies did not improve survival compared with the control arm (placebo, hazard ratio, 1.02; 95% confidence interval, 0.91-1.15; P = .69). However, a small advantage in the 1-year OS rate (risk ratio, 1.21; 95% confidence interval, 0.9-1.63; P = .21) was observed. Maintenance with targeted therapies failed to improve the survival of patients with SCLC with an increased rate of toxicity. The detected survival advantage suggests that perhaps the maintenance approach could be used to increase the 1-year OS rate. However, this finding requires confirmation in further studies, perhaps of patients selected according to their tumor biologic profile.

Background The VERITAS (A Phase 1B open-label study to assess the safety and tolerability of e ve rolimus in combination with e ri bulin in t riple-negative bre a st cancer s ) trial (EudraCT number: 2014-000135-17) is a phase Ib, open label, multicenter, dose-escalation, safety, pharmacokinetic, and pharmacodynamic study based on the combination of everolimus with eribulin in sequential cohorts of metastatic triple negative breast cancer (TNBC) patients. Patients and Methods The primary objective of the study is to identify the recommended dose of everolimus in combination with eribulin. Secondary endpoints include the assessment of pharmacokinetics and antitumor activity of the experimental treatment. The sample size is based on the Bayesisan approach with regards to the maximum tolerated dose (MTD) and maximum tolerated dose (MTD) observed. An average sample size of approximately 12 patients is deemed reasonable based on simulations. Conclusion The VERITAS trial is expected to determine the recommended dose of everolimus in combination with eribulin in TBNC. This study may open the way for further analysis of this combination in phase II studies in this orphan disease of active drug combination such as the TNBC subset.

As of today, the level of individualization of cancer therapies has reached a level that 20 years ago would be considered visionary. However, most of the diagnostic, prognostic, and therapy-predictive procedures which aim to improve the overall level of personalization are based on the evaluation of tumor tissue samples, therefore requiring surgical operations with consequent low compliance for patients and high costs for the hospital. Hence, the research of a panel of circulating indicators which may serve as source of information about tumor characteristics and which may be obtainable by a simple withdrawal of peripheral blood today represents a growing field of interest. This review aims to objectively summarize the characteristics of the currently available breast cancer circulating biomarkers, also providing an overview about the multitude of novel potential soluble predictors which are still under evaluation. Specifically, the usefulness of a so-called “liquid biopsy” will be discussed in terms of improvements of diagnosis, prognosis, and therapy-prediction, but an overview will be given also on the potentiality of the molecular characterization arising from the isolation of circulating biomarkers and cells. Although this review will focus on the specific case of the breast, in the future liquid biopsies will hopefully be available for virtually any type of neoplasms.

e15538 Background: The presence of BM in AGC is a relatively uncommon finding and has a poor prognosis [Leporini C. 2015]. At diagnosis the presence of BM occurs in approximately 10-15% of pts with AGC.[Park 2011; Silvestris 2013]. Aim of this study is to describe the main features of pts with AGC and BM at diagnosis and the prognostic implications. Methods: A consecutive series of AGC followed at Cremona Oncology Division from November 2004 to Dicember 2016 and included in three consecutive prospective trials [Dalla Chiesa M. 2011; Tomasello G. 2013], were analyzed. All pts were treated with a modified DCF (docetaxel, cisplatin, fluorouracil) given as a dose-dense regimen, every 14 days. We analyzed pts with BM at diagnosis (BMaD) and pts without BMaD. We evaluated baseline clinical and pathological parameters, the presence of coagulation disorders (CD) together with efficacy measures in the two groups. Results:218 pts with AGC were identified (38 with BMaD and 180 without BMaD).Main pts characteristics and results are reported in the Table below. Conclusions: The presence of BM at diagnosis in pts with AGC is not a rare event (21%) and identifies a population with a significantly poorer outcome and a higher incidence of CD, that need a clinical monitoring of coagulation parameters. More efforts are required to understand the reasons of the different prognosis and to find specific treatments to improve the survival. [Table: see text]

e15588 Background: Chemotherapy (CT) and chemoradiotherapy (CTRT) both in neoadjuvant (neoadj) or adjuvant (adj) setting are associated with better overall survival (OS) over surgery alone in patients (pts) with resectable gastroesophageal (GE) adenocarcinoma (ADK). The best sequence and timing of treatments have still not been defined. A large cohort of GE ADKs derived from 2 high-volume Italian centers was analyzed to describe clinical outcomes and prognostic factors. Methods: 497 patients (pts) diagnosed with GE ADK who underwent surgery with curative intent from 2007 to 2016 were considered. Variables analyzed were: age, sex, tumor location, histology, T, N, M, R, G, HER-2, Helicobacter Pylori (HP) infection, (neo)adj CT, and adj CTRT. Analysis was performed according to ITT principle. Results: Median age at diagnosis was 71 years (range 35-92). At 26.7 months (mo) median follow-up, median OS was 27.6 mo (range 1-127) and median time to recurrence (TTR) 10.8 mo (range 7.8-13.1). Adj CT was administered in 203 cases (41%); 116 pts (23%) had adj CTRT and 47 (9%) neoadj CT. Statistically significant variables for OS and/or TTR at 12 months at univariate analysis were: age, T, N, M, R, G, adj CTRT, neoadj CT and adj CT. Results of multivariate analysis (MVA) are shown in Table 1. Conclusions: Despite a short follow-up, our analysis performed on a very large cohort of consecutive pts confirms the prognostic value of T and N for both OS and TTR. Adj CT and CTRT had a significant impact on 1 year OS, while neoadj CT gave only a 12 months TTR significant benefit. Based on these results, perioperative treatment strategies should always be considered in the management of resectable GE cancer. [Table: see text]

e16012 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 .