Application of liquid biopsies in metastatic gastrointestinal cancer to identify candidate therapeutic targets

1P Application of liquid biopsies in metastatic gastrointestinal cancer to identify candidate therapeutic targets L. Pe´rez 1 , P. Saiz L opez 2 ,R.S  anchez-Escribano 3 , A. Rodrigo 4 , M. Garc  ıa Gonz alez 3 , M. Dur an 5 , M. Infante 5 , A. Terradez 4 , I. Faull 6 , E.A. Lastra 7 1 Facultad de Ciencias, Universidad de Burgos, Burgos, Spain, 2 Department of Pathological Anatomy, Complejo Hospitalario de Burgos - Hospital General Yagu¨e, Burgos, Spain, 3 Complejo Hospitalario de Burgos - Hospital General Yagu¨e, Burgos, Spain, 4 Scientific Department, BioSequence-OncoDNA, Paterna, Valencia, Spain, 5 Instituto de Biolog  ıa y Gene´tica Molecular (IBGM), Valladolid, Spain, 6 Guardant Health, Barcelona, Spain, 7 Complejo Hospitalario de Burgos - Hospital General Yagu¨e, Burgos, Spain Background: Next-generation sequencing (NGS) of cell-free tumor DNA (ctDNA) has great potential for liquid biopsy in cancer diagnostics and to identify patients with actionable genomic alteration. This study, a prospective longitudinal study, focused in a cohort of metastatic cancer patients without standard effective active antineoplastic medical treatment options to establish the rate of patients with actionable genomic alteration and the rate of patients accessing medical treatment. The final objective was to determine the clinical performance based on non-invasive tumor sequencing. Methods: We collected plasma of 10 metastatic gastrointestinal patients with known status of the RAS genes and microsatellites instability in tumor tissue. CtDNA was extracted from plasma and genomic alterations were analyzed by Guardant 360 (Guardant Health, Biosequence, OncoDNA), a next generation sequencing panel. This panel consists of 73 cancer related genes and is able to identify different types of genomic alterations. Informed consent was obtained from all patients. Results: We were able to identify 78 somatic mutations in total resulting in a median number of eight somatic mutations per patient. The most common altered genes are well known tumor suppressor and oncogenes like TP53, APC, KRAS, MYC andEGFR. At least one actionable alteration in plasma cfDNA were detected in eight from the 10 patients (80%) but the proportion of patients for which a genomic identified recommended therapy was available to effectively initiate the treatment were only 37,5% (3/8). In these patients, the identification of alterations like c-MET amplification, FGFR1 amplification or PIK3CA c.1633G>A (p.E545K) mutation, involved in clinically actionable pathways, allowed the selection of a specific therapy. For the rest of cases the main causes of non-access to medical treatment associated with a specific mutation were, among others, the advanced pre-treated patient and clinical trial logistical access difficulties. Conclusions: Our findings confirm the percentage of cases with potentially druggable aberrations is similar to other studies using this strategy and emphasizes their clinical value to identify candidate therapeutic targets. Legal entity responsible for the study: Dr. Enrique Lastra, Hospital de Burgos. Funding: Asociacion Caballeros Pur ısima Concepcion. Disclosure: A. Rodrigo, A. Terradez: Employee of Biosequence-OncoDNA. I. Faull: Employee of Guardant Health. All other authors have declared no conflicts of interest. 2P RETROSPHER. ERBB2 amplification detection in the plasma at diagnosis for early high-risk HER2-positive breast cancer R. Sabatier 1 , S. Garnier 2 , N. Carbuccia 2 , A. Guille 2 , C. Tarpin 1 , A. Goncalves 1 , D. Birnbaum 2 1 Medical Oncology, Institut Paoli Calmettes, Marseille, France, 2 Predictive Oncology Lab, CRCM, Aix-Marseille University, Institut Paoli-Calmettes, Marseille, France Background: Despite recent advances, early high-risk HER2-positive breast cancers (BC) have a risk of relapse close to 20%, with no validated prognostic biomarker. Circulating tumour DNA has been described to have a prognostic value for some early BC. Most published studies monitored mutations previously identified on tumour tissue. An alternate way to monitor plasma from patients with HER2-positive BC might be to look for ERBB2/HER2 amplification. Methods: We selected 40 HER2-positive high-risk early BC (cT 2 and/or Nþand/or residual disease after neoadjuvant chemotherapy) included in our institutional BCBIO-IPC 2009-005 prospective program (NCT01521676). Plasma samples were collected at diagnosis and cell-free DNA (cfDNA) was isolated using the Qiagen EZ1 ccfDNA Midi kits. We then used commercial kits (BioRad) for ERBB2 and TERT (reference gene), and looked for ERBB2 amplification by digital PCR (BioRad QX200). Results: After DNA isolation from 1.5 to 2ml of plasma, cfDNA was eluted in 55mlof buffer. The median cfDNA concentration was 0.08 ng/ll (range <0.05 - 0.306, Qubit), with 25 cases having a concentration below 0.1 ng/ll. Median concentration was 4.68 ng/ll for metastatic cases. After droplet generation, 25 samples had enough droplets to allow the reading and analysis of ERBB2 amplification results. Of these samples, 52% were amplified, the others being equivocal. None of these samples were classified as "non-ERBB2 amplified". All controls were accurately classified. Except for age (p ¼0.05, T-test), identification of circulating ERBB2 amplification did not correlate to usual clinicopathological features, including survival (but relapse (12%) and deaths (8%) rates were low in this set). However, it tended to be correlated to cfDNA concentration (p ¼0.06, T-test). Conclusions: ERBB2 amplification detection in plasma is feasible and can be observed for more than 50% of patients with early high-risk HER2-positive BC. If confirmed, these results may lead to propose plasma ERBB2 amplification monitoring at diagnosis and during follow-up, to optimize the systemic management in case of persistence or increase of ERBB2 amplification during or after standard treatments. Clinical trial identification: NCT01521676. Legal entity responsible for the study: Institut Paoli Calmettes. Funding: Novartis. Disclosure: R. Sabatier: This work has been partly funded by Novartis. All other authors have declared no conflicts of interest. 3P Autotaxin: A possible new biological marker of endometrial cancer R. de Nola 1 , E. di Naro 2 , L.M. Schonauer 2 , M. Loverro 3 , T. Marrano 2 , A. Mazzocca 4 1 Tissues and Organs Transplantation and Cellular Therapies, D.E.O.T., University of Bari, Bari, Italy, 2 Interdisciplinary Department of Medicine, Gynaecology and Obstetrics Clinic; School of Medicine, University of Bari, Bari, Italy, 3 Department of Obstetrics and Gynaecology, Division of Gynaecologic Oncology, Teaching and Research Hospital "Agostino Gemelli" Foundation, Rome, Italy, 4 Interdisciplinary Department of Medicine; Experimental Pathology and Laboratory Medicine; School of Medicine, University of Bari, Bari, Italy Background: Endometrial cancer is the most common neoplasm of the female genital tract in Western Countries, with an incidence of 150000 new cases/year. Despite its high frequency, limited data are available about its molecular features. It is known that phospholipids play a key role in the cellular proliferation and dissemination in many human diseases. Some previous studies have demonstrated the importance of the lysophosphosphatidic acids’ (LPAs) metabolism and their signalling pathways in human endometrial cells. LPAs are produced via phospholipase A2 (PLA2) and phospholipase D (PLD), also known as autotaxin (ATX). Methods: In the present work, we performed a prospective study involving 60 patients divided into three groups after a hysteroscopic guided biopsy: the first included 26 patients with a histological diagnosis of endometrial cancer; the second was made of 5 patients affected by histologically evidenced endometrial hyperplasia without atypia; the third was composed of 29 patients characterized by benign condition. All the groups underwent hysterectomy, with either open or laparoscopic surgery, and a second endometrial biopsy on the surgical specimen, in order to perform a quantitative real-time PCR using pre-designed ATX/PLD primers. Significant differences between groups were determined via unpaired two-way or one-way Student’s t test and ANOVA. A Pvalue <0.05 was considered statistically significant. Results: From our data, we demonstrated a strong positive correlation between the gene expression of ATX in the surgical specimen and the endometrial cancers. Notably, we found other statistically significant results from the analysis of the population affected by endometrial cancer. In particular, the expression of autotaxin gene was higher in the endometrioid histotype, in case of type I endometrial cancer versus type II, in pre-menopausal women, in obese patients (BMI>30) or in women with diabetes. Conclusions: We could consider a possible role of ATX as a biomarker of endometrial cancer, mostly in endometrioid histotypes, reflecting the pathogenic conditions of type I endometrial cancer. Legal entity responsible for the study: University of Bari, Italy. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest. V C2018 by the Molecular Analysis for Personalised Therapy (MAP) organisers: ESMO, CRUK and UNICANCER. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected]. Annals of Oncology 29 (Supplement 6): vi1–vi3, 2018 doi:10.1093/annonc/mdy316 EARLY DETECTION AND DIAGNOSIS (CIRCULATING DNA)