Abstract 1866
Background
In metastatic colorectal cancer (mCRC), circulating tumour DNA (ctDNA) monitoring can be used to genotype tumors and track clonal evolution. We investigated the clearance of RAS mutated clones under chemotherapy pressure by ctDNA analysis in patients with a RAS mutated mCRC.
Methods
Patients with a RAS mutated tumour included in the prospective PLACOL study, were monitored for ctDNA. Analyzes were based on optimized targeted next generation sequencing and/or droplet-based digital PCR (ddPCR). For plasma samples without detectable mutations, we tested the methylation status of WIF1 and NPY genes using methylation-ddPCR (met-ddPCR) to validate the presence of ctDNA.
Results
Among the 36 patients with positive plasma samples for RAS mutations at inclusion, 28 (77.8%) remained RAS positive at disease progression, and 8 (22.2%) became negative. Subsequent met-ddPCR for methylated markers showed that only 2 out of the 8 patients with RAS negative plasma had detectable ctDNA at progression. Therefore, only two samples among 36 were confirmed for clearance of RAS mutation in our series.
Conclusions
This study suggests that the clearance of RAS mutations in patients treated by chemotherapy for a RAS mutated mCRC is a rare event. Monitoring tumor mutations in plasma samples should be combined with a strict control of the presence of ctDNA. The therapeutic impacts of RAS clearance need to be further explored.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
The Ministère de l’Enseignement Supérieur et de la Recherche, the Université Paris-Descartes, the Centre National de la Recherche Scientifique (CNRS), the Institut National de la Santé et de la Recherche Médicale (INSERM), the Institut National du Cancer (INCA, n° 2009-1-RT-03-US-1 and 2009-RT-03-UP5-1), the Association pour la recherche contre le cancer (ARC, no. SL220100601375), the Agence Nationale de la Recherche (ANR Nanobiotechnologies; no. ANR-10-NANO-0002-09), the SIRIC CARPEM, the ligue nationale contre le cancer (LNCC, Program “Equipe labelisée LIGUE”; no. EL2016.LNCC/VaT) and Advanced Merieux Research Grant and canceropole funding (no. 2011-1-LABEL-UP5-2).
Disclosure
H. Blons: Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Merck; Advisory / Consultancy: Amgen; Advisory / Consultancy: Boehringer Ingelheim; Advisory / Consultancy: Pfizer. V. Taly: Advisory / Consultancy: Servier; Advisory / Consultancy: Boehringer Ingelheim; Advisory / Consultancy: Raindance Technologies. W. Shu-Fang: Research grant / Funding (institution): Servier. S. Pernot: Advisory / Consultancy: Amgen; Advisory / Consultancy: Sanofi. J. Taieb: Advisory / Consultancy, Speaker Bureau / Expert testimony: Merck; Advisory / Consultancy, Speaker Bureau / Expert testimony: Roche; Advisory / Consultancy, Speaker Bureau / Expert testimony: Amgen; Advisory / Consultancy, Speaker Bureau / Expert testimony: Eli Lilly; Advisory / Consultancy, Speaker Bureau / Expert testimony: Sanofi; Advisory / Consultancy, Speaker Bureau / Expert testimony: Celgene; Advisory / Consultancy, Speaker Bureau / Expert testimony: Sirtex; Advisory / Consultancy, Speaker Bureau / Expert testimony: Shire; Advisory / Consultancy, Speaker Bureau / Expert testimony: MSD; Advisory / Consultancy, Speaker Bureau / Expert testimony: Servier; Advisory / Consultancy, Speaker Bureau / Expert testimony: Pierre Fabre. P. Laurent-Puig: Advisory / Consultancy: Amgen; Advisory / Consultancy: Merck-Serono; Advisory / Consultancy: Sanofi; Advisory / Consultancy: Boehringer Ingelheim; Advisory / Consultancy: Roche; Advisory / Consultancy: Lilly. A. Zaanan: Advisory / Consultancy: Amgen; Advisory / Consultancy: Baxter; Advisory / Consultancy: Lilly; Advisory / Consultancy: Merck-Serono; Advisory / Consultancy: MSD; Advisory / Consultancy: Sanofi; Advisory / Consultancy: Roche; Advisory / Consultancy: Servier. All other authors have declared no conflicts of interest.
Resources from the same session
5629 - Outcome of triple negative inflammatory breast cancers (TNIBC) treated with dose dense neoadjuvant epirubicin cyclophosphmide, prognostic impact of pre and post neoadjuvant chemotherapy (NAC) tumor infiltrating lymphocytes (TIL) and post NAC lymphovascular invasion
Presenter: Luca Campedel
Session: Poster Display session 2
Resources:
Abstract
5792 - A novel PET parameter for cancer stem cell metabolism: early prediction of chemosensitivity to neoadjuvant chemotherapy in locally advanced breast cancer
Presenter: Chanwoo Kim
Session: Poster Display session 2
Resources:
Abstract
3728 - Using nodal ratio to predict recurrence in patients with 4 or more positive lymph nodes early stage breast cancer
Presenter: Besma Graja
Session: Poster Display session 2
Resources:
Abstract
3395 - Re-sentinel node biopsy for local recurrence after breast-conserving surgery
Presenter: Yuka Matsubara
Session: Poster Display session 2
Resources:
Abstract
4302 - Assessment of prognostic and therapeutic factors in men with breast cancer
Presenter: Daniel Herrero Rivera
Session: Poster Display session 2
Resources:
Abstract
4263 - Genomic Profiling of Chinese Breast Cancer Patients
Presenter: Zhonghua Tao
Session: Poster Display session 2
Resources:
Abstract
2406 - Genome copy number alteration burden represents predictor of response in long-term, never relapse exceptional responders of trastuzumab-treated HER2+ metastatic breast cancer
Presenter: Naomi Walsh
Session: Poster Display session 2
Resources:
Abstract
2575 - Next-generation DNA Sequencing (NGS) Results for Tumors From Phase 2 ABRAZO Study of Talazoparib After Platinum or Cytotoxic Non-Platinum Regimens in Patients (pts) With Advanced Breast Cancer (ABC) and Germline BRCA1/2 (gBRCA) Mutations
Presenter: Nicholas C. Turner
Session: Poster Display session 2
Resources:
Abstract
4499 - FGFR1 and CCND1 gene amplifications are associated with breast cancer resistance to aromatase inhibitors
Presenter: Evgeny Imyanitov
Session: Poster Display session 2
Resources:
Abstract
4110 - Clinicopathologic features of BRCA mutated breast cancer patients: Hacettepe Experience
Presenter: Sercan Aksoy
Session: Poster Display session 2
Resources:
Abstract