Abstract 4590
Background
Liquid biopsies (LB) allow monitoring of genetically different and co-occurring cancer cell clones. 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. 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 progression. 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. 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.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
MEDeA Onlus.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
1908 - Androgen Receptor (AR) Aberrations in Patients (Pts) With Metastatic Castration-Sensitive Prostate Cancer (mCSPC) Treated With Apalutamide (APA) Plus Androgen Deprivation Therapy (ADT) in TITAN
Presenter: Kim Chi
Session: Poster Display session 3
Resources:
Abstract
4058 - 68Ga-PSMA guided bone biopsies for molecular diagnostics in metastatic castration resistant prostate cancer patients
Presenter: Anouk de Jong
Session: Poster Display session 3
Resources:
Abstract
2226 - Spatial-Temporal Change in Quantitative Total Bone Imaging (QTBI) and Circulating Tumor Cells (CTCs) in Metastatic Castration-Resistant Prostate Cancer (mCRPC) Treated With Enzalutamide (ENZA)
Presenter: Glenn Liu
Session: Poster Display session 3
Resources:
Abstract
5795 - Efficacy of Enzalutamide in Hormone-sensitive Metastatic Prostate Cancer: Clinical Utility of 18F-Choline PET and Whole Body MRI.
Presenter: Susanne Osanto
Session: Poster Display session 3
Resources:
Abstract
899 - Urine extracellular vesicle GATA2 mRNA alone and in a multigene test predicts initial prostate biopsy result
Presenter: Jungreem Woo
Session: Poster Display session 3
Resources:
Abstract
3094 - Circulating tumor cell (CTC) genomic landscape in neuroendocrine prostate cancer (NEPC) by single cell copy number analysis
Presenter: Vincenza Conteduca
Session: Poster Display session 3
Resources:
Abstract
2527 - Circulating Tumor Cells (CTC) count and Prostate-Specific Antigen (PSA) response measures in metastatic Castration-Resistant Prostate Cancer (mCRPC) patients (pts) treated with Docetaxel (Doc)
Presenter: Rebeca Lozano Mejorada
Session: Poster Display session 3
Resources:
Abstract
6106 - Assessing the clinical relevance of drug–drug interactions (DDI) with darolutamide (DARO)
Presenter: Christian Zurth
Session: Poster Display session 3
Resources:
Abstract
2237 - KEYNOTE-921: phase 3 study of pembrolizumab (pembro) plus docetaxel and prednisone for enzalutamide (enza)- or abiraterone (abi)-pretreated patients (pts) with metastatic castration-resistant prostate cancer (mCRPC).
Presenter: Daniel Petrylak
Session: Poster Display session 3
Resources:
Abstract
2241 - KEYNOTE-641: Phase 3 Study of Pembrolizumab (pembro) Plus Enzalutamide for Metastatic Castration-Resistant Prostate Cancer (mCRPC)
Presenter: Julie Graff
Session: Poster Display session 3
Resources:
Abstract