Abstract 5602
Background
Genotyping of ctDNA characterizes the molecular profile and monitors tumor molecular dynamics, but the clinical applicability of next generation sequencing (NGS) DNA sequencing has not been assessed in a large prospective cohort of mCRC patients (pts).
Methods
mCRC pts with RAS wt tumors treated in first line with chemotherapy (CT) + cetuximab in 16 Spanish hospitals were included. Plasma samples were collected baseline (BL) and every 2 cycles until progression. ctDNA was isolated and sequenced with NGS platform Oncomine Colon cfDNA Assay which identifies hotspot mutations (mut) in AKT1, BRAF, CTNNB1, EGFR, ERBB2, FBXW7, GNAS, KRAS, MAP2K1, NRAS, PIK3CA, SMAD4, TP53 and APC. RAS ctDNA mut were also assessed by dPCR (BEAMing) at BL. Detection of any mut in plasma was considered as ctDNA+. Mut in BRAF/RAS/MAP2K1/PIK3CA were considered as anti-EGFR resistance.
Results
101 pts were enrolled (65.3% male; median age 64.5y; 77.6% left colon). RAS mut were detected in 11 pts BL by BEAMing. After quality assessment, 84 samples were sequenced by NGS BL and at least one mut was detected in 65 samples (77.3%; median 1, range 0-5) and 10 RAS mut were detected. Plasma samples from 47 pts were also analyzed after 4 cycles of treatment (C4) and mut were detected in 30 pts (63.8%; median 1, range 0-3). Median mutant allele fraction for paired samples was 24.9 at BL and 0.56 at C4 (p = 0.0045). Treatment clinical benefit (CB: PR, CR and SD ≥ 16weeks) was observed in 72 out of 85 pts. BL ctDNA+ or C4 ctDNA change were not associated with CB (p = 0.722). Assessment of RAS BL mut was not associated with CB (p = 0.243 by NGS and p = 0.712 by BEAMing), while the absence of RAS mut at C4 predicted treatment CB (93.2% vs. 6.8% RAS mut p = 0.02). Median PFS for all pts was 10.13 month. ctDNA+ at BL or C4 were not correlated with PFS (HR 0.8; p = 0.73). No differences in PFS were found in ctDNA RAS mut vs RAS wt BL (BEAMing+ HR = 1.2 p = 0.79 and NGS+ HR = 2.6 p = 0.052). Among all anti-EGFR resistant mut, only ctDNA RAS mut were detected at C4 (N = 4). Persistence or emergence of RAS mut at C4 were strongly associated with PFS (12.9m vs. 4.2. HR 8.8 p = 0.0003).
Conclusions
Early RAS ctDNA dynamics predicts benefit to first line CT+cetuximab in mCRC pts.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Grupo de Tratamiento de los Tumores Digestivos (TTD), Spain.
Funding
Merck-Serono.
Disclosure
J. Vidal Barrull: Honoraria (self), Advisory / Consultancy: Merck-Serono; Advisory / Consultancy: Amgen; Honoraria (self): Sysmex-Inostics. E. Elez Fernández: Honoraria (self), Advisory / Consultancy: Amgen; Honoraria (self), Advisory / Consultancy, Research grant / Funding (self): Merck-Serono; Honoraria (self), Advisory / Consultancy: Roche; Honoraria (self), Advisory / Consultancy: Sanofi. F. Losa: Honoraria (self): Amgen; Honoraria (self): Merck-Serono. R. Salazar: Honoraria (self), Advisory / Consultancy: Amgen; Honoraria (self), Advisory / Consultancy: Merck-Serono; Advisory / Consultancy: Guardant-Helth; Honoraria (self), Advisory / Consultancy: Roche; Honoraria (self), Advisory / Consultancy: Ferrer; Advisory / Consultancy: Pfizer; Honoraria (self), Advisory / Consultancy: Novartis; Advisory / Consultancy: Lilly; Honoraria (self), Advisory / Consultancy: MSD. J. Tabernero: Honoraria (self), Advisory / Consultancy: Array Biopharma; Honoraria (self), Advisory / Consultancy: Merck-Serono; Honoraria (self), Advisory / Consultancy: Molecular Partners; Honoraria (self), Advisory / Consultancy: Sanofi; Honoraria (self), Advisory / Consultancy: Roche; Honoraria (self), Advisory / Consultancy: Novartis; Honoraria (institution), Advisory / Consultancy: MSD; Honoraria (self), Advisory / Consultancy: Foundation Medicine; Honoraria (self), Advisory / Consultancy: Halio DX SAS. E. Aranda Aguilar: Honoraria (self): Celgene; Honoraria (self): Merck-Serono; Honoraria (self): Roche; Honoraria (self): Sanofi. B. Bellosillo: Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Merck-Serono; Advisory / Consultancy: Roche; Honoraria (self), Advisory / Consultancy: Biocartis; Advisory / Consultancy: Novartis; Advisory / Consultancy: Thermofisher. C. Montagut Viladot: Honoraria (self), Advisory / Consultancy: Amgen; Honoraria (self), Advisory / Consultancy, Research grant / Funding (self): Merck-Serono; Advisory / Consultancy: Sysmex-Inostics; Advisory / Consultancy: Sanofi; Honoraria (self), Advisory / Consultancy: Roche; Advisory / Consultancy: Bayer; Honoraria (self), Advisory / Consultancy: Biocartis; Honoraria (self), Advisory / Consultancy: BMS; Honoraria (self), Advisory / Consultancy: Guardant-Helth; Advisory / Consultancy: Symphogen. All other authors have declared no conflicts of interest.
Resources from the same session
3516 - Palbociclib Rechallenge in Hormone Receptor (HR)[+]/HER2[-] Advanced Breast Cancer (ABC). PALMIRA Trial
Presenter: Antonio Llombart Cussac
Session: Poster Display session 2
Resources:
Abstract
4616 - Alpelisib (ALP) + Endocrine Therapy (ET) by Last Prior Therapy in Patients (pts) With PIK3CA-Mutated Hormone-Receptor Positive (HR+) Human Epidermal Growth Factor Receptor-2-Negative (HER2–) Advanced Breast Cancer (ABC): Additional Study Cohort in BYLieve
Presenter: Eva Ciruelos
Session: Poster Display session 2
Resources:
Abstract
3592 - PRECYCLE: Impact of CANKADO-based eHealth-support on quality of life in metastatic breast cancer patients treated with palbociclib and endocrine therapy.
Presenter: Tom Degenhardt
Session: Poster Display session 2
Resources:
Abstract
4168 - Efficacy and safety of oral poly (ADP-ribose) polymerase inhibitor fluzoparib in patients with BRCA1/2 mutations and platinum sensitive recurrent ovarian cancer
Presenter: Ning Li
Session: Poster Display session 2
Resources:
Abstract
2785 - Effect of response to last platinum-based chemotherapy in patients (pts) with platinum-sensitive, recurrent ovarian carcinoma in the phase 3 study ARIEL3 of rucaparib maintenance treatment
Presenter: Jonathan Ledermann
Session: Poster Display session 2
Resources:
Abstract
3496 - Integrated safety analysis of the poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib in patients (pts) with ovarian cancer in the treatment and maintenance settings
Presenter: Rebecca Kristeleit
Session: Poster Display session 2
Resources:
Abstract
2844 - Clinical factors associated with prolonged response and survival under olaparib as maintenance therapy in BRCA mutated ovarian cancers
Presenter: S.Intidhar Labidi-Galy
Session: Poster Display session 2
Resources:
Abstract
1955 - A Prospective Evaluation of Tolerability of Niraparib Dosing Based on Baseline Body Weight (BW) and Platelet (plt) Count: Blinded Pooled Interim Safety Data from the NORA Study
Presenter: Xiaohua Wu
Session: Poster Display session 2
Resources:
Abstract
2539 - Evaluation of Niraparib 200 mg/d as Maintenance Therapy in Recurrent Ovarian Cancer and Associated Thrombocytopenia in a Real-World US Setting
Presenter: Premal Thaker
Session: Poster Display session 2
Resources:
Abstract
1290 - Niraparib initial dose and its’ management in patients with recurrent high-grade serous ovarian cancer.
Presenter: Jacek Grabowski
Session: Poster Display session 2
Resources:
Abstract