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Late-breaking and deferred publication abstracts Gastrointestinal tumours, colorectal| Volume 30, SUPPLEMENT 5, v867, October 01, 2019

Analysis of circulating tumour DNA (ctDNA) from patients enrolled in the IDEA-FRANCE phase III trial: Prognostic and predictive value for adjuvant treatment duration

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      Abstract

      Background

      ctDNA has been recently suggested as a major prognostic factor in resected stage II and III colon cancer patients (pts)1,2. Its predictive value for adjuvant treatment intensity or duration is currently unknown. We have analyzed here ctDNA from pts enrolled in the IDEA-FRANCE trial3, its prognostic value and its predictive value for treatment duration (3 or 6 months).

      Methods

      ctDNA was tested by using the detection of 2 methylated markers (WIF1 and NPY) by digital droplet PCR accordingly to a method developed and validated for colorectal cancer 4-6. Comparisons for pts and tumour characteristics and DFS will be done between the ctDNA tested pts and the full study population and between ctDNA positive and negative pts. DFS has been analyzed in the 6 and 3M treatment arms according to ctDNA results. Subgroup analyses for high- and low-risk pts were pre-planned.

      Results

      Of the 1345/2010 pts that consented to the IDEA translational research program, with available blood sample for ctDNA testing, 805 have been sampled before chemotherapy start and fully analyzed. More PS 0 (77% vs 71%) and more T4 and/or N2 (28% vs 23%) were observed in the 805 pts studied here than in the 1205 pts left. 696 pts were found ctDNA- and 109 ctDNA + (13.5%). ctDNA+ pts were more often T4, poorly differentiated and with tumour perforation. 2-year DFS was 64% vs 82% in ctDNA+ and – pts, respectively (HR :1.75 (95%CI 1.25-2.45) p = 0.001). In multivariate analysis including Age, Gender, MSI, perforation, T stage, N stage and treatment arm, ctDNA was confirmed as an independent prognostic marker (adj.HR: 1.85 (95%CI 1.31 to 2.61) p < 0.001). Adjuvant treatment for 6 months was superior to 3 months in both ctDNA– (HR :0.69 (95%CI 0.52 to 0.93) p = 0.015) and ctDNA+ pts (HR: 0.50 (95%CI 0.27 to 0.95) p = 0.033). Interestingly ctDNA+ pts treated 6 months had a similar prognosis to ctDNA- pts treated 3 months.

      Conclusions

      In this first ctDNA assessment on a large series coming from a phase III clinical trial we found 13.5% of pts with ctDNA post-surgery. ctDNA was confirmed as an independent prognostic marker. In this series, 6 months of treatment seems better in both ctDNA+ and- pts. [1]Tie J, et al. Circulating tumor DNA analysis detects minimal residual disease and predicts recurrence in patients with stage II colon cancer.Sci Transl Med. 2016 Jul 6;8(346):346ra92. [2]Schøler LV, et al. Clinical Implications of Monitoring Circulating Tumor DNA in Patients with Colorectal Cancer. Clin Cancer Res. 2017 Sep 15;23(18):5437-5445. [3] André T, et al.Three Versus 6 Months of Oxaliplatin-Based Adjuvant Chemotherapy for Patients With Stage III Colon Cancer: Disease-Free Survival Results From a Randomized, Open-Label, International Duration Evaluation of Adjuvant (IDEA) France, phase III Trial.J Clin Oncol. 2018 May 20;36(15):1469-1477. [4] Garrigou S, et al. A Study of Hypermethylated Circulating Tumor DNA as a Universal Colorectal Cancer Biomarker. Clin Chem. 2016;62:1129-1139. [5] Garlan F, et al. Early Evaluation of Circulating Tumor DNA as Marker of Therapeutic Efficacy in Metastatic Colorectal Cancer Patients (PLACOL Study). Clin Cancer Res.2017;23:5416-5425. [6] Bachet JB, et al. RAS mutation analysis in circulating tumor DNA from patients with metastatic colorectal cancer: the AGEO RASANC prospective multicenter study. Ann Oncol. 2018May 1;29(5):1211-1219.

      Clinical trial identification

      NCT00958737.

      Legal entity responsible for the study

      Gercor-Prodige.

      Funding

      Clinical trial: INCa, GERCOR; Translational project: ARC (Association de Recherche contre le Cancer, Paris, France).

      Disclosure

      J. Taieb: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: roche; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: merck; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: amgen; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: Servier; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: pierre fabre; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: MSD; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: Lilly; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: Sanofi. D. Vernerey: Honoraria (self), Advisory / Consultancy: HalioDX; Honoraria (self), Advisory / Consultancy: Celgene; Honoraria (self), Advisory / Consultancy: Janssen. J. Bennouna: Honoraria (self), Advisory / Consultancy: MSD; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: Roche; Honoraria (self), Advisory / Consultancy: AstraZeneca; Honoraria (self), Advisory / Consultancy: Bristol-Myers Squibb; Honoraria (self), Advisory / Consultancy: Boehringer Ingelheim. All other authors have declared no conflicts of interest.