Clin Cancer Res. 2021 Feb 05. pii: clincanres.4699.2020. [Epub ahead of print]
Paolo Manca,
Salvatore Corallo,
Adele Busico,
Sara Lonardi,
Francesca Corti,
Carlotta Antoniotti,
Letizia Procaccio,
Matteo Clavarezza,
Valeria Smiroldo,
Gianluca Tomasello,
Roberto Murialdo,
Andrea Sartore-Bianchi,
Patrizia Racca,
Filippo Pagani,
Giovanni Randon,
Antonia Martinetti,
Elisa Sottotetti,
Federica Palermo,
Federica Perrone,
Elena Tamborini,
Michele Prisciandaro,
Alessandra Raimondi,
Maria Di Bartolomeo,
Federica Morano,
Filippo Pietrantonio.
BACKGROUND: The routine use of liquid biopsy is not recommended for the choice of initial treatment of patients with metastatic colorectal cancer (mCRC).EXPERIMENTAL DESIGN: We included patients with left-sided, RAS/BRAF wild-type, HER2-negative and microsatellite stable mCRC, treated with upfront FOLFOX-panitumumab in the Valentino study. We performed amplicon-based genomic profiling of 14 genes in baseline plasma samples and compared these data with tumor tissue ultra-deep sequencing results. Specific gene mutations in ctDNA and their clonality were associated with PFS, OS and radiological dynamics.
RESULTS: Ten and 15 out of 120 patients had a mutation of RAS and PIK3CA in ctDNA, with a positive concordance with tissue deep-sequencing of only 31.3% and 47.1%, respectively. Presence of RAS or PIK3CA mutations in baseline ctDNA was associated with worse median PFS (8.0 vs. 12.8 months; HR=2.49, 95%CI: 1.28-4.81, p=0.007; 8.5 vs 12.9 months; HR=2.86, 95%CI: 1.63-5.04, p<0.001) and median OS (17.1 vs. 36.5 months; HR=2.26, 95%CI: 1.03-4.96, p=0.042; 21.1 vs 38.9 months; HR=2.18, 95%CI: 1.16-4.07, p=0.015). RAS mutations in ctDNA were associated with worse RECIST response, early tumor shrinkage and depth of response, while PIK3CA mutations were not. Patients with higher levels of RAS/PIK3CA variant allele fraction (VAF) in ctDNA had the worst outcomes (VAF {greater than or equal to}5% vs all-wild-type: median PFS: 7.7 vs 13.1 months, HR: 4.02, 95%CI: 2.03-7.95, p<0.001; median OS: 18.8 vs 38.9 months, HR: 4.07, 95%CI: 2.04-8.12, p<0.001).
CONCLUSION: Baseline ctDNA profiling may add value to tumor tissue testing to refine the molecular hyperselection of mCRC patients for upfront anti-EGFR-based strategies.