Circulating tumor DNA in unresectable pancreatic cancer is a strong predictor of first-line treatment efficacy: The KRASCIPANC prospective study.

BACKGROUND: There is no robust predictor of response to chemotherapy (CT) in unresectable pancreatic adenocarcinomas (UPA). The objective of the KRASCIPANC study was to analyze the kinetics of cell-free DNA (cfDNA)/circulating tumor DNA (ctDNA) as a predictor of response to CT in UPA. METHODS: Blood samples were collected just before first CT and at day 28. The primary endpoint was the kinetics of KRAS-mutated ctDNA by digital droplet PCR between D0 and D28 as a predictor of progression-free survival (PFS). RESULTS: We analyzed 65 patients with a KRAS-mutated tumor. A high level of cfDNA and KRAS-mutated ctDNA at D0, as well as the presence of KRAS-mutated ctDNA at D28, were strongly associated with lower centralized disease control rate (cDCR), shorter cPFS and OS in multivariate analysis. A score combining cfDNA level at diagnosis ≥ or <30 ng/mL and presence or not of KRAS-mutated ctDNA at D28 was an optimal predictor of cDCR (OR=30.7, IC95% 4.31-218 P=.001), PFS (HR=6.79, IC95% 2.76-16.7, P<.001) and OS (HR=9.98, IC95% 4.14-24.1, P<.001). CONCLUSION: A combined score using cfDNA level at diagnosis and KRAS-mutated ctDNA at D28 is strongly associated with patient survival/response to chemotherapy in UPA. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04560270.