Molecular characterization of KRAS wild type tumors in patients with pancreatic adenocarcinoma.

KRAS mutation (MT) is a major oncogenic driver in PDAC. A small subset of PDACs harbor KRAS-wild-type (WT). We aim to characterize the molecular profiles of KRAS-WT PDAC to uncover new pathogenic drivers and offer targeted treatments.Tumor tissue obtained from surgical or biopsy material was subjected to next-generation DNA/RNA sequencing, microsatellite-instability (MSI) and mismatch-repair (MMR) status determination.Of the 2,483 patients (male 53.7%, median-age 66 years) studied, 266 tumors (10.7%) were KRAS-WT. The most frequently mutated gene in KRAS-WT-PDAC was TP53 (44.5%), followed by BRAF (13.0%) . Multiple mutations within the DNA-damage-repair (BRCA2, ATM, BAP1, RAD50, FANCE, PALB2), chromatin-remodeling (ARID1A, PBRM1, ARID2, KMT2D, KMT2C, SMARCA4, SETD2), and cell-cycle-control pathways (CDKN2A, CCND1, CCNE1) were detected frequently. There was no statistically-significant difference in PDL1-expression between KRAS-WT (15.8%) and MT (17%) tumors. However, KRAS-WT-PDAC were more likely to be MSI-high (4.7% vs 0.7%; p<0.05), TMB-high (4.5% vs 1%; p<0.05), and exhibit increased infiltration of CD8+ T-cells, NK-cells and myeloid dendritic cells. KRAS-WT-PDACs exhibited gene fusions of BRAF (6.6%), FGFR2 (5.2%), ALK (2.6%), RET (1.3%) and NRG1 (1.3%), as well as amplification of FGF3 (3%), ERBB2 (2.2%), FGFR3 (1.8%), NTRK (1.8%) and MET (1.3%). Real-world evidence reveals a survival advantage of KRAS-WT patients in overall cohorts as well as in patients treated with gemcitabine/nab-paclitaxel or 5FU/oxaliplatin.KRAS-WT PDAC represents 10.7% of PDAC and is enriched with targetable alterations, including immuno-oncologic markers. Identification of KRAS-WT patients in clinical practice may expand therapeutic options in a clinically meaningful manner.