Impact of KRAS mutational status on outcomes in patients with pancreatic cancer (PDAC).

Authors

null

Lucy Xiaolu Ma

Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada

Lucy Xiaolu Ma , Gun Ho Jang , Amy Zhang , Robert Edward Denroche , Anna Dodd , Stephanie Ramotar , Shawn Hutchinson , Yifan Wang , Mustapha Tehfe , Ravi Ramjeesingh , James Joseph Biagi , Bernard Lam , Julie Wilson , Faiyaz Notta , Sandra Fischer , Robert C Grant , George Zogopoulos , Steven Gallinger , Jennifer J. Knox , Grainne M. O'Kane

Organizations

Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada, Ontario Institute for Cancer Research, Toronto, ON, Canada, Ontario institute for Cancer Research, Toronto, ON, Canada, Princess Margaret Cancer Center, University Health Network, Toronto, ON, Canada, Princess Margaret Cancer Center, Toronto, ON, Canada, Research Institute of the McGill University Health Centre, Montreal, QC, Canada, Centre Hospitalier de l'Université de Montréal (CHUM), Montréal, QC, Canada, Nova Scotia Cancer Center, Dalhousie University, Nova Scotia, NS, Canada, Queen's University, Cancer Center of Southeastern Ontario, Kingston, ON, Canada, Toronto General Hospital, University Health Network, Toronto, ON, Canada, Division of Medical Oncology and Hematology, Princess Margaret Cancer Center, Toronto, ON, Canada, McGill University Health Center, Montréal, QC, Canada

Research Funding

Other
This study was conducted with the support of the Ontario Institute for Cancer Research (PanCuRx Translational Research Initiative) through funding provided by the Government of Ontario, the Wallace McCain Centre for Pancreatic Cancer supported by the Prin

Background: KRAS mutations (m) (KRASm) are present in over 90% of pancreatic adenocarcinomas (PDAC) with a predominance of G12 substitutions. KRAS wildtype (WT) PDAC relies on alternate oncogenic drivers, and the prognostic impact of these remains unknown. We evaluated alterations in WT PDAC and explored the impact of specific KRASm and WT status on survival. Methods: WGS and RNAseq were performed on 570 patients (pts) ascertained through our translational research program from 2012-2021, of which 443 were included for overall survival (OS) analyses. This included 176 pts with resected and 267 pts with advanced PDAC enrolled on the COMPASS trial (NCT02750657). The latter cohort underwent biopsies prior to treatment with first line gemcitabine-nab-paclitaxel or mFOLFIRINOX as per physician choice. The Kaplan-Meier and Cox proportional hazards methods were used to estimate OS. Results: KRAS WT PDAC (n = 52) represented 9% of pts, and these cases trended to be younger than pts with KRASm (median age 61 vs 65 years p = 0.1). In resected cases, the most common alterations in WT PDAC (n = 23) included GNASm (n = 6) and BRAFm/fusions (n = 5). In advanced WT PDAC (n = 27), alterations in BRAF (n = 11) and ERBB2/3/4 (n = 6) were most prevalent. Oncogenic fusions (NTRK, NRG1, BRAF/RAF, ROS1, others) were identified in 9 pts. The BRAF in-frame deletion p.486_491del represented the most common single variant in WT PDAC, with organoid profiling revealing sensitivity to both 3rd generation BRAF inhibitors and MEK inhibition. In resected PDAC, multivariable analyses documented higher stage (p = 0.043), lack of adjuvant chemotherapy (p < 0.001), and the KRAS G12D variant (p = 0.004) as poor prognostic variables. In advanced disease, neither WT PDAC nor KRAS specific alleles had an impact on prognosis (median OS WT = 8.5 mths, G12D = 8.2, G12V = 10.0, G12R = 12.0, others = 9.2, p = 0.73); the basal-like RNA subtype conferred inferior OS (p < 0.001). A targeted therapeutic approach following first line chemotherapy was undertaken in 10% of pts with advanced PDAC: MMRd (n = 1), homologous recombination deficiency (HRD) (n = 19), KRASG12C (n = 1), CDK4/6 amplification (n = 3), ERBB family alterations (n = 2), BRAF variants (n = 2). OS in this group was superior (14.7 vs 8.8 mths, p = 0.04), mainly driven by HRD-PDAC where KRASm were present in 89%. Conclusions: In our dataset, KRAS G12D is associated with inferior OS in resected PDAC, however KRAS mutational status was not prognostic in advanced disease. This suggests that improved OS in the WT PDAC population can only be achieved if there is accelerated access to targeted drugs for pts.

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Abstract Details

Meeting

2021 ASCO Annual Meeting

Session Type

Poster Session

Session Title

Gastrointestinal Cancer—Gastroesophageal, Pancreatic, and Hepatobiliary

Track

Gastrointestinal Cancer—Gastroesophageal, Pancreatic, and Hepatobiliary

Sub Track

Pancreatic Cancer

Citation

J Clin Oncol 39, 2021 (suppl 15; abstr 4142)

DOI

10.1200/JCO.2021.39.15_suppl.4142

Abstract #

4142

Poster Bd #

Online Only

Abstract Disclosures

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