Circulating tumor DNA–based genomic landscape of KRAS wild-type pancreatic adenocarcinoma.

Authors

null

Brendon Fusco

Department of Hematology & Medical Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ;

Brendon Fusco , Jill Tsai , Keelia Clemens , Pat Gulhati

Organizations

Department of Hematology & Medical Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ; , Guardant Health, Inc., Redwood City, CA; , Rutgers Cancer Institute of New Jersey, New Brunswick, NJ;

Research Funding

No funding received
None.

Background: Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer deaths. KRAS is a primary oncogenic driver in the majority of PDAC patients. KRAS wild-type (wt) PDAC (~10%) is a molecularly heterogeneous subgroup that may harbor alternate drivers and targetable alterations. In this study, we sought to characterize the circulating tumor DNA (ctDNA) landscape of alterations in PDAC patients harboring KRAS mutations (KRAS mut) compared to KRAS wt. Methods: We analyzed ctDNA samples from 2000 patients (N= 1000 each for KRAS mut and KRAS wt) collected prospectively between 2019-2022 using a 74-83 gene next generation sequencing panel (Guardant360). KRAS mutation not detected was used as a proxy for KRAS wt. To limit bias from low tumor shed, samples were excluded if they did not have maximum variant allele fraction (VAF) > 0.34% and if the only maximum VAF > 0.34% was within putative germline range (40-60%). Statistical analyses were performed using Fisher’s exact test or t-test. Results: No significant gender differences were noted between KRAS wt and KRAS mut patients. Median age was 72yo in KRAS wt and 69yo in KRAS mut patients. Overall, KRAS wt patients had higher frequency of alterations in ATM, BRAF, ERBB2, FGFR2, JAK3,MET and NOTCH1 compared to KRAS mut (all p < 0.05). Meanwhile, KRAS wt patients had lower frequency of alterations in CDKN2A, SMAD4, CDK6, ARID1A, and TP53 compared to KRAS mut (all p < 0.05). The most frequently mutated gene in KRAS wt PDAC was TP53 (46%), followed by ATM (26%) and EGFR (11%). The most common currently targetable alterations identified in KRAS wt patients were ATM (26%), BRCA1/2 (12%), EGFR (11%; 70% mutations, 30% amplifications), FGFR1/2 (9%), BRAF (8%; 91% mutations, 9% amplifications), PIK3CA (7%), MET (7%; 80% mutations, 20% amplifications) and ERBB2 (5.8%; 79% mutations, 21% amplifications) among others. Median tumor mutational burden for KRAS wt patients was higher than KRAS mut (10.0 vs. 7.77 mut/Mb, p = 0.035). There were no significant differences in rates of MSI-H between KRAS wt and KRAS mut patients (1.9% vs. 1.3%, p = 0.37). KRAS wt patients harbored higher number of oncogenic gene fusions compared to KRAS mut (1.6% vs 0.2%, p = 0.0013). The most common fusion partners among KRAS wt patients included FGFR2 (0.4%), BRAF (0.4%), ALK (0.2%), NTRK (0.2%), RET (0.2%), FGFR3 (0.1%) and EGFR (0.1%). Potential germline variants (pathogenic/likely pathogenic) were detected in both KRAS wt and mut patients, most commonly in the DNA-damage repair genes, including ATM (3.5%), BRCA2 (1.8%) and BRCA1 (0.6%). Conclusions: Targetable alterations and oncogenic rearrangements are enriched in KRAS wt PDAC compared to KRAS mut. These analyses provide additional therapeutic options and may improve outcomes for KRAS wt patients, warranting blood-based ctDNA genomic profiling in PDAC, especially when a tissue biopsy is not feasible or sufficient for comprehensive genomic profiling.

Disclaimer

This material on this page is ©2024 American Society of Clinical Oncology, all rights reserved. Licensing available upon request. For more information, please contact licensing@asco.org

Abstract Details

Meeting

2023 ASCO Gastrointestinal Cancers Symposium

Session Type

Poster Session

Session Title

Poster Session B: Cancers of the Pancreas, Small Bowel, and Hepatobiliary Tract

Track

Pancreatic Cancer,Hepatobiliary Cancer,Neuroendocrine/Carcinoid,Small Bowel Cancer

Sub Track

Tumor Biology, Biomarkers, and Pathology

Citation

J Clin Oncol 41, 2023 (suppl 4; abstr 747)

DOI

10.1200/JCO.2023.41.4_suppl.747

Abstract #

747

Poster Bd #

M14

Abstract Disclosures

Similar Abstracts

First Author: Ben George

First Author: Alexander Hua Xiao

Abstract

2023 ASCO Annual Meeting

Relations between mutant KRAS and TP53 subtypes and other co-mutations in pancreatic cancer.

First Author: Soniya Abraham