Homologous recombination repair pathway alterations and their relationship to homologous recombination deficiency in advanced pancreatic cancer patients.

Authors

null

Hitendra Patel

University of California San Diego Moores Cancer Center, La Jolla, CA

Hitendra Patel , Alex Barrett , Elizabeth Mauer , Shumei Kato , Benjamin D. Leibowitz , Aatur D. Singhi , Milind M. Javle , Andrew M. Lowy

Organizations

University of California San Diego Moores Cancer Center, La Jolla, CA, Tempus Labs, Chicago, IL, University of California San Diego, Moores Cancer Center, La Jolla, CA, Tempus Labs, Inc., Chicago, IL, Department of Pathology, University of Pittsburgh, Pittsburgh, PA, University of Texas MD Anderson Cancer Center, Houston, TX, UCSD Moores Cancer Center, La Jolla, CA

Research Funding

No funding received

Background: Homologous recombination repair (HRR) is critical for limiting DNA damage arising from double strand breaks. Disrupting HRR has emerged as a therapeutic strategy in pancreatic cancer given the development of PARP inhibitors that can specifically target tumors with homologous recombination deficiency (HRD). While HRD is strongly associated with loss-of-function mutations in BRCA1/2, a broad range of pathogenic alterations have been identified in other HRR genes. Identification of pathogenic alterations that predict response to PARP inhibition remains a critical knowledge gap in the field. Methods: We retrospectively analyzed de-identified records from 895 patients with advanced pancreatic cancer that underwent next generation sequencing (NGS) with the Tempus|xT assay (DNA-seq of 648 genes at 500x coverage, matched normal, full transcriptome RNA-seq). HRD-positivity and genome-wide loss of heterozygosity (LOH) were compared across groups, which were defined based on alterations to BRCA1/2 or other HRR pathway genes. Results: We identified 293/895 (33%) pancreatic cancer patients to be HRD-positive. Among HRD positive patients, 23/895 (2.6%) tumors harbored two alterations in BRCA1/2 (BRCA++), 179/895 (20%) harbored a single alteration in BRCA1/2 (BRCA+), 25/895 (2.8%) harbored two alterations in at least one other non-BRCA HRR gene (other HRR++), 367/895 (41%) harbored a single alteration in one other HRR gene (other HRR+), and 143/895 (16%) had pathogenic alterations in neither BRCA1/2 nor other HRR genes. In terms of HRD status, 23/23 (100%) of BRCA++ cases, 179/337 (53%) of BRCA+ cases, 4/25 (16%) of other HRR++ cases, and 87/367 (24%) of other HRR+ cases were HRD-positive. We observed no cases that were HRD-positive without an alteration in either BRCA1/2 or other HRR gene. Within the other HRR+ group, we found that single alterations in CHEK1/2, FANCA/L, MRE11, PALB2, and RAD51B were all significantly associated with HRD-positivity whereas CDK12, for instance, was not (Table). Conclusions: Comprehensive genomic profiling demonstrates that approximately 1 in 4 patients without BRCA alterations may potentially benefit from PARP inhibition due to alterations in other HRR genes. Future studies may examine the role of PARP inhibition in this population of HRR+ pancreatic cancer patients.

HRR+ Gene
Overall

(n = 367)
HRD Negative

(n = 280)
HRD Positive

(n = 87)
CDK12
15 (4.1%)
9 (3.2%)
6 (6.9%)
CHEK1
42 (11%)
21 (7.5%)
21 (24%)
CHEK2
108 (29%)
64 (23%)
44 (51%)
FANCA
35 (9.5%)
21 (7.5%)
14 (16%)
FANCL
31 (8.4%)
12 (4.3%)
19 (22%)
MRE11
47 (13%)
25 (8.9%)
22 (25%)
PALB2
46 (13%)
22 (7.9%)
24 (28%)
RAD51B
64 (17%)
39 (14%)
25 (29%)

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

2022 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

DOI

10.1200/JCO.2022.40.4_suppl.609

Abstract #

609

Poster Bd #

L4

Abstract Disclosures

Similar Abstracts

Abstract

2022 ASCO Genitourinary Cancers Symposium

Immune profiling of advanced prostate cancer harboring homologous recombination deficiency.

First Author: Maryam Soleimani

First Author: June Evelyn Jeon