Abstract 6462: Somatic mutational profile in MUTYH- associated colorectal cancers (MUTYH-CRCs)

Abstract Background: Biallelic inactivation of MUTYH leads to hereditary predisposition to colorectal polyposis and CRC. Herein we evaluated co-alterations in somatic next-generation sequencing (NGS) in patients with MUTYH-CRC, mainly KRAS G12C, high tumor mutational burden and microsatellite instability (MSI-H) /mismatch repair deficiency (dMMR). Methods: Data was collected on patients with MUTYH-CRC in the period between 2015 and 2023 at Moffitt Cancer Center (Tampa, Florida, United States). All patients with MUTYH-CRC were included regardless disease stage. Different germline panels were used to detect MUTYH and Foundation One, Caris and Moffitt STAR (in house NGS) were used to detect somatic co-alterations. Results: A total of 36 patients were identified with MUTYH- CRC, the median age at diagnosis was 44-year-old, 55% were men. All patients had a somatic NGS available, 18 patients (50%) had KRAS mutation, and specifically KRAS G12C was detected in 9 patients (24%), 6 patients (17%) had MSI-H/dMMR, 5 patients (14%) had BRAF mutation and 4 patients (11%) with BRCA2 mutation. Conclusion: MUTYH-CRC is associated with a high incidence of targetable alterations including KRAS G12C and BRAF. Considering unique characteristics in MUTYH-CRC tumor microenvironment, including T cell infiltrate, trials combining KRAS G12C/BRAF inhibitors and immune checkpoint inhibitors are warranted. Citation Format: David Kaldas, Tiago Biachi de Castria. Somatic mutational profile in MUTYH- associated colorectal cancers (MUTYH-CRCs) abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 6462.