Dataset Information

Mutational landscape of pan-cancer patients with PIK3CA alterations in Chinese population.

ABSTRACT:

Purpose

To analyze the mutational landscape of pan-cancer patients with PIK3CA mutations in Chinese population in real-world.

Methods

We analyzed PIK3CA mutation status in sequencing data of cell-free DNA from plasma and genomic DNA from matched peripheral blood lymphocyte in 11,904 Chinese pan-cancer patients, and compared them with genomic data from the Catalogue of Somatic Mutations in Cancer (COSMIC) database. Besides, concomitant genomic aberrations in PIK3CA-mutated samples were detected to investigate cancer driver genes, as well as their enriched pathways. Meanwhile, the mutations of Alpelisib targeting genes were screened and their co-alterations were analyzed according to OncoKB definition to identify the potential actionable ones.

Results

The proportion of patients with PIK3CA mutations varied among 21 types of cancer, with the top being BRCA, CESC, SCL, and UCEC. The most common PIK3CA mutation hotspots were found to be E545K, E542K and H1047R. The Chinese cohort had significantly lower frequencies of PIK3CA mutations in breast and stomach cancers, but markedly higher PIK3CA mutation frequencies in large intestine, kidney and lung cancers than the COSMIC cohort. Compared with COSMIC cohort, the mutation frequencies of Alpelisib-targeted genes in breast cancer were significantly reduced in the Chinese cohort. All PIK3CA-mutated patients had concomitant genomic aberrations. While the most common concomitant genomic alterations occurred in TP53, EGFR and FAT1, these co-mutated genes were mainly enriched in RTK/RAS pathway, PI3K pathway and P53 pathway. Moreover, 83.6% of patients carrying mutations in Alpelisib-targeted genes had at least one actionable concomitant alteration. Level 1 actionable alteration was identified in LUAD, BRCA, COAD, LUSC, READ, and STAD.

Conclusion

Compared with the Western cohort, the mutation frequency of PIK3CA in breast cancer was reduced in the Chinese cohort. RTK/RAS pathway, PI3K pathway and P53 pathway were identified as the most common co-mutation pathways, suggesting that they may potentially serve as targets for possible Alpelisib-based combination therapy.

SUBMITTER: Huang Q

PROVIDER: S-EPMC9248192 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundGenetic testing for breast cancer (BC) patients may shift the paradigm towards more personalized management and treatment strategies. While gene alterations may be ethnic-specific in breast cancer, our understanding of genetic epidemiology of BC remains mainly driven by data from Caucasian populations and further limited to selected handful of genes.MethodsWe collected whole blood samples from 356 BC patients at metastatic first line BC and primary stage IV disease at Beijing Cancer Hospital between Jan. 2013 to Dec. 2019. A comprehensive 600-gene cancer panel was used to detect germline variants in the covered genes with a median 300x sequencing depth. Variants were classified into pathogenic, likely pathogenic, variant of uncertain significance, likely benign and benign groups according to the ACMG/AMP Standards and Guidelines. Pathogenic and likely pathogenic variants were considered as deleterious mutations.ResultsThe median age of 356 BC patients was 49 years (range, 21-87 years) at the first diagnosis of BC. Deleterious germline mutations across 48 cancer-related genes were identified in 21.6% (77/356) of the patients. The most prevalent mutations were BRCA1/2 mutations (7.0%), followed by ATM and RAD50 mutations (1.4% each). In addition, patients with family history were more likely to carry BRCA1 mutations (P=0.04). Moreover, patients with triple-negative breast cancer (TNBC) were more likely to harbor BRCA1 mutations than those with HR+ or HER2+ breast cancer (P=0.006). While there was no significant survival difference observed in BRCA1/2 carriers relative to non-carriers, patients with DNA damage repair (DDR) gene mutations (mostly frequently BRCA, ATM, RAD50) had worse disease-free survival (P=0.02).ConclusionsThe most prevalent germline mutations in a large cohort of Chinese patients with advanced BC were BRCA1/2 mutations, followed by ATM and RAD50 mutations. In total, approximately 16.0% (57/356) of patients carry deleterious mutations in DDR pathway. Patients with breast or ovarian cancer family history were more likely to carry BRCA1/2 mutations, and ones with DDR mutations had worse survival. These findings suggest that DDR mutations are prevalent in Chinese BC patients who may potentially benefit from treatment with Poly (ADP-ribose) polymerase inhibitors.