Abstract P2-03-05: TP53 mutations in circulating tumor DNA associate with klebsiella pneumoniae inbreast cancer
Authors: Hou Ming-Feng , Chiang Chih-Po , Chang Chuan-Hsin , Lien Wei-Ting , Yang Ming-Je , Yeh Yao-Tsung 
Published: March 2020

Abstract
Background Breast cancer is a heterogeneous disease with different molecular pathological types and different clinical manifestations. Liquid-based analysis of tumor heterogeneity in circulating tumor DNA (ctDNA) can be used for cancer detection, monitoring disease progression, etc. The gut microbiome has emerged as an important mediating factor of breast cancer. Dysbiosis may contribute to the development of breast cancer. In this study, we aimed to identify risk-associated microbiome and whether some of specific microbiomes correlate with tumor-specific mutation burdens and disease progression in Taiwan breast cancer patients. Methods A total of 141 normal female subjects and 52 breast cancer patients were enrolled randomly. The study was approved from the Internal Review Board of Kaohsiung Medical University Hospital and informed consents were obtained from each subject. The Oncomine™ breast cfDNA assays with 10-gene panel of 152-associated mutational hotspot loci was performed to detect circulating breast tumor-derived DNA (ctDNA). The microbiota composition in fecal samples was analyzed using 16S ribosome RNA gene (V3-V4 region) amplicon sequencing on Illumina Miseq platform. 16S rRNA sequencing data were analyzed using CLC genomics workbench (Qiagen, Germany) and MeTaxon software (DNArails Co., Ltd, Taipei, Taiwan, ROC). Results Multiple logistic regression was used to compare the differences of druggable gene mutations and 59.2% of patients harbored at least one somatic mutation. Compared to TP53, the odds of mutations of PIK3CA, ERBB2, AKT, KRAS, and SF3B1 were 94.4%, 98.5%, 99.3%, 99.3%, and 99.7% were significantly lower than those of TP53 (all p&lt;0.001), after adjusting for tumor staging. As compared with stage I&II, the risk of harboring gene mutations was significantly higher in stage III (OR=9.519; 95% CI: 2.862-31.661), after adjusting for the effect of mutation type. Further investigation of the gut microbiota in breast cancer patients and normal controls showed that patients had an increased fecal microbiota composition (β-diversity) (ANOSIM, R2=0.0799, p=0.01 for Bray Curtis distances) but a lower α-diversity (pChao1=0.02) when compared with control women. Patients in stage I&II group had higher relative abundance of Streptococcus, Pasteurellaceae, Klebsiella pneumoniae, Blautia and Lachnospiraceae, as compared with control (p=0.003, &lt;0.001, 0.001, &lt;0.001 and 0.01).The ratio of increased microbial group (Streptococcus, Pasteurellaceae, Klebsiella pneumoniae, and Blautia) to decreased one (Sphingobacteriaceae and Akkermansia muciniphila) could obtain a score to discriminate stage I&II from normal control (AUC=0.783, p&lt;0.001). Intriguingly, Lachnospiraceae wasincreased along with stage progression. In addition, the patients with TP53 mutations had higher levels of Klebsiella and those ones with PIK3CA mutations had higher levels of Lachnospiraceae and Sphingobacteriaceae. Blautia was increased when patients presented with both TP53 and PIK3CA mutations. More importantly, the proportion of TP53 mutations was higher and specially enriched with Klebsiella pneumoniae. Conclusion Our results showed that several microbiomes were significantly changed in breast cancer patients and the ratio of increased microbial group to decreased one could discriminate stage I&II from normal control. In addition, these microbiomes were correlated to specific ctDNA mutation patterns. Mutations of TP53 was associated with the enrichment of Klebsiella pneumoniae which was highly represented in breast cancer. Dysbiosis of specific gut microbiome may serve as novel biomarkers for early detection and prevention of breast cancer. The mechanisms underlying specific association between gut microbiome and gene mutations require further investigations.
Citation Format: Ming-Feng Hou, Chih-Po Chiang, Chuan-Hsin Chang, Wei-Ting Lien, Ming-Je Yang, Yao-Tsung Yeh. TP53 mutations in circulating tumor DNA associate with klebsiella pneumoniae inbreast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-03-05.