Prognostic Value of the TP53 Mutation Location in Metastatic Breast Cancer as Detected by Next-Generation Sequencing

Han Bai,1 Jianjun Yu,2 Shidong Jia,2 Xiaoran Liu,1 Xu Liang,1 Huiping Li1 1Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Breast Oncology, Peking University Cancer Hospital and Institute, Beijing, 100142, People’s Republic of China; 2Huidu Shanghai Medical Sciences, Shanghai, 201499, People’s Republic of ChinaCorrespondence: Xu Liang; Huiping LiKey Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Breast Oncology, Peking University Cancer Hospital and Institute, No. 52, Fucheng Road, Haidian District, Beijing, 100142, People’s Republic of ChinaTel/Fax +86-10-88196739Email liangxu15@outlook.com; huipingli2012@hotmail.comPurpose: The status of TP53 mutations was measured in cell-free DNA from patients with metastatic breast cancer (MBC) to investigate disease characteristics and the prognostic role of different locations of the TP53 mutation site.Patients and Methods: Blood samples were taken from a total of 187 patients diagnosed with MBC who were treated at the Department of Breast Oncology, Peking University Cancer Hospital between January 2013 and March 2020. Next-generation sequencing was used to investigate the TP53 mutation spectra of circulating free DNA in these blood samples.Results: Among the 187 MBC patients, TP53-mutated patients had a significantly shorter median disease-free survival (DFS) and overall survival (OS) compared with TP53 wild-type patients (P=0.001 and P=0.006, respectively). Additionally, in hormone receptor positive/HER2 negative (HR+/HER2-) and triple negative (TNBC) cohorts, TP53-mutated patients had a significantly shorter median DFS than TP53 wild-type patients (P=0.038 and P=0.023, respectively). The 79 patients with TP53 mutations carried 87 somatic TP53 mutations, of which most (77.0%) mapped to the DNA-binding domain (DBD) of the protein encoded by TP53 exons 5– 8. In patients with TP53 mutations, those occurring in the non-DBD had a significantly shorter median DFS and OS than TP53 wild type (P< 0.001 and P=0.001, respectively). Additionally, patients with non-missense mutations in the DBD had a significantly shorter median DFS and OS than TP53 wild-type patients (P=0.001 and P< 0.001, respectively). TP53-mutated patients had a significantly shorter DFS than TP53 wild-type patients in the adjuvant endocrine therapy sensitive group (P=0.008), but differences in the endocrine therapy resistant group were not significant.Conclusion: TP53-mutated MBC patients had a significantly worse outcome than TP53 wild-type patients especially those in HR+/HER2– and TNBC cohorts. Of TP53-mutated patients, those with non-missense mutations in the DBD had worse breast cancer-related survival. TP53 mutations were also associated with endocrine resistance.Keywords: advanced breast cancer, TP53 mutation, NGS, adjuvant endocrine therapy, DNA-binding domain