Abstract PO1-15-08: Genomic characterization of triple-negative breast cancer metastases reveals PKD1 as a novel biomarker for immunotherapy

Abstract Background: While primary triple-negative breast cancer (TNBC) garners significant research attention, the genomic alterations that occur in metastasis remain insufficiently understood, especially within Asian populations. Furthermore, the genomic information obtained from the primary tumor inadequately guides metastatic cancer treatment, highlighting the critical need for in-depth investigations into metastatic TNBC. Methods: We constructed the largest cohort of TNBC metastases (n = 296) among advanced TNBC patients treated at Fudan University Shanghai Cancer Center (FUSCC) between October 2018 and December 2020. Comprehensive DNA sequencing was conducted on the collected metastatic samples to analyze genomic alterations associated with treatment response. The underlying mechanisms of specific biomarkers were also explored. Results: We presented the genomic landscape of 296 TNBC metastases, encompassing mutant genes, mutation sites and copy number variations. Through multidimensional analysis, significant disparities in TNBC were observed between Western and Asian populations, primary and metastatic tumors, as well as different metastatic sites. Notably, our findings underscore the importance of sequencing TNBC metastases to guide precision therapy, which was associated with longer progression-free survival compared to physician-chosen treatments, shedding light on the pivotal clinical value of genomic studies in metastatic settings. Furthermore, efficacy analysis suggested that PKD1 mutations enriched in metastases mediated resistance to immunotherapy. These findings were further validated through three clinical trials (NCT03805399, NCT04129996, and NCT04395989). Mechanistic studies unveiled the involvement of PKD1 in TNBC immune evasion by upregulating CCL2, thereby facilitating the recruitment of M2-type tumor-associated macrophages. Conclusion: Our study emphasizes the critical significance and necessity of genomic profiling of metastases in guiding precision therapy for TNBC. Moreover, our findings reveal PKD1 as a novel and promising biomarker for immunotherapy. Citation Format: Xiu-Zhi Zhu, Yi-Fan Zhou, Yun-Yi Wang, Xiao-Hong Ding, Xi Jin, Zhi-Ming Shao, Yi-Zhou Jiang, Zhong-Hua Wang. Genomic characterization of triple-negative breast cancer metastases reveals PKD1 as a novel biomarker for immunotherapy abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-15-08.