Abstract The mechanisms that allow triple negative breast cancer tumors to survive neoadjuvant chemotherapy are incompletely understood. Evidence suggests that proliferative heterogeneity may contribute to primary chemotherapy resistance in patients with triple negative breast cancer. AKT1low quiescent cancer cells (QCCs) are a quiescent, epigenetically plastic, and chemotherapy resistant subpopulation initially identified in experimental cancer models. Here, we identify QCCs in primary and metastatic human breast tumors using automated, quantitative, immunofluorescence microscopy coupled with computational and statistical analysis. We show that QCCs exist as non-random and heterogeneously distributed clusters within primary tumors. In addition, these QCC clusters persist after treatment with multi-agent, multi-cycle, neoadjuvant chemotherapy in both residual primary tumors as well as nodal and distant metastases in patients with triple negative breast cancer. Together, these data qualify QCCs as a non-genetic mechanism of chemotherapy resistance in triple negative breast cancer patients that warrants further study. Citation Format: Sheheryar Kabraji, Xavier Sole, Ying Huang, Clyde Bango, Michaela Bowden, Aditya Bardia, Dennis Sgroi, Massimo Loda, Sridhar Ramaswamy. AKT1low quiescent cancer cells persist after neoadjuvant chemotherapy in triple-negative breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3173. doi:10.1158/1538-7445.AM2017-3173