Takafumi Morisaki

Abstract Triple-negative breast cancer (TNBC) is an aggressive subtype with limited treatment options beyond chemotherapy. Since programmed cell death ligand 1 inhibitors (PD-L1i), a type of immune checkpoint inhibitor, show limited efficacy in TNBC, effective combination strategies are needed. This study evaluated the therapeutic effects of API-1, a prolyl isomerase 1 inhibitor (Pin1i), and the PD-L1i atezolizumab, with or without eribulin, in TNBC models.

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1. Introduction Approximately fifteen percent of all breast cancer cases are triple-negative [1]. Triple-negative breast cancer (TNBC) is defined as not expressing estrogen receptors (ERs), progesterone receptors (PRs), or human epidermal growth factor receptor 2 (HER2). TNBC is treated with endocrine therapy and anti-HER2 therapy and chemotherapy. TNBC has a higher grade of malignancy, a higher frequency of distant metastases, and a poorer prognosis than other breast cancer subtypes [1].