Capecitabine In Combination With Cemiplimab In Patient With Metastatic Breast Cancer

Inclusion Criteria: * Able to provide a written informed consent and any locally required authorization prior to performing any protocol-related procedures,including screening evaluations. * Female or male, age 18 years or older * Eastern Cooperative Oncology Group (EGOG) performance status 0 through 2 * Pathologic confirmation of noninvasive breast cancer that is Hormone-receptor positive (HR+) (ER \[estrogen-receptor\] and/or PR \[progesterone-receptor\] \>/= 1%, locally advanced, or metastatic disease. * Invasive breast cancer is Human Epidermal Growth Factor Receptor 2 (HER2) negative defined as 0 or 1+ by immunohistochemistry (IHC) or with an in situ hybridization (ISH) ratio (HER2 gene copy/chromosome 17) \< 2 or as defined by ASCO/CAP guidelines * Measurable or non-measurable disease * Any line of prior endocrine therapy in the unresectable and /or metastatic setting * Adequate organ and marrow function as defined in protocol * Participants must be willing and able to comply with the protocol for the duration of the study. This compliance includes undergoing treatment, scheduled visits, and examinations, including follow-up. * If taking herbal or natural remedies that may have immune modulatory effects, participants must be willing to discontinue them before first dose of cemiplimab * Body weight greater than 30 kg Exclusion Criteria: * Participation in another clinical study with an investigational product during the last 4 weeks * Concurrent enrollment in another …