Abstract

R. Harsha Sree*, K. Sravani, G. Imran, S. Aisha and Dr. K. Thirumala Naik

ABSTRACT

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer characterized by the absence of estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptor 2 (HER2) as determined by immunohistochemistry (IHC). TNBC accounts for 15–25% of all breast cancer cases and is associated with unique molecular profiles, limited treatment options, and poor prognosis. Epidemiological studies highlight various risk factors, including prolonged oral contraceptive use, younger age at first childbirth, higher parity, and modifiable lifestyle factors such as body mass index and smoking. Pembrolizumab, a humanized monoclonal antibody targeting the programmed cell death protein 1 (PD-1) pathway, has emerged as a promising therapeutic option for TNBC. By blocking the PD-1/PD-L1 interaction, pembrolizumab reactivates T-cells to effectively target and eliminate tumor cells. Its efficacy has been demonstrated in multiple cancers, leading to FDA approval for advanced melanoma, non-small cell lung cancer (NSCLC), and other solid tumors, including TNBC. Administered intravenously at fixed doses, pembrolizumab offers convenience and cost-effectiveness compared to weight-based dosing. Adverse effects associated with pembrolizumab include immune-mediated reactions such as colitis, pneumonitis, endocrinopathies, and infusion-related hypersensitivity. Despite these risks, pembrolizumab represents a breakthrough in TNBC management by addressing its immune-evasive nature. Ongoing clinical trials continue to expand its therapeutic applications, providing hope for improved outcomes in this challenging cancer subtype.