Keytruda (pembrolizumab) is a groundbreaking immunotherapy drug that has revolutionized cancer treatment since its FDA approval in 2014 for advanced melanoma. Developed by Merck & Co., it is now approved in India for 14 indications across eight tumor types. Oncologists, like Dr. Pooja Babbar from Fortis Hospital Manesar, emphasize its effectiveness in treating various cancers, including lung, head and neck, and triple-negative breast cancer. Keytruda functions as an immune checkpoint inhibitor, targeting the PD-1 receptor on T-cells, which allows the immune system to better recognize and destroy cancer cells. This mechanism not only leads to enhanced patient outcomes but also minimizes the side effects typically associated with conventional chemotherapy. Oncologists prescribe Keytruda when specific biomarkers, such as PD-L1 expression or microsatellite instability, are present, particularly in advanced stages of cancer. The drug has shown promising results in improving long-term survival rates and reducing recurrence risks. However, it is crucial to note that Keytruda is produced by a single manufacturer, making it essential for patients to seek treatment under the guidance of qualified oncologists.