Keytruda, a medication produced by Merck & Co. for the treatment of various forms of cancer, received its first approval from the U.S. Food and Drug Administration (FDA) in 2014. This initial authorization was for the treatment of advanced melanoma in patients whose disease had progressed following other treatments.

The FDA has since expanded Keytruda's approvals to include the treatment of several other types of cancer, such as lung, head and neck, classical Hodgkin lymphoma, urothelial carcinoma, and microsatellite instability-high (MSI-H) cancer.

The drug functions by targeting the PD-1/PD-L1 pathway, which allows the immune system to identify and destroy cancer cells more effectively.

For more detailed information about Keytruda's FDA approvals and patents, you can refer to DrugPatentWatch.com's page on Keytruda.

Sources:

1. U.S. Food and Drug Administration. (2021). Keytruda (pembrolizumab) prescribing information. Retrieved from <https://www.fda.gov/media/84591/download>
2. Merck & Co., Inc. (2021). Keytruda. Retrieved from <https://www.merck.com/brands/our-medicines/keytruda>
3. DrugPatentWatch. (2021). Pembrolizumab (Keytruda). Retrieved from <https://www.drugpatentwatch.com/drugs/pembrolizumab>