Keytruda, a drug used for the treatment of several types of cancer, was approved by the U.S. Food and Drug Administration (FDA) in 2014. The drug, which is also known as pembrolizumab, was initially approved for the treatment of advanced melanoma in September 2014 [1][3].

Since its initial approval, Keytruda has received additional approvals for the treatment of other types of cancer. In May 2017, the FDA approved Keytruda in combination with chemotherapy for the first-line treatment of patients with metastatic squamous non-small cell lung cancer (NSCLC) [3]. In September 2017, the FDA expanded the approval of Keytruda to include the treatment of patients with metastatic or unresectable recurrent head and neck squamous cell carcinoma (HNSCC) [3]. In December 2017, the FDA approved Keytruda for the treatment of patients with unresectable or metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) solid tumors [3].

It is important to note that the FDA's approval of Keytruda for the treatment of various types of cancer is based on the results of clinical trials that have demonstrated the drug's safety and efficacy for these indications [2].

In summary, the FDA approved Keytruda for the treatment of advanced melanoma in September 2014, and has since expanded its approval to include the treatment of other types of cancer.

Sources:
[1] <https://www.drugpatentwatch.com/p/biologics/tradename/KEYTRUDA>
[2] <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5679831/>
[3] <https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-pembrolizumab-chemotherapy-her2-negative-gastric-or-gastroesophageal-junction>