Merck & Co. Inc. (MRK) has sought FDA approval for the expanded use of its blockbuster cancer drug Keytruda as adjuvant therapy in the treatment of patients with resected, high-risk stage III melanoma.Melanoma is a cancer that usually starts in a certain type of skin cell, i.e., melanocytes.Melanoma is much less common than basal cell and squamous cell skin cancers but is more dangerous because it’s much more likely to spread to other parts of the body if not caught early. (Source: American Cancer Society).The regulatory agency’s decision on the proposed new indication is expected on February 16, 2019. Keytruda, co-developed and co-commercialized with AstraZeneca, is already approved for the treatment of melanoma, non-small cell lung cancer, head, and neck squamous cell carcinoma, classical Hodgkin lymphoma, primary mediastinal large B-cell lymphoma, urothelial carcinoma, microsatellite instability-high cancer, gastric cancer, cervical cancer, hepatocellular carcinoma, and Merkel cell carcinoma. The drug fetched revenue of $3.81 billion for Merck in full-year 2017, and $5.02 billion in the first nine months of 2018.MRK closed Tuesday’s (Jan.29, 2019) trading at $73.23, up 0.43%.