Merck & Co., Inc. MRK announced that the FDA has approved a supplemental biologics license application (sBLA) for its blockbuster PD-1 inhibitor, Keytruda. The sBLA sought approval of Keytruda as a monotherapy for patients with recurrent or metastatic cutaneous squamous cell carcinoma (cSCC) whose disease is not curable by surgery or radiation. The cSCC cancer is the second most common form of skin cancer.Keytruda, Merck’s biggest product, is already approved for use in more than 20 indications across several different tumor types in the United States. However, this is the first approval for the drug for cSCC indication in any treatment setting.The approval was based on data from the phase II KEYNOTE-629 study. Data from the study showed that Keytruda achieved an objective response rate of 34%. The complete response rate was 4% and partial response rate was 31%. However, following a median follow-up time of 9.5 months the median duration of response had not been reached.Merck’s shares have declined 16.6% this year so far, compared with the industry’s 1.8% decline.Keytruda generated sales of $3.3 billion in the first quarter of 2020, representing growth of 44.7% year over year. Launch of the drug in new indications, globally, drove sales. Keytruda sales, particularly, are benefiting from strong momentum in the first-line lung cancer indication.Merck is spending billions on research and development of Keytruda to secure more approvals in earlier lines of treatment. Regulatory approvals to Keytruda show that the development program is progressing well. The company is currently studying the drug for more than 30 types of cancer in over 1200 studies including 600 plus combination studies. Merck has collaborated with several companies including Amgen, Incyte INCY, Glaxo GSK and Pfizer PFE separately for the evaluation of Keytruda in combination with other regimens.Undoubtedly, Keytruda’s solid growth prospects are based on increased utilization, approval for new indications and expectation of additional approvals worldwide.Merck Co., Inc. Price Merck Co., Inc. price | Merck Co., Inc. QuoteZacks RankMerck currently has a Zacks Rank #3 (Hold). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.5 Stocks Set to DoubleEach was hand-picked by a Zacks expert as the #1 favorite stock to gain +100% or more in 2020. Each comes from a different sector and has unique qualities and catalysts that could fuel exceptional growth.Most of the stocks in this report are flying under Wall Street radar, which provides a great opportunity to get in on the ground floor.Today, See These 5 Potential Home Runs >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Pfizer Inc. (PFE): Free Stock Analysis Report Merck Co., Inc. (MRK): Free Stock Analysis Report Incyte Corporation (INCY): Free Stock Analysis Report GlaxoSmithKline plc (GSK): Free Stock Analysis Report To read this article on Zacks.com click here.