After Merck announced that the FDA had approved the company's Keytruda treatment for the first-line metastatic non-small cell lung cancer with tumor proportion scores of 50% or higher, SunTrust analyst John Boris says that such patients represent about 30% "of the prevalent first-line population." He adds that the approval was earlier than expected and gives Keytruda an approximately 15 month lead over competing drugs in NSCLC. The analyst thinks that the early approval will enable the company's 2021 revenue to beat expectations by a significant amount, and he recommends buying the stock on the news.