Shares of Merck & Co. Inc. /zigman2/quotes/209956077/composite MRK +1.04% gained 0.1% in premarket trading on Wednesday after it received a complete response letter from the Food and Drug Administration for an application to approve Keytruda in combination with Eisai Co. Ltd.'s /zigman2/quotes/203064480/delayed JP:4523 +2.74% Lenvima for a new indication. The regulator said the data that was provided in the application for the investigational combination therapy as a first-line treatment for unresectable hepatocellular carcinoma didn't demonstrate "a meaningful advantage" over existing therapies. The companies plan to conduct a new Phase 3 trial, which is already fully enrolled. They are also testing the Keytruda/Lenvima combination in 17 other clinical trials. Merck's stock has declined 13.4% year-to-date. The S&P 500 /zigman2/quotes/210599714/realtime SPX -0.20% is down 2.6%.