Shares of Merck & Co. Inc. /zigman2/quotes/209956077/composite MRK -0.40% were up 0.7% in trading on Friday, the day after the company said it will voluntarily withdraw an accelerated approval for Keytruda as a third-line treatment for some patients with gastric cancer in the next six months. Keytruda is Merck's top-selling drug; it brought in $14.4 billion in sales in 2020. The decision to withdraw the drug for this indication is part of the Food and Drug Administration's efforts to assess whether certain cancer medicines that received a type of approval dependent on confirmatory post-market clinical studies should stay on the market. The withdrawal is not expected to have a material impact on company shares, according to Mizuho Americas analysts. Merck's stock is up 0.7% so far this year, while the broader S&P 500 /zigman2/quotes/210599714/realtime SPX -0.91% is up 14.4%.