Regeneron Pharmaceuticals (NASDAQ: REGN) has four significant medications on the market, including three that have won Food and Drug Administration approval since 2015, and it’s investing big money in research and development to provide it with a steady stream of new products. One of the most important drugs in its research pipeline is REGN-2810, a cancer-fighting drug that inhibits PD-1 so that cancer can’t hide from the immune system.