Key TakeawaysJohnson & Johnson said Monday that it bought Ambrx Biopharma for about $2 billion to boost its oncology portfolio.The$28-per-share all-cash offer is at a 105% premium to Ambrx's closing price on Friday.Ambrx's clinical and preclinical treatments use antibody drug coagulates to attack a variety of cancer cells.Ambrx shares more than doubled following the news, hitting an all-time high.Ambrx Biopharma Inc. (AMAM) shares more than doubled Monday on news that Johnson & Johnson (J&J) (JNJ) would pu ...