Investors have heavily invested in finding a successor to Merck's Keytruda, but recent data suggests that a single dominant cancer drug may be fading. Summit Therapeutics' ivonescimab initially appeared promising, outperforming Keytruda in a Chinese trial by offering patients a median survival increase of four months. However, skepticism remains due to demographic limitations in the trial, including age and gender disparities. The upcoming international study will be pivotal in determining ivonescimab's competitiveness against Keytruda in the U.S. market. This new class of bispecific antibodies aims to enhance cancer treatment by activating the immune system while simultaneously starving tumors of their blood supply, a strategy that could redefine oncology. Nevertheless, the risks associated with cutting off blood supply, such as bleeding and clots, particularly affect older patients, who represent the majority of lung cancer cases in the U.S. With potential copycat versions of Keytruda expected by 2028, the cancer treatment landscape is shifting towards more specialized therapies, offering patients a variety of options but presenting investors with a more complex market.