The breast cancer treatment ‘Ibrance (palbociclib)’ was what established Pfizer Korea as the ‘anticancer drug power’ in Korea. The company had other excellent anticancer drugs such as ‘Xalkori,’ and ‘Sutene,’ but none had received as much spotlight as Ibrance. As the ‘first CDK4/6 inhibitor,’ and ‘the first new breast cancer drug in 50 years,’ Ibrance had quickly rose to the ranks and became a blockbuster drug.

◆ The first CDK4/6 inhibitor, unrivaled status despite controversy

Ibrance selectively inhibits Cyclin-dependent kinases (CDK) 4/6 that regulate cell division and cell growth to block the proliferation of tumor cells. Lilly’s Verzenio (abemaciclib),’ and Novartis’s