ASCO Upsets CDK4/6 Class: Strong Data For Lilly's Abemaciclib, But Pfizer's Ibrance Disappoints

Phase III progression-free survival data from the MONARCH 2 study presented at the American Society of Clinical Oncology meeting put Eli Lilly & Co. in a good position to file the CDK4/6 inhibitor abemaciclib in the second quarter as planned, though a different release by rival Pfizer Inc.'s Ibrance raised questions about whether the class will be able to show an overall survival benefit.

MONARCH 2 tested abemaciclib with the selective estrogen receptor degrader fulvestrant in 669 hormone-receptor positive (HR+), human epidermal growth factor receptor-2 negative (HER2-) metastatic breast cancer patients who relapsed or...