The FDA has granted breakthrough therapy designation to Lilly’s abemaciclib, which is part of a new class of breast cancer treatments.

Abemaciclib is a cyclin-dependent kinase (CDK) 4 and 6 inhibitor, for the treatment of patients with refractory hormone-receptor-positive (HR+) advanced or metastatic breast cancer.

If approved the drug would be the first rival to Pfizer’s Ibrance (palbociclib), which earlier this year became the first CDK inhibitor to be given the greenlight by the FDA after also receiving accelerated review. In Europe, the EMA validated Pfizer’s application to market the drug in August.

It remains to be seen if Lilly’s drug will be able to differentiate itself enough from Pfizer’s in the market. Abemaciclib's breakthrough therapy designation was granted based on data from the Phase I JPBA trial.

"If caught before it spreads, patients can survive breast cancer,” says Richard Gaynor, senior vice president of product development and medical affairs for Lilly Oncology. “However, for the nearly 10 percent of patients who are initially diagnosed at stage IV, and the nearly 30 percent of patients whose early-stage cancer will re-occur as metastatic disease, there remains an urgent need for effective therapy options.

"We are pleased that the FDA has designated abemaciclib as a breakthrough therapy for patients with advanced breast cancer and Lilly will work closely with the FDA in this process to expedite its development and review."