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The FDA has granted breakthrough therapy designation to LEE011 (ribociclib), in combination with letrozole, for the treatment of hormone receptor positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced or metastatic breast cancer. LEE011 is a selective cyclin-dependent kinase (CDK4/6) inhibitor.

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The breakthrough therapy designation is based primarily on positive results of the phase III MONALEESA-2 trial of LEE011 in combination with letrozole in postmenopausal women who had received no prior therapy for their advanced disease. The MONALEESA-2 trial met the primary endpoint of clinically meaningful improvement in progression free survival at a pre-planned interim analysis.


Up to one-third of patients with early-stage breast cancer will subsequently develop metastatic disease. The 5-year relative survival rate for stage 3 breast cancer is approximately 72 percent, while metastatic (stage 4) breast cancer has a 5-year relative survival rate of approximately 22 percent.