The US Food and Drug Administration (FDA) has accepted Novartis' New Drug Application (NDA) for filing and granted Priority Review for LEE011 (ribociclib) as first-line treatment of postmenopausal women with hormone-receptor positive, human-epidermal growth factor receptor-2 negative (HR+ / HER2-) advanced or metastatic breast cancer in combination with letrozole.

This NDA is based on a thorough clinical package, which comprises results of the Phase III MONALEESA-2 trial.

The study indicated LEE011 with letrozole cut down the risk of progression or death by 44% over letrozole alone, thereby significantly improving progression-free survival (PFS) across all patient subgroups.

Novartis also announced that the EMA has accepted for review the marketing authorisation application filed for LEE011 and letrozole in the same patient population.

Novartis Oncology CEO Bruno Strigini said: "These regulatory milestones, along with the FDA Breakthrough Therapy designation granted in August, underscore the need for new treatment options for women living with HR+ / HER2- advanced breast cancer.

"Priority Review allows a shorter review period compared with FDA standard review in the US, helping us to potentially bring LEE011 with letrozole to patients more quickly. We also are working diligently with the EMA and other health authorities to bring this treatment to patients around the world as fast as possible."

When the proteins are over-activated in a cell, they can enable cancer cells to grow and divide too quickly. Targeting CDK4/6 with improved precision may help in restricting uncontrollable growth of cancer cells.

LEE011 was developed by the Novartis Institutes for BioMedical Research (NIBR) under a research collaboration with Astex Pharmaceuticals.

Novartis continues to review LEE011 through the Mammary Oncology Assessment of LEE011's Efficacy and Safety (MONALEESA) clinical trial programme, which includes MONALEESA-2, MONALEESA-3, and MONALEESA-7.

These studies are analysing LEE011 in multiple endocrine therapy combinations across a wide range of patients, including men and premenopausal women.