TRIO Completes Enrollment of Phase III NATALEE Breast Cancer Clinical Trial

April 21, 2021

Translational Research In Oncology (TRIO) today announced completion of enrollment for Novartis phase III clinical trial of ribociclib with endocrine therapy in the adjuvant treatment of HR-positive, HER2-negative early breast cancer (EBC). The trial, referred to as NATALEE (New Adjuvant TriAl with LEE), has enrolled 5101 patients globally.

Rapid enrollment of this randomized, phase III study can be attributed to the strength of TRIO’s global network consisting of 405 active investigator sites, including TRIO-US and its regional partners, and current unmet needs among the eBC patient population that includes intermediate-risk patients, as well as high-risk stage III patients.

“Completing enrollment of a phase III study under normal circumstances is a key milestone for any clinical research organization. Accomplishing this during an evolving global pandemic speaks to the strength of our global clinical trial network and the entire TRIO team,” stated Dennis J. Slamon, MD, PhD, TRIO Chairman/Executive Director and Director of Clinical Translational Research at the University of California, Los Angeles Jonsson Comprehensive Cancer Center. “We appreciate and thank the clinical investigators, trial coordinators and of course the patients for their participation and contributions. We are especially pleased to continue our partnership with Novartis to advance ribociclib through the phase III study and are grateful for their continued confidence.”

Ribociclib belongs to a class of targeted therapies called CDK4/6 inhibitors. Cyclin-dependent kinases 4 and 6 are proteins that help regulate cell replication and proper cell cycle function. Overexpression of these proteins has been observed in breast cancer, and this leads to uncontrolled cell growth contributing to tumour formation. CDK4/6 inhibitors prevent CDKs from triggering cell growth and division, leading to irreversible cell cycle arrest. Preclinical data show that ribociclib is distinct from other CDK4/6 inhibitors in its selectivity to CDK4 and CDK6, as well as its preferential inhibition to CDK4 which, in breast cancer, plays a pivotal role in disease progression.

This clinical trial will provide insight into the role of ribociclib and duration of treatment in intermediate and high risk EBC. The efficacy, safety, and validity of ribociclib in the treatment of present and future EBC patients is the ultimate goal of TRIO and Novartis. As previously announced, the primary endpoint of the study is invasive disease-free survival (iDFS).

“Ribociclib is distinct from other CDK4/6 inhibitors, having demonstrated unparalleled overall survival evidence in a diverse set of metastatic breast cancer patients with multiple combination partners,” said Jeff Legos, Ph.D., MBA, Senior Vice President and Head of Oncology Drug Development. “We’re proud to collaborate with a partner like TRIO, that has a mission to find the shortest path to saving lives, as we work toward the same goal and study the potential of ribociclib plus endocrine therapy in early breast cancer populations with high-unmet need.”

TRIO’s experience with breast cancer clinical trials is well-established, having been involved in the development of trastuzumab for HER2-positive breast cancer, docetaxel for early-stage breast cancer, and other CDK4/6 inhibitors. TRIO’s commitment to breast cancer positions them as leaders in the field, with a long-standing desire to improve the lives of people with breast cancer.

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

About TRIO

TRIO advances translational cancer research by introducing innovative and novel targeted therapeutic concepts into the clinical trial setting. With international offices in Edmonton (Canada), Paris (France), Montevideo (Uruguay), TRIO’s global reach is expansive. Our goal as a not-for-profit clinical research organization is to find the shortest path to saving lives. Additional information on TRIO can be found by visiting

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