A Phase III, Multicenter, Randomized, Double-Blind, Placebo-Controlled Study Evaluating the Efficacy and Safety of Inavolisib Plus a CDK4/6 Inhibitor and Letrozole Versus Placebo Plus a CDK4/6 Inhibitor and Letrozole in Patients With Endocrine-Sensitive PIK3CA-Mutated, Hormone Receptor-Positive, HER2-Negative Advanced Breast Cancer

This study is testing a new drug combination to see if it works better than the standard treatment for a specific type of advanced breast cancer. It focuses on patients whose cancer cells have a particular genetic change called a PIK3CA mutation, which helps doctors better target the cancer's growth.

This trial is for men and women with advanced breast cancer that is hormone receptor-positive and HER2-negative. You must have the PIK3CA genetic mutation, and you should not have received prior systemic (full-body) treatment for your advanced cancer.

Participants will be randomly assigned to receive either the new drug, inavolisib, or a placebo, alongside two other standard treatments (a CDK4/6 inhibitor and letrozole). A placebo is an inactive pill that contains no medicine, used to help researchers clearly see the effects of the new treatment.

The study is currently recruiting patients at medical centers in Phoenix, Arizona, and Burbank and La Jolla, California. It is a Phase 3 study, which is the final stage of testing before a new treatment can be submitted for approval.