On September 8, the U.S. Food and Drug Administration (FDA) alerted health-care professionals, oncology clinical investigators, and patients that a clinical trial studying the use of atezolizumab and paclitaxel in patients with previously untreated, inoperable, locally advanced or metastatic triple-negative breast cancer showed the drug combination did not significantly reduce the risk of disease progression and death compared with placebo and paclitaxel in the study population.
The trial, IMpassion131, was a phase III, multicenter, randomized, double-blind, placebo-controlled trial of atezolizumab in combination with paclitaxel compared with placebo and paclitaxel for patients with metastatic triple-negative breast cancer.
Atezolizumab in combination with paclitaxel is not approved for use in breast cancer. However, atezolizumab in combination with nab-paclitaxel (also known as paclitaxel protein-bound)—a different combination therapy—is currently approved for the treatment of adult patients with metastatic triple-negative breast cancer whose tumors express PD-L1 (PD-L1–stained tumor-infiltrating immune cells of any intensity covering ≥ 1% of the tumor area) as determined by an FDA-approved test. Continued approval of atezolizumab in combination with nab-paclitaxel may be contingent on proven benefit of the treatment in additional trials.
Health-care professionals should not replace nab-paclitaxel with paclitaxel in clinical practice.
In IMpassion131, treatment with atezolizumab and paclitaxel did not significantly reduce the risk of disease progression and death compared with placebo and paclitaxel in the PD-L1–positive patient population. Additionally, interim overall survival results favored paclitaxel/placebo vs paclitaxel/atezolizumab in both the PD-L1–positive population and the total population.
The FDA will review the findings of IMpassion131 and will communicate new information regarding the study results and any potential changes to prescribing information. The FDA is also evaluating the use of atezolizumab and paclitaxel in ongoing clinical trials for breast cancer and will recommend additional changes as appropriate.
Patients taking atezolizumab and paclitaxel for other approved uses should continue to take their medication as directed by their health-care professional. Health-care professionals and patients should report any adverse events or side effects related to the use of these products and other similar products to FDA’s MedWatch Adverse Event Reporting program.