The FDA has issued an alert regarding the combination of atezolizumab (Tecentriq®, Genentech) and paclitaxel for the treatment of patients with previously untreated, inoperable locally advanced or metastatic triple-negative breast cancer (TNBC). In addition to being ineffective, atezolizumab/paclitaxel can negatively impact overall survival.
While atezolizumab/paclitaxel is not approved for the treatment of breast cancer, atezolizumab in combination with paclitaxel protein-bound particles, also known as nab-paclitaxel, is currently approved for patients with metastatic TNBC whose tumors express programmed death ligand-1 (PD-L1). The phase 3 IMpassion131 trial, the results of which provided the basis for the FDA's alert, investigated the combination of atezolizumab/paclitaxel for patients with locally advanced or metastatic TNBC.
"Chemotherapy (including paclitaxel) remains the predominant treatment for metastatic TNBC, but clinical outcomes remain poor," commented the study investigators, led by first author David Miles, MD, a consultant medical oncologist at Mount Vernon Cancer Centre, in their abstract summarizing the study methodology, presented at the 2017 San Antonio Breast Cancer Symposium. "Therefore, new therapeutic approaches are needed."
IMpassion131 enrolled 600 adult patients with previously untreated, inoperable locally advanced or metastatic TNBC with an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. Patients were randomized in a 2:1 ratio to receive 90 mg/m2 intravenous paclitaxel in combination with either 840 mg intravenous atezolizumab or placebo until disease progression, unacceptable toxicity, or study completion. The study's primary end point was progression-free survival, with secondary endpoints of overall survival, objective response, duration of response, quality of life, and safety.
Compared with paclitaxel/placebo, atezolizumab/paclitaxel was not associated with a significant reduction in risk of cancer progression and mortality in patients whose tumors expressed PD-L1. Furthermore, in both the PD-L1–positive subgroup and the overall study population, interim overall survival results favored paclitaxel/placebo compared with the atezolizumab combination. Overall survival results will be reassessed at the final analysis.
According to the FDA's alert, clinicians should not replace nab-paclitaxel with paclitaxel for the treatment of their patients with TNBC. Potential changes to the prescribing information for atezolizumab and paclitaxel will be made upon further review of the trial results.
Patients who are currently receiving atezolizumab or paclitaxel for other approved uses should continue their treatment as directed. The safety and efficacy of atezolizumab and paclitaxel continue to be investigated in ongoing clinical trials.
For More Information
Miles D, André F, Gligorov J, et al (2018). IMpassion131: a phase III study comparing 1L atezolizumab with paclitaxel vs placebo with paclitaxel in treatment-naive patients with inoperable locally advanced or metastatic triple negative breast cancer (TNBC). Cancer Res (San Antonio Breast Cancer Symposium Abstracts), 78(suppl_4). Abstract OT1-01-01. DOI:10.1158/1538-7445.SABCS17-OT1-01-01
Clinicaltrials.gov (2020). A study of atezolizumab and paclitaxel versus placebo and paclitaxel in participants with previously untreated locally advanced or metastatic triple negative breast cancer (TNBC) (IMpassion131). NLM identifier: NCT03125902.
US Food and Drug Administration (2020). FDA issues alert about efficacy and potential safety concerns with atezolizumab in combination with paclitaxel for treatment of breast cancer. Available at: https://www.fda.gov/drugs/resources-information-approved-drugs/fda-issues-alert-about-efficacy-and-potential-safety-concerns-atezolizumab-combination-paclitaxel
Image credit: Kevin Janes. Courtesy of the National Cancer Institute/University of Virginia Cancer Center.