In consultation with the FDA, the accelerated approval of atezolizumab (Tecentriq®, Genentech) in combination with nab-paclitaxel has been voluntarily withdrawn from the treatment of patients with programmed death ligand 1 (PD-L1)–positive unresectable locally advanced or metastatic triple-negative breast cancer (TNBC).
"Triple-negative breast cancer is a heterogenous disease entity with a high unmet medical need," wrote David Miles, MD, Lead Clinician for Breast Cancer at Mount Vernon Cancer Centre in the United Kingdom, and colleagues, in their August 2021 publication of the results of IMpassion131 (NCT03125902). Designed to serve as the confirmatory trial for the accelerated approval, IMPassion131 provided the basis for the withdrawal.
The phase 3 trial enrolled 651 patients with advanced TNBC, 45% of whom had PD-L1–positive disease. Eligible patients had not received prior systemic therapy or had received neoadjuvant chemotherapy at least 12 months before enrollment. Patients were randomized 2:1 to receive atezolizumab 840 mg or placebo on Days 1 and 15 in combination with nab-paclitaxel 90 mg/m2 on Days 1, 8, and 15 of each 28-day cycle, until disease progression or unacceptable toxicity. The primary end point was investigator-assessed progression-free survival, with a secondary end point of overall survival.
At the primary analysis, atezolizumab/nab-paclitaxel was not associated with a statistically significant improvement in investigator-assessed progression-free survival compared with placebo/nab-paclitaxel in patients with PD-L1–positive tumors (6.0 vs 5.7 months). Atezolizumab/nab-paclitaxel produced a higher unconfirmed best overall response rate (63% vs 55%) and a longer median duration of response (7.2 vs 5.5 months) compared with the placebo/nab-paclitaxel group. Final overall survival results were not improved for atezolizumab/nab-paclitaxel compared with placebo (22.1 vs 28.3 months). The safety profiles were consistent with known toxicities for each agent.
"Results from IMpassion131 do not show a significant benefit from combining atezolizumab with paclitaxel, contrasting with findings from previously published trials of first-line immune checkpoint blockade for metastatic TNBC," concluded Dr. Miles and colleagues in their publication in Annals of Oncology. "The reasons for this difference remain undefined."
Patients currently receiving atezolizumab for TNBC should discuss their treatment with their health care provider. The withdrawal does not affect other approved indications for atezolizumab.
For More Information
Miles D, Gligorov J, André F, et al (2021). Primary results from IMpassion131, a double-blind, placebo-controlled, randomised phase III trial of first-line paclitaxel with or without atezolizumab for unresectable locally advanced/metastatic triple-negative breast cancer. Ann Oncol, 32(8):994-1004. DOI:10.1016/j.annonc.2021.05.801
Genentech (2021). Genentech provides update on Tecentriq U.S. indication for PD-L1–positive, metastatic triple-negative breast cancer. Available at: https://www.gene.com/media/press-releases/14927/2021-08-27/genentech-provides-update-on-tecentriq-u
Clinicaltrials.gov (2021). 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.
Image credit: Kevin Janes. Courtesy of the National Cancer Institute/University of Virginia Cancer Center