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Atezolizumab
Source: Breast Cancer Treatment (PDQ®)–Health Professional Version, National Cancer Institute.
Source updated: April 25, 2025 · Captured 2026-09-09.
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The addition of atezolizumab, a PD-L1–positive antibody, to first-line chemotherapy for patients with HER2-negative hormone receptor–negative, advanced breast cancer was evaluated in the phase III, randomized, placebo-controlled IMpassion130 trial (NCT02425891).[58,59] Participants (N = 902) were randomly assigned 1:1 to atezolizumab plus nanoparticle albumin-bound (nab)-paclitaxel or to placebo plus nab-paclitaxel. Participants were stratified according to the presence of liver metastases (yes/no), receipt of previous taxane therapy (yes/no), and PD-L1 status (positive or negative). PD-L1 expression of 1% or greater was defined as positive. Co-primary end points included PFS and OS, both of which were evaluated in the ITT population and in the PD-L1–positive population (n = 369).
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Based on the initial publication of PFS data from IMPassion130, the FDA granted accelerated approval for the use of atezolizumab in combination with protein-bound paclitaxel for patients with unresectable locally advanced or metastatic TNBC whose tumors express PD-L1. However, a 2021 final analysis revealed no OS benefit in the ITT population.[58,59]
IMpassion131 (NCT03125902) was a phase III, randomized, placebo-controlled, double-blind trial of first-line paclitaxel with or without atezolizumab for patients with unresectable locally advanced or metastatic TNBC. The study included 651 patients, 45% of whom had PD-L1–positive TNBC. This trial also did not demonstrate a benefit from the addition of atezolizumab to paclitaxel in this population.[60] Accordingly, the sponsor voluntarily withdrew this approval.
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IMpassion130 reported PFS data with a median follow-up of 12.9 months.[58]
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IMpassion130 reported PFS data with a median follow-up of 12.9 months.[58]
In the ITT population, PFS was improved with the addition of atezolizumab (median PFS, 7.2 months vs. 5.5 months; HR, 0.80; 95% CI, 0.69–0.92; P = .0025).
IMpassion130 reported PFS data with a median follow-up of 12.9 months.[58]
In the PD-L1–positive population, PFS was improved with the addition of atezolizumab (median PFS, 7.5 months vs. 5 months; HR, 0.62; 95% CI, 0.49–0.78; P < .001).
IMpassion130 reported PFS data with a median follow-up of 12.9 months.[58]
Adverse events occurred as expected. Adverse events that were potentially immune-related were more frequent in the atezolizumab arm.
The primary PFS analysis from IMpassion131 revealed that adding atezolizumab to paclitaxel did not improve investigator-assessed PFS in the PD-L1–positive population. The median PFS was 6.0 months for patients who received atezolizumab and paclitaxel compared with 5.7 months for patients who received placebo and paclitaxel (HR, 0.82; 95% CI, 0.60–1.12; P = .20).[60]
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The primary PFS analysis from IMpassion131 revealed that adding atezolizumab to paclitaxel did not improve investigator-assessed PFS in the PD-L1–positive population. The median PFS was 6.0 months for patients who received atezolizumab and paclitaxel compared with 5.7 months for patients who received placebo and paclitaxel (HR, 0.82; 95% CI, 0.60–1.12; P = .20).[60]
The final OS results showed no difference between the treatment arms. The median OS was 22.1 months for patients who received atezolizumab and paclitaxel compared with 28.3 months for patients who received placebo and paclitaxel in the PD-L1–positive population (HR, 1.11; 95% CI, 0.76–1.64).
The primary PFS analysis from IMpassion131 revealed that adding atezolizumab to paclitaxel did not improve investigator-assessed PFS in the PD-L1–positive population. The median PFS was 6.0 months for patients who received atezolizumab and paclitaxel compared with 5.7 months for patients who received placebo and paclitaxel (HR, 0.82; 95% CI, 0.60–1.12; P = .20).[60]
Results in the ITT population were consistent with the PD-L1–positive population. The safety profile was consistent with known effects of each study drug.
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