Trial results for the Phase 3 study (NCT03371017) investigating atezolizumab plus chemotherapy for patients with early relapsing recurrent triple-negative breast cancer were posted on ClinicalTrials.gov on 2025-11-12. The study found that atezolizumab plus chemotherapy did not significantly improve overall survival compared to placebo plus chemotherapy, with a median OS of 12.09 months versus 11.24 months, respectively, in the PD-L1-positive population.
Background
This study evaluated the efficacy and safety of atezolizumab in combination with chemotherapy for patients diagnosed with inoperable recurrent triple-negative breast cancer (TNBC).
Trial design
The study (NCT03371017) was a Phase 3 trial that enrolled 595 participants. It investigated atezolizumab plus chemotherapy compared with placebo plus chemotherapy in patients with inoperable recurrent triple-negative breast cancer. Participants received either atezolizumab in combination with chemotherapy (gemcitabine, capecitabine, or carboplatin) or placebo plus the same chemotherapy regimen.
Key results
The trial measured overall survival (OS) and survival rates in both the PD-L1-positive population and the modified intent-to-treat (mITT) population:
- In the PD-L1-positive population, the median Overall Survival (OS) was 12.09 months for the atezolizumab + chemotherapy group, compared to 11.24 months for the placebo + chemotherapy group.
- In the mITT population, the median Overall Survival (OS) was 10.35 months for the atezolizumab + chemotherapy group, compared to 9.79 months for the placebo + chemotherapy group.
- The 12-month survival rate in the PD-L1-positive population was 50.26% for atezolizumab + chemotherapy versus 47.58% for placebo + chemotherapy.
- The 12-month survival rate in the mITT population was 46.20% for atezolizumab + chemotherapy versus 42.44% for placebo + chemotherapy.
- The 18-month survival rate in the PD-L1-positive population was 33.63% for atezolizumab + chemotherapy versus 32.48% for placebo + chemotherapy.
- The 18-month survival rate in the mITT population was 27.05% for atezolizumab + chemotherapy versus 25.68% for placebo + chemotherapy.
Key analyses for overall survival and survival rates included:
- A Log Rank analysis reported a Hazard Ratio (HR) of 0.93 (95.0% CI: 0.73 to 1.2) with a p-value of 0.5891.
- Another Log Rank analysis reported a Hazard Ratio (HR) of 0.94 (95.0% CI: 0.76 to 1.18) with a p-value of 0.6139.
- Z-tests for the difference in event-free rates showed p-values of 0.6264, 0.475, 0.8315, and 0.7738 for various time points and populations, indicating no statistically significant differences.
What this means
The results from this Phase 3 trial indicate that adding atezolizumab to chemotherapy did not lead to a statistically significant improvement in overall survival or survival rates for patients with inoperable recurrent triple-negative breast cancer, neither in the PD-L1-positive population nor the modified intent-to-treat population. The observed differences in median OS and survival rates between the treatment arms were small and not statistically significant.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT03371017, titled "A Study of the Efficacy and Safety of Atezolizumab Plus Chemotherapy for Patients With Early Relapsing Recurrent Triple-Negative Breast Cancer," were posted on 2025-11-12 on clinicaltrials.gov.