Atezolizumab in combination with chemotherapy could be a first line treatment option for patients with metastatic triple-negative breast cancer with high PD-L1 expression, the second interim OS analysis from the IMpassion130 trial suggests.
The encouraging results seen with drugs inhibiting PD-L1 and PD-1 in non-breast tumours may also be expected with some patients with triple-negative breast cancer, according to results published in Lancet Oncology.
The multinational study that enrolled 902 patients with metastatic and unresectable locally advanced breast cancer found that while there was no overall survival (OS) benefit with atezolizumab and nab-paclitaxel combination over nab-paclitaxel alone, there was a OS benefit in patients with PD-L1 immune cell-positive disease.
At the second interim analysis with a median follow-up of 18 months the median OS in the intention-to-treat patients was 21·0 months with atezolizumab and 18·7 months with placebo (HR 0·86).
In the subgroup of 41% of patients whose tumours had ≥1% PD-L1 expression, the median overall survival was 25·0 months (95% CI 19·6–30·7) with atezolizumab versus 18·0 months (13·6–20·1) with placebo (stratified HR 0·71, 0·54–0·94]). The respective figures for progression free survival were 7·5 months with atezolizumab and 5·3 months with placebo.
The 24-month overall survival was 50·7% in the atezolizumab group versus 36·9% in the placebo group.
Grade 3 or 4 adverse events were seen in 49% of patients in the atezoliumab group and 43% of the placebo group, with peripheral neuropathy being more common in the atezolizumab group than the placebo group (6% vs 3%).
The study investigators said the findings showed there was a clinically meaningful overall survival benefit with atezolizumab for patients with PD-L1 immune cell-positive metastatic triple-negative breast cancer, suggesting it could be “an important therapeutic option in a disease with high unmet need.”
An accompanying commentary by Professor Wendy Woodward from the University of Texas MD Anderson Cancer Center said the results should be seen as ‘exploratory’ but showed the promise of combination chemotherapy and immunotherapy in a subset of patients with metastatic triple-negative breast cancer.
“This finding solidly gives validity to the enthusiasm for immunotherapy combinations in triple-negative breast cancer and provides a framework for future progress,” she wrote.