IMpassion130 was a phase III clinical trial that enrolled 902 patients with untreated metastatic or locally advanced unresectable triple negative breast cancer and randomised them equally to receive either atezolizumab with nab-paclitaxel or placebo with nab-paclitaxel. The study had four pre-specified co-primary endpoints that included progression free survival in both the intent to treat patient population overall, so the entire population, as well as specifically in the PD-L1 positive patient population, that’s PD-L1 positivity in immune cells, and that was for progression free survival. It also had co-primary endpoints for overall survival in those two groups as well.

We found that there was a statistically significant improvement in progression free survival, particularly for the PD-L1 positive patient population, that was clinically meaningful with an increase in progression free survival of 2.5 months compared to the placebo arm. There was also a clinically meaningful improvement in overall survival, specifically in the PD-L1 positive patient population, of almost 10 months. These are really important findings because triple negative breast cancer is typically treated only with chemotherapy. There are a couple of classes of agents that are targeted agents such as bevacizumab or PARP inhibitors which are used in very selected circumstances but neither of these have resulted in overall survival benefit as of yet. So it looks like this immunotherapy that targets PD-L1 appears to be one of the first targeted agents that may confer an overall survival benefit in a well-defined group of patients with metastatic triple negative breast cancer and that is those patients that express PD-L1 on their immune cells within their tumour.