Patients with an aggressive form of advanced breast cancer can benefit from immunotherapy when used in combination with chemotherapy as first-line treatment, according to the results of a large international Phase III clinical trial and led by a researcher at the UPMC Hillman Cancer Center.

The study is the first large clinical trial to support the use of immunotherapy in treating triple-negative breast cancer and establishes a new standard of care in PD-L1+ patients, senior trial investigator and study author Leisha Emens, M.D., Ph.D., co-leader of the UPMC Hillman Cancer Immunology and Immunotherapy Program, explained.

Results were presented today at the annual meeting of the European Society for Medical Oncology in Munich, Germany. Breast cancer is the most common cancer in women, with an estimated 2 million new cases diagnosed in 2018 alone.

Triple-negative breast cancer

About 10 to 20% of patients have triple-negative breast cancer, an aggressive form of breast cancer that has a higher chance of recurrence and metastasis, and lower survival.

"While chemotherapy is the current standard of treatment for triple-negative breast cancer, there is an urgent need for newer, more effective therapies," said Emens.

"The results of this trial showed that adding the immunotherapy drug atezolizumab to chemotherapy was well-tolerated and resulted in a clear increase in clinical benefit for some patients with triple-negative breast cancer," said Emens.

The IMpassion130 trial was designed to evaluate whether atezolizumab, approved by the U.S. Food and Drug Administration to treat both bladder cancer and non-small cell lung cancer, could be used along with chemotherapy to improve clinical outcomes in patients with triple-negative breast cancer.

Atezolizumab belongs to a class of immunotherapy medications known as checkpoint inhibitors. The drug targets the PD-L1 protein, which in triple-negative breast cancer patients is found mostly on immune cells that infiltrate the tumor.

Blocking PD-L1 reinvigorates these immune cells, allowing them to attack the tumor. The trial enrolled 902 patients with either metastatic or locally advanced triple-negative breast cancer that could not be surgically removed.

Patients were enrolled at 246 sites in 41 countries across the world and were randomly assigned to receive either atezolizumab or a placebo, along with the chemotherapy drug nab-paclitaxel.

Both progression-free survival the length of time the patient lives after receiving the therapy without the tumor growing or spreading, and overall survival the length of time the patient survives from the start of the trial, were recorded.

In the overall patient population, the researchers found a statistically significant increase in progression-free survival in patients treated with both nab-paclitaxel and atezolizumab 7.2 months when compared to 5.5 months in patients who received chemotherapy alone.

In the group of patients who expressed the PD-L1 protein on tumor-infiltrating immune cells, the combination treatment had a more significant impact on progression-free survival 7.5 months versus 5 months.