Atezolizumab and Nab-Paclitaxel in Advanced Triple-Negative Breast Cancer

Authors: Schmid, P. et. al.
Source: NEJM doi: 10.1056/NEJMoa1809615

Triple negative breast cancer has poorer outcomes compared to other types of breast cancer. Researchers are trying to identify cellular targets to create effective therapies for this disease. One such target is a group of immune cells that can exist among the cancer cells. These cells have a receptor that, when activated, can turn off the immune cell and allow the cancer cells to grow. Researchers hypothesize that inhibiting that receptor activity can allow the immune cells to function and kill cancer cells. Atezolizumab is a chemotherapy agent that does just that. It is used in urologic and lung cancer cases. The investigators in this current study looked at the effectiveness of using atezolizumab with or without a taxane (a standard chemotherapy agent for triple- negative breast cancer) for cases of triple-negative breast cancer.

Patients with metastatic or unresectable triple-negative breast cancer were selected for the study. Just over 900 women from 41 countries participated. Half of these women received atezolizumab and a taxane, while the other half received atezolizumab and a placebo. They were all followed for progression-free and overall survival.

Median progression-free survival was 7.2 months in the first group compared to 5.5 months in the second group. Median overall survival was also better in the first group: 21.3 months compared to 17.6 months.

The investigators also looked at the women whose tumor cells harbored the specific cellular structure that atezolizumab targets. The trends were the same: women who received atezolizumab and the taxane had improved progression-free and overall survival compared to the women who received atezolizumab and a placebo.

Most study participants experienced side effects. Alopecia (hair loss) was most common. Women who received atezolizumab and the taxane had more frequent episodes of nausea, cough, low immune cell counts, fever and hypothyroidism.

This study provides evidence that a chemotherapy agent specifically targeted to cellular features in triple negative breast cancer may be effective for women with inoperable disease. While it paves the way for more research into its use, it also validates theories that finding cellular targets in breast cancer remains a very worthwhile path to discovering more effective treatments.