Atezolizumab Plus Chemotherapy Prolongs PFS in Triple-Negative Breast Cancer

A phase 3 trial recently investigated if nanoparticle albumin-bound (nab)—paclitaxel enhances the treatment of atezolizumab in unresectable locally advanced or metastatic triple-negative breast cancer. The results were published in the New England Journal of Medicine,

Researchers randomly assigned patients with untreated metastatic triple-negative breast cancer in a 1:1 ratio to receive atezolizumab plus nab-paclitaxel or a placebo plus nab-placlitaxel. Patients continued on their assigned treatment until disease progression or an unacceptable level of toxicity. Stratification factors were if patients had undergone or not undergone neoadjuvant or adjuvant taxane therapy, the presence or absence of liver metastases at baseline, and programmed death ligand 1 (PD-L1) expression at baseline (positive versus negative).

The 2 primary endpoints included progression-free survival (PFS), in the intention-to-treat population and PD-L1-positive subgroup, and overall survival, first tested in the intention-to-treat population; if the finding was significant, then it would be tested in the PD-L1—positive subgroup.

In total, each arm of the study enrolled 451 patients with a median follow up of 12.9 months. The median PFS in the intention-to-treat arm was 7.2 months, compared with 5.5 months in the placebo plus nab-paclitaxel arm (hazard ratio [HR] for progression or death, 0.80; 95% CI, 0.69 to 0.92; P = .002). Among patients with PD-L1-positive tumors, the median PFS was 7.5 months and 5 months, respectively (hazard ratio, 0.062, 95% CI, 0.49 to 0.78; P <.001).

In terms of the second primary endpoint, the researchers found that in the intention-to-treat group, the median overall survival was 21.3 months, compared with 17.6 months in the placebo plus nab-paclitaxel (HR for death, 0.084; 95% CI, 0.69 to 1.02; P = .08). In patients with PD-L1 positive tumors, the median overall survival was 25 months and 15.5 months, respectively (HR 0.62; 95% CI, 0.45 to 0.86). In addition, any identified adverse events were consistent with the known safety profiles of each agent.

Overall, the study authors found that atezolizumab plus nab-paclitaxel prolonged PFS among patients with metastatic triple-negative breast cancer in both the intention-to-treat population and the PD-L1—positive subgroup. However, the authors also noted that “It is important for patients’ PD-L1 expression status on tumor-infiltrating immune cells to be taken into consideration to inform treatment choices for patients with metastatic triple-negative breast cancer.”

Reference

Schmid P, Adams S, Rugo H. Atezolizumab and nab-paclitaxel in advanced triple-negative breast cancer [published online October 20, 2018]. N Engl J Med. doi: 10.1056/NEJMoa1809615