Can Immunotherapy Improve Outcomes in Triple-Negative Breast Cancer?

Combining chemotherapy with immunotherapy may offer improved survival for patients with triple-negative breast cancer (TNBC), according to a new study presented at the European Society for Medical Oncology (ESMO) 2018 Congress, held in Munich. Combining atezolizumab with nab-paclitaxel resulted in improved progression-free survival (PFS), primarily in patients with programmed death ligand 1 (PD-L1)–positive tumors.

Peter Schmid, MD, PhD, of St. Bartholomew’s Breast Cancer Centre in London, presented the results at the ESMO meeting, and said the findings “will change the way TNBC is treated,” according to a press release.

The phase III IMpassion 130 trial included a total of 902 patients with metastatic TNBC who had not received any prior therapy for metastatic disease. Patients were randomized to receive either nab-paclitaxel plus the anti–PD-L1 agent atezolizumab (451 patients), or to the same chemotherapy agent plus placebo (451 patients). They were followed for a median of 12.9 months.

In the full intention-to-treat cohort, the median PFS was 7.2 months with atezolizumab and 5.5 months with placebo, for a hazard ratio (HR) of 0.80 (95% CI, 0.69–0.92; P = .0025). There was a trend toward improved overall survival, at a median of 21.3 months with the immunotherapy agent and 17.6 months with placebo, for an HR of 0.84 (95% CI, 0.69–1.02; P = .0840).

In a subgroup analysis consisting only of patients with PD-L1–positive tumors (185 in the atezolizumab group, 184 in the placebo group), the results were more stark. The median PFS was 7.5 months with atezolizumab compared with 5.0 months with placebo, for an HR of 0.62 (95% CI, 0.49–0.78; P < .0001). The median overall survival was 25.0 months with immunotherapy and 15.5 months without it, for an HR of 0.62 (95% CI, 0.45–0.86; P = .0035).

The objective response rate in the full cohort was 56% with atezolizumab and 46% without it; in the PD-L1–positive group, it was 59% and 43%, respectively. The duration of response was also longer with atezolizumab, at 7.4 months vs 5.6 months in the full cohort, and 8.5 months vs 5.5 months in the PD-L1–positive patients.

All-cause adverse events occurred in 99% of atezolizumab patients and in 98% of placebo patients, with grade 3/4 events occurring in 49% and 42%, respectively. Several adverse events were at least 5% more common with atezolizumab, including nausea, cough, neutropenia, pyrexia, and hypothyroidism.

“This combination should become a new treatment option for patients with metastatic TNBC,” Schmid said.

Marleen Kok, MD, PhD, of the Netherlands Cancer Institute in Amsterdam, commented on the study, and agreed on the study’s importance. “The IMpassion 130 data will probably change the treatment landscape for our metastatic TNBC patients,” she said. She noted that trials are ongoing to help determine the best chemotherapy backbone to pair with immunotherapy, and that biomarkers for selecting patients are still needed.