Long-Term Update on Neoadjuvant Pembrolizumab Plus Chemotherapy in Early-Stage Triple-Negative Breast Cancer

By: Jenna Carter, PhD
Posted: Thursday, December 28, 2023

Neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab has yielded improvements in pathologic complete response and event-free survival in patients with early-stage triple-negative breast cancer. In a study presented at the 2023 San Antonio Breast Cancer Symposium (SABCS; Abstract LBO1-01), Peter Schmid, MD, PhD, of Barts Cancer Institute, Queen Mary University, London, and colleagues reported that after a median follow-up of approximately 5 years, 145 patients (18.5%) in the pembrolizumab group and 108 patients (27.7%) in the placebo group had an event-free survival event, defined as disease progression that precluded definitive surgery.

A total of 1,174 eligible patients with early-stage triple-negative breast cancer were randomly assigned on a 2:1 basis to receive pembrolizumab (n = 784) or placebo (n = 390) groups. Both groups received four cycles of paclitaxel plus carboplatin, followed by four cycles of doxorubicin or epirubicin plus cyclophosphamide. After definitive surgery, patients received adjuvant pembrolizumab or placebo for nine cycles or until disease recurrence or unacceptable toxicity. The dual primary endpoints were pathologic complete response and event-free survival.

Findings revealed the 60-month event-free survival rate was 81.3% (95% confidence interval [CI] = 78.4%–83.9%) vs 72.3% (95% CI = 67.5%–76.5%), respectively, with and without neoadjuvant pembrolizumab. The benefit of neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab vs neoadjuvant chemotherapy alone was consistent with the primary event-free survival results in all five sensitivity analyses. In a prespecified, nonrandomized, exploratory analysis, the 5-year event-free survival rates in the pembrolizumab and placebo groups were 92.2% vs 88.2% in patients with a pathologic complete response and 62.6% vs 52.3% in patients without a pathologic complete response.

Disclosure: Dr. Schmid has received consulting fees from Eli Lilly &. Company and Gilead Sciences.

2023 San Antonio Breast Cancer Symposium

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