Dr Schmid on Pembrolizumab Plus Chemotherapy in High-Risk, Early-Stage TNBC

What we haven’t [had] until now were the long-awaited overall survival data. This is only a key secondary end point, but it’s of course, from a patient perspective, the most important end point.”

Peter Schmid, MD, PhD, FRCP, professor, cancer medicine, Barts Cancer Institute, Queen Mary University of London, discusses the updated long-term overall survival (OS) results from the phase 3 KEYNOTE-522 trial (NCT03036488), which evaluated pembrolizumab (Keytruda) plus chemotherapy in patients with high-risk, early-stage triple-negative breast cancer (TNBC). Updated data were presented at the 2024 ESMO Congress.

The KEYNOTE-522 trial assessed pembrolizumab in combination with neoadjuvant chemotherapy followed by surgery and adjuvant pembrolizumab or placebo for patients with high-risk, early-stage TNBC. Schmid explains that earlier results showed that the addition of pembrolizumab to chemotherapy significantly increased pathologic complete response (pCR) rates by approximately 30.6%, with a pCR rate of 64.8% (95% CI, 59.9%-69.5%) vs 51.2% (95% CI, 44.1%-58.3%) in the placebo arm (estimated treatment difference, 13.6%; 95% CI, 5.4%-21.8%; P < .001).

At a median follow-up of 75.1 months (range, 65.9-84.0), the 60-month event-free survival (EFS) rate was statistically significant in favor of the pembrolizumab plus chemotherapy arm, at 81.2% compared with 72.2% in the placebo plus chemotherapy arm (HR, 0.65; 95% CI, 0.51-0.83), Schmid reports.

Additionally, the proportion of patients experiencing an EFS event, such as recurrence, progression, or death, was lower in the pembrolizumab group, at 20.3% compared with 29.2% in the placebo group. These results underscore the long-term benefit of pembrolizumab in combination with chemotherapy for patients with high-risk, early-stage TNBC, Schmid notes.

Furthermore, the 5-year OS rates were 86.6% (95% CI, 84.0%-88.8%) in the pembrolizumab arm vs 81.7% (95% CI, 77.5%-85.2%) in the placebo arm (HR, 0.66; 95% CI, 0.50-0.87; P = .00150). In total, 14.7% of patients in the pembrolizumab arm had an OS event vs 21.8% of those in the placebo arm.

Schmid concludes that these long-term data further solidify the role of pembrolizumab as part of the standard treatment strategy for this patient population.