Results from the phase 3 KEYNOTE-522 study showed neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab as a monotherapy performed better than neoadjuvant chemotherapy followed by adjuvant placebo in patients with high-risk early-stage triple-negative breast cancer regarding event-free survival (EFS).
A release from the manufacturer noted that the findings from the study mark the “first time an anti-PD-1/L1 therapy has demonstrated a statistically significant EFS result as combined neoadjuvant and adjuvant therapy for these patients.” The release noted that after a median follow-up of 39 months, patients prescribed pembrolizumab saw a 37% lower risk of EFS events (HR=0.63 [95% CI, 0.48-0.82]; P =0.00031) versus patients receiving chemotherapy and placebo.
Researchers defined EFS as the time from randomization to first occurrence of disease progression that precluded surgery, a local/distant recurrence, a second primary cancer, or death from any cause. Previously released information showed the study met the dual primary endpoint of pathological complete response at the first interim analysis. The trial is ongoing to evaluate the key secondary endpoint of overall survival.
“Given the high rates of recurrence within the first five years of diagnosis, patients with high-risk early-stage TNBC need new treatment options,” Peter Schmid, FRCP, MD, PhD, from the Center for Experimental Cancer Medicine at the Barts Cancer Institute, said in the release. “KEYNOTE-522 was designed to study whether the combined neoadjuvant and adjuvant regimen with KEYTRUDA could help treat the cancer earlier. Now, with more than three years of follow-up, we see the potential of this approach.”
The most recent release noted that the data so far show a 28% reduction in the risk of death with pembrolizumab versus the chemotherapy-placebo regimen (HR=0.72 [95% CI, 0.51-1.02]; P =0.03214). The safety profile was also determined to be consistent with what was already known about the two treatment options, with no new safety concerns.
Schmid called the findings from the study so far “very encouraging for patients,” showing that the combination could be an effective treatment for the disease.
The most recent findings from the study were presented during an ESMO Virtual Plenary session.
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