The five-year follow-up data from the phase 3 KEYNOTE-671 trial, presented at ESMO 2025, demonstrate sustained and clinically meaningful improvements in overall survival (OS) and event-free survival (EFS) with perioperative pembrolizumab (Keytruda) plus chemotherapy, followed by adjuvant pembrolizumab, compared to placebo in patients with resectable non-small cell lung cancer (NSCLC)179.
At 36 months, the overall survival rate was 71% for perioperative pembrolizumab versus 64% for placebo23. The hazard ratio (HR) for overall survival was 0.72 (95% CI, 0.56-0.93), showing a statistically significant reduction in the risk of death3.
Event-free survival was also improved, with a HR of 0.59 (95% CI, 0.48-0.72). The estimated 3-year EFS rate was 19% higher with pembrolizumab than with placebo3.
This benefit was consistent across clinical subgroups, including stage II and III disease, and in both squamous and non-squamous histologies. However, patients with EGFR mutations or ALK rearrangements may still benefit more from targeted therapies rather than immunotherapy alone2.
No new safety concerns were identified after four to five years of follow-up; adverse events were manageable, though >10% of patients discontinued due to adverse effects43.
KEYNOTE-671’s results have reinforced the adoption of perioperative immunotherapy as a standard of care for resectable early-stage NSCLC, which is reflected in recent FDA (October 2023) and EMA (April 2024) approvals of pembrolizumab in this setting31.
Sources:
1. https://www.merck.com/news/keytruda-pembrolizumab-demonstrates-long-term-survival-benefit-in-certain-patients-with-earlier-or-advanced-stages-of-non-small-cell-lung-cancer-nsclc/
2. https://www.curetoday.com/view/perioperative-immunotherapy-is-the-revolution-in-nsclc
3. https://www.esmo.org/guidelines/esmo-mcbs/esmo-mcbs-for-solid-tumours/esmo-mcbs-scorecards/scorecard-402-1
4. https://www.cancernetwork.com/view/perioperative-pembrolizumab-combo-improves-responses-in-nsclc-subgroups
7. https://www.pharmacytimes.com/view/keynote-trial-data-presented-at-esmo-2025-congress-reiterate-pembrolizumab-s-benefits-in-nsclc
9. https://www.lungcancerstoday.com/post/keynote-671-dr-wakelee-shares-5-year-follow-up-data-on-perioperative-pembrolizumab-in-early-stage-nsclc