KEYNOTE-671

In resectable stage II–IIIB (N2) NSCLC, does perioperative pembrolizumab plus platinum-doublet chemotherapy improve outcomes over chemotherapy and surgery alone?

Evidence snapshot updated 23 October 2026. Source links are provided below; this is an evidence summary, not a substitute for current local guidelines or individual clinical judgement.

Population and treatment

797 participants with previously untreated, resectable stage II, IIIA or IIIB (N2) NSCLC.

Intervention and comparator: Pembrolizumab 200 mg IV every 3 weeks for 4 neoadjuvant cycles with platinum-doublet chemotherapy, followed by surgery and up to 13 adjuvant pembrolizumab cycles; comparator placebo plus the same chemotherapy and surgery.

ClinicalTrials.gov: NCT03425643 ↗

Key results

5-year EFS 49.9% (95% CI 44.6–55.0) vs 26.5% (21.7–31.5); HR 0.58 (95% CI 0.48–0.69). Five-year OS 64.6% vs 53.6%; HR 0.74 (95% CI 0.59–0.92).

5-year event-free survival · 5 years

Absolute-effect interpretation: Absolute 5-year EFS difference 23.4 percentage points; approximate NNT 5 over 5 years, calculated from the reported fixed-time EFS rates. Do not calculate NNT from the hazard ratio.

Toxicity and treatment burden

Grade 3–5 treatment-related adverse events at the earlier primary analysis were 45% vs 38%; immune-mediated toxicity and chemotherapy toxicity need monitoring. Five-year report described safety as consistent with known profiles and no HRQoL detriment.

Interpretation and limitations

Five-year follow-up supports durable benefit from a perioperative approach. Applicability depends on resectability, stage, fitness for platinum chemotherapy, operability and local approvals. Do not conflate perioperative pembrolizumab with adjuvant-only immunotherapy.

Use endpoint definitions, follow-up, analysis population and comparator exactly as reported. Do not infer NNT from a hazard ratio or median survival. Subgroup findings should not be treated as predictive unless the trial design and interaction testing support that interpretation.

Primary source and further reading

Primary publication / authoritative source ↗

Trial registry (NCT03425643) ↗

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