PEARLS / KEYNOTE-091

After complete resection of stage IB–IIIA NSCLC, does adjuvant pembrolizumab improve disease-free survival compared with placebo?

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

1,177 patients with completely resected stage IB (tumours ≥4 cm)–IIIA NSCLC; adjuvant chemotherapy was permitted/used when indicated.

Intervention and comparator: Pembrolizumab 200 mg IV every 3 weeks for up to 18 cycles versus placebo after complete resection, with adjuvant chemotherapy according to standard practice.

ClinicalTrials.gov: NCT02504372 ↗

Key results

In the overall population, median DFS was 53.6 vs 42.0 months; HR 0.76 (95% CI 0.63–0.91; P=.0014). In the PD-L1 TPS ≥50% subgroup, DFS HR was 0.82 (95% CI 0.57–1.18), not statistically significant at that analysis. Grade ≥3 AEs were 34% vs 26%.

Disease-free survival · Median DFS; primary interim analysis

Absolute-effect interpretation: Median DFS difference is not an NNT. A fixed-time DFS risk difference should be calculated only from a source-reported landmark estimate with matching follow-up.

Toxicity and treatment burden

Immune-mediated pneumonitis, endocrinopathies and other immune toxicities are important; grade ≥3 adverse events were more frequent with pembrolizumab.

Interpretation and limitations

This is an adjuvant-only trial and distinct from perioperative KEYNOTE-671. The primary interim report showed DFS benefit in the overall population, while the high PD-L1 subgroup did not demonstrate a statistically significant DFS benefit at that analysis. Confirm current local label/guideline criteria and driver-mutation considerations.

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 (NCT02504372) ↗

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