Reviews/Perioperative Immunotherapy Solid Tumours/Perioperative pembrolizumab event-free and overall survival in non-small cell lung cancer
Nsclc · PERIO-NSCLC-02 · v2
This claim makes two promises at once: that adding pembrolizumab around surgery helps patients live longer before their cancer comes back (event-free survival), and that it helps them live longer overall (overall survival). The first promise is carried cleanly by the one large trial that tested this exact drug and patient group, which showed a clear reduction in cancer events [1][16] and the same pattern in the earlier-stage patients [12]. The second promise is shakier: in the detailed primary report the overall-survival difference did not reach the bar set for significance [1][16], and in the stage II subgroup the survival benefit was not statistically firm [12]. A later conference report states a significant survival benefit but gives no supporting number [10]. Because all of the pembrolizumab-specific evidence comes from a single trial, with only related drugs for support [2][7], the panel accepted the event-free survival half firmly but treated the survival half as only partly supported.
In the single pembrolizumab-specific phase 3 trial, event-free survival at 24 months was 62.4% with pembrolizumab versus 40.6% with placebo (hazard ratio 0.58; 95% CI 0.46 to 0.72; P<0.001) in resectable stage II, IIIA, or IIIB (N2) NSCLC [1], with the same hazard ratio reported at the ASCO interim (P<0.00001) [16]. The benefit held in the stage II subgroup (EFS hazard ratio 0.50; 95% CI 0.34-0.74) [12]. For overall survival, the 24-month estimate was 80.9% versus 77.6% (P=0.02, which did not meet the significance criterion) [1], and at interim the OS hazard ratio was 0.73 (95% CI 0.54-0.99) with the significance boundary not crossed on 177 events [16]. The class approach is corroborated by perioperative nivolumab (EFS hazard ratio 0.58) [2] and the single-arm NADIM trial (5-year OS 69.3%) [7]. The contested point: The division is over the overall-survival half of the conjunctive claim: the detailed primary evidence reports OS not crossing its significance boundary [1][16], the stage II OS hazard ratio of 0.69 (95% CI 0.43-1.11) crosses 1 [12], yet a later PRO-focused abstract asserts a significant OS improvement with no reported statistic [10]. Event-free survival is not contested; the survival endpoint is, and it rests on a single trial.
All 30 papers behind this claim with their DOIs and what each does to it, the panel’s arbitration, the evidence gap map and the open research questions. Free, and sent to your inbox.
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The claim conjoins EFS AND OS improvement, but the landmark primary publication [1] states OS 'did not meet the significance criterion' and the ASCO interim [16] states the OS 'significance boundary for OS was not crossed' (HR 0.73, 0.54-0.99). The only corpus statement of a significant OS benefit is a PRO-focused conference abstract [10] that reports no OS HR, CI, or P value. The OS half is not firmly carried by the detailed primary evidence.
All pembrolizumab-specific evidence derives from a single trial (KEYNOTE-671) presented four times — [1], [16], [10], [12]. There is no independent replication of the pembrolizumab regimen; evidential independence for the exact drug is effectively zero.
Where it remains uncertain. Overall survival did not meet its significance criterion at the first interim (80.9% vs 77.6%, P=0.02) [1] and was non-significant in the stage II subgroup (hazard ratio 0.69; 95% CI 0.43-1.11) [12], while a later abstract claims a significant OS benefit without a statistic [10].
Aleatory
The interim OS analysis rests on only 177 events [16], so the survival estimate is subject to sampling variability until follow-up matures.
The load-bearing papers from a corpus of 30, each classified by what it does to the claim. Every DOI is taken from the corpus the claim was graded on.
Primary RCT evidence that the pembrolizumab regimen significantly improves EFS in the exact claim population.
“The estimated 24-month overall survival was 80.9% in the pembrolizumab group and 77.6% in the placebo group (P = 0.02, which did not meet the significance criterion).”
Panel auditInternal validity: high · scope of inference: Resectable stage II/IIIA/IIIB(N2) NSCLC treated with perioperative pembrolizumab plus chemotherapy versus chemotherapy alone.Key limitations: OS did not meet significance at this interim analysis · 25.2-month median follow-up (early)
Class-level corroboration that a perioperative anti-PD-1 plus chemotherapy improves EFS (different drug, nivolumab).
“the percentage of patients with 18-month event-free survival was 70.2% in the nivolumab group and 50.0% in the chemotherapy group (hazard ratio for disease progression or recurrence, abandoned surgery, or death, 0.58; 97.36% confidence interval [CI], 0.42 to 0.81; P<0.001).”
Panel auditInternal validity: high · scope of inference: Perioperative nivolumab plus chemotherapy in resectable stage IIA-IIIB NSCLC.Key limitations: different agent (nivolumab) than the claim · interim analysis · OS immature
Later trial report asserting a significant OS benefit; supports OS half but provides no OS HR/CI (conflicts with [1] at earlier cutoff).
“resection, and adjuvant (adj) pembro (pembro arm; n=397) significantly improved EFS, OS, pCR, and mPR and had an expected safety profile versus neoadj placebo (pbo) + chemo, resection, and adj pbo”
Panel auditInternal validity: high · scope of inference: Quality-of-life impact of perioperative pembrolizumab in resectable early-stage NSCLC.Key limitations: endpoint is HRQoL not EFS/OS · efficacy mentioned only as background
Single-arm design reports 5-year PFS/OS with no comparator against chemotherapy alone, and the agent is nivolumab, so a comparative direction for pembrolizumab cannot be read.
Panel auditInternal validity: medium · scope of inference: Long-term survival after perioperative chemotherapy plus nivolumab in resectable stage IIIA NSCLC.Key limitations: no comparator · different agent (nivolumab) · small single-arm cohort
4 of 30 papers shown. The full review lists all of them, with the panel’s arbitration →
Claims are graded at each quarterly release, and re-graded between releases only when a pivotal trial lands. Every change is a new version of the claim.
EFS is Established-grade but the conjunctive OS claim is only partially and inconsistently carried by a single-trial corpus, placing the combined claim at the lower-to-mid Likely band.
Release 2026-q4 re-graded every claim from its corpus under protocol v0.19. An earlier release's grade is shown for the record; it came from an earlier protocol and is not a movement.
Assumptions that carry weight but are not themselves established.
The panel records the gap that would most move the claim, and the study that would close it.
Mature, statistically reported OS. The claim's OS half rests on an interim that did not cross significance [1][16] and an abstract with no statistic [10]; a final OS analysis with a reported hazard ratio and CI would settle it. The panel rates this the highest-importance open gap for the claim, and names the study design that would close it: Report the prespecified final overall-survival analysis of KEYNOTE-671 at the planned event count with full statistics.
Open question: Does perioperative pembrolizumab plus chemotherapy produce a statistically significant overall-survival benefit at mature follow-up? Why it is still open: At the first interim OS did not meet its significance criterion (80.9% vs 77.6%, P=0.02) [1] with the boundary not crossed (hazard ratio 0.73; 95% CI 0.54-0.99) [16], and the only positive statement [10] reports no statistic.
Priors is a sceptical first reader, not peer review, and not medical advice.
Release 2026-q4 · graded 21 Oct 2026 · protocol v0.19