This narrative review (Carlisle, Steuer, Owonikoko, Saba; Emory Winship) synthesizes phase 3 immunotherapy evidence in NSCLC and HNSCC as of 2020. The quantitative backbone is trial-level overall survival (OS) and progression-free survival (PFS) hazard ratios, which consistently favored checkpoint inhibitorβcontaining regimens over chemotherapy: KEYNOTE-024 OS HR 0.50 (95% CI 0.37β0.68) in PD-L1 TPS β₯50% NSCLC, KEYNOTE-189 OS HR 0.49 in nonsquamous NSCLC, PACIFIC PFS HR 0.52 after chemoradiation in stage III, IMpower133 OS HR 0.70 in extensive-stage SCLC, and KEYNOTE-048 OS HR 0.61 (CPS β₯20) in frontline HNSCC.
Key qualitative claims are well-sourced: six FDA-approved checkpoint inhibitors across ~18 histologic types; sequencing between single-agent pembrolizumab and chemoimmunotherapy in high PD-L1 disease remained unresolved (INSIGNA trial cited); EGFR-mutant NSCLC requires molecular profiling before PD-(L)1 blockade because sequential osimertinibβimmunotherapy produced serious irAEs in 24% (95% CI 10%β45%) versus 0%, and combination osimertinibβdurvalumab trials were halted for interstitial lung disease in 13/38 patients.
The authors acknowledge their central limitations: it is explicitly a narrative, not systematic, review; nearly all summarized evidence comes from sponsor-funded phase 3 trials (disclosed funding: Merck, Roche, BMS, Regeneron, Pfizer, AstraZeneca); PD-L1 assay heterogeneity (TPS vs CPS, multiple companion diagnostics) and intratumoral/metastatic-site heterogeneity undermine cross-trial comparison. Blind spots they under-address: subgroup analyses (e.g., PACIFIC PD-L1 <1% favoring placebo post hoc) are treated briefly; MPR as a neoadjuvant surrogate endpoint is presented optimistically with no OS data yet; the EAGLE and CheckMate 331 negative trials are summarized but lessons from immunotherapy failure modes in SCLC/HNSCC are not mechanistically dissected; no formal risk-of-bias assessment or PRISMA-style search strategy is applied. Since publication, subsequent trials (e.g., CheckMate 9LA matured OS, KEYNOTE-604 final OS) and adjuvant/neoadjuvant approvals have updated the landscape, so the review has a bounded knowledge half-life.
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