Cross-study synthesis of perioperative/window-of-opportunity immunotherapy in resectable HNSCC.
| Domain | Cross-study synthesis (manuscript-aligned wording) | Evidence basis (representative, not exhaustive) |
|---|---|---|
| Pathologic response (PD-1/PD-L1 monotherapy) | Across neoadjuvant PD-1/PD-L1 monotherapy trials, pCR is uncommon and MPR is modest at the primary tumor site; pathologic response is best framed as an indicator of immune engagement, not a validated surrogate endpoint across all designs. | Masarwy et al. [22] pooled estimates across neoadjuvant PD-1/PD-L1 studies: MPR 9.7% and pCR 2.9% (primary tumor). |
| Pathologic response (intensified neoadjuvant strategies) | Intensified regimens (dual checkpoint blockade, chemoimmunotherapy, targeted combinations) can yield higher short-term radiographic and pathologic response metrics than monotherapy in selected cohorts, but cross-trial comparisons are limited by heterogeneity in regimen, endpoints, and response definitions, and combination approaches can narrow the perioperative safety margin. | Randomized dual ICI window trials report higher major/near-complete pathologic responses in combination arms with more grade ≥ 3 toxicity. Chemoimmunotherapy single-arm phase II studies show high ORR/MPR/pCR rates but require randomized confirmation. Zhu et al. [23] meta-analysis reports higher pooled response measures for chemoimmunotherapy vs. chemotherapy in included studies, with heterogeneity. |
| Radiographic response | Radiographic responses during short neoadjuvant windows are variable and can be discordant with pathologic regression; radiographic shrinkage should not be assumed to reflect immune-mediated pathologic response. | CheckMate 358 [15] reports radiographic reductions with limited linkage to pathologic response in available evaluable specimens; several window designs emphasize pathologic endpoints over radiographic response. |
| Clinical benefit (survival endpoints) | The strongest evidence for curative-intent benefit comes from phase III perioperative strategy. For neoadjuvant chemoimmunotherapy as a class, pooled survival conclusions remain uncertain due to heterogeneity and limited randomized long-term outcomes. | KEYNOTE-689 [10] demonstrates EFS improvement with perioperative pembrolizumab (overall HR reported in the trial). Zhu et al. [23] meta-analysis survival subgroup analyses do not establish a consistent OS/PFS advantage for chemoimmunotherapy vs. chemotherapy across included datasets. |
| Feasibility (surgical timing) | “Surgical delay” is definition-dependent (protocol-defined vs. any delay). Across many neoadjuvant ICI trials, protocol-defined immunotherapy-related delays are uncommon, but delays can occur—especially in extended perioperative regimens—even when overall surgical completion is similar between arms. | Masarwy et al. [22] reports very low pooled surgical delay signals in included neoadjuvant PD-1/PD-L1 studies. In contrast, KEYNOTE-689 [10] reports more surgery delays in the perioperative pembrolizumab arm despite similar overall surgical completion, highlighting the importance of specifying definitions and denominators. |
| Safety (where toxicity “lands”) | In pooled neoadjuvant PD-1/PD-L1 monotherapy experience, preoperative grade 3–4 TRAEs are generally low, but toxicity burden increases with combination therapy and with extended perioperative regimens (especially when layered onto adjuvant RT/CRT). Manuscript wording should specify grade, attribution (TRAE/irAE), and treatment phase (neoadjuvant vs. adjuvant). | Masarwy et al. [22] pooled preoperative grade 3–4 TRAEs 8.4%. Dual-checkpoint trials report higher grade ≥ 3 events than monotherapy. KEYNOTE-689 [10] reports substantial grade ≥ 3 TRAEs in both arms, with higher immune-mediated toxicity in the pembrolizumab arm and notable discontinuation rates—underscoring that “acceptable safety” depends on context and window. |
| Biomarkers (signal vs. ready-for-prime-time) | PD-L1/CPS is widely measured and used for stratification in large trials, but across smaller perioperative cohorts its association with pathologic response is inconsistent; it should be framed as a contextual marker rather than a universal predictor. Immune-inflamed/IFN-γ-related signatures and immune infiltration measures show signals of association in some studies, but remain exploratory. | KEYNOTE-689 [10] reports EFS by CPS strata (supports CPS as a stratification/selection framework at scale). Smaller perioperative cohorts show variable associations between PD-L1 and response; immune gene-expression/infiltration signals are frequently exploratory. Zhu et al. [23] emphasizes the need for biomarker-driven refinement and additional randomized validation. |
| Evidence strength (how confident we should be) | Evidence spans small window trials and phase II single-arm cohorts to phase III perioperative data. Meta-analyses provide pooled benchmarks but may include heterogenous designs and partially reported datasets, so synthesis should be presented as supportive context, not definitive proof. | Masarwy et al. [22] includes a limited number of heterogeneous neoadjuvant ICI studies (some abstract-level), useful for pooled feasibility/safety/pathologic response benchmarks. KEYNOTE-689 [10] provides the highest-level evidence for perioperative efficacy. Zhu et al. [23] meta-analysis underscores heterogeneity and the need for higher-quality randomized survival data. |
Summary of cross-study patterns (patterns across studies, not individual trials) in perioperative and window-of-opportunity immunotherapy for resectable HNSCC. Rather than listing individual trials, it synthesizes recurring themes that inform clinical interpretation and trial design: (i) pathologic response behavior across treatment platforms, (ii) feasibility considerations with emphasis on how “surgical delay” is defined, (iii) safety signals stratified by treatment phase (neoadjuvant vs. extended perioperative/adjuvant), (iv) biomarker signals that are associative/exploratory versus clinically implementable, and (v) evidence strength across study designs (phase II vs. phase III; randomized vs. single-arm). Pooled benchmarks are drawn from systematic reviews/meta-analyses and interpreted alongside the phase III perioperative pembrolizumab trial (KEYNOTE-689) and representative perioperative cohorts included in Table 1. Because response definitions (e.g., MPR/pCR/pTR) and reporting windows vary across studies, synthesis statements are framed to avoid implying validated prediction unless supported by the underlying data. CPS: combined positive score; CRT: chemoradiotherapy; EFS: event-free survival; HNSCC: head and neck squamous cell carcinoma; ICI: immune checkpoint inhibitor; IFN-γ: interferon-gamma; irAE: immune-related adverse event; MPR: major pathologic response; ORR: objective response rate; OS: overall survival; pCR: pathologic complete response; PD-1: programmed cell death 1; PD-L1: programmed death-ligand 1; PFS: progression-free survival; pTR: pathologic tumor response; RT: radiotherapy; TRAEs: treatment-related adverse events.