Tertiary lymphoid structures: prognostic insights and implications for immunotherapy in HPV-negative head and neck cancer

Treatment of head and neck squamous cell carcinoma (HNSCC) remains a major clinical challenge, particularly in human papillomavirus (HPV)-negative cases, which are associated with poor prognosis and limited responsiveness to immunotherapy (1). In a recent article published in Oral Oncology, Xu et al. present an integrated analysis of the tumor microenvironment (TME) in HNSCC. Their study introduces an immune-based stratification system based on the abundance of tertiary lymphoid structures (TLSs) and tumor-infiltrating lymphocytes (TILs), offering novel insights with potential translational relevance (2).

First, transcriptomic data from The Cancer Genome Atlas (TCGA; 520 HNSCC cases; 97 HPV-positive, 423 HPV-negative) were analyzed to define five ribonucleic acid (RNA)-based squamous cell carcinoma immune classes (SCCICs; classes A-E), employing a classification strategy similar to that previously described for sarcoma by Petitprez et al. (3). SCCIC E, characterized by increased expression of genes associated with TLS components and immune activity, displayed the highest overall survival, in line with the findings of Petitprez et al. in sarcoma. Notably, the prognostic aspect of SCCIC E regarding overall survival was confined to HPV-negative cases.

A simplified histological stratification system, referred to as immunoscore, was subsequently established, classifying HNSCC tumors into TLS-positive, TIL-high and TIL-low, and assessed across two independent clinical cohorts from the investigators’ own institution. In 247 patients with HPV-negative HNSCC treated with surgery followed by radiochemotherapy, TLS-positive tumors were significantly associated with superior 5-year overall survival. Notably, stratification by immunoscore appeared to outperform conventional tumor-node-metastasis (TNM) staging and histopathological grading in prognostic discrimination within this cohort, although statistical significance was not demonstrated. In addition, the restriction to surgically treated patients receiving adjuvant radiochemotherapy may have introduced selection bias by excluding patients presenting with either very early stage or metastatic disease requiring different treatment approaches, thereby reducing the prognostic granularity of the TNM system. Further prospective validation will therefore be essential to substantiate this intriguing finding.

To evaluate the prognostic utility of the immunoscore, especially the presence of TLSs, in a different clinical context, Xu et al. applied this stratification system to a separate cohort of 35 patients with recurrent or metastatic (r/m) HPV-negative HNSCC treated with chemotherapy plus programmed cell death protein 1 (PD-1) blockade. In this setting, TLS-positive tumors were again associated with improved overall survival and also higher objective response rates to immune checkpoint inhibition. To substantiate their findings, the authors further analyzed publicly available transcriptomic data from 102 patients with r/m HNSCC, incorporating outcome data following immune checkpoint inhibition. Consistently, gene signatures indicative of TLS formation were associated with improved overall survival and better response to immunotherapy, reinforcing the findings observed in the smaller cohort.

Whereas in other tumor entities, most notably sarcoma and melanoma, TLSs have already been shown to extend overall survival and responsiveness to immune checkpoint blockade (4), data on HNSCC, especially HPV-negative cases, have remained scarce. Notably, a recent TME study in HNSCC by Markovits et al. reported that TLSs in HPV-negative tumors are enriched for immunosuppressive cell populations, including macrophages, granulocytes, and regulatory T cells, suggesting that the beneficial impact of TLSs in HPV-negative HNSCC may be less clear (5). Therefore, the work by Xu et al. makes a valuable contribution by analyzing two new patient cohorts of 247 and 35 cases, respectively, and demonstrating that TLS presence is nevertheless associated with improved clinical outcome and enhanced responsiveness to immunotherapy in HPV-negative HNSCC.

However, it remains unclear to what extent the observed survival advantage reflects an intrinsic prognostic effect of TLSs versus a genuinely predictive role for immunotherapy responsiveness. Mechanistically, TLSs appear to organize adaptive anti-tumor immunity through induction of antibody-producing plasma cells and cytotoxic cluster of differentiation (CD) 8⁺ T cells (6). Therefore, it is conceivable that the largely checkpoint-independent plasma cell component drives a prognostic effect of TLSs, whereas the checkpoint-sensitive CD8⁺ T-cell component accounts for a predictive role—both ultimately contributing to improved patient survival. Given these beneficial effects of TLSs, also their therapeutic induction has emerged as a promising new avenue of immunotherapy research (4).

The findings of Xu et al. raise an intriguing question for perioperative immunotherapy in HNSCC. If TLSs are key mediators of CD8⁺ T-cell-driven antitumor immunity and predictors of response to immune checkpoint inhibition, this provides a strong rationale for neoadjuvant immunotherapy. Following surgical resection, both the tumor and its associated TLSs are removed, potentially eliminating an important site for local immune activation. Recent results from the KEYNOTE-689 trial further support this hypothesis, showing that addition of neoadjuvant (and adjuvant) checkpoint inhibition to standard care (surgery and adjuvant radiotherapy with or without concomitant cisplatin) improves event-free survival markedly (7).

From a diagnostic perspective, the study underscores the value of integrating TLS assessment into patient stratification, capturing aspects of TME biology not reflected by conventional TIL counts or programmed cell death ligand 1 (PD-L1) expression, potentially informing trial enrollment and personalized therapy decisions. TLS assessment may refine risk stratification beyond traditional staging, considering the improved prognostic performance of the immunoscore compared to TNM staging stated by Xu et al. Further refinement could be obtained by distinguishing between immature and mature TLSs, with the latter defined by the presence of germinal centers, since recent evidence indicates that mature TLSs are specifically associated with improved prognosis in HNSCC (6).

A limitation of TLS-based stratification lies in the requirement of sufficient tumor tissue, which is not always feasible—for example, in a neoadjuvant immunotherapy setting, as discussed above, in inoperable cases, small core biopsies, or patients treated with definitive radiotherapy. To overcome this limitation, considerable research efforts are focusing on blood-based biomarkers. For instance, a recently published study identified several blood-based biomarkers, including interleukin 6, that correlate with poorer overall survival in patients with r/m HNSCC treated with immune checkpoint inhibitors (8). Future studies may identify blood-based biomarkers that correlate with the presence of TLSs. In addition, imaging-based approaches to detect TLSs in situ have been proposed, which could offer non-invasive means to assess the TME and guide therapeutic decision-making (9).

In summary, Xu et al. contribute compelling evidence to the growing body of research indicating that TLSs represent a strong prognostic biomarker in HNSCC, with potential predictive relevance for immunotherapy. This work highlights the importance of intratumoral immune architecture in shaping outcomes and sets the stage for future studies to validate TLSs as a predictive marker and explore their translational potential in perioperative settings.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the Editorial Office, Translational Cancer Research. The article has undergone external peer review.

Peer Review File: Available at https://tcr.amegroups.com/article/view/10.21037/tcr-2025-aw-2459/prf

Funding: This work was supported by the Goldschmidt Jacobson Foundation (to T.A.), and the Mertelsmann Foundation (to M.B.).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tcr.amegroups.com/article/view/10.21037/tcr-2025-aw-2459/coif). The authors have no conflicts of interest to declare.

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