ObjectivesAlterations of cellular metabolism have been implicated in immune dysfunction in the tumor microenvironment (TME) of head and neck squamous cell carcinoma (HNSCC). Metformin has recently emerged as a candidate of interest for combination with immunotherapy in HNSCC. This study investigated the effect of metformin on immune cell infiltrates of HNSCC.MethodsRetrospective analysis of T cell infiltrates in primary tumor specimens from patients enrolled in a clinical window of opportunity trial of presurgical metformin. Metformin was titrated to a standard diabetic dose (2000 mg/day) for a minimum of 9 days (mean 13.6 days) prior to surgical resection. Pre and posttreatment surgical specimens from 36 patients (16 HPV+, 20 HPV−) were comparatively analyzed. FOXP3+ and CD8+ immune cell infiltrates in the tumor and peritumoral stroma of pre and posttreatment HNSCC specimens were quantified by digital image analysis using Visiopharm software.ResultsMetformin treatment was associated with a 41.4% decrease in FOXP3+ T cells in intratumor regions of interest (P = .004) and a 66.5% increase in stromal CD8+ T cells at the leading edge of the tumor (P = .021) when compared to pretreatment biopsies. This was reflected in increased CD8+/FOXP3+ cell ratios within the tumor (P < .001) and stromal compartments (P < .001). The effects of metformin occurred independently of HPV status.ConclusionMetformin treatment may favorably alter the immune TME in HNSCC independent of HPV status.Level of Evidence1b. This study is most accurately described as a non‐randomized controlled trial and therefore may reflect a level of evidence below 1b but above 2a from the provided “levels of evidence” chart. Laryngoscope, 130:E490–E498, 2020

Background: Metformin, an oral anti-hyperglycemic drug which inhibits mitochondrial complex I and oxidative phosphorylation has been reported to correlate with improved outcomes in head and neck squamous cell carcinoma (HNSCC) and other cancers. This effect is postulated to occur through disruption of tumor-driven metabolic and immune dysregulation in the tumor microenvironment (TME). We report new findings on the impact of metformin on the tumor and immune elements of the TME from a clinical trial of metformin in HNSCC.Methods: Human papilloma virus—(HPV–) tobacco+ mucosal HNSCC samples (n = 12) were compared to HPV+ oropharyngeal squamous cell carcinoma (OPSCC) samples (n = 17) from patients enrolled in a clinical trial. Apoptosis in tumor samples pre- and post-treatment with metformin was compared by deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Metastatic lymph nodes with extra-capsular extension (ECE) in metformin-treated patients (n = 7) were compared to archival lymph node samples with ECE (n = 11) for differences in immune markers quantified by digital image analysis using co-localization and nuclear algorithms (PD-L1, FoxP3, CD163, CD8).Results: HPV–, tobacco + HNSCC (mean Δ 13.7/high power field) specimens had a significantly higher increase in apoptosis compared to HPV+ OPSCC specimens (mean Δ 5.7/high power field) (p < 0.001). Analysis of the stroma at the invasive front in ECE nodal specimens from both HPV—HNSCC and HPV+ OPSCC metformin treated specimens showed increased CD8+ effector T cell infiltrate (mean 22.8%) compared to archival specimens (mean 10.7%) (p = 0.006). Similarly, metformin treated specimens showed an increased FoxP3+ regulatory T cell infiltrate (mean 9%) compared to non-treated archival specimens (mean 5%) (p = 0.019).Conclusions: This study presents novel data demonstrating that metformin differentially impacts HNSCC subtypes with greater apoptosis in HPV—HNSCC compared to HPV+ OPSCC. Moreover, we present the first in vivo human evidence that metformin may also trigger increased CD8+ Teff and FoxP3+ Tregs in the TME, suggesting an immunomodulatory effect in HNSCC. Further research is necessary to assess the effect of metformin on the TME of HNSCC.

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ImportanceDue to lack of data from high-powered randomized clinical trials, the differences in functional and survival outcomes for patients with oropharyngeal squamous cell carcinoma (OPSCC) undergoing primary transoral robotic surgery (TORS) vs primary radiation therapy and/or chemoradiation therapy (RT/CRT) are unclear.ObjectivesTo compare 5-year functional (dysphagia, tracheostomy dependence, and gastrostomy tube dependence) and survivorship outcomes in patients with T1-T2 OPSCC receiving primary TORS vs RT/CRT.Design, Setting, and PopulationThis national multicenter cohort study used data from a global health network (TriNetX) to identify differences in functional and survival outcomes among patients with OPSCC who underwent primary TORS or RT/CRT in 2002 to 2022. After propensity matching, 726 patients with OPSCC met inclusion criteria. In the TORS group, 363 (50%) patients had undergone primary surgery, and in the RT/CRT group, 363 (50%) patients had received primary RT/CRT. Data analyses were performed from December 2022 to January 2023 using the TriNetX platform.ExposurePrimary surgery with TORS or primary treatment with radiation therapy and/or chemoradiation therapy.Main Outcomes and MeasuresPropensity score matching was used to balance the 2 groups. Functional outcomes were measured at 6 months, 1 year, 3 years, 5 years, and more than 5 years posttreatment and included dysphagia, gastrostomy tube dependence, and tracheostomy dependence according to standard medical codes. Five-year overall survivorship was compared between patients undergoing primary TORS vs RT/CRT.ResultsPropensity score matching allowed a study sample with 2 cohorts comprising statistically similar parameters with 363 (50%) patients in each. Patients in the TORS cohort had a mean (SD) age of 68.5 (9.9) vs 68.8 (9.7) years in RT/CRT cohort; 86% and 88% were White individuals, respectively; 79% of patients were men in both cohorts. Primary TORS was associated with clinically meaningful increased risk of dysphagia at 6 months (OR, 1.37; 95% CI, 1.01-1.84) and 1 year posttreatment (OR, 1.71; 95% CI, 1.22-2.39) compared with primary RT/CRT. Patients receiving surgery were less likely to be gastrostomy tube dependent at 6 months (OR, 0.46; 95% CI, 0.21-1.00) and 5 years posttreatment (risk difference, −0.05; 95% CI, −0.07 to −0.02). Differences in overall rates of tracheostomy dependence (OR, 0.97; 95% CI, 0.51-1.82) between groups were not clinically meaningful. Patients with OPSCC, unmatched for cancer stage or human papillomavirus status, who received RT/CRT had worse 5-year overall survival than those who underwent primary surgery (70.2% vs 58.4%; hazard ratio, 0.56; 95% CI, 0.40-0.79).Conclusions and RelevanceThis national multicenter cohort study of patients undergoing primary TORS vs primary RT/CRT for T1-T2 OPSCC found that primary TORS was associated with a clinically meaningful increased risk of short-term dysphagia. Patients treated with primary RT/CRT had an increased risk of short- and long-term gastrostomy tube dependence and worse 5-year overall survival than those who underwent surgery.