Hideki Nakayama

Immune checkpoint inhibitors (ICIs) have become an important therapeutic option for oral cancers; however, reliable biomarkers predicting treatment efficacy remain limited. In this study, we investigated the association between intratumoral immune cell subsets, regional lymph node (RLN) immune status, and clinical responses to ICIs in patients with recurrent oral cancer. Pretreatment tumor tissues and RLNs were analyzed by immunohistochemistry to evaluate tumor-infiltrating lymphocytes, including CD8 ⁺ , CD103 ⁺ , CD3 ⁺ , ICOS ⁺ , and CD163 ⁺ cells, as well as programmed death-ligand 1 (PD-L1) expression and CD169 ⁺ sinus macrophages. Treatment responses were assessed according to RECIST version 1.1. Responders to ICIs exhibited higher densities of CD8 ⁺ and CD103 ⁺ T cells compared with non-responders, whereas no significant associations were observed for CD3 ⁺ , ICOS ⁺ , CD163 ⁺ cells, or PD-L1 expression. Elevated pretreatment serum C-reactive protein (CRP) levels were associated with poorer responses. CD169 ⁺ sinus macrophages in RLNs did not correlate significantly with treatment efficacy or T-cell infiltration. These findings suggest that intratumoral effector and tissue-resident memory–like T-cell infiltration, together with systemic inflammatory status, may influence ICI efficacy in recurrent oral cancer, and could improve patient stratification for immunotherapy.

Background: Small mothers against decapentaplegic homologue 4 (SMAD4) plays an important role in transforming growth factor (TGF)‐β signaling and is associated with various cancers. However, little is known about SMAD4 expression in oral squamous cell carcinoma (OSCC). Aim: To investigate the clinical and biological significance of SMAD4 expression in OSCC. Methods and Results: Immunohistochemical analysis was performed to detect SMAD4 expression in 90 OSCC specimens obtained from patients who underwent preoperative chemoradiotherapy and surgery (phase II study). We also investigated the correlation between SMAD4 expression and various clinicopathological features. In vitro experiments were performed to assess the effects of SMAD4 expression on chemosensitivity and changes in apoptosis‐related molecules. Notably, low SMAD4 expression was significantly correlated with an increased risk of lymph node metastasis, poor response to chemoradiotherapy, and adverse prognosis in patients with OSCC who underwent preoperative 5‐FU‐based chemoradiotherapy. Additionally, SMAD4 downregulation in OSCC cells decreased sensitivity to cisplatin and 5‐fluorouracil and was associated with an increase in cIAP2 expression. Conclusion: The reduced expression of SMAD4 has been linked to both chemotherapy resistance and prognosis in OSCC. However, it may not function as an independent prognostic biomarker. Further research is necessary to determine whether these findings can be generalized to the broader OSCC population.

Background: Squamous cell carcinoma of the buccal mucosa (SCCBM) is a prevalent malignancy of the oral cavity with high morbidity and mortality rates. The pterygomandibular raphe (PMR) connects the oral cavity, pharynx, and masticator space, serving as a key anatomical landmark during surgical resection. However, PMR invasion into SCCBM remains poorly understood. This study assessed the prognostic significance of PMR invasion in patients with resectable SCCBM. Methods: The study included 82 patients with SCCBM, excluding those with T4b, who underwent radical resection at Kumamoto University Hospital between 2000 and 2017. Patients were categorized into three groups based on PMR invasion patterns: non-contact, contact, and invasion. The relationship between PMR invasion and clinicopathological characteristics was analyzed using the Fisher’s exact test. The Kaplan–Meier method, log-rank test, and propensity score-matched analyses were used for survival analysis. Results: Contact or invasion into the PMR was significantly associated with advanced clinical T and N stages, clinical stage, endophytic growth pattern, high-grade invasion pattern, and poor tumor differentiation. Patients with PMR invasion had a higher proportion of recurrences in the buccal subcutaneous, mandibular, and masticator spaces. Univariate analysis indicated that contact- or invasion-type PMR invasion predicted worse overall survival (OS). The impact of PMR invasion on OS was confirmed using a propensity score-matched analysis. Conclusion: This study revealed that PMR invasion is a potential novel grading and prognostic factor for resectable SCCBM, with significance in planning the extent of SCCBM resection.

Background: Virus‐related cancers are malignancies caused by specific viruses, such as human papillomavirus (HPV), hepatitis B virus, and human T‐cell leukemia virus, contributing significantly to the global cancer burden through persistent infection and oncogenic transformation. The current study aimed to develop a robust HPV‐16 detection method for formalin‐fixed cancer specimens.Materials and Methods: To prevent false negatives resulting from DNA fragmentation, a DNA quality check step was added. Additionally, this study used multiplex polymerase chain reaction (PCR) covering the entire HPV‐16 genome to mitigate effects caused by viral sequence variation. To prove this concept, we analyzed genomic DNA extracted from oropharyngeal cancer tissues known as HPV‐16‐positive. Subsequently, the protocol was tested on oral squamous cell carcinoma (OSCC) samples in our cohort. Given the wide variation in HPV‐16 positivity in previous studies, it remains elusive how frequently HPV‐16 is positive in OSCC.Results: The results showed faint bands or smears in the multiplex PCR of 7 out of 112 cases. Droplet digital PCR confirmed variable positivity levels of HPV‐16, suggesting two scenarios of HPV‐16 positivity in cancer tissue: cancer cells derived from infected cells or only a portion being HPV‐16‐positive. Finally, we comprehensively analyzed the case and identified the integration of a deleted HPV‐16 genome into the intronic region of the host gene TMEM94 on chromosome 17. To the best of our knowledge, this is the first evidence showing the integration of HPV‐16 in OSCC cells and providing its complete viral sequence.Conclusions: The established protocol should be applicable to various cancer tissues for analyzing the association with HPV‐16 infection.