BACKGROUND: The prognosis of advanced oral squamous cell carcinoma is poor. We investigated the effect of cetuximab-based sequential therapy as a primary treatment. METHODS: Forty-seven treatment-naive patients with advanced tumors originating from the oral cavity or oropharynx were enrolled. Neoadjuvant cetuximab, paclitaxel, and cisplatin were administered, followed by cetuximab-based radiotherapy. Immunohistochemical staining was applied to study the tissues. RESULTS: The best overall response rate was 70.2%, including 4 patients with a complete response and 29 with a partial response. The median progression-free and overall survival rates were 10.3 and 15.2 months, respectively. Patients with more than 50% tumor reduction with neoadjuvant therapy had better survival outcomes. Twenty-two patients had severe adverse events with mostly dermatological complications. Of the 16 patients who received operations, 9 had increased PD-L1 staining compared to pretreatment biopsy in the post hoc study. CONCLUSION: The regimen was effective in selected patients. Increased PD-L1 suggested altered tumor features.
