This is a prospective, single center phase II clinical study with a planned enrollment of 33 patients. The main objective is to evaluate the efficacy and safety of the PD-1 inhibitor toripalimab combined with cetuximab, cisplatin, and 5-FU regimen in the treatment of locally advanced oral squamous cell carcinoma patients who are initially unresectable.

In the past decade, the treatment plan for non-surgical locally advanced HNSCC patients who are suitable for receiving synchronous radiotherapy and chemotherapy has remained unchanged, and innovative treatment methods are urgently needed. Based on the above research, immunotherapy combined with chemotherapy and immunotherapy combined with cetuximab have good efficacy and safety in non-surgical HNSCC patients. Therefore, combining PD-L1 antibodies with chemotherapy, surgery to further improve the efficacy of comprehensive treatment may become a new direction in tumor treatment. The achievement of pCR or MPR in conversion therapy is related to better OS and DFS outcomes in patients. In the era of immunotherapy, conversion therapy centered around surgery has become a hot topic in the field of treatment for locally advanced oral squamous cell carcinoma that cannot be surgically removed upon initial diagnosis.

There is no particularly preferred standard conversion chemotherapy regimen for patients with locally advanced head and neck squamous cell carcinoma that cannot be surgically removed initially. The combination of PD-1 inhibitor toripalimab, cetuximab, and chemotherapy may benefit the efficacy of these patients. Therefore, this prospective phase II clinical trial was designed to evaluate the efficacy and safety of PD-1 inhibitor toripalimab combined with chemotherapy and cetuximab conversion therapy in locally advanced oral squamous cell carcinoma patients who were initially unresectable.

Inclusion Criteria:

• Histologically confirmed squamous cell carcinoma of tongue, floor of mouth, gingival, buccal
• Initial NCCN TNM stage III and IVA patients
• PS score 0-1 points
• Age≥18 years old
• Measurable lesions that meet RECIST 1.1 standards
• Normal function of important organs
• All patients must provide tissue specimens

Exclusion Criteria:

• Active, known or suspected autoimmune disease patients
• According to the judgment of the researcher, there are accompanying diseases that seriously endanger the safety of the subjects or affect the completion of the study by the patients
• Merge with other malignant tumors
• Subjects with known central nervous system metastasis and/or cancerous meningitis
• Uncontrolled pleural effusion, pericardial effusion, or ascites that require repeated drainage
• Received significant surgical treatment or obvious traumatic injury within the first 28 days of randomization
• Have experienced arterial/venous thrombotic events within the first 6 months of randomization, such as cerebrovascular accidents
• Individuals with a history of abuse of psychotropic substances who are unable to quit or have mental disorders
• Subjects with any severe and/or uncontrollable diseases
• Exclusion criteria related to concomitant medications
• Participated in other clinical trials within four weeks
• Have received preventive or attenuated vaccines within 4 weeks before the first administration