A Study Testing Emactinib Sulfate With Chemotherapy and Immunotherapy Before Surgery for Advanced Head and Neck Cancer

The goal of this clinical trial is to evaluate the efficacy and safety of a novel combination therapy for locally advanced head and neck squamous cell carcinoma (HNSCC). The therapy combines the JAK1 inhibitor Sulfamethoxazole, the anti-PD-L1 antibody Adebrelimab, and chemotherapy (Nab-paclitaxel + Cisplatin) as a neoadjuvant treatment (given before surgery). The main questions it aims to answer are: * For patients with resectable locally advanced HNSCC: Can this combination improve the pathological complete response (pCR) rate (the absence of viable cancer cells in the surgical specimen) compared to current neoadjuvant therapies? * For patients with potentially resectable or unresectable locally advanced HNSCC: Can this combination improve the objective response rate (ORR) (the percentage of patients with significant tumor shrinkage), potentially making surgery possible or reducing its scope? Researchers will also assess secondary outcomes including event-free survival (EFS), overall survival (OS), and the safety profile of the combination. Participants will: * Receive neoadjuvant treatment with the combination of Sulfamethoxazole, Adebrelimab, and chemotherapy. A key feature is the timed sequencing of the JAK inhibitor, which will be started on day 8 of each treatment cycle. * Be evaluated for surgery after the neoadjuvant treatment. For those who undergo surgery, the pathological response will be analyzed. * Have regular follow-up assessments, including imaging studies (such as CT or MRI scans) and safety monitoring, to evaluate long-term treatment response, survival, and side effects. * Provide tissue and/or blood samples for exploratory biomarker analysis (e.g., Interferon-Stimulated Gene signature) to help identify patients who benefit most from this treatment.