A Clinical Trial Comparing the Efficacy and Safety of Anyouping® and Platinum-based Chemotherapy With or Without Enlituo® in Advanced Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma.

Inclusion Criteria: * Voluntarily sign the written informed consent form and be willing to comply with all requirements specified in the study protocol; * Aged ≥ 18 years; * Histologically or cytologically confirmed recurrent or metastatic squamous cell carcinoma of the head and neck (including oral cavity, oropharynx, hypopharynx, larynx), deemed incurable after local therapy; * Have not received any systemic therapy for recurrent or metastatic disease. Note: If disease progression occurs during neoadjuvant/adjuvant therapy, concurrent radiotherapy, or within 6 months after treatment discontinuation, the anti-tumor therapy administered during neoadjuvant/adjuvant therapy or concurrent radiotherapy (including platinum-based chemotherapy, anti-EGFR monoclonal antibodies, PD-1/PD-L1 inhibitors, etc.) will be regarded as first-line systemic therapy, and such subjects will be excluded. (Remark: Subjects previously treated with PD-1/PD-L1 inhibitors may be enrolled provided a washout period of ≥ 12 months is met.) * Have at least one measurable evaluable target lesion per RECIST v1.1, or a measurable lesion with definitive radiological progression following local therapy, and the lesion must be suitable for repeated precise measurement; * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, with no disease deterioration within 2 weeks prior to enrollment; * For participants with oropharyngeal carcinoma, human papillomavirus (HPV) status test results based on tumor tissue samples must be available prior to enrollment. Exclusion Criteria: * Primary tumor site (any histologic type) located in nasopharynx, nasal cavity, paranasal sinus, salivary gland, thyroid or parathyroid gland, skin, or unknown primary origin; * Participants who have been diagnosed with a malignancy other than squamous cell carcinoma of the head and neck within 3 years prior to enrollment. Exceptions include cured basal cell carcinoma of the skin, cutaneous squamous cell carcinoma, and/or carcinoma in situ of the cervix and/or breast cancer treated with curative resection; * Participants with an expected survival of less than 6 months and/or rapidly progressive disease (e.g., participants experiencing rapid disease progression within 1-2 months during therapy planned prior to enrollment); * Participants eligible for curative-intent local therapy; * Pregnant or breastfeeding participants, or those planning pregnancy or conception during the anticipated study period (from screening visit through 180 days after the last dose); * Known history of psychiatric disorder or substance abuse that would interfere with compliance with study requirements; * Any other condition that renders the participant unsuitable for enrollment in the opinion of the investigator.