Inclusion Criteria:
1. Have the ability to give informed consent, have signed informed and able to comply with the treatment plan to visit the tests and other procedural requirements.
2. The age of signing the informed consent is \>= 18 years, regardless of gender.
3. Subject with advanced or distant metastatic squamous cell carcinoma of the head and neck confirmed by histology or cytology.
4. Tumors with primary foci located in the oropharynx, oral cavity, hypopharynx and larynx.
5. Provide archived or fresh tumor tissue for test.
6. At least one measurable lesion according to RECIST v1.1 criteria.
7. The ECOG score is 0 or 1.
8. Expected survival ≥12 weeks.
9. Good level of organ function.
10. Male subjects whose partners are women of childbearing age and female subjects who are fertile are required to use highly effective contraceptive methods.
Exclusion Criteria:
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1\. Subjects will not be screened if they meet any of the following conditions:
1. Primary tumor located in the nasopharynx, salivary glands, sinuses, skin, or squamous cell carcinoma of unknown primary origin;
2. Locally advanced patients who are candidates for curative surgery or local therapy and have the intention to undergo such treatment;
3. Presence of necrotic lesions or significant tumor invasion into adjacent organs or blood vessels, as assessed by the investigator, posing a high risk of major bleeding.
2\. Known hypersensitivity to the investigational drug or any of its excipients, or a history of severe allergic reactions to other monoclonal antibodies.
3\. Prior treatments or medications before the first dose of the study drug:
1. Use of any investigational drug within 4 weeks before the first dose;
2. Concurrent enrollment in another clinical trial, unless it is an observational (non-interventional) study or follow-up in an interventional study;
3. Last dose of anticancer therapy (including chemotherapy, biologic therapy, immunotherapy, targeted therapy, etc.) within 4 weeksbefore the first dose; for small-molecule targeted drugs, within 2 weeks or 5 half-lives (whichever is longer); traditional Chinese medicine with antitumor indications within 2 weeks before the first dose.
4\. Active autoimmune disease or a history of autoimmune disorders. 5、 Residual toxicity from prior anticancer therapy not resolved to ≤Grade 1 (CTCAE v5.0) (except for non-safety risks, such as alopecia) or not meeting the inclusion/exclusion criteria.
6、 Uncontrolled or symptomatic active CNS metastases. 7、 Symptomatic visceral metastases with imminent life-threatening complications .
8、 Known or suspected interstitial lung disease (ILD) or severe pulmonary conditions.
9、 Other active malignancies within 3 years before study entry. 10、 Clinically significant cardiovascular disease. 11、 Active or chronic infections of clinical significance. 12、 Pregnancy or lactation. 13、 Other factors that, in the investigator's judgment, may lead to premature study discontinuation.
