Inclusion Criteria:

1. Age 18-70 years;

2. ECOG Performance Status 0 or 1;

3. Histologically confirmed diagnosis of head and neck squamous cell carcinoma;

4. Subjects with distant metastasis or local recurrence not suitable for curative
treatment; local recurrence patients must have previously received radiotherapy
(postoperative or radical);

5. No prior systemic chemotherapy; subjects who have ceased chemotherapy for locally
advanced disease as part of multidisciplinary treatment for more than 6 months may
be enrolled;

6. At least one measurable lesion available for evaluation by enhanced CT or MRI
according to RECIST 1.1;

7. Adequate organ function:

8. Estimated survival greater than 3 months;

9. Voluntary signing of informed consent form, with good compliance expected, and
ability to follow up as required by the protocol.

Exclusion Criteria:

1. Nasopharyngeal carcinoma；

2. Known allergic reaction against any of the components of the trial treatment;

3. a. Previous treatment with immune checkpoint inhibitors (ICIs) (Prior receipt of
ICIs is allowed if they were given as part of curative-intent neoadjuvant therapy,
with more than 6 months between the last dose and disease recurrence, or as adjuvant
ICI monotherapy that achieved disease control for over 6 months); b. Previous
treatment with cetuximab (Prior receipt of cetuximab is allowed if they were given
as part of curative-intent therapy, with more than 6 months between the last dose
and disease recurrence); c．Previous treatment with chemotherapy (Prior receipt of
chemotherapy is allowed if they were given as part of curative-intent neoadjuvant
and adjuvant therapy, with more than 6 months between the last dose and disease
recurrence) The end date of the therapies mentioned above is the date of the last
administration.

4. Clinically significant heart disease, including severe heart failure: NYHA heart
failure class III~IV, ischemic heart disease (e.g., myocardial infarction or
angina), acute myocardial infarction or congestive heart failure or QTc interval
greater than 500 ms within the last 6 months;

5. Undergoing or expected to undergo secondary or higher surgeries within three weeks
prior to the first dose;

6. Autoimmune diseases requiring treatment or a history of syndromes requiring systemic
use of corticosteroids or immunosuppressants, such as pituitary inflammation,
pneumonia, colitis, hepatitis, nephritis, hyperthyroidism, hypothyroidism, etc.;

7. Other serious uncontrolled concomitant diseases affecting protocol compliance or
result interfere, including uncontrolled diabetes or pulmonary diseases
(interstitial pneumonia, obstructive lung disease, and symptomatic bronchospasm
history);

8. Known active central nervous system metastasis and/or leptomeningeal disease; Note:
Subjects with previously treated brain metastases may participate provided they are
stable (without evidence of progression by imaging (using the identical imaging
modality for each assessment, either MRI or CT scan) for at least 4 weeks prior to
the first dose of trial treatment and any neurologic symptoms have returned to
baseline), have no evidence of new or enlarging brain metastases, and are not using
steroids for at least 7 days prior to trial treatment. This exception does not
include carcinomatous meningitis which is excluded regardless of clinical stability.

9. Hepatitis B (HBV) (HBsAg positive and HBV-DNA≥ 103 IU/ml), hepatitis C (HCV)
infection (HCV antibody positive and detectable HCV-RNA); and other acquired or
congenital immunodeficiency diseases, including but not limited to HIV infection;

10. Pregnant or breastfeeding women, or women planning to conceive during treatment and
within 6 months after the last dose of study medication. Fertile women and sexually
active men unwilling to use highly effective contraception during the study and for
6 months afterward.

11. Severe active infections;

12. Severe neurological or psychiatric history, including dementia or epilepsy;

13. Drug abuse, medical, psychological, or social conditions that may interfere with the
subject's participation in the trial or the assessment of results;

14. Other reasons deemed unsuitable for enrollment by the investigator.