• The subjects voluntarily participated in the study and signed the informed consent.

• Male and female aged between 18 and 75 years old, regardless of gender.

• Patients with recurrent/metastatic advanced HNSCC who have been diagnosed by histology or cytology, progressed or intolerant after previous immunotherapy containing anti-PD-1/anti-PD-L1 and platinum, and have no indication of radical local treatment. Subjects should not receive more than 2 lines of treatment in the past.

• During the screening period, subjects must provide tumor tissues and blood samples for biomarker detection. If the subject does not have an archived tumor tissue sample, he or she will undergo a fresh tumor biopsy during the screening period to obtain the corresponding tumor sample. If the subject can't provide archived or fresh tumor tissue samples, but can provide the previous test reports of qualified institutions, including all biomarker indicators specified in this scheme, they can be screened after communicating with the sponsor.

• There must be at least one measurable lesion as the target lesion (according to RECIST v1.1 standard). Tumor lesions located in previous radiotherapy areas or other local regional treatment sites are generally not measurable lesions unless the lesion has definite progression.

• The ECOG physical fitness score is 0-1.

• The laboratory test results meet the requirements.

• The expected survival time is ≥ 3 months.

• In fertile female subjects, the blood pregnancy test must be negative within 7 days before the first medication. Subjects of reproductive age (including male subjects) had no family planning during the trial period and within 6 months after the last administration and voluntarily took effective contraceptive measures.