Inclusion Criteria:
1. Voluntary enrolment in the study with written informed consent and ability to comply with protocol requirements visits and related procedures as specified in the protocol.
2. Age≥18 \& ≤75.
3. Recurrent or metastatic vulvar and vaginal carcinoma not amenable to curative treatment, diagnosed histologically or cytologically, with a pathological type of squamous, adenocarcinoma or adenosquamous carcinoma.
4. Has at least one measurable lesion based on Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 assessed by investigator. Lesions located in previously irradiated areas are considered measurable if they show progression in such lesions.
5. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
6. Life expectancy of at least 3 months.
7. Prior immunotherapy, targeted therapies are permitted if treatment has not been discontinued due to a grade ≥2 adverse event.
8. The end of prior systemic therapy must be ≥ 4 weeks or 5 half-lives, whichever is shorter, from the first dose of this study. and the treatment-related AE returned to CTCAE 5.0 ≤ Grade 1 (except alopecia and malaise).
9. All participants must provide an archived tumour tissue sample (formalin-fixed paraffin-embedded \[FFPE\] tissue wax block or a minimum of 5 unstained tumour tissue section samples, preferably newly obtained tumour tissue samples) within 2 years prior to randomisation.
10. Has adequate organ function.
11. Have agreed to take effective contraception from the date of signing the informed consent form until 120 days after the last administration.
12. Ability to understand and sign written informed consent and to comply with programme visits and related procedures.
Exclusion Criteria:
1. Participants who have received prior systemic anticancer therapy (including study drug) within 4 weeks prior to the first dose of study treatment. Note: If participants have undergone major surgery, they must have fully recovered from the toxicity and/or complications of the treatment prior to starting study treatment. Patients who require elective major surgical treatment during the study period are not eligible for enrolment.
2. Participants must have recovered to grade ≤1 or baseline level from all AEs resulting from prior treatment.
3. Received radiotherapy within 2 weeks prior to the first dose. For patients who have received radiotherapy prior to 2 weeks before the first dose, all of the following conditions must be met for enrolment: glucocorticosteroids are not required, and radiation pneumonitis, radiation hepatitis, and radiation enteritis are excluded. Patients with palliative radiotherapy to bone lesions more than 7 days from the first dose may be enrolled. Reirradiation of previously treated sites is not permitted.
4. Received an immunomodulatory drug within 2 weeks prior to randomisation.
5. Active Hepatitis B or Hepatitis C.
6. History of severe bleeding tendency or coagulation disorder.
7. Pregnant or lactating female patients.
8. Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the study, interfere with the subject\'s participation for the full duration of the study, or is not in the best interest of this subject to participate, in the opinion of the treating investigator.
