This study is a single-arm, single-center prospective clinical study that will evaluate the clinical feasibility and efficacy of immunotherapy combined with chemotherapy in the neoadjuvant treatment of ovarian cancer, in order to explore the progression-free survival of the study population.

Inclusion Criteria:

1. Histologically or cytologically confirmed epithelial ovarian cancer, fallopian tube carcinoma, or primary peritoneal carcinoma, FIGO 2014 stage III-IV disease;
2. Female patients aged 18 to 75 years;
3. Willing and able to provide written informed consent and comply with study visits and protocol-specified procedures;
4. Candidates for cytoreductive surgery (debulking surgery);
5. At least one measurable lesion according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1;
6. Eastern Cooperative Oncology Group (ECOG) performance status of 0-1;
7. Estimated life expectancy of at least 6 months;
8. Women of childbearing potential must agree to use effective contraception during the study period, and a negative serum or urine pregnancy test is required prior to enrollment;
9. Adequate organ function.

Exclusion Criteria:

1. Histological subtypes other than epithelial ovarian carcinoma, including mucinous carcinoma and clear cell carcinoma.
2. Pregnant women or patients whose most recent pregnancy was terminated within 2 weeks prior to screening.
3. Clinically significant hydronephrosis not amenable to stenting or nephrostomy, or presence of CNS metastases or carcinomatous meningitis.
4. History of other malignancies within 3 years, except for adequately treated curable cancers (e.g., skin basal cell carcinoma, skin squamous cell carcinoma, superficial bladder cancer, or carcinoma in situ of the breast).
5. Prior treatment with immune checkpoint inhibitors or other immunomodulatory anticancer therapies.
6. Major surgery within 4 weeks before study treatment, or planned major surgery during the study period.
7. Severe cardiovascular or cerebrovascular disease.
8. Unresolved ≥ Grade 2 toxicity (CTCAE v5.0) from prior anticancer therapy, excluding alopecia.
9. Known hypersensitivity to study drugs or their components.
10. Any condition that may compromise patient safety or interfere with study evaluation, as judged by the investigator.