Inclusion Criteria:
* 1\) Age: 18-75 years; 2) Histologically confirmed cervical squamous cell carcinoma, adenosquamous carcinoma, or adenocarcinoma; 3) Locally advanced disease (Stage III-IVA per FIGO 2018 staging criteria, including IIIC1/IIIC2), confirmed by imaging evaluation; 4) ECOG performance status 0-1; 5) Expected to be able to complete external beam radiation therapy (EBRT) combined with brachytherapy; 6) No definite contraindications to radiotherapy; 7) Able to provide pathological specimens (≥18 qualified tissue slides) for biomarker testing; 8) No prior surgery, radiotherapy, chemotherapy, systemic therapy (including investigational drugs), or immunotherapy for cervical cancer; 9) At least one measurable lesion (per RECIST 1.1: ≥10 mm longest diameter for non-lymph node lesions on CT; ≥15 mm short axis for lymph node lesions on CT); 10) Expected survival ≥6 months; 11) Adequate major organ function. Hematology (without transfusion or blood products within 14 days): ANC ≥1.5×10⁹/L; platelets ≥80×10⁹/L; hemoglobin ≥9 g/dL. Biochemistry: total bilirubin \<1.5×ULN; AST and ALT ≤2.5×ULN; serum creatinine ≤1.5×ULN, or creatinine clearance ≥40 mL/min (using the standard Cockcroft-Gault formula); 12) Participants have signed informed consent and agree to comply with follow-up; 13) Women of childbearing potential must agree to use effective contraception during the study and for at least 12 months after the last dose (postmenopausal women or women not of childbearing potential are exempt).
Exclusion Criteria:
* 1\) Diagnosed with other malignancies within 5 years prior to first dose, excluding radically treated cutaneous basal cell carcinoma, cutaneous squamous cell carcinoma, radically excised carcinoma in situ, and/or papillary thyroid carcinoma; 2) Histologically confirmed small cell (neuroendocrine) cervical carcinoma, cervical carcinosarcoma, or gastric-type cervical adenocarcinoma; 3) FIGO 2018 Stage IVB disease; 4) Prior total hysterectomy (defined as removal of the entire uterus) or planned hysterectomy as part of initial cervical cancer treatment; 5) Bilateral hydronephrosis, unless at least one side has been stented or resolved by nephrostomy, or considered mild and not clinically significant by the investigator; 6) Anatomical or tumor geometric contraindications to intracavitary brachytherapy or combined intracavitary and interstitial brachytherapy, or any other contraindications; 7) Live vaccine administration within 30 days prior to first dose of study treatment; 8) Systemic immunostimulatory agents, colony-stimulating factors, interferons, interleukins, or vaccine combinations within 6 weeks or 5 half-lives (whichever is shorter) prior to Day 1 of Cycle 1; 9) Prior treatment with anti-programmed cell death receptor 1 (PD-1), anti-programmed cell death ligand 1 (PD-L1), or anti-programmed cell death ligand 2 (PD-L2) agents, or agents targeting other stimulatory or co-inhibitory T-cell receptors (e.g., CTLA-4, OX-40, CD137); 10) Systemic anti-cancer therapy within 4 weeks prior to randomization, including investigational drugs; 11) Currently participating in or previously participated in a study with an investigational drug; 12) Contraindications to cisplatin use; 13) Diagnosed with immunodeficiency or receiving chronic systemic corticosteroid therapy (\>10 mg/day prednisone equivalent) or any other form of immunosuppressive therapy within 7 days prior to first study treatment; 14) Hypersensitivity to any study drug; 15) Active autoimmune disease requiring systemic therapy within the past 2 years; 16) History of (non-infectious) pneumonitis/interstitial lung disease requiring corticosteroids, or current pneumonitis/interstitial lung disease; 17) Active infection requiring systemic treatment; 18) Known history of human immunodeficiency virus (HIV) infection; 19) Known history of hepatitis B or known active hepatitis C viral infection; 20) Any condition, treatment, laboratory abnormality, or other circumstance that may increase risk associated with study participation or administration of study treatment, or may interfere with interpretation of study results, and judged by the investigator or sponsor to render the participant unsuitable for this study; 21) Known psychiatric or substance abuse disorders that would interfere with the participant's ability to comply with study requirements; 22) Prior allogeneic tissue/solid organ transplantation; 23) Evidence of metastatic disease per RECIST 1.1, including lymph nodes in the inguinal region or above the level of the L1 vertebral body; 24) Women with pregnancy desire, pregnant women, or breastfeeding women.
