Inclusion Criteria:
* 1\. Voluntary participation with signed informed consent and willingness to comply with study procedures.
2\. Age 18 years or older. 3. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 and estimated life expectancy of at least 3 months.
4\. Histologically confirmed advanced non-clear cell renal cell carcinoma, including papillary or unclassified renal cell carcinoma, but excluding chromophobe renal cell carcinoma, collecting duct carcinoma, and renal medullary carcinoma. Advanced disease includes stage IV, unresectable, locally recurrent, or metastatic disease. Tumors with a predominantly non-clear cell component are eligible.
5\. At least one measurable lesion according to RECIST 1.1. 6. Adequate organ function, defined as:
* Hemoglobin \>=80 g/L.
* Absolute neutrophil count \>=1.5 x 10\^9/L.
* White blood cell count \>=3.5 x 10\^9/L.
* Platelet count \>=80 x 10\^9/L.
* Alanine aminotransferase and aspartate aminotransferase \<=2.5 times the upper limit of normal (ULN), or \<=5 times ULN in participants with liver or bone metastases.
* Total bilirubin \<=1.5 times ULN.
* Serum creatinine \<=1.5 times ULN or creatinine clearance \>=60 mL/min.
* Activated partial thromboplastin time, international normalized ratio, and prothrombin time \<=1.5 times ULN.
7\. Women of childbearing potential must be confirmed not pregnant before enrollment. All participants must use adequate contraception throughout treatment and for 4 weeks after treatment ends.
Exclusion Criteria:
* 1\. Chromophobe renal cell carcinoma, collecting duct carcinoma, or renal medullary carcinoma.
2\. Known hypersensitivity to benmelstobart, anlotinib, sunitinib, or any excipient of the study drugs.
3\. Antitumor monoclonal antibody therapy or other investigational drug treatment within 4 weeks before enrollment; prior systemic anti-PD-1 or anti-PD-L1 treatment for metastatic disease.
4\. Prior anlotinib, sunitinib, or other systemic antiangiogenic therapy for metastatic disease.
5\. Use of immunosuppressive agents or systemic corticosteroids for immunosuppression at doses greater than 10 mg/day of prednisone or equivalent within 2 weeks before enrollment.
6\. Active autoimmune disease or a history of autoimmune disease. 7. Congenital or acquired immunodeficiency. 8. Local radiotherapy within 4 weeks before enrollment. 9. Gastrointestinal perforation or major surgery within 4 weeks before enrollment. Diagnostic biopsy and placement of a peripherally inserted central catheter or infusion port are permitted.
10\. Arterial or venous thromboembolic events within 6 months before enrollment or randomization, including cerebrovascular accident, transient ischemic attack, deep vein thrombosis, or pulmonary embolism. Prior catheter-related thrombosis associated with chemotherapy may be permitted if considered resolved by the investigator.
11\. Active bleeding or a bleeding tendency, including clinically significant hemoptysis greater than 50 mL/day within 3 months before enrollment, gastrointestinal bleeding, bleeding gastric ulcer, positive baseline fecal occult blood, or vasculitis.
12\. Urine protein \>=2+ requires assessment of 24-hour urinary protein. Participants must meet the protocol requirements for urinary protein excretion.
13\. Corrected QT interval \>470 milliseconds. Participants whose QT prolongation is attributed to a pacemaker, without other cardiac abnormalities, require discussion with the sponsor's study physician before eligibility is determined.
14\. Suspected additional primary cancer or an uncured malignancy within the previous 5 years, except clearly cured or curable malignancies such as basal cell or squamous cell skin cancer, cervical carcinoma in situ, breast carcinoma in situ, or localized low-risk prostate cancer. Participants with prostate cancer meeting the protocol criteria of stage \<=T2b, Gleason score \<=7, and prostate-specific antigen \<=20 ng/mL, if measured, may participate after definitive treatment without biochemical recurrence.
15\. Hypertension not adequately controlled with medication, defined as systolic blood pressure \>=160 mmHg or diastolic blood pressure \>=100 mmHg.
16\. Myocardial infarction, severe or unstable angina, cardiac dysfunction above New York Heart Association class II, clinically significant supraventricular or ventricular arrhythmia, or symptomatic congestive heart failure within 6 months before randomization.
17\. Interstitial lung disease, noninfectious pneumonitis, or uncontrolled systemic disease, including uncontrolled diabetes, pulmonary fibrosis, or acute pneumonia.
18\. Live attenuated vaccination within 28 days before the first study dose or planned live attenuated vaccination during the study.
19\. Human immunodeficiency virus infection or known acquired immunodeficiency syndrome; active hepatitis B, defined as HBV DNA \>=500 IU/mL; active hepatitis C, defined as HCV RNA above the assay detection limit; or concurrent hepatitis B and hepatitis C infection.
20\. Severe infection within 4 weeks before the first study dose, including bacteremia or severe pneumonia requiring hospitalization; an active infection of CTCAE grade \>=2 requiring systemic antibiotics within 2 weeks before the first dose; or unexplained fever \>38.5 degrees Celsius during screening or before the first dose, unless considered tumor-related by the investigator. Evidence of active tuberculosis within 1 year before the first dose.
21\. Previous or planned allogeneic bone marrow transplantation or solid organ transplantation.
22\. Peripheral neuropathy of grade \>=2. 23. Active brain metastases, carcinomatous meningitis, spinal cord compression, or brain or leptomeningeal disease identified on screening imaging. Treated brain metastases may be eligible if treatment was completed at least 14 days before enrollment, symptoms are stable, and imaging confirms no intracranial hemorrhage.
24\. Conditions significantly affecting oral drug absorption, including inability to swallow, chronic diarrhea, or clinically significant intestinal obstruction.
25\. Pregnancy, breastfeeding, or planned pregnancy during the study. 26. Other serious physical or psychiatric illness, laboratory abnormalities, or circumstances that may increase study-related risk, interfere with study results, or make participation inappropriate in the investigator's judgment.
