Inclusion Criteria:
* Age at Diagnosis: ≥18 years.
* Histologically confirmed locally advanced or metastatic clear cell renal cell carcinoma.
* Disease progression or intolerance during or following first-line systemic therapy.
* ECOG Performance Status: 0-1.
* At least one measurable lesion as defined by RECIST v1.1.
* Life expectancy ≥12 weeks.
* Adequate bone marrow function: White blood cell count \> 4.0×10⁹/L, Hemoglobin \> 90 g/L, Platelet count \> 100×10⁹/L.
* Adequate hepatic and renal function: Total bilirubin ≤ 1.5 × ULN; Aspartate aminotransferase and/or Alanine aminotransferase ≤ 2.5 × ULN; Alkaline phosphatase ≤ 2.5 × ULN; Serum creatinine ≤ 1.5 × ULN.
* Adequate coagulation function: International Normalized Ratio (INR) ≤1.5 × ULN, Activated Partial Thromboplastin Time (APTT) ≤1.5 × ULN.
* The patient must provide signed informed consent and be willing and able to comply with scheduled visits, treatment plans, laboratory tests, and other study procedures as specified in the study protocol.
* Female subjects of childbearing potential must agree to use reliable contraceptive methods (e.g., condoms, prescribed oral contraceptives taken regularly) from screening until 1 year after the end of treatment.
Exclusion Criteria:
* Allergy to any component of macromolecular protein preparations; contraindications or hypersensitivity to any ingredient of Iparomlimab and Tuvonralimab Injection, Lenvatinib, or Axitinib.
* Major surgery within 28 days prior to the first dose (excluding diagnostic laparoscopy; local surgery for isolated lesions is acceptable).
* Positive Hepatitis B surface antigen (HBsAg) with HBV DNA \>1×10³ copies/mL, or positive anti-Hepatitis C virus (HCV) antibody.
* Positive anti-HIV antibody or a diagnosis of Acquired Immunodeficiency Syndrome (AIDS).
* Active, known, or suspected autoimmune disease (including but not limited to uveitis, enteritis, hepatitis, pituitary disorders, nephritis, vasculitis, systemic lupus erythematosus, hyperthyroidism, hypothyroidism, asthma requiring bronchodilator therapy). Exceptions include type I diabetes mellitus, hypothyroidism requiring hormone replacement therapy only, and skin disorders not requiring systemic treatment (e.g., vitiligo, psoriasis, or alopecia).
* Renal failure requiring hemodialysis or peritoneal dialysis.
* History of interstitial lung disease (ILD) or pneumonitis requiring oral or intravenous steroids within the past year; administration of Vancomycin within the past month.
* Chronic systemic glucocorticoid therapy (at a dose equivalent to ≥10 mg prednisone daily) or any other form of immunosuppressive therapy. Subjects using inhaled or topical corticosteroids are eligible.
* Uncontrolled cardiac disease, such as: 1) Heart failure, NYHA class ≥ II; 2) Unstable angina; 3) Myocardial infarction within the past year; 4) Supraventricular or ventricular arrhythmia requiring treatment or intervention.
* Thromboembolic events within 6 months prior to the start of study treatment, such as cerebrovascular accident (including transient ischemic attack, cerebral hemorrhage, cerebral infarction), or pulmonary embolism, etc.
* Known central nervous system metastases.
* Urinalysis indicating urine protein ≥ +++ and confirmed 24-hour urinary protein \>1.0 g.
* Pregnant or lactating women (a pregnancy test should be considered for sexually active women of childbearing potential).
* Prior or concurrent other malignancies, except for adequately treated non-melanoma skin cancer, carcinoma in situ of the cervix, and papillary carcinoma of the thyroid.
* Active infection requiring systemic therapy within one week.
* Administration of a live vaccine within 30 days prior to the first dose of Iparomlimab and Tuvonralimab Injection.
* History of organ transplantation or hematopoietic stem cell transplantation.
* Any other condition that, in the investigator's assessment, may compromise patient safety or compliance, such as severe concomitant illnesses (including psychiatric disorders) requiring prompt treatment, severely abnormal laboratory test results, or the presence of other psychological, familial, or sociogeographic factors posing high-risk.
