A Phase I/IIa Clinical Study to Evaluate the Safety, Tolerability, Pharmacokinetic Characteristics, Immunogenicity, and Preliminary Efficacy of SGT003 in Patients With Advanced Solid Tumors

Inclusion Criteria:

1. Patient can fully understand the trial, participates voluntarily, and signs informed consent form (ICF) prior to any study procedures
2. Patients aged 18 to 75 years at the time of ICF signature.
3. Study population:

   * Phase I (dose-escalation study): Patients with advanced solid tumors confirmed histologically or cytologically, who have failed at least one standard therapy for advanced disease, are intolerant to standard therapy, or have no available standard treatment options.
   * Phase IIa (dose-expansion study): Patients with advanced solid tumors who have received at least first-line but not up to third-line standard systemic therapy and experienced disease progression or intolerance to such therapy.
4. ECOG 0 or 1.
5. Radiographic evidence (CT/MRI, etc.) of disease progression documented during or after the most recent prior treatment.
6. Patients must have adequate bone marrow reserve and organ function.

Exclusion Criteria:

1. Subjects who have received chemotherapy, radiotherapy, biotherapy, endocrine therapy, immunosuppressive therapy or other anti-tumor therapy within 4 weeks prior to the first administration of the investigational product.
2. Subjects who have received systemic immunosuppressant therapy within 14 days prior to the first administration of the investigational product.
3. Subjects receiving anticoagulants such as therapeutic-dose heparin or vitamin K antagonists.
4. Subjects who have received any live or attenuated live vaccine within 28 days prior to the first administration of the investigational product.
5. Subjects who have undergone major surgery within 4 weeks prior to the first administration of the investigational product.
6. Subjects with a history of Grade ≥3 immune-related adverse events (irAEs), hypersensitivity reactions, or Grade ≥2 immune-related myocarditis.
7. Subjects with active autoimmune disease or prior autoimmune disease with a risk of recurrence. Exceptions: well-controlled type 1 diabetes, hypothyroidism controlled solely by hormone replacement therapy, and skin diseases that do not require systemic treatment.
8. Subjects with current or prior active interstitial lung disease (ILD). Subjects with radiation-induced pulmonary fibrosis that does not require steroid therapy are eligible.