Inclusion Criteria:
* 1: Patients with unresectable, advanced, or metastatic solid tumors who have been histologically or cytologically confirmed, have failed standard treatment, lack standard treatment options, or refuse standard treatment. Preferred tumor types include pancreatic cancer, breast cancer, and soft tissue sarcoma, and must meet any of the following tumor-specific criteria:
1. Patients with advanced or metastatic TNBC who have progressed after or are intolerant to at least 2 lines of systemic therapy;
2. Patients with HER2-positive advanced or metastatic breast cancer who have progressed after or are intolerant to at least 2 lines of HER2-targeted therapy;
3. Patients with HR/HER2-negative advanced or metastatic breast cancer who have progressed after or are intolerant to at least 2 lines of systemic therapy;
4. Patients with advanced or metastatic high-grade soft tissue sarcoma (excluding chordoma) who have progressed after or are intolerant to at least 1 line of systemic therapy;
5. Patients with advanced or metastatic pancreatic cancer who have progressed after or are intolerant to at least 1 line of systemic therapy.
* 2: Age \>= 18 years, regardless of sex;
* 3: Able to understand and sign informed consent and willing and able to comply with study and follow-up procedures;
* 4: ECOG performance status score of 0 or 1;
* 5: FAP expression in tumor lesions confirmed positive by FAPI PET/CT;
* 6: Agree to provide archived or fresh tumor tissue for immunohistochemical evaluation (if available);
* 7: At least 1 measurable lesion according to RECIST 1.1 criteria;
* 8: Previous anti-tumor toxicities recovered to grade 0-1;
* 9: Organ function meets requirements before first administration;
1. Hematology: Absolute neutrophil count (ANC) \>= 1.5×10\^9/L; Hemoglobin (Hb) \>= 80 g/L; Platelet count (PLT) \>= 75×10\^9/L;
2. Liver function: Total bilirubin (TB) \<= 1.5×ULN; AST and ALT \<= 3×ULN, and if there is hepatic tumor metastasis, ALT and AST \<= 5×ULN;
3. Renal function: Creatinine clearance \>= 50 mL/min (Cockcroft-Gault formula); ECG: QTcF \<= 470 ms;
* 10: Fertile subjects voluntarily use effective contraception during treatment and for 4 months (male) or 7 months (female) after the last dose of study drug.
Exclusion Criteria:
* 1: Subjects with brain metastases, meningiomas, or other central nervous system lesions at screening
* 2: Severe allergy to contrast agents or claustrophobia
* 3: Expected survival period \< 6 months
* 4: Receipt of blood transfusion within 2 weeks before the first dose to meet the eligibility criteria
* 5: Administration of systemic antitumor therapies (including targeted therapy, immunotherapy, traditional Chinese medicine antitumor treatment, chemotherapy, etc.) within 4 weeks prior to the first dose
* 6: Participation in other clinical trials involving investigational drugs or devices within 4 weeks before the first dose
* 7: Major surgery within 4 weeks before the first dose or planned major surgery during the study period
* 8: Active bacterial, fungal, viral, or other infections requiring intravenous medication within 4 weeks before the first dose
* 9: Previous systemic radionuclide therapy (excluding I-131 treatment for thyroid cancer) or external beam radiotherapy (EBRT) within 4 weeks prior to the first dose
* 10: History of other malignancies within 5 years before the first dose
* 11: Severe cardiovascular or cerebrovascular diseases, or poorly controlled diabetes
* 12: Presence of pleural effusion or ascites requiring treatment or judged by the investigator as uncontrolled at screening
* 13: Females who are pregnant or breastfeeding
* 14: Subjects considered by the investigator to have poor compliance and inability to cooperate with treatment and follow-up at screening.
