This study is an open-label, multicenter, dose-escalation and expansion, non-randomized Phase I clinical study to evaluate the safety, tolerability, pharmacokinetic characteristics, and preliminary efficacy of BL-ARC002 for injection in patients with locally advanced or metastatic solid tumors.

The study consists of two phases: a dose-escalation phase (Phase Ia) and an expansion phase (Phase Ib).

Inclusion Criteria:

1. Voluntarily sign the informed consent form and comply with the protocol requirements;
2. No gender restrictions;
3. Age: ≥18 and ≤75 years (Phase Ia); ≥18 years (Phase Ib);
4. Expected survival time ≥3 months;
5. Histopathologically and/or cytologically confirmed locally advanced or metastatic solid tumors that have failed standard treatment;
6. Agree to provide archived tumor tissue specimens or fresh tissue samples from the primary or metastatic lesions within the past 2 years;
7. Must have at least one measurable lesion as defined by RECIST v1.1;
8. Eastern Cooperative Oncology Group performance status of 0 or 1;
9. Toxicities from prior anti-tumor therapy must have recovered to ≤ Grade 1 as defined by NCI-CTCAE v5.0;
10. No severe cardiac dysfunction, with left ventricular ejection fraction ≥50%;
11. Organ function levels must meet the required criteria;
12. Coagulation function: International normalized ratio ≤1.5 and activated partial thromboplastin time ≤1.5 × upper limit of normal;
13. Urine protein ≤2+ or ≤1000 mg/24 hours;
14. For premenopausal women of childbearing potential, a pregnancy test must be performed within 7 days before starting treatment, with serum pregnancy test being negative, and they must not be breastfeeding; all enrolled patients (regardless of sex) must practice adequate barrier contraception throughout the entire treatment period and for 6 months after treatment completion.

Exclusion Criteria:

1. Use of chemotherapy, biotherapy, immunotherapy, etc., within 4 weeks or 5 half-lives prior to the first dose;
2. History of serious heart disease;
3. QT interval prolongation, complete left bundle branch block, or third-degree atrioventricular block;
4. Active autoimmune diseases and inflammatory diseases;
5. Diagnosis of another malignancy within 5 years prior to the first dose;
6. Hypertension inadequately controlled by two antihypertensive medications;
7. History of ILD requiring steroid therapy, current ILD, or ≥ Grade 2 radiation pneumonitis;
8. Active symptoms of central nervous system metastasis;
9. History of allergy to recombinant humanized or human-mouse chimeric antibodies, or allergy to any excipient component of BL-ARC002;
10. Prior organ transplantation or allogeneic hematopoietic stem cell transplantation;
11. Cumulative anthracycline dose > 360 mg/m² from prior (neo)adjuvant anthracycline-based therapy;
12. Positive for human immunodeficiency virus antibody, active tuberculosis, active hepatitis B virus infection, or active hepatitis C virus infection;
13. Active infection requiring systemic therapy;
14. Participation in another clinical trial within 4 weeks prior to the first dose;
15. Pregnancy or breastfeeding;
16. Study participants with claustrophobia or any condition preventing them from lying still to complete examinations;
17. Other conditions deemed by the investigator to make the participant unsuitable for this clinical trial.