First in Human Study of YB1-X7 Injection

This clinical trial is an open-label, dose-escalation study designed to evaluate the safety, tolerability, pharmacokinetic, and preliminary efficacy of YB1-X7 injection in subjects with advanced solid tumors. YB1-X7 injection is an attenuated Salmonella-based tumor therapy. It selectively accumulates in hypoxic tumor regions while being rapidly cleared from normal organs. After proliferating in the tumor microenvironment, YB1-X7 invades tumor cells and releases its therapeutic payload, leading to tumor cell death and tumor regression. Conditions：To treat subjects with advanced and/or metastatic solid tumors who do not to respond to conventional standard treatment or who lack effective standard treatment.

Inclusion Criteria: 1. Age ≥18 years, no gender limitatlon 2. Subjects with advanced or metastatic solid tumors confirmed by pathological histology. 3. Subjects with advanced malignant solid tumors for whom standard treatment has failed or no other effective standard treatment available. 4. At least one measurable solid tumor by RECIST 1.1. 5. Subjects assigned to intratumoral injection must have at least one tumor that is suitable for biopsy or intratumoral injection. 6. Life expectancy must be at least 3 months. 7. Eastern Cooperative Oncology Group (ECOG) performance status score 0-1. 8. Male and female subjects of childbearing potential should take effective contraceptive measures. ① Fertile women and men must agree to use acceptable contraceptive methods from the start of informed consent until at least 6 months after the last administration. 9. Laboratory blood test results during the screen period: (1)No blood cell growth factors received within 14 days prior to testing. ① Absolute neutrophil count (ANC)≥1.5×109/L. ② Platelets≥90×109/L. Hemoglobin ≥90 g/L (blood transfusion is allowed to correct). (2) Serum albumin \>30 g/L, total bilirubin \