This study aims to explore the safety, tolerability, PK characteristics, immunogenicity, and preliminary anti-tumor efficacy of SCTB14 as a monotherapy in adult patients with advanced malignant solid tumours. This study is an open label, multicentre, dose-escalation and dose-expansion Phase I/II clinical trial.

Inclusion Criteria:

1. Voluntarily sign the informed consent form (ICF);
2. Male or female, 18 years old ≤ age ≤ 75 years old;
3. Survival duration more than 3 months;
4. ECOG score ≤ 1 point;
5. Participants in Phase Ia (dose-escalation phase) are required to meet the following criteria: histologically or cytologically confirmed diagnosis of advanced malignant solid tumour;
6. Participants in Phase Ib (dose-expansion phase) and Phase II are required to meet the following criteria: Histologically or cytologically confirmed specific type advanced malignant solid tumours;
7. Adequate organ and bone marrow function.

Exclusion Criteria:

1. Participants with brainstem, meningeal, spinal metastases, or compression; active central nervous system metastases;
2. Other malignancies diagnosed within 5 years prior to the enrollment, except effectively treated malignant solid tumour (such as basal cell carcinoma of the skin, squamous cell carcinoma of the skin, cervical cancer in situ, breast cancer in situ, etc.);
3. History of hypertensive crisis or hypertensive encephalopathy; presence of uncontrolled hypertension. History of arterial thrombosis or deep vein thrombosis within 6 months prior to enrollmen;
4. Presence of any active autoimmune disease or a history of autoimmune disease with an expected recurrence;
5. Received chemotherapy, immunotherapy, biologic therapy, or other anti-tumor treatments within 4 weeks before enrollment;
6. Need for immunosuppressive drugs within 2 weeks prior to enrollment or anticipated during the study;
7. Significant coagulopathy or other evident risk of bleeding;
8. Major surgery or significant trauma within 4 weeks prior to enrollment; presence of unhealed skin wounds, surgical sites, trauma sites, severe mucosal ulcers, or fractures, or if the Investigator deems the participant unsuitable for the study;
9. History of permanent discontinuation of immunotherapy due to immune-related toxicity or occurrence of ≥ Grade 3 irAEs;
10. History of severe allergies, severe drug allergies (including unapproved investigational drugs), or known allergy to any component of the IMP;
11. History of organ transplantation or stem cell transplantation;
12. Pregnant or breastfeeding female; women of childbearing potential with positive pregnancy test within 7 days before the enrollment; participants (including males of childbearing potential and their female partners, and females of childbearing potential and their male partners) unwilling to use medically recognized effective contraception during the study and for 6 months after treatment ends.