This study aims to evaluate the safety, tolerability, PK characteristics, immunogenicity, and preliminary anti-tumor efficacy of SCTB41 in combination with SCTB39G with or without standard therapy in adult patients with advanced malignant solid tumors. 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 and ≤ 75 years old;
3. Survival duration more than 3 months;
4. ECOG score ≤ 1 point;
5. Histologically or cytologically confirmed diagnosis of advanced malignant solid tumor；
6. At least one measurable tumor lesion according to RECIST v1.1;
7. Adequate organ and bone marrow function.

Exclusion Criteria:

1. Has participated in another clinical study within 4 weeks prior to the first dose;
2. Has previously received other immunotherapies other than PD-(L)1 inhibitors；
3. Other malignancies diagnosed within 5 years prior to the enrollment;
4. Participants with brainstem, meningeal, spinal metastases, or compression; active central nervous system metastases;
5. Significant bleeding risk;
6. Presence of pleural effusion, peritoneal effusion, or ascites;
7. Received chemotherapy, immunotherapy, biologic therapy, or other antitumor treatments within 4 weeks before enrollment；
8. History of permanent discontinuation of immunotherapy due to immune-related toxicity or occurrence of ≥ Grade 3 irAEs;
9. Presence of any active autoimmune disease or a history of autoimmune disease with an expected recurrence;
10. History of severe allergies, severe drug allergies (including unapproved investigational drugs);
11. History of organ transplantation or stem cell transplantation;
12. Need for immunosuppressive drugs within 2 weeks prior to enrollment or anticipated during the study;
13. Pregnant or breastfeeding female.