A Study of FG-B901 Monotherapy or Combination With Chemotherapy in Advanced or Metastatic Solid Tumors

Inclusion Criteria:

* Voluntarily sign the informed consent form, understand the study, are willing to comply with and have the ability to complete all trial procedures;
* Age 18-75 years (inclusive), any gender;
* Have histologically or cytologically confirmed locally advanced or metastatic solid tumors, and have failed standard therapy, or are intolerant to standard therapy, or for whom standard therapy is not available;
* Able to provide tumor tissue specimens and peripheral blood samples that meet testing requirements, or provide prior test reports that meet the requirements;
* ECOG performance status of 0 or 1;
* Expected survival ≥3 months;
* Have at least one measurable tumor lesion according to RECIST 1.1 criteria;
* Adequate cardiac, bone marrow, liver, renal function;

Exclusion Criteria:

* Have received a live vaccine within 3 months prior to randomization;
* Have received radiotherapy within 4 weeks prior to randomization;
* Have received other anti-tumor drug therapy within 4 weeks or within 5 half-lives of the anti-tumor drug prior to randomization;
* Have undergone major surgery within 4 weeks prior to randomization;
* Have received any clinical study drug treatment within 4 weeks prior to randomization;
* Have undergone major surgery within 4 weeks prior to randomization;
* Have a history of other (non-study tumor) malignancies within 3 years prior to randomization;
* Have received any organ transplant or bone marrow transplant;
* Have previously received any tumor necrosis factor receptor (TNFR) agonist antibody therapy, such as anti-CD40, anti-OX40, anti-CD137, anti-CD27, anti-CD357 antibodies, etc;
* Have experienced Grade ≥3 immune-related adverse events (irAEs) from prior immunotherapy;
* Have a history of severe allergic reactions or are allergic to the investigational drug (FG-B901);
* Have a history of central nervous system metastases and/or carcinomatous meningitis;
* Have adverse reactions from prior treatments that have not recovered to CTCAE v5.0 Grade ≤1 (excluding alopecia and anemia) prior to randomization;
* Have a history of severe respiratory disease;
* Have experienced a clinically significant cardiac disease within 6 months before the first dose of study drug;
* Have uncontrolled systemic diseases assessed by the investigator, including diabetes, hypertension, pulmonary fibrosis, interstitial lung disease, etc.;
* The investigator judges the subject to have obvious active gastrointestinal bleeding;
* Known history of Hepatitis C or chronic active Hepatitis B;
* Have experienced systemic treatment with corticosteroids within ≤2 weeks prior to randomization;
* Any other condition of the subject (e.g., psychological, geographical, or medical condition) that does not permit compliance with the study and follow-up procedures;
* Are pregnant or breastfeeding;