This study is designed to evaluate the safety and efficacy of QLF31907 combination therapy in advanced malignant tumors.

Inclusion Criteria:

1. subjects voluntarily participated and signed a written informed consent form;
2. age ≥18 years, male or female;
3. ECOG PS 0-1;
4. histopathologically diagnosed advanced malignant tumors;
5. at least 1 measurable lesion according to RECIST v1.1 criteria or Lugano (2014) criteria;
6. adequate organ function;

Exclusion Criteria:

1. previous treatment with 4-1BB agonist or 4-1BB recombinant fusion protein;
2. received anti-tumor therapy within 4 weeks prior to the first study treatment;
3. history of autoimmune disease;
4. history of other active malignancies within 3 years prior to the first treatment;
5. history of serous cardiovascular events;