Immune checkpoint inhibitors, such as programmed death 1 (PD-1) and programmed cell death-Ligand 1 (PD-L1), offer new approaches for systemic treatment of tumors, but clinical efficacy remains limited. Previous studies by our team have found that methotrexate can activate anti-tumor immunity. The discovery of a new effect of this drug will improve tumor response to immunotherapy and prognosis of patients.

Malignant tumor is a systemic and complex disease that seriously endangers human health, surgery is the preferred treatment for solid tumors. Due to the extensive invasion and metastasis of advanced tumors, radiotherapy and chemotherapy are the main treatment options. However, the tolerance of tumor to chemoradiotherapy often leads to treatment failure and poor prognosis. Immunotherapy provides a new approach for the systemic treatment of tumors, but the clinical efficacy is still limited. Therefore, it is important to find effective drugs to improve the tumor response to radiotherapy and immunotherapy. Previous studies by our team have found that methotrexate can activate anti-tumor immunity. The discovery of a new effect of this drug will improve tumor response to immunotherapy and prognosis of patients. The objective of this clinical trial is to explore the efficacy and safety of methotrexate combined with immunotherapy and radiotherapy in patients with unresectable/recurrence solid tumors.

Inclusion Criteria:

1. Subjects have unresectable/ metastatic solid tumors;
2. ≥ 18 years old;
3. Life expectancy of at least 3 months;
4. Eastern Cooperative Oncology Group performance status 0-2;
5. Have at least one measurable lesion ≥ 1 cm as defined by response criteria;
6. Adequate organ function.

Exclusion Criteria:

1. Subjects with a history of autoimmune diseases or syndromes;
2. Serious uncontrolled medical disorders or active infections;
3. Women who are pregnant or breastfeeding;
4. Subjects have other factors that may cause them to terminate the study, such as other serious medical conditions (including mental illness) that require combined treatment.