The purpose of this study is to explore the efficacy and safety of high- and low-dose radiotherapy (HD-RT/LD-RT) combined with envafolimab (I) in the treatment of metastatic solid tumors that have failed first-line immunotherapy or above.

Inclusion Criteria:

1. Patients with metastasis (including recurrence) solid tumors and failure with first-line or above immunotherapy (PD-1/PD-L1/CTLA-4 inhibitors), and no subsequent standard treatment regimen.
2. Previous histopathologic confirmation of malignancy.
3. Tumor diameter > 5 cm or the number of metastases is 6-15 (at least one measurable lesion, bone metastases are not used as target lesions), not suitable for conventional radiotherapy, surgery, radiofrequency ablation, and other treatments.
4. Patients with an ECOG score of 0 or 1, and an expected survival period of ≥6 months.
5. During the study, they are willing to follow the arrangement and not use other systemic anti-tumor drugs such as chemotherapy, targeted, Chinese herbal medicine, and proprietary Chinese medicine.
6. 18-70 years old, no gender limit.

Exclusion Criteria:

• 1. Patients with glioma or brain metastases. 2. Those with a history of severe immediate allergy to the drugs used in this study.

  3. Suffered from other malignant tumors other than nasopharyngeal carcinoma within 5 years (except for tumors with an expected 5-year OS>90%, such as non-melanoma skin cancer or pre-invasive cervical cancer).

  4. Cancer patients who require urgent surgical intervention, such as high-risk pathological fractures, life-threatening bleeding symptoms, etc.

  5. Any of the following conditions in the 6 months before screening: myocardial infarction, severe/unstable angina, coronary artery/peripheral artery bypass graft, symptomatic congestive heart failure, cerebrovascular accident, transient cerebral ischemia Onset or symptomatic pulmonary embolism. Patients with known coronary artery disease, congestive heart failure that does not meet the above criteria or left ventricular ejection fraction <50% must adopt an optimized and stable medical plan determined by the treating doctor. If appropriate, you can consult a cardiologist.

  6. Received systemic anti-tumor therapy such as targeted therapy and biological drug therapy within 3 weeks before the first dose; Have received any Chinese herbal medicine or proprietary Chinese medicine with anti-tumor indications within 7 days before the first dose.