Intestinal Low Dose Radiotherapy Combined With Immunotherapy in Immune-resistant Metastatic Solid Tumors

Inclusion criteria

• Age ≥18 years, ≤80 years, regardless of gender.
• ECOG level 0-2.
• Expected life span>3 months.
• At least one accessible and measurable lesion should be selected as the target lesion for observation according to RECIST criteria.
• Patients with metastatic solid tumors (of any histology) without standard therapy options, who have previously received immunotherapy, immunotherapy combined with chemotherapy, or immunotherapy combined with anti-angiogenesis treatment and have shown disease progression.
• The patient is considered ineligible for surgical treatment.
• Patients with brain metastases assessed as clinically stable after treatment through repeated CT and/or MRI scans are eligible.
• Patients have complete clinical and pathological information.
• Any psychological, family, social or geographical conditions may hinder compliance with the research protocol.
• Patients are able to understand the informed consent form, voluntarily participate, and sign the informed consent form.
• Other indicators accord with the general inclusion criteria for clinical trials.

Exclusion criteria

• Patients with contraindications to radiation therapy and immunotherapy.
• Previous occurrence of unacceptable immune related toxic side effects (immune myocarditis, pneumonia, etc.).
• Patients who were assessed as hyperprogressive disease (HPD).
• Patients who have received pelvic and abdominal radiation therapy within 6 months prior to enrollment.
• The adverse reactions from prior treatment have not yet recovered to a CTCAE5.0 rating of ≤ 1 (excluding toxicity that has been determined to be risk-free, such as fatigue or hair loss).
• Accompanied by severe infections.
• Serious liver disease (such as cirrhosis), kidney disease, respiratory disease, or chronic system diseases such as uncontrollable diabetes and hypertension; Patients who cannot tolerate radiation therapy.
• Clinical symptoms of brain metastases or meningeal metastasis.
• The patients with known allergies or allergies to the test drug ingredients.
• Substance/alcohol abuse.
• Patients who are pregnant or planning to.
• Patients participating in other clinical studies that may affect the efficacy/safety of this clinical study.
• Patients who have undergone major surgical procedures within 30 days.
• Patients who have received antibiotics, antifungal drugs, antiviral, antiparasitic drugs, or probiotics within 4 weeks.