Fecal Microbiota Transplant (FMT) Capsule for Improving the Efficacy of Anti- PD-1

Inclusion Criteria: 1. Patient had a histologically or cytologically confirmed diagnosis of unresectable or metastatic solid tumors originating from the GI tract. 2. Patient was able and willing to provide pathological tissue embedded in wax blocks or paraffin sections. 3. Patient had received any number of radiation therapy, chemotherapy, vaccine therapy or other oncological therapy are permitted. 4. Patient was receiving or has received at least 2-dose injections of systemic PD-(L)1 immunotherapy, and imaging results confirmed progressive disease (PD). According to iRECIST, PD is defined as an increase in the length of the lesion \> 20% or occurrence of new lesion or non-target lesion progression. Anti-PD-(L)1 drugs can contain pembrolizumab, nivolumab or any other anti-PD-(L)1 drugs that have passed phase 2 clinical development. Patients are eligible when the previous failed anti-PD-(L)1 treatment was initiated within one year of the first dose of this trial. 5. Patient was willing and able to swallow at least 20 FMT capsules. 6. Patient was willing and able to sign the informed consent form. 7. Patient consented to receive follow-up medical imaging to determine disease progression and provide stool samples before and after taking capsules at each follow-up visit. 8. Patient was at least 18 years old, male or female. 9. Patient had an ECOG performance of 0 or 1. 10. For women with childbearing potential, the results of blood pregnancy test within 7 days prior to enrollment or the results of urine pregnancy test within 72 hours prior to enrollment had to be negative. 11. Patient must have had basic body function. Blood test results needed to reach the following indexes: Absolute neutrophil count (ANC)≥1500/mcL, platelets≥100,000/mcL, hemoglobin≥9 g/dL or 5.6 mmol/L, no transfusion or EPO dependency (within 7 days of assessment), serum creatinine≤1.5×upper limit of normal (ULN) or creatinine clearance≥60 mL/min, serum total bilirubin≤1.5×ULN or direct bilirubin≤ULN, AST (SGOT) and ALT (SGPT)≤2.5×ULN for patients with serum total bilirubin \>1.5 ULN or ≤5×ULN for patients with liver metastases, albumin≥2.5 mg/dL, coagulation indexes INR or PT ≤1.5×ULN. Unless patient was receiving anticoagulant therapy, coagulation indexes were within normal range of therapy. 12. Expected survival duration ≥3 months. Exclusion Criteria: 1. Patient with irritable bowel syndrome, toxic megacolon, and severe dietary allergies (including severe allergic to shellfish, nuts, seafood). 2. Patient had responded to anti-PD-(L)1 therapy or had a stable disease status (per iRECIST at CR, PR, or SD). 3. Patient had participated in any other clinical trial within 4 weeks before the first dose of FMT capsule treatment. 4. Patient had highly severe symptoms including rapidly declining ECOG performance; rapidly worsening symptoms; lesion transferring to critical sites and requiring urgent medical intervention. 5. Patient had a known history of malignant blood diseases, primary brain tumor or sarcoma, or other primary solid tumors except gastrointestinal tumors. 6. Patient had progressing CNS metastases or leptomeningeal metastases. Patients with stable brain metastases had to be re-screened by brain MRI or CT scan within two weeks before enrollment to ensure no disease progression, and simultaneously take ≤10mg steroid daily one week prior to treatment. Patients with no history of CNS metastases and no signs of CNS metastases did not need another medical imaging examination for brain diseases. 7. Patient had a severe hypersensitivity or reaction to anti-PD-(L)1 immunotherapy. 8. Patient had an autoimmune disease or a history of autoimmune disease or required treatment with systemic steroid (prednisone \>10 mg daily or equivalent dose of similar drugs) or immunosuppressive agents. The following cases were exceptions: local, ophthalmic, intra-articular, intranasal, or inhaled corticosteroids with extremely low systemic absorption; hormone replacement therapy; short-term (≤7 days) treatment of corticosteroids for preventative use (e.g., allergy to contrast agents). 9. Patient had pneumonitis or had a history of (non-infectious) pneumonitis requiring steroid therapy. 10. Patient had severe cardiovascular disease (e.g., drug-uncontrolled congestive heart failure, hypertension, cardiac ischemia, myocardial infarction, and severe cardiac arrhythmia), bleeding disorders, severe obstructive or restrictive pulmonary diseases, or systemic infections. 11. Patient had active human immunodeficiency virus (HIV) infection (performance as HIV 1/2 antibodies and/or positive). 12. Patient had active Hepatitis B (HBV) or Hepatitis C (HCV) infection. 13. Patient had known active tuberculosis. 14. Patient had received a live vaccine or live attenuated vaccine within 4 weeks prior to enrollment. 15. Patient had reported adverse events (per CTCAE 5.0, ≥grade 2) due to drug treatment within 4 weeks and not recovered from it. Patients who had undergone major surgery had to have completely recovered from toxicity and complications of previous interventions prior to participating in the study. 16. Patient had received anti-tumor therapy except experimental drugs (e.g., chemotherapy, targeted small molecule therapy or radiotherapy) within 2 weeks prior to screening or planned to receive anti-tumor therapy except experimental drugs (e.g., chemotherapy, targeted small molecule therapy or radiotherapy) during the study period. Radiotherapy used for pain control was an exception. 17. Patient had a known history of psychiatric disorders or drug abuse. 18. Patient was pregnant or breastfeeding, or subjects (including male subject and his female spouse) could not take effective contraceptive measures at the time of signing the informed consent until 120 days after the final anti-PD-1 therapy combined with FMT treatment. 19. Patient could not stop antibiotics treatment 24 hours before administration due to infection, etc. 20. Other cases that investigators qualified as relevant for patients who could not participate in the study, e.g., any medical history, treatment history, or history of abnormal test data that possibly confuses the study results, or interferes with patients' participation in the whole study, or damages patient interests.