Fecal Microbiota Transplant and Re-introduction of Anti-PD-1 Therapy (Pembrolizumab or Nivolumab) for the Treatment of Solid Tumors in Anti-PD-1 Non-responders

Inclusion Criteria

• At least 18 years of age on the day of signing informed consent
• Histologically/cytologically confirmed diagnosis of solid tumor
• Tumor that is deficient in mismatch repair (dMMR) or microsatellite instability high (MSI-H) as determined by one of three methods: * Immunohistochemistry determined dMMR by complete loss of MLH1, PMS2, MSH2 or MSH6 * Polymerase chain reaction (PCR) determined microsatellite instability at > 30% of tested microsatellites * Next-generation determined MSI-H based upon instability at multiple microsatellites as determined by the specific next generation sequencing panel
• Have metastatic disease that is measurable based on Immune-Modified Response Evaluation Criteria in Solid Tumors (iRECIST) version (v)1.1
• Demonstrated prior progression on anti-PD1/L1 based therapy by radiographic progression. The potential for pseudoprogression should be excluded by concurrent carcinoembryonic antigen (CEA) or other tumor marker or circulating tumor-derived deoxyribonucleic acid (ctDNA) elevation, or clinical symptom progression, or short interval repeat imaging confirming progression * Must have received at least 2 doses of a PD1/PD-L1 inhibitor * Progressive disease either during therapy or within 2 months of last dose of therapy
• An Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1
• Patients must be willing to undergone mandatory tumor biopsies at pre-treatment, at time of colonoscopy if possible and on-treatment (unless deemed unsafe by interventional radiology or by approval by study principal investigator [PI])
• The participant provides written informed consent for the trial. Patients for whom English is not their primary language are eligible for participation with translator assistance during the informed consent process
• Estimated life-expectancy of > 4 months
• White blood cell (WBC) count >= 3,000/microL
• Platelet count >= 75,000/microL
• Hemoglobin (Hgb) >= 8 g/dL
• Total bilirubin level =< 1.5 x the upper limit of normal (ULN) (except if Gilberts syndrome and then total bilirubin =< 3 x is allowed)
• Aspartate aminotransferase (AST), level =< 2.5 x ULN, and an alanine aminotransferase (ALT) level =< 2.5 x ULN. If liver metastases are present, then AST and ALT levels must be =< 4 x ULN
• Estimated creatinine clearance > 30 mL/min according to the Cockcroft-Gault formula or by a creatinine clearance measurement from a 24-hour urine collection
• Highly effective contraception for both male and female subjects if the risk of conception exists. Highly effective contraception must be used 30 days prior to first study-drug administration, for the duration of trial treatment, and for at least for 6 months (women and men after taking your last dose of any of the trial drugs. Should a female patient (or male patient’s sexual partner) become pregnant or should either the female patient (or male patient’s partner) suspect she is pregnant while the patient’s study-participation is ongoing, the treating physician should be informed immediately

Exclusion Criteria

• Has received prior systemic anti-cancer therapy including investigational agents within 2 weeks of study treatment (excluding continuation of ongoing nivolumab or pembrolizumab therapy)
• If participant received major surgery within last 4 weeks, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting study treatment
• Has an ileostomy or colostomy bag
• Has received prior radiotherapy within 2 weeks of start of study treatment. Participants must have recovered from all radiation-related toxicities (excluding skin toxicity), not require corticosteroids, and not have had radiation pneumonitis
• Has received a live vaccine within 30 days prior to the first dose of study drug. Examples of live vaccines include, but are not limited to, the following: measles, mumps, rubella, varicella/zoster (chicken pox), yellow fever, rabies, Bacillus Calmette–Guerin (BCG), and typhoid vaccine. Seasonal influenza vaccines for injection are generally killed virus vaccines and are allowed; however, intranasal influenza vaccines (e.g., FluMist®) are live attenuated vaccines and are not allowed
• Has a diagnosis of immunodeficiency (excluding immunoglobulin A [IgA] deficiency)
• Has an active autoimmune condition and is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form of immunosuppressive therapy within 7 days prior to the first dose of study drug * Subjects requiring hormone replacement with corticosteroids are eligible if the steroids are administered only for the purpose of hormonal replacement and at doses =< 10 mg of prednisone or equivalent per day * Administration of steroids for other conditions through a route known to result in a minimal systemic exposure (topical, intranasal, intro-ocular, or inhalation) is acceptable
• Has severe hypersensitivity (>= grade 3) to pembrolizumab or nivolumab and/or any of its excipients
• Serious adverse immune related adverse events (grade 3 or 4) with previous immune checkpoint therapy, that were symptomatic and required prolong immunosuppression (> 6 weeks)
• Has an active infection requiring systemic therapy
• Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the study, interfere with the subject’s participation for the full duration of the study, or is not in the study subject’s best interest to participate, in the opinion of the treating investigator
• Has known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the trial
• Pregnant or nursing women
• For women of childbearing age, a positive urine pregnancy test within 72 hours prior to enrollment. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required