Prebiotic Food-enriched Diet (PreFED) to Enhance the Microbiome and Response to First-line Immunotherapy in Unresectable Melanoma

Eligibility Criteria

• * Age ≥18 years old
• * Able to self-complete study assessments monitoring diet and gastrointestinal symptom burden
• * Body mass index (BMI) 18.5-45 kg/m2
• * ECOG performance status of 0 or 1
• * Histologically confirmed stage III/IV, unresectable cutaneous or mucosal melanoma. Asymptomatic brain metastases are allowed.
• * Planned initiation of 1st line standard-of-care approved immune checkpoint blockade (anti-PD1 +/- anti-CTLA4 or anti-LAG3 inhibitors) in the metastatic setting (prior ICB in adjuvant setting is allowed if last exposure ≥ 6 months prior). Prior targeted therapy is also allowed.
• * Returning to MD Anderson for restaging and follow-up (ICB treatment may occur locally)
• * WOCP must have negative UPT within 1 week of beginning dietary intervention.
• * Self-reported willingness to eat the provided foods (with some tailoring to their food preferences)
• * Self-reported willingness to comply with scheduled visits, undergo venipuncture, provide stool samples.
• * Uveal melanoma previous ICB treatment in the metastatic setting
• * History of inflammatory bowel disease, total colectomy, or bariatric surgery.
• * Currently taking steroids \> Prednisone 10 mg/day or equivalent
• * Medical contraindications to the Intervention Diet as determined by the treating physician.
• * Self-reported major dietary restrictions, including but not limited to relevant food allergies, celiac disease, or diets such as vegan, ketogenic, extended fasting.
• * Insulin-dependent diabetes or condition requiring bile acid sequestrants
• * Unable or unwilling to undergo study procedures.
• * IV antibiotic use in the past month or oral antibiotic use in past 2 weeks.
• * Regularly taking supplements containing prebiotics, fiber and/or probiotics, and unable/unwilling to discontinue for the purpose of the study.
• * Current smoker or heavy drinker (defined as \>14 drinks per week) or current illicit drug use.
• * Currently pregnant, planning to become pregnant, or lactating.
• * Concurrent malignancy requiring systemic therapy other than hormonal therapy.
• * Cognitively impaired adults