To learn about the possible effects of a prebiotic food-enriched diet (PreFED) targeting the gut microbiome in participants with melanoma who are starting immune checkpoint blockade (ICB) therapy.

Primary Objectives

• Evaluate the effect of dietary intervention on the abundance of Faecalibacterium in stool samples from baseline to 12 weeks

Secondary Objectives

• Determine the best overall response rate (BORR) to PreFED + ICB regimens and landmark ORR at 12 weeks (intervention) and 24 weeks (maintenance)
• Determine progression-free survival (PFS) and overall survival (OS) with PreFED + ICB regimens
• Compliance and adherence to the dietary intervention at 12 weeks and maintenance at 24 weeks
• Determine the safety (diet-related AEs) and tolerability (GSRS-IBS) of the dietary intervention at 12 weeks and maintenance at 24 weeks
• Assess the rate of immune related adverse events in patients on ICB regimens receiving dietary intervention at 12 weeks and maintenance at 24 weeks
• Assess the effects of dietary intervention on systemic and tumor immunity
• Assess the effect of dietary intervention on overall gut microbiome composition and networks at 12 weeks and maintenance at 24 weeks
• Assess the effects of dietary intervention on gut metabolic output and systemic metabolism at 12 weeks and maintenance at 24 weeks
• Assess the effects of dietary interventions on quality of life and other patient reported outcomes (PROs) at 12 weeks and maintenance at 24 weeks

Inclusion Criteria:

• Age ≥18 years old
• English-speaking
• Body mass index (BMI) 18.5-45 kg/m2
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• Histologically confirmed stage III/IV, unresectable cutaneous, uveal, acral 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 or talimogene laherparepvec T-VEC) in the metastatic setting. Prior targeted therapy or ICB in the adjuvant setting is allowed.
• Returning to MD Anderson for restaging and follow-up (ICB treatment may occur locally)
• Measurable disease per RECIST 1.1 or RANO criteria. Up to 10 patients without measurable can be enrolled.
• 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.

Exclusion Criteria:

• 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