Impact of a Prebiotic Food-enriched Diet (PreFED) in Combination With Ipilimumab/Nivolumab Combination Immune Checkpoint Blockade (ICB) in ICB-refractory Melanoma Patients

Inclusion Criteria:

Age ≥ 18 years old
English-speaking
Body mass index (BMI) 18.5-45 kg/m2
ECOG performance status of 0 or 1
Histologically confirmed stage III/IV, unresectable cutaneous melanoma. Asymptomatic brain metastases are allowed.
Prior treatment with anti-PD1 or anti-PD-1 + anti-LAG3 agents and documented disease progression either while on these agents or after stopping therapy without intervening therapy.
Planned initiation of standard-of-care Ipilimumab 3 mg/kg + Nivolumab 1 mg/kg
Measurable disease per RECIST 1.1
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:

Prior treatment with anti-CTLA4
Mucosal or uveal melanoma
Concurrent malignancy requiring systemic therapy other than hormonal therapy.
History of inflammatory bowel disease, total colectomy, or bariatric surgery
Currently taking steroids > Prednisone 10 mg/day or equivalent
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.
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 conditions requiring bile-acid sequestrants.
Current smoker or heavy drinker (defined as >14 drinks per week) or current illicit drug use.
Currently pregnant, planning to become pregnant, or lactating.
Cognitively impaired adults