Neoadjuvant Immune Checkpoint Blockade + a Prebiotic Food-enriched Dietary Intervention to Optimize Immune Response in Melanoma: NEO-PreFED

Inclusion criteria

• Age ≥ 18 years old.
• Body mass index (BMI) 18.5-45 kg/m2
• Able to self-complete study assessments monitoring diet and gastrointestinal symptom burden
• ECOG performance status of 0 or 1
• Histologically confirmed resectable stage IIIB-D or oligometastatic Stage IV cutaneous melanoma or locally invasive/advanced mucosal melanoma as determined by multidisciplinary review
• Planned initiation of standard-of-care neoadjuvant ipilimumab +/- nivolumab or nivolumab +/- relatlimab
• Measurable disease per RECIST 1.1
• 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.
• Archival tissue specimen or planned to undergo tumor biopsy as part of standard of care treatment.

Exclusion criteria

• Uveal melanoma
• 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 conditions requiring bile-acid sequestrants
• Unable or unwilling to undergo study procedures
• Intravenous (IV) antibiotic \>1 dose in the past month or 1 dose IV/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