Pilot Study of Intermittent Fasting With Immune Checkpoint Inhibitors

This single-site, randomized pilot study will evaluate whether intermittent fasting is feasible and safe for patients with advanced solid tumors who are starting immune checkpoint inhibitor (ICI) therapy at the WVU Cancer Institute. Participants will be assigned to 1 of 3 groups: usual care with no fasting, alternate-day fasting (ADF), or time-restricted eating (TRE). Participants in the ADF group will follow cycles of 12 hours of eating followed by 36 hours of fasting every other day. Participants in the TRE group will eat all daily calories within an 8-hour window each day. The fasting intervention will begin within 1 week of starting ICI treatment and continue for approximately 20-24 weeks during 8 cycles of therapy. The study will evaluate adherence to the fasting regimens and compare side effects between groups. Researchers will also study changes in metabolic and immune biomarkers, fatigue, sleep, and quality of life. Participants will be followed for 30 days after completion of the intervention to monitor safety and tolerability.

Inclusion Criteria: * Diagnosis of advanced esophageal, gastric, non-small cell lung cancer (NSCLC), HCC, cholangiocarcinoma, melanoma, RCC, or MSI-H cancer * Planned treatment with ICI-based therapy * ECOG 0-2 * Ability to provide informed consent * Willingness to follow dietary guidance and record adherence * BMI = 23-40 Exclusion Criteria: * Diabetes requiring insulin * Active eating disorders * Sarcopenia and/or cachexia (mild, moderate, severe), including sarcopenic obesity * A history of hypoglycemia, including idiopathic and postbariatric hypoglycemia * Patients taking sulfonylureas (concern for hypoglycemia with fasting) * Night shift workers (at discretion of investigator) * \>10% weight loss within the past 3 months through self-reporting or chart review. * Any uncontrolled autoimmune condition or recent high-dose steroid use * Severe GI or endocrine disorders precluding fasting including but not limited to malabsorption syndromes, gastroparesis, or Addison's/Cushing's * Pregnant or breastfeeding