This clinical trial assesses an effective and translatable care model to understand and reduce the adverse effects that cancer patients experience during their treatment therapies and thereby enhance their well-being and quality of life. Excessive immune activation can affect multiple organs with the most common adverse effects being skin rash, diarrhea, colitis, fatigue, hypothyroidism and anorexia. A restrictive calorie diet, mostly of fat and complex carbohydrates, will mimic fasting and increase resiliency to protect patients from the adverse effects of cancer treatments, by managing the adverse side effects of immune checkpoint inhibitors (ICI) treatments in select cancer patients. The fast mimicking diet (FMD) (Xentigen®) is a calorie restrictive, low-calorie, low-protein, high complex carbohydrate, high-fat diet. The FMD program is a plant-based diet program designed to attain fasting-like effects while providing both macro- and micronutrients to minimize the burden of fasting and adverse effects. The FMD consists of 100% ingredients which are generally regarded as safe (GRAS) and comprises mainly of vegetable-based soups and broths, energy bars, energy drinks, cracker snacks, herbal teas, and supplements. Following a FMD may reduce the adverse effects that some cancer patients experience while following immunotherapy treatments.