Beta Glucan's Effect on Pembrolizumab Immunologic Response in Stage III-IV Melanoma

Inclusion Criteria: * Any patients with suspected (clinical) or definitive (tissue) diagnosis of Stage III-IV melanoma starting or continuing adjuvant Pembrolizumab without active evidence of disease (NED). * Must be treatment naïve or have had treatment no less than 6 months prior to enrollment * 18 years or older * Must be able to take pills * ECOG performance status of 0-3 * Ability to understand and willingness to sign a written informed consent * Members of all racial and ethnic groups are eligible for this study Exclusion Criteria: * History of hypersensitivity reactions attributed to beta-glucan * Patients receiving continuous or other ongoing immunosuppressive therapy * Uncontrolled intercurrent illness including, but not limited to, autoimmune diseases, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements * Any patients who have serious autoimmune toxicity during the study period, or those who have disease recurrence during the 6-week study period should be excluded and analyzed separately * Patients with mucosal melanoma * Patients with concurrent malignancy or recent history thereof