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