Muscadine Grape Skin Extract in Treating Patients With Malignancy That Is Metastatic or Cannot Be Removed by Surgery

PRIMARY OBJECTIVES: I. To determine the safety and maximum tolerated dose (MTD) of MGE (muscadine grape skin extract) after 4 weeks of administration for patients with metastatic cancer. Secondary Objectives: I. To monitor adverse events/toxicity every 4 weeks while on treatment. II. To evaluate change in phenolic levels (total and component, blood and urine) from baseline to 4 and 8 weeks. III. To evaluate change in serum cytokines and growth factors from baseline to 4 and 8 weeks on MGE. IV. To observe the response rate of MGE in patients with metastatic cancer. V. To assess overall and progression-free survival in patients with metastatic cancer receiving MGE. VI. To assess global quality of life (Functional Assessment of Cancer Therapy-General \[FACT-G\] and fatigue (Patient Reported Outcomes Measurement Information System \[PROMIS\]-fatigue Short Form \[SF\]) in cancer patients taking MGE. VII. To assess adherence to MGE treatment. OUTLINE: This is a dose-escalation study. Patients receive muscadine grape skin extract orally (PO) twice daily (BID). Treatment continues for 8 weeks in the absence of disease progression or unacceptable toxicity. Patients experiencing benefit from muscadine grape skin extract may continue treatment in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up for 30 days and then every 6 weeks.