Muscadine Plus (MPX) In Men With Prostate Cancer

Prostate specific antigen (PSA) is a single-chain glycoprotein produced by the epithelial cells of the prostate. PSA has been used for early detection and monitoring of patients with prostate cancer who receive a variety of treatments. Due to the widespread use of serum PSA to monitor for prostate cancer recurrence following primary treatment, there exists a group of men with a rising PSA as their only evidence of recurrence. These patients may not demonstrate clinical or radiographic evidence of disease progression for an average 8 years from the time of detectable PSA to detectable metastatic disease by standard imaging. Currently there are limited treatment options for these patients that may delay disease progression or improve survival, including salvage radiation for prior surgical patients, hormonal therapy, and active surveillance. Although some surgical patients are candidates for salvage radiation, not all patients will want salvage radiation. Even the early initiation of hormonal therapy (e.g., luteinizing hormone releasing hormone (LHRH) analogs) has not demonstrated a survival benefit, although Schroder et al suggests an advantage for early hormone therapy in the setting of metastatic regional lymph nodes. Furthermore, early initiation of androgen ablation is associated with significant morbidity and impact on quality of life, including fatigue, hot flashes, loss of libido, decreased muscle mass, and osteoporosis with long term use. This group of relatively well men with biochemical recurrence are currently offered androgen ablation therapy or active surveillance (regular PSA monitoring and annual scans) until there is evidence of metastatic disease, because other options have not been available. These patients are excellent candidates for innovative treatments hypothesized to slow the progression of clinical prostate cancer and delay the development of metastatic disease. As the previous section documents, preclinical studies of muscadine grape skin offer evidence that it may extend the time between biochemical recurrence and development of metastatic disease. While the Phase II study described above found no significant difference in PSA doubling time between placebo and either dose of MPX, there was a signal of benefit in the subgroup analysis of men with the Alanine/Alanine superoxide dismutase 2 (SOD2) genotype that received high dose MPX. It is therefore proposed to test the benefits of high dose MPX in capsule formulation in a randomized, controlled study of men who have failed primary therapy, either radiation, surgery or cryotherapy, as primary treatment for prostate cancer. Eligible subjects will have a rising PSA and will have 3 PSA values at least 7 days apart with a recovered testosterone to be able to calculate a baseline PSA doubling time. The primary endpoint of this study will be mean PSA slope during the study period.