Phase 2 trial of muscadine grape extract added to ADT for recurrent prostate cancer fatigue

A Phase 2 randomized controlled trial investigated the addition of a dietary supplement to standard therapy for men with recurrent prostate cancer. The study enrolled 106 men who were already receiving androgen deprivation therapy (ADT). Participants were randomized to receive either muscadine grape extract (MGE) plus their ongoing ADT or a placebo plus ADT. The specific dosing regimen for MGE and the exact duration of the intervention period were not reported. The study setting was also not reported. The primary objective was to assess changes in patient-reported fatigue at the 6-month time point.

For the primary outcome of change in fatigue at 6 months, no results were reported. The study did not provide any data on the magnitude of change, effect size, absolute numbers of participants experiencing improvement or worsening, confidence intervals, or p-values. The direction of any effect (beneficial or harmful) was also not reported. This complete lack of primary outcome data means the trial's central hypothesis regarding fatigue mitigation remains untested in the available information.

Several key secondary outcomes were planned, but similarly, no results were provided. These outcomes included levels of fatigue measured at other time points (3, 9, and 12 months), overall quality of life, and assessments of physical function, physical fitness, and body composition. The study also planned to evaluate time to prostate-specific antigen (PSA) progression and progression-free survival, both measured from study entry. With a reported median follow-up of 72.7 months, these long-term oncologic endpoints were presumably tracked, but no data on event rates, hazard ratios, or statistical significance were reported.

Detailed safety and tolerability findings were not reported. The available information does not include rates of adverse events, serious adverse events, or treatment discontinuations due to side effects. There is no data on how well participants tolerated the muscadine grape extract supplement compared to placebo, or whether any specific safety signals emerged during the trial. This absence of safety data is a significant gap, as the profile of any adjunctive therapy, especially a supplement, is critical for clinical consideration.

Without reported results, a direct comparison to prior landmark studies in prostate cancer supportive care or dietary supplementation is not possible. The study design addresses a recognized need—managing fatigue in men on long-term ADT—but it does not yet contribute evidence to inform comparisons with other interventions like exercise programs, psychostimulants, or other nutritional supplements studied in this context. The 72.7-month follow-up suggests an intention to collect meaningful long-term data, but the value of that follow-up cannot be assessed without the results.

Key methodological limitations stem entirely from the lack of reported data. While the randomized controlled trial design is robust, the absence of results for primary and secondary outcomes introduces a high risk of reporting bias. It is unknown if the trial was underpowered, if there were issues with adherence, or if data collection was incomplete. The funding source was the lead sponsor, Wake Forest University Health Sciences; potential conflicts of interest for investigators were not reported. The population was specifically men with recurrent disease on ADT, so findings, if they existed, would not be generalizable to other prostate cancer populations.

The clinical implications of this study, based solely on the provided structured input, are null. With no efficacy or safety results reported, this trial cannot currently inform practice decisions regarding the use of muscadine grape extract for fatigue in men with prostate cancer on ADT. Clinicians should be aware that this intervention has been studied in a Phase 2 trial, but its benefits and risks are unknown. It remains an experimental approach without evidence to support its recommendation.

Substantial questions remain unanswered. The core question of whether MGE reduces fatigue compared to placebo is unanswered. The impact on quality of life and physical function is unknown. The long-term oncologic safety and any effect on PSA progression or survival are unclear. The tolerability and common side effects of the supplement in this patient population have not been described. Furthermore, the optimal dosing and duration of MGE supplementation are not defined. Future research would need to first report the results of this trial before designing subsequent studies to address these gaps.