Prostate cancer patients (pts) with non-metastatic prostate specific antigen (PSA) progression after local therapy and a long PSA doubling time (PSADT) usually have a period of PSA observation prior to starting on androgen deprivation therapy (ADT). We report results of an investigator-initiated, IRB-approved Phase II clinical trial ( investigating grape seed extract (GSE) in pts with PSA-only recurrence after maximum local therapy for prostate cancer. Pts with baseline PSA ≥ 0.2 ng/mL and rising PSA on 2 separate occasions and no evidence of metastases were eligible. Pts with baseline PSADT < 4 weeks (if absolute PSA > 2 ng/mL) were excluded. Pts were given 150mg of GSE orally twice daily for 12 months. GSE was administered as a formulation Leucoselect Phytosome-Indena S.p.A. (~100% proanthocyanidins, enriched in lower procyanidin oligomers complexed with soy phospholipids, about 1:2.6 w/w), with increased bioavailability. Study endpoints included PSA response (defined as an increase in PSADT by 30%) and change in PSA velocity. PSA was checked at baseline, 6 weeks and 3, 6, 9, and 12 months after starting GSE. Pts were removed from the trial with clinical/radiographic progression or if PSADT was less than 3 months. Pts completed dietary surveys and provided biologic specimens for tissue banking. The association of time and PSA level was assessed using a mixed effect modeling approach with the intention of calculating the doubling time. The natural log of PSA was taken to satisfy the linearity assumption of this method. Notably, pts on observation with a rising PSA after treatment for prostate cancer could be accrued rapidly to clinical trials; 27 pts were screened for this clinical trial at two sites (between January 2018 - August 2018) with 20 pts registered and started on treatment. Median (range) age and baseline PSA of pts enrolled were 71 (60 - 83) and 2.65 (0.44 - 17.44), respectively. Mean pretreatment PSADT was 5.4 months. GSE was well tolerated without serious adverse effects. 8 patients were withdrawn early due to PSADT progression of <3 months. The remaining 12 patients completed 12 months of follow-up. Mean post-treatment PSADT was 6.4 months. 9 patients met the endpoint of a PSADT increase of 30% or more. Taken together these results indicate that 300mg of daily GSE may improve PSA kinetics in pts with a rising PSA after maximum local therapy. This work was supported by NCI P30 CA46934 Cancer Center Support Grant, Cancer League of Colorado, the Writer Foundation, and the Barbara and Richard Gardner Fund for Prostate Cancer Research.

Citation Format: Paul Maroni, Elizabeth R. Kessler, Rodrigo Rodrigues-Pessoa, Andrew Nicklawsky, Thomas Flaig, Elaine Lam, Brandon Bernard, James Moore, Kyra Anderson, Dexiang Gao, Komal Raina, Rajesh Agarwal. A phase II trial using grape seed extract for prostate cancer patients with non-metastatic PSA progression after local therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT207.