Patients with a diagnosis of high risk prostate cancer with a Gleason score of 8 or greater are eligible for this trial. The study will enroll 20 subjects in 3 years. This is a single-arm study including two parts. Part 1 will be a modified dose escalation and de-escalation study to determine maximum tolerated dose (MTD) and the recommended phase II dose (RP2D) based on acute toxicity measures. Part 2 will be a cohort expansion study to further evaluate the safety and tolerability of the RP2D based on toxicities measured at 1 year.
For Part 1, the primary endpoint is to assess if a patient can undergo a radical prostatectomy after SBRT without a post-operative GU and/or GI grade 3 or higher toxicity (according to Clavien-Dindo Classification) at 30 days.
For Part 2, the primary endpoint is to assess GU and/or GI grade 3 or higher toxicity based on CTCAE v5.0 at 1 year.
The previously entered quality-of-life measure was removed to align the record with the primary and secondary endpoints as pre-specified in the IRB-approved protocol.
Exploratory objectives will include analysis of tumor and normal biopsied and resected tissue and serum markers and interpretation of interfraction and intrafraction MRIs.
