Background: Non-hormonal treatments for biochemically recurrent non-metastatic prostate cancer (nmPC) are limited. SM88 is a novel combination of proprietary tyrosine isomer (TI) and other repurposed agents (CYP3a4 inducer, mTOR inhibitor and catalyst) designed to selectively increase metabolic oxidative stress in cancer cells. Early data reported SM88 activity in solid tumors without significant toxicity (Hoffman et al J Clin Oncol 2013; e22095, Hoffman et al Ann Onc 2016: vi551). Methods: This is an open-label multi-center, dose escalating, dose expansion study in nmPC who have failed or refused androgen deprivation. The study includes a dose escalation phase Ib and dose expansion phase 2. The primary objectives are to determine the effect of SM88 on circulating tumor cells (CTC), and progression-free survival. Secondary objectives are: LDH, bone-specific alkaline phosphatase, urinary N-telopeptide, neutrophyll/llymphocyte ratio, cutaneous hyper-pigmentation correlation, PSA doubling times, safety, and patient reported outcomes. As of Jan ‘17, Phase 1b cohorts 1 and 2, with TI and component PK evaluations, have completed enrollment with adequate numbers to establish the Phase 2 dose without DLT. Phase 2 has begun, with 33 patients planned for at least 6 cycles (@28d) to reach the desired power. This would be followed by a pivotal Phase 3 study in the same group of patients. We propose to conduct a pivotal randomized phase 3 of SM88 in rising PSA, nmPC versus patient’s and clinician’s choice, limited to 2 options i.e. observation or ADT therapy. Inclusion would include doubling time < 9 months, elevated CTCs and recurrent disease after localized curative intent therapy (the same population as our completed Phase I and ongoing phase II). Outcomes will include delay of radiographic PFS, and delay of time to subsequent toxic therapy i.e. cytotoxic systemic chemo and/or radiation therapy. We proposed this pivotal trial will lead to a successful NDA for an indication in this population of patients. Rapid accrual is expected at several institutions because of the urgent need for less toxic alternatives to androgen deprivation therapy.