A Phase 1b Dose Escalation Trial of PSK®/Placebo With Docetaxel to Treat Metastatic Castration-resistant Prostate Cancer

This is a phase 1b study that follows a 3+3 dose escalation design and consists of a 21-day lead-in period of oral Polysaccharide Krestin (PSK)/placebo (study drug) alone followed by the addition to study drug of standard intravenous docetaxel at 75 mg/m2 every 3 weeks for three cycles. Study drug will be discontinued on day 15 of the third docetaxel cycle to allow for a 7-day washout period before the fourth dose of docetaxel. Pharmacokinetic (PK) analysis of docetaxel will be conducted during docetaxel cycle 1 (combination therapy) and cycle 4 (docetaxel alone). Serum for future PSK PK analysis will be collected on days 1, 3, and 15 of PSK/placebo lead-in and during cycles 1 and 4.