The purpose of this study is to test an approach of stimulating the body's immune system to attack prostate cancer. This study will test injection of a substance polylysine and carboxymethylcellulose (Poly-ICLC, Hiltonol®)through a needle guided by MRI (magnetic resonance imaging) ultrasound fusion technology into the prostate gland. Poly ICLC has been used to help the body in its fight against cancer. The first aim of the study is to determine the highest dose of a substance Poly-ICLC (Hiltonol®) that can be safely tolerated by the study participants. The second aim of the study is to find out the toxicity or side effects of poly-ICLC.