A Pilot Study of Parenteral Testosterone and Oral Etoposide as Therapy for Men With Castration Resistant Prostate Cancer

Based on our preclinical data, high levels of androgens can lead to significant growth suppressive effects in prostate cancer cells in vitro and in vivo. Mechanistic data in in vitro models suggests that this growth suppression may be due to the accumulation of androgen induced TOP2B mediated double strand breaks at AR target sites occurring after stimulation of prostate cancer cells with high levels of androgens. Provocatively, the number of double strand breaks was significantly increased (Figure 3 B) if the cells were treated with etoposide, an agent that leads to formation of double strand breaks at TOP2 target sites, concurrently with high-dose androgen stimulation. We hypothesize that co-administration of testosterone with etoposide could produce high levels of double strand breaks in prostate cancer cells, overwhelming DNA repair and survival mechanisms and leading to cancer cell death or growth arrest. To test whether this possibility holds promise for therapy of advanced prostate cancer, we propose the following clinical trial of parenteral testosterone therapy in combination with oral etoposide in men with evidence of progressive prostate cancer during chronic androgen ablation.