BPS-001, a complex biologic agent extracted from the medicinal leech (Huridinaria manillensis) for treatment of metastatic castration-resistant prostate cancer.

209 Background: We established that subcutaneous BPS-001 reduced tumor size and inhibited tumor growth in PC3, LNCaP and 22RV-1 mouse xenografts; and, tumor lHC demonstrated an increase in caspase-3 and decreases in expression of P21, Ki-67 and PCNA. We also showed that BPS-001 reduced PSA expression in both In vitro and in In vivo xenografts (LNCaP and 22RV1). We now demonstrate that BPS-001 inhibits angiogenesis in the xenografts; and, In vitro studies demonstrate that BPS-001 affects expression of adhesion molecules and the androgen receptor. In addition, BPS-001 inhibited tumor growth in a TRAMP allograft model. Methods: CD31 expression was measured using IHC of the previous mouse xenografts. In vitro androgen receptor and adhesion molecule expression were assessed by Western blot. Transplantable TRAMP-C2 mouse prostate cancer in B57CL allografts were grown to 5 mm prior to initiation of treatment. Immune markers in TRAMP allograft tumors were measured by IHC. Results: Mechanistic studies show BPS-001 acts by blocking angiogenesis demonstrated by a > 50% decrease in expression of CD31 in the LNCaP and 22RV-1 xenografts. Furthermore, preliminary toxicology studies show similar efficacy to docetaxel with no weight loss in the longer-term PC3 xenograft study as was observed with docetaxel. Preliminary toxicology studies of BPS-001 also support a favorable toxicity profile, and the therapeutic dose (1-5 mg/Kg, QW or BIW) is well within the margin of safety. Dose limiting toxicity (bleeding) was observed at doses of 20mg/Kg daily. In vitro studies showed BPS-001 decreased expression of both N- and P- cadherins and the androgen receptor. BPS-001 inhibited tumor growth in the TRAMP allograft models. IHC analyses of the TRAMP allograft tumors suggest immunomodulation. Conclusions: BPS-001 exhibits anticancer activity with no observed toxicity in the therapeutic range. Effects of BPS-001 include inhibition of angiogenesis, downregulation of adhesion molecules associated with advanced prostate cancer and inhibition of androgen receptor signaling. Elucidation of the mechanism of action is ongoing.