Warburg Pincus made a C$8.3 million (about $8.1 million) investment in Protox Therapeutics as part of a previously agreed investment deal signed in September 2010. The agreement gives Warburg Pincus Private Equity X and Warburg Pincus X Partners the right to invest up to C$35 million (roughly $34.2 million) in Protox. An initial investment of C$10 million ($9.8M) was made under the agreement in November 2010.
Protox is focused on engineering naturally occurring proteins into targeted therapeutics for the treatment of prostate diseases and different forms of cancer. The firm’s pipeline is based on its PORxin™ and INxin™ technology platforms and is headed by two Phase II-stage candidates.
PRX302 is a PSA-activated prodrug in development for treating benign prostatic hyperplasia (BPH) and localized prostate cancer. The candidate is a genetically engineered version of the naturally occurring pore forming protein proaerolysin, in which the native furin cleavage and activation sequence has been replaced with a sequence that is activated by PSA. When activated by PSA, the PRX302 inserts itself into the membranes of prostate cells forming pores that disrupt membrane integrity, which leads to cell death.
Just last week Protox reported completing dosing a second cohort of patients into a Phase II study evaluating transrectal administration of PRX302 for the treatment of BPH. The firm has partnered with Kissei Pharmaceuticals for the development and commercialization of PRX302 in Japan.
PRX321 is in development for the treatment of glioblastoma multiforme and astrocytoma. The candidate comprises IL-4 attached to Pseudomonas exotoxin and has been designed to bind with high specificity to IL-4 receptors on the surface of cancer cells. Once the construct is internalized in the cancer cells the toxin induces apoptosis.