News Releases

Protox Announces Collaboration with FDA

Vancouver, British Columbia, April 30, 2008 – Protox Therapeutics Inc. (TSX:PRX) today announced that it has entered into a collaboration with the U.S. Food and Drug Administration (FDA) under the terms of a Cooperative Research and Development Agreement (CRADA).  The collaborative research and development program will be conducted by the principal investigators Dr. Sam Denmeade, MD, Chief Scientific Officer of Protox and Dr. Raj Puri, MD, PhD, Director, Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research at the FDA.

Dr. Puri is a pioneer in the research of interleukin-4 receptors as a potential drug target in cancer and has published extensively in this area.  The collaboration will focus on characterizing interleukin-4 receptors on various human tumors, determining the mechanism of up regulation of these receptors, developing assays and animal models to evaluate the safety and efficacy of interleukin-4 receptor–directed therapeutic agents, such as PXR321, and using laboratory analyses to assess the clinical potential of PRX321, either as a monotherapy or in combination with other therapeutic agents.  In addition, novel compounds targeting interleukin-4 receptors will be engineered and tested.  Under the terms of the CRADA, Protox has an exclusive option to license any future inventions developed under the research program.

Dr. Puri and colleagues reported new findings for PRX321 in Cancer Research, Volume 67(20):9903-9912. In this publication, PRX321, when combined with gemcitabine, a chemotherapeutic agent currently used to treat advanced pancreatic cancer, was shown to have a synergistic anti-tumour effect both in vitro and in a clinically relevant mouse model of advanced pancreatic cancer.  Specifically, those mice treated with a combination of PRX321 and gemcitabine showed a significant decrease in tumour burden and improved survival compared to treatment with either PRX321 or gemcitabine alone.  This study demonstrates for the first time the potential of combining PRX321 with a chemotherapeutic agent for treating patients with pancreatic cancer.

“We are very excited to be collaborating with Dr. Puri and his colleagues at the FDA,” said Dr. Sam Denmeade.  “Dr. Puri, as a co-inventor of PRX321, has been actively involved in the discovery and subsequent development of PRX321.  This collaboration will support our upcoming primary brain cancer clinical trial as well as serve to demonstrate the full potential of PRX321 as a selective and potent therapeutic targeting a large number of tumours that overexpress interleukin-4 receptors.”

About PRX321
PRX321 is a novel targeted protein in which a cytokine, interleukin-4 (IL-4), is linked to a Pseudomonas exotoxin, a potent substance that can destroy cancer cells. The IL-4 portion of the fusion protein binds to IL-4 receptors found on the surface of various types of cancer cells. The drug subsequently enters the target cell where the toxin component causes cell death by inhibiting protein synthesis.  PRX321 is in clinical development for the treatment of primary brain cancer. Results from a Phase 2a clinical trial completed in patients with recurrent and progressive glioblastoma multiforme showed potent anti-tumor effects without drug-related systemic toxicity in the majority of patients. PRX321 has also been studied in a completed Phase 1 trial in which patients with recurrent, unresponsive metastatic renal cell and non-small cell lung carcinomas were treated. In addition, PRX321 has shown promising pre-clinical results in a number of cancers over-expressing IL-4 receptors including pancreatic, ovarian, breast, head and neck, melanoma, prostate and blood cancers such as chronic lymphocytic leukemia (CLL) and Hodgkin’s lymphoma. Protox has an exclusive worldwide license to issued patents covering PRX321.

About Protox
Protox Therapeutics is a leader in advancing novel, receptor targeted fusion proteins. Two novel drug candidates derived from the company’s INxin™ and PORxin™ platforms are being developed in three clinical programs. A Phase 2a clinical trial evaluating PRX321 (INxin) for the treatment of primary brain cancer has been completed and the drug has received Fast Track Designation and Orphan Drug Status from the US FDA. Phase 2a clinical trials evaluating PRX302 (PORxin) for the treatment of localized prostate cancer and benign prostatic hyperplasia (enlarged prostate) have also been initiated. Protox is also collaborating with the U.S. National Institutes of Health (NIH) on a research program focused on the discovery of next generation fully human targeted therapeutics.

Certain statements included in this press release may be considered forward-looking. Such statements involve known and unknown risks, uncertainties and other factors that may cause actual results, performance or achievements to be materially different from those implied by such statements, and therefore these statements should not be read as guarantees of future performance or results. All forward-looking statements are based on Protox’ current beliefs as well as assumptions made by and information currently available to Protox and relate to, among other things, anticipated financial performance, business prospects, strategies, regulatory developments, market acceptance and future commitments. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release.  Due to risks and uncertainties, including the risks and uncertainties identified by Protox in its public securities filings; actual events may differ materially from current expectations. Protox disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

For further information contact:

James Beesley
Director, Investor Relations
Protox Therapeutics
604-688-0199
jbeesley@protoxtherapeutics.com

Michael Moore
Investor Relations
The Equicom Group
416-815-0700 x 241
mmoore@equicomgroup.com