News Releases

Protox Successfully Doses First Patient in Prostate Cancer Trial using PRX302

Tuesday, May 2, 2006 - Vancouver, British Columbia - Protox Therapeutics Inc. (TSX-V: PRX) today announced the enrollment and successful dosing of the first patient in a Phase I clinical study evaluating their lead drug, PRX302, to treat localized recurrent prostate cancer. PRX302 is a targeted pro-drug that turns into a potent anti-cancer agent once activated by the enzyme, prostate specific antigen (PSA), produced in high levels by prostate cancer and hyperplastic prostate cells. Once activated, PRX302 destroys the cells by punching holes in the cell membrane.

In pre-clinical studies, PRX302 has been shown to selectively and potently kill PSA-producing cells without harming adjacent healthy tissues or organs. PRX302 has the potential to address the unmet needs of millions of men suffering from localized prostate cancer and enlarged prostates (benign prostatic hyperplasia or BPH).

Dr Fahar Merchant, President and CEO of Protox, commented, "The entry of our first compound into clinical development is an important corporate milestone and emphasizes the excellent progress made by the company during the past year. Molecular-targeted therapies such as those being developed by Protox are the fastest growing segment of the cancer therapy market, underlining our belief in the commercial potential of our PORxin™ platform."

Dr Merchant added, “The novel approach utilized by PRX302, along with our plans to build a solid pipeline of targeted toxin therapeutics, will allow Protox to offer a broad range of potential new therapies for the treatment of cancer and proliferative disorders.”

The first patient was treated at Scott & White Memorial Hospital in Temple, Texas. Two additional US sites have been planned and will be initiated as soon as each center’s internal review board (IRB) approval has been granted. Patient enrollment is expected to be completed and interim results made public by the end of 2006.

“The fact that PRX302 is delivered locally to the prostate makes it very promising since the likelihood of causing serious adverse events associated with current treatments is so much lower with this approach,” said Dr. Scott Coffield, a Urologist-Oncologist at Scott & White and Principal Investigator of the Phase I study. “We are excited to offer our patients this new and unique approach to combat the disease that still takes the lives of too many men.”

The primary objective of this open label, single arm, multiple-site Phase I clinical trial is to assess the safety, tolerability and therapeutic activity of an ascending dose of PRX302, in approximately 30 patients with localized recurrent prostate cancer. PRX302 will be injected into the prostate gland under ultrasound guidance and changes in PSA levels will be measured and prostate biopsies performed after 30 days. Patients will be followed for a total of three months.

This study is also designed to recommend the optimum dose range for subsequent Phase II studies. Additionally, the trial will seek to define the pharmacokinetic profile of PRX302 and to collect preliminary data on anti-tumor activity.

About Prostate Cancer:
Prostate cancer is a leading cause of cancer death in North American men. One in every six men is diagnosed with prostate cancer during their lifetime. The American Cancer Society estimates that during 2006 approximately 234,500 new cases of prostate cancer will be diagnosed and over 27,000 men will die from the disease in the U.S. Current treatment options for localized prostate cancer include surgery (radical prostatectomy), brachytherapy (implantation of radioactive seeds), and external beam irradiation. Serious side effects are associated with all these therapies including erectile dysfunction, incontinence, urinary dysfunction and bowel problems. There are currently limited therapies with significant side-effects to treat locally recurrent prostate cancer.

About Scott and White:
Scott and White is the largest multi-specialty practice in Texas with more than 500 physicians and considered to be one of the foremost healthcare institutions in the US. The hospital is ranked among the top 15 major teaching hospitals in the US. Scott and White is affiliated with the Texas A&M University College of Medicine and its physicians are involved in clinical trials that focus on improving patient care, treatment outcomes and medical safety.

About Protox Therapeutics:
Protox Therapeutics is a product-focused development-stage company and a leader in advancing novel, targeted protein toxin therapeutics for treatment of cancer and other diseases. Through the company’s PORxin™ technology platform, therapeutic candidates are generated by engineering the naturally occurring protein, pro-aerolysin. These proteins become potent anti-cancer agents when activated at a tumor site by specific proteases produced by cancer cells. Once activated, the drug punches holes in the cancer cells causing the contents to leak out and ultimately, cell death. Protox has received clearance from the FDA to commence Phase 1 clinical trials with the lead compound, PRX302, for the treatment of localized prostate cancer. PRX302 is also being developed for treatment of benign prostatic hyperplasia.

For more information, contact:
Elayne Wandler
Director, Investor Relations and Corporate Communications, Protox Therapeutics Inc.
Direct: 604-688-4369
Cell: 778-865-0172
Fax: 604-688-0173
ewandler@protoxtherapeutics.com