Protox Therapeutics Inc. (TSX: PRX), a leader in the development of receptor targeted fusion proteins, today announced positive 12 month data from its Phase 1 study of PRX302 in patients with benign prostatic hyperplasia (BPH), a common and bothersome urological condition among the aging male population. The trial results indicate that PRX302 continues to show very promising signs of therapeutic activity at 12 months following a single treatment of PRX302.

 "The impact of PRX302 on the quality of life of most patients has continued to be dramatic," commented Dr. Peter Pommerville, co-principal investigator at Can-Med Clinical Research Centre in Victoria, B.C. "Unlike other minimally invasive techniques, the most impressive feature of PRX302 treatment is the sustainability of symptom improvement and a low side effect profile."

 "We are very pleased with the twelve month data and the positive response from our clinical investigators," said Dr. Fahar Merchant, President and Chief Executive Officer of Protox. "The extended duration of improvement in symptom scores following a single treatment are compelling especially when a reduction in IPSS by greater than four points is deemed to be highly clinically significant."

 

Study Design:

 This study was an open-label, multi-centre, dose escalation study where the primary endpoint was safety and tolerability following a single intra-prostatic administration of PRX302. The secondary endpoint was to determine therapeutic activity as measured by the change in International Prostate Symptom Score (IPSS) following treatment, when compared to screening. In addition, changes in Quality of Life (QoL) scores and prostate volume were also monitored. A total of 15 patients with moderate to severe BPH were treated in this trial. Most patients treated in this study were either refractory or intolerant to oral therapy.

 

Study Results:

 Therapeutic activity of PRX302 was evaluated at 12 months post-treatment using standardized symptom indices, namely, IPSS and QoL. IPSS assesses the severity of seven key symptoms of BPH, (incomplete emptying, frequency, intermittency, urgency, weak stream, straining and nocturia). The QoL score is measured on a scale from 0-6 with 0 defined as "delighted" and 6 defined as "terrible" with respect to patient quality of life due to BPH.

 As reported earlier this year, treatment related symptomatic relief was rapid and substantial benefits were noticed by day-30 post-treatment without any safety issues. Both symptom scores (IPSS and QoL) continued to show further improvements in all cohorts at the end of the active study period (day-90 post-treatment) indicating a potential for sustained benefit following a single treatment with PRX302.

 Following the active study period, 14 of 15 patients continued to be followed at 12 months post treatment and the IPSS scores continue to show a statistically significant improvement from screening (p (less than) 0.01). The mean IPSS values improved by an average of 6.5 points from 19.2 +/- 4.5 at screening to 12.7 +/- 4.6 at 12 months post treatment. The improvements were observed across all seven symptom sub-scores.

 Improvement in QoL scores were observed in all five cohorts. Independent of the treatment group, QoL scores continue to show a statistically significant improvement from an average of 4.6 +/- 1.0 at screening to 2.6 +/- 1.6 at 12 months (p (less than) 0.01), a 44% improvement. Furthermore, prostate volume decreased in all cohorts. Irrespective of cohort assignment, the mean prostate volume decreased by over 13% from 43.6 cc at screening to 38.1 cc at 12 month post-treatment.

 As announced previously, enrollment of Protox's Phase 2a study evaluating PRX302 for the treatment of BPH has been completed. Top-line data from this study will be released in the fourth quarter of 2008.

 

About BPH

 BPH is a common urological condition characterized by painful and bothersome symptoms that include difficulty in initiating a urine stream, a sense of urgency, leaking, dribbling and presence of blood in the urine. The condition affects over 50 million men throughout North America, Europe and Japan. More than half of all men will have symptoms of BPH by age 60 and as many as 90% may suffer from BPH after the age of 70. Left untreated, it can result in serious and possibly irreversible bladder damage. Current drug therapies only provide symptomatic relief and may trigger a range of side effects including impote
nce and hypotension. Surgical options such as TURP (transurethral resection of the prostate), which constitute the second-largest item in the US Medicare budget, can cause impotence, incontinence as well as other more serious procedure related effects. According to Wood Mackenzie (2007), the market opportunity for therapies used to treat BPH was US $5.5 billion in drug therapies and US $4 billion in surgical procedures.

 

About PRX302

 PRX302 is the lead drug in the company's PORxin(TM) technology platform. PORxin drugs are pore-forming pro-drugs that are activated by specific proteases produced at elevated levels on the surface of target cells. PRX302 has been generated by engineering the naturally occurring toxin proaerolysin so that it is activated by prostate-specific antigen (PSA), an enzyme that is overproduced in patients suffering from prostate cancer and BPH (benign prostatic hyperplasia or enlarged prostate). Once activated, the drug punches holes in the cells causing the contents to leak out and ultimately cell death.

 

About Protox

 Protox Therapeutics is a leader in advancing novel, receptor targeted fusion proteins. Two novel drug candidates derived from the company's INxin(TM) and PORxin(TM) 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 and EMEA. Phase 2a clinical trials evaluating PRX302 (PORxin) for the treatment of localized prostate cancer and benign prostatic hyperplasia (enlarged prostate) are ongoing. 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.