Protox announces positive final results from BPH study

Protox(TM) Therapeutics Inc. today announced positive final results from its Phase 1 study evaluating PRX302 in patients with benign prostatic hyperplasia (BPH), a common condition among the aging male population

VANCOUVER, Canada | January 3, 2007 | Protox(TM) Therapeutics Inc. (TSX-V: PRX), a leader in advancing novel, targeted protein toxin therapeutics for the treatment of cancer and other proliferative diseases, today announced positive final results from its Phase 1 study evaluating PRX302 in patients with benign prostatic hyperplasia (BPH), a common condition among the aging male population. The trial results indicate that PRX302 is safe and well tolerated and shows very promising signs of therapeutic activity for the treatment of BPH.

"The impact of PRX302 in the quality of life of most patients has been dramatic," commented Dr. Peter Pommerville, co-principal investigator at Can-Med Clinical Research Centre in Victoria, B.C. "In addition to the rapid treatment response, the effect of PRX302 continued to improve with time and showed that symptomatic relief was sustained over time. Furthermore, patient satisfaction with the single ten minute office-based minimally invasive treatment for BPH is high."

"We are very pleased with these data as PRX302 continues to deliver impressive results in the clinic," said Dr. Fahar Merchant, President and Chief Executive Officer of Protox. "In addition to the excellent safety and tolerability profile, PRX302 has demonstrated substantial symptomatic benefit in most patients who failed existing oral therapies."

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) throughout the study, when compared to screening. In addition, changes in Quality of Life (QoL) scores, prostate volume and uroflow parameters were also monitored. A total of 15 patients with moderate to severe BPH were treated in this trial. The dose was increased 14-fold between cohort 1 and cohort 4, keeping the dosing volume constant, whereas one additional cohort received cohort 1 dose at a 4-fold higher volume. Patient parameters at screening were as follows: age - 64.8 years (range: 52-82); prostate size - 41.3 mL (range: 30.0-80.1); IPSS - 19.1 (range: 12-26); QoL - 4.3 (range: 3-6). Most patients treated in this study were either refractory or intolerant to oral therapy.

Study Results

Despite a 14-fold escalation in dose, no safety issues were identified and the maximum tolerated dose was not reached in this study. Results indicate that PRX302 was well tolerated with no serious adverse events observed. Treatment related adverse events were generally reported as being mild, local and transient in nature.

Therapeutic activity of PRX302 was evaluated at day-30 and day-90 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.

Treatment related symptomatic relief was rapid and substantial benefits were noticed by day-30 post-treatment. 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.

Across all treatment groups, IPSS scores showed a statistically significant improvement from screening to Day 30 (p (less than) 0.01) and continued to Day 90 post-treatment (p (less than) 0.001). The mean IPSS values improved by an average of 5.8 points from 19.1 +/- 4.3 at screening to 14.3 +/- 5.7 at day-30 post treatment. By day-90, IPSS improved by an average of 8.5 points (10.6 - 5.9) with 8 of 15 patients showing a 10 point or greater improvement in IPSS values. The improvements were observed across all seven symptom sub-scores, each decreasing by at least 30%. Although early, these results are compelling especially when a reduction in IPSS by greater than four points is deemed to be highly clinically significant.

Improvement in QoL scores were observed in all five cohorts. Independent of the treatment group, QoL scores improved from an average of 4.3 +/- 1.1 at screening to 2.5 +/- 1.6 by day-30 (p (less than) 0.01) and continued to show a 50% improvement by day-90 (QoL = 2.1 - 1.6; p (less than) 0.01)). Furthermore, prostate volume decreased in all cohorts. Irrespective of cohort assignment, the mean prostate volume decreased by over 26% from 41.6 cc at screening to 30.5 cc at day-90 post-treatment (p (less than) 0.05).

Based on the encouraging data from this study, plans are currently underway to commence a Phase 2 BPH clinical trial in the first 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 impotence 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, targeted protein toxin therapeutics for the treatment of cancer and other proliferative diseases. 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. Phase 1 clinical trials evaluating PRX302 (PORxin) have been completed for the treatment of localized prostate cancer and benign prostatic hyperplasia (enlarged prostate).


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.

SOURCE: Protox Therapeutics Inc.

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