Protox announces positive Phase 2b BPH results
VANCOUVER, Jan. 11 /CNW/ - Protox Therapeutics Inc. (TSX: PRX), a leader in the development of receptor targeted fusion proteins, today announced positive top-line results from its double-blinded placebo controlled Phase 2b study of PRX302 (study name: TRIUMPH) in patients with moderate to severe benign prostatic hyperplasia (BPH), a painful and bothersome urological condition that affects more than 50 million men worldwide. The study achieved its primary clinical endpoint of a statistically significant improvement in International Prostate Symptom Score (IPSS) for patients treated with PRX302 versus subjects receiving placebo (p=0.0238, ANCOVA).
"We are very excited about the results of the TRIUMPH study," said Dr. Fahar Merchant, President and Chief Executive Officer of Protox. "We believe that PRX302 has an immense commercial opportunity and look forward to sharing these impressive data with our potential partners."
"The future for new drug development is to create molecules that target the organ or cell of interest and affect it as needed with minimal collateral damage. PRX302 is an excellent example of such a designer drug that targets cells producing PSA which is limited to the prostate gland," commented Dr. Mostafa M. Elhilali, OC, M.D., Ph.D. Chief Co-Principal Investigator and Stephen Jarislowsky Chair of Urology at McGill University. "The study results from this placebo controlled trial showed that injecting PRX302 in the prostate produced the desired effects with minimal side effects which is quite exciting. Furthermore, improvements in symptoms were also associated with improvements in flow rates and Quality of Life measures."
Study Design: -------------
TRIUMPH was a double-blinded, placebo-controlled, multi-centre Phase 2b study in subjects with moderate to severe BPH. Enrolment criteria included baseline IPSS scores greater than or equal to 15, a maximum urinary flow rate (Qmax) of less than 12 milliliters per second and prostate volume between 30 and 100 milliliters. Each subject was treated with either PRX302 (3 microgram/mL) or placebo at a volume equivalent to 20 percent of the total prostate volume via a single ultrasound guided injection into each lobe of the prostate.
The trial's primary clinical endpoint of the study was to determine the efficacy of PRX302, as demonstrated at 90 days post-treatment, by a statistically significant improvement in IPSS from baseline when compared to placebo. IPSS is a validated primary clinical endpoint used to assess the treatment benefit in BPH trials. This index is measured on a 0 to 35 scale with 0 being defined as having no problems and 35 defined as the high end of severe symptoms.
Study Results: --------------
Of the 73 per protocol efficacy evaluable subjects, 52 received PRX302 and 21 received placebo. The PRX302 arm showed an average IPSS improvement at 90 days of 9.1 (+/- 5.9) points versus an average IPSS improvement of 5.8 (+/- 5.4) points for the placebo arm, a statistically significant improvement of 3.3 points (p=0.0238, ANCOVA). Baseline average IPSS for the PRX302 and placebo groups were 23.5 and 22.9 points, respectively.
A sub-group analysis was performed for subjects with severe BPH (baseline IPSS(greater than)22, n=40). Results of this sub-group analysis showed that those treated with PRX302 had an average IPSS improvement at 90 days from baseline of 10.8 (+/- 6.0) versus an improvement of 5.8 (+/- 6.2) for those receiving placebo for an overall 5.0 point improvement over placebo.
No significant safety issues were identified in this study. There were no drug related serious adverse events or Grade 3 or greater adverse events reported in the study. PRX302 related adverse events were mild to moderate, transient in nature (resolved within days) and localized to the urinary tract. In addition, no sexual dysfunction was reported in any of the subjects.
A total of 92 subjects were enrolled on a 2-to-1 basis (treatment to placebo) and randomized based on their baseline IPSS and prostate size. At 90 days, the number of per protocol efficacy evaluable subjects was 21 (mean age of 64.5 years) of the 31 that were dosed at baseline in the placebo arm and 52 (mean age of 63.7 years) of the 61 dosed at baseline in the PRX302 arm. The decrease in efficacy evaluable subjects was due to protocol violations, medical interventions, or patient withdrawal and included three subjects that needed surgery to treat BPH (all from the placebo arm).
Detailed results from this study will be presented by Professor Mostafa Elhilali during a podium session at the Annual Meeting of the American Urological Association to be held in San Francisco, May 29 - June 3, 2010.
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. Once activated, the drug punches holes in the cells causing the contents to leak out and ultimately cell death.
BPH is a common urological condition characterized by painful and bothersome symptoms that include difficulty in initiating a urine stream, a sense of urgency, dribbling, incomplete emptying of the bladder, waking several times during the night to urinate and sometimes the presence of blood in the urine. More than half of all men will have symptoms of BPH by the age of 60 and as many as 90% may suffer from BPH after the age of 80. Current oral therapies mainly provide symptomatic relief and can trigger a range of side effects including sexual dysfunction and hypotension. It is estimated that in the seven largest global markets approximately 10 million men are treated annually with oral therapies and these products encompass approximately U.S. $4 billion of sales each year. Surgical options, including minimally invasive procedures, can cause sexual dysfunction, incontinence as well as other more serious procedure-related effects. Surgical measures can require hospitalization, significant recovery time and requires catheterization for variable time intervals. Nearly 600,000 surgical procedures are conducted annually in the seven largest markets.
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. Protox's lead program, PRX302 (PORxin), has announced positive results from its Phase 2b placebo controlled trial called TRIUMPH, to treat benign prostatic hyperplasia (BPH or enlarged prostate). In addition to these positive results, data from the Phase 2a study demonstrated durability at 12 months. PRX302 is also being evaluated for the treatment of localized prostate cancer. 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. 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.
Posted: January 2010