VANCOUVER, Jan. 3 /CNW/ - 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
"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."
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.
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
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.
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.
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).
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For further information:
For further information: James Beesley, Director, Investor Relations,
Protox Therapeutics, (604) 484-0975, firstname.lastname@example.org; Michael
Moore, Investor Relations, Equicom Group, (416) 815-0700 x 241,