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Protox Reports Promising Interim Results from Prostate Cancer Study

VANCOUVER, Jan. 18 /CNW/ - Protox(TM) Therapeutics Inc. (TSX-V:PRX) today announced interim results from its ongoing Phase I clinical trial evaluating PRX302 in patients with localized, recurrent prostate cancer. The findings to date indicate that PRX302 is well tolerated and shows encouraging signs of therapeutic activity following a single intra-prostatic injection.

"First and foremost, we are pleased with the safety profile of PRX302 thus far," said Dr. Fahar Merchant, President and Chief Executive Officer of Protox. "We have now reached the mid-point of this study with no significant safety concerns and with signs of a therapeutic effect, even at these low dosages. These data, although preliminary, support our expectations for this treatment, both in prostate cancer and in our approved BPH trial planned to commence this year."

The Phase I study is being led by Dr. Scott Coffield at Scott and White Memorial Hospital, with other participating sites including M. D. Anderson Cancer Center, Urology San Antonio and the University of Vermont. This trial is intended to examine the safety, tolerability and therapeutic activity of PRX302 in patients with localized recurrent prostate cancer who show signs of disease progression as evidenced by rising levels of PSA.

Using well-established, image-guided brachytherapy techniques, PRX302 was injected directly into the prostate. To date 12 patients at four clinical trial sites have been treated, with each new cohort of 3 patients receiving a higher dose once safety of the drug is established in the previous cohort. The dose has escalated 20-fold since the study commenced.

No safety issues relating to PRX302 treatment have been encountered to date. PRX302 was well-tolerated in all patients and there has been no evidence of systemic toxicity. No serious adverse events were reported relating to PRX302 and most other adverse events reported were those typically associated with the injection procedure, rating no higher than Grade 1 (mild) or Grade 2 (moderate) on the National Cancer Institute's 5-stage grading scale.

Early assessment of potential therapeutic activity was determined by measuring PSA (prostate specific antigen) levels throughout the study and conducting prostate biopsies at 30 days post-treatment. PSA is one of the most widely recognized disease markers in oncology and levels of PSA in the blood are used in the diagnosis of prostate cancer, monitoring cancer progression and tracking patient responses to its treatment.

Results show that eight of nine patients for whom 90-day data are available reported a decrease in PSA levels compared to baseline during at least one of the 14-, 30-, 60- or 90-day follow-up intervals. For six out of the nine patients, reductions in PSA levels continue to be observed through day 90 or longer, with PSA levels falling by 6% to 42% compared to baseline.

A comparison of prostate biopsies taken at baseline and at 30 days post-treatment shows that 8 of the 10 patients for whom data are available had a decrease in cancer-positive biopsies. The average decrease was 36% with four patients showing a 50% or greater reduction, including two who showed a 100% reduction.

"Patient responses have been encouraging at these low doses with few adverse events and observable decreases in cancer-positive biopsies and PSA levels," said the study's lead investigator, Dr. Scott Coffield of Scott & White Memorial Hospital. "As the dose is escalated to levels found to produce substantial prostatic destruction in relevant pre-clinical models, we expect more of the patients will manifest absence of cancer on post-therapy biopsy with concomitant decrease in PSA levels."

The company expects to complete the study by mid-year and begin planning for Phase II to commence by year-end.

Conference call

Protox will host a conference call and live webcast today at 10:00 a.m. E.T. to discuss these interim results. To access the conference call by telephone, dial 416-644-3414 or 1-800-733-7560. Please connect approximately ten minutes prior to the beginning of the call to ensure participation. The conference call will be archived for replay until February 20, 2007 at midnight. To access the archived conference call, dial 416-640-1917 or 1-877-289-8525 and enter the reservation number 21216654 followed by the number sign.

A live audio webcast of the conference call will be available at Please connect at least ten minutes prior to the conference call to ensure adequate time for any software download that may be required to join the webcast. The webcast will be archived at the above website for 30 days.

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 and radiation therapy. Serious side effects are associated with these therapies including erectile dysfunction, incontinence, urinary dysfunction and bowel problems. Current therapies to treat locally recurrent prostate cancer are associated with significant side effects.

About PRX302

PRX302 is the lead drug in the company's PORxin(TM) technology platform. PORxin drugs are 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 to create a potent anti-cancer agent with a distinct mode of action. The drug has been engineered so that it is activated by prostate-specific antigen (PSA), an enzyme that is overproduced in patients suffering from prostate cancer and enlarged prostate (benign prostatic hyperplasia or BPH). 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 treatment of cancer and other proliferative diseases. The company is actively developing two distinct but complementary platforms, INxin(TM) and PORxin(TM), and currently has three clinical programs in development. A Phase IIa clinical trial into the use of 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. In addition, a Phase I trial has been completed for PRX321 to treat patients with renal cell carcinoma and non-small cell lung cancer. Patient enrolment is underway for a Phase I clinical study into the use of PRX302 (PORxin) to treat localized prostate cancer. PRX302 has also been approved by Health Canada to commence a Phase I clinical study for the treatment of benign prostatic hyperplasia.


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.


/For further information: Anthony Boone, Director, Investor Relations and Corporate Communications, Protox Therapeutics, T: (604) 688-4369, C: (778) 996-4369,; Michael Moore, Investor Relations, Equicom Group, (416) 815-0700 x 241,

Posted: January 2007