Protox Therapeutics Inc. Announces Positive Clinical Data from Prostate Cancer Study
"The completion of the PRX302 Phase 1 trial is encouraging from two perspectives," said Dr. Scott Coffield, Principal Investigator from the lead site, Scott and White Memorial Hospital. "First, there was therapeutic benefit demonstrated through overall PSA reduction in study patients, as well as a reduction in the number of positive biopsies after treatment. Second, there was no significant adverse side effect profile at the highest dose of PRX302 given to patients in this trial."
"It is heartening to see promising results at this stage of the clinical development program in a patient population which has limited therapeutic options," said Dr. Fahar Merchant, President and Chief Executive Officer of Protox. "These data support our heightened confidence regarding the potential of PRX302 for the treatment of not only prostate cancer, but also BPH, which is currently being evaluated in an ongoing Phase I trial."
This study 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 (prostate specific antigen) following radiation treatment. Using a well-established, image-guided technique, PRX302 was administered directly into the prostate. A total of 24 patients were treated in this trial. Protox has concluded that despite a 100-fold escalation in dose, the maximum tolerated dose (MTD) was not reached in this study while encouraging signs of therapeutic activity were observed.
No significant safety issues relating to PRX302 treatment were encountered in this clinical trial. One patient in the study, who met inclusion criteria in spite of having borderline liver abnormalities, showed a transient rise in liver enzymes (Grade 3 on the National Cancer Institute's 5-stage grading scale) that quickly returned to screening levels. An expanded cohort was enrolled at this dose in order to collect additional safety data. No safety issues were observed in any patients within the expanded cohort or in further cohorts that received higher doses. In summary, no serious adverse events were reported relating to PRX302 and all other adverse events reported were mostly associated with the injection procedure, rating no higher than Grade 1 (mild).
Assessment of potential therapeutic activity was determined by measuring PSA levels throughout the study and conducting prostate biopsies at 30 days post-treatment. PSA is one of the most widely recognized disease markers in prostate cancer 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.
A comparison of prostate biopsies taken at baseline and at 30 days post-treatment shows that 18 of the 24 patients tested in this trial had a decrease in the percentage of cancer-positive biopsies. Three of the patients showed a complete absence of cancer in their day 30 biopsy.
Two specific measurement indicators, PSA doubling time (PSADT) and PSA velocity (PSAV), are key parameters in predicting clinical progression, metastasis and mortality in patients with prostate cancer. Of the 24 patients tested in this study, 90 day PSA data is available for 15 patients at this time. Comparison of PSA levels pre- and post-treatment shows a clear and desirable trend towards an increase in PSADT (15 of 15 patients) and a decrease in PSAV (11 of 15 patients), both of which are very positive outcomes for the patient. Results show that in 10 of 15 patients PSA levels were below baseline at 90 days or longer post-treatment. In 14 of the 15 patients, a decrease in PSA levels was observed during at least one of the, 30-, 60- or 90-day follow-up intervals.
The company expects that a final report that will include top-line PSA data with expanded analysis of PSADT and PSAV will be available for release in October. Plans are underway to commence a Phase 2 study before the end of the year.
Conference call
Protox will host a conference call and live webcast today at 12:00 p.m. E.T. to discuss these results. To access the conference call by telephone, dial 416-644-3414 or 1-800-732-9307. Please connect approximately ten minutes prior to the beginning of the call to ensure participation. The conference call will be archived for replay until August 10, 2007 at midnight. To access the archived conference call, dial 416-640-1917 or 1-877-289-8525 and enter the reservation number 21240373 followed by the number sign.
A live audio webcast of the conference call will be available at www.protoxtherapeutics.com. 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 Protox
Protox Therapeutics is a leader in advancing novel, targeted protein toxin therapeutics for the 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 four programs in clinical development. A Phase 2a clinical trial evaluating PRX321 (INxin) for the treatment of primary brain cancer has been completed and the product candidate has received Fast Track Designation and Orphan Drug Status from the US FDA. In addition, a Phase 1 clinical trial evaluating PRX321 for the treatment of patients with renal cell carcinoma and non-small cell lung cancer has been completed. Patient enrollment has been completed for a Phase 1 clinical trial evaluating PRX302 (PORxin) for the treatment of localized prostate cancer. A Phase 1 clinical trial evaluating PRX302 for the treatment of benign prostatic hyperplasia (enlarged prostate) is ongoing.
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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
James Beesley, Director, Investor Relations, Protox Therapeutics, (604) 688-0199, jbeesley@protoxtherapeutics.com Michael Moore, Investor Relations, Equicom Group, (416) 815-0700 x 241, mmoore@equicomgroup.com
Source: Protox Therapeutics Inc.