For release - March 12, 1998

Vancouver - In the world's first clinical trial of its kind for prostate cancer, a new therapy that blocks the function of cancer-causing genes is being tested on patients at the BC Cancer Agency. The trial tests the effectiveness of using small segments of DNA in genes, called antisense oligonucleotides, to reduce or eliminate tumours.

"Antisense therapy is a new experimental treatment option for men with prostate cancer-an option that may be the way of the future," says Dr. Tony Tolcher, a medical oncologist at the BC Cancer Agency in Vancouver and principal investigator for the study in B.C.

Antisense therapy blocks the function of cancer-causing genes. These genes produce copies of themselves, called messenger RNA. The messanger RNA is a template for protein formation that signals cells to grow uncontrollably in cancer-causing genes. The new therapy uses a modified strand of DNA, an antisense oligonucleotide. It appears to the messenger RNA as a complimentary copy of itself and specifically affects the gene's ability to send messages, thus disrupting cancer cell behaviour and growth. Because this gene activity is seen in other tumours in the body, the treatment holds potential for other cancer sites.

I was a little unnerved knowing I was the second man on the planet to take this therapy," says 69-year-old James "Harve" Ritchie. Diagnosed with prostate cancer in 1992, he says his prognosis was poor from the start. "I'm in this trial for selfish reasons: I want the therapy to arrest the cancer and the onset of bone pain. But every month I see more than 100 men in my patient support group in Victoria. And every meeting there are new faces. I would be happy if my participation in this study helped even one of them down the line."

Interested patients who meet the following criteria should discuss the study with their physician: prostate cancer that has spread and is resistant to hormone therapy; mild to moderate symptoms; a PSA level above 20; no narcotics use; relatively good health; and close proximity to Vancouver. The National Cancer Institute of Canada is funding and coordinating the study. ISIS Pharmaceuticals developed the drug. Treatment centres in Toronto, Hamilton, Edmonton and Calgary will also be participating.

he BC Cancer Agency is a leader in prostate cancer research with one of the largest research groups in Canada. The group's many projects focus on discovering what causes prostate cancer, how it progresses and how to identify more effective treatments. Antisense therapy is among many new cancer treatments on the horizon as researchers learn more about the composition of genes in human cells. The BC Cancer Agency's Genome Sequence Centre, which will open in late 1998 and will be operational in 1999, will play a leading role in developing non-invasive cures for cancer.