Promising prostate cancer drug developed in B.C. hits clinical trials

VANCOUVER – The eureka moment for a British Columbia prostate cancer researcher came when she saw photos of drastically shrunken tumors in mice she’d treated with a promising new drug.

“I remember running around the building and showing everyone those photographs in sheer delight,” Dr. Marianne Sadar said about that day in 2006.’ “I could not sleep for two weeks I was just so wound up. It was such an exciting moment.”

Nearly a decade later, the B.C. Cancer Agency scientist has hit another monumental milestone.

That same drug dubbed EPI-506 has now been approved for clinical trials, an accomplishment that Sadar said is reached in only one out of every 1,000 drugs that show initial promise in a lab.

What’s most encouraging for Sadar is the unique way in which the new treatment works.

EPI-506 targets the back of a protein on prostate cancer cells to make them more vulnerable to hormones such as testosterone, she told a news conference at the B.C. Cancer Research Centre.

While the effectiveness of earlier trial drugs that focus on the protein’s front quickly waned as cells developed resistance techniques, lab research suggests the new mechanism slows tumour growth past the early stages of treatment.

“This part that we’re directing our drug to is the Achilles heel,” Sadar said Wednesday. “It’s our hope and our expectation that this drug may actually work where all the other drugs are failing.”

Sadar described EPI-506 as a first-in-class drug, meaning it isn’t a copy of a previously engineered substance.

She said it’s also the first of its kind to identify its target no matter what shape the protein takes to disguise itself.

Wednesday’s announcement included a group of golfers from a club that raised $1 million over the last 15 years to help with Sadar’s research.

“I’m just very pleased. It makes all the work worthwhile,” said prostate cancer survivor Garry McClure, who is charity chairman of the senior men’s group at the Country Meadows Golf Club in Richmond.

The first phase of clinical trials began Wednesday at sites across North America, including at the B.C. Cancer Agency, under the direction of medical oncologist Dr. Kim Chi.

“This is a very exciting development,” Chi said. “This is a novel way of targeting prostate cancer. It hasn’t been done before.”

The initial stage will involve up to 50 participants to determine optimum dosage levels and preliminary effects, he said.

The second, larger phase would test the drug’s efficacy and whether it warrants expanding the test to a final, large-scale trial stage.

Chi noted that just as in any drug trial, volunteers face possible risks due to unknown side effects.

The drug could be available within five years if it’s approved, he said.