Shares of OncoGenex Pharmaceuticals nearly doubled in value on Wednesday, as the company's experimental prostate-cancer treatment showed very promising interim results in a midstage clinical trial.

Shares of OncoGenex Pharmaceuticals nearly doubled in value on Wednesday, as the company’s experimental prostate-cancer treatment showed very promising interim results in a midstage clinical trial.

Patients taking the drug survived about 11 months longer than those taking the standard therapy, the company said. The results “exceeded our expectations,” said OncoGenex Chief Executive Officer Scott Cormack.

The company’s stock closed at $3.95, up 76 percent.

The results seem to be a coup for the newly formed company, which resulted from the merger of Sonus Pharmaceuticals, of Bothell, with Vancouver, B.C.-based OncoGenex Technologies.

But prostate-cancer patients may have to wait at least three years before the treatment is made commercially available. The product must successfully complete a more extensive clinical trial before the U.S. Food and Drug Administration considers approving it.

OncoGenex says the late-stage trial is ready to go, but it needs to raise money to bankroll the testing. The company had about $17 million in cash and short-term investments at the end of the quarter.

The midstage study, conducted in 82 patients, showed those treated with its OGX-011 drug in combination with docetaxel and prednisone had a 40 percent lower death rate than those taking docetaxel and prednisone alone. Those receiving OGX-011 had a median survival of 27.5 months, compared to 16.9 months for the others.

Sonus Pharmaceuticals saw its fortunes collapse last fall when its lead therapy for breast cancer failed in a clinical trial. Still, it had some cash left, a good match for OncoGenex Technologies’ research pipeline.

Most of Sonus’ staffers were let go in the merger. OncoGenex kept the Bothell headquarters, and moved its small Seattle research team there.

Ángel González: 206-515-5644