Updated

OncoGenex Pharmaceuticals Inc said it was exploring strategic alternatives after its experimental drug failed to show survival benefit in a late-stage study in patients with advanced prostate cancer.

The Bothell, Washington-based company's stock tumbled about 35 percent to 58 cents in premarket trading.

The drug, custirsen, did not show a statistically significant improvement in overall survival in patients with metastatic castrate-resistant prostate cancer whose disease progressed despite treatment with the chemotherapeutic agent, docetaxel.

Metastatic castrate-resistant prostate cancer is when the cancer has spread to parts of the body other than the prostate, and is able to grow despite hormonal therapy to lower the amount of male sex hormones being used to manage the cancer.

OncoGenex said on Tuesday it planned to evaluate options with the U.S. Food and Drug Administration (FDA) related to an early analysis of a late-stage trial testing custirsen in patients with the most common form of lung cancer.

The announcement adds to a slew of disappointments OncoGenex has experienced over the last year.

In January, the company said interim data showed its experimental cancer drug, apatorsen, did not reach statistical significance required for progression-free survival in a mid-stage study in certain lung cancer patients.

The company has lost about 69 percent of its value since September, when OncoGenex announced that the intravenous apatorsen failed to induce a survival benefit in pancreatic cancer patients in a mid-stage study. (Reporting by Natalie Grover in Bengaluru; Editing by Martina D'Couto)