(OGXI) Update on Phase 3 ENSPIRIT Trial Of Custirsen In Lung Cancer

BOTHELL, Wash. and VANCOUVER, British Columbia, Aug. 21, 2014 — OncoGenex Pharmaceuticals, Inc. (NASDAQ: OGXI) announced today that the Phase 3 ENSPIRIT trial, evaluating custirsen in the treatment of non-small cell lung cancer (NSCLC), is continuing as planned per the recommendation of the Independent Data Monitoring Committee (IDMC) based upon completion of the first interim futility analysis.

“While the results of the study remain blinded to OncoGenex and Teva, we are very pleased that ENSPIRIT has passed this important early interim futility analysis,” said Scott Cormack, President and CEO of OncoGenex. “We remain strong in our belief that targeting mechanisms of treatment resistance is a critical path forward in the fight against cancer and we continue to actively pursue this approach through the two ongoing Phase 3 trials of custirsen and the seven Phase 2 trials of apatorsen in four tumor types.”

The Phase 3 ENSPIRIT trial is an international, randomized, open-label trial designed to evaluate a survival benefit for custirsen in the treatment of advanced or metastatic non-small cell lung cancer in 1,100 patients who have progressed after initial chemotherapy treatment. Patients are randomized to receive custirsen plus docetaxel or docetaxel alone. Patient enrollment to ENSPIRIT was initiated by Teva in September 2012. Two interim futility analyses are planned for stopping the trial. The first of these two futility analyses has now been completed which allows for acceleration of further enrollment. A second futility analysis will be conducted later in the trial. The U.S. Food and Drug Administration (FDA) has granted Fast Track designation for the evaluation of custirsen in the ENSPIRIT trial.

Custirsen is also being evaluated in the ongoing Phase 3 AFFINITY trial with second-line chemotherapy in men with metastatic castrate-resistant prostate cancer. The expected timing of AFFINITY results is based on a pre-specified number of death events, however the Company currently expect final results to be announced in late 2015 or early 2016.

About Custirsen

Custirsen is an experimental drug that is designed to block the production of the protein clusterin, which may play a fundamental role in cancer cell survival and treatment resistance. Clusterin is upregulated in tumor cells in response to treatment interventions such as chemotherapy, hormone ablation and radiation therapy and has been found to be overexpressed in a number of cancers, including prostate, lung, breast and bladder. Increased clusterin production has been linked to faster rates of cancer progression, treatment resistance and shorter survival duration. By inhibiting clusterin, custirsen is designed to alter tumor dynamics, slowing tumor growth and resistance to partner treatments, so that the benefits of therapy, including survival, may be extended.

As part of Phase 1 and Phase 2 clinical trials, custirsen was administered to 294 patients with various types of cancer. The majority of adverse events were mild. The most common adverse events associated with custirsen consisted of flu-like symptoms. The most common serious adverse events (SAE) associated with custirsen were febrile neutropenia, fever, pleural effusion, and dyspnea. Each SAE event was observed in approximately 2%-4% of patients. In the Phase 3 SYNERGY trial in men with metastatic CRPC, adverse events observed were similar to custirsen’s known adverse event profile.

About OncoGenex

OncoGenex is a biopharmaceutical company committed to the development and commercialization of new therapies that address treatment resistance in cancer patients. OncoGenex has a diverse oncology pipeline, with each product candidate having a distinct mechanism of action and representing a unique opportunity for cancer drug development. OncoGenex and Teva Pharmaceutical Industries Ltd. (NYSE: TEVA) have entered a global collaboration and licensing agreement to develop and commercialize OncoGenex’ lead drug candidate, custirsen. Custirsen is currently in Phase 3 clinical development as a treatment in men with metastatic castrate-resistant prostate cancer and in patients with advanced, unresectable non-small cell lung cancer. Apatorsen is in Phase 2 clinical development and OGX-225 is currently in pre-clinical development. More information is available at www.OncoGenex.com and at the company’s Twitter account https://twitter.com/OncoGenex_IR.

OncoGenex’ Forward Looking Statements

This press release contains forward-looking statements within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995, including, but not limited to, statements concerning our anticipated product development activities, such as expected clinical trial completion and design, statements regarding timing of enrollment and trial completion and statements regarding the potential benefits and potential development of our product candidates. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. These statements are based on management’s current expectations and beliefs and are subject to a number of risks, uncertainties and assumptions that could cause actual results to differ materially from those described in the forward-looking statements. Such forward-looking statements are subject to risks and uncertainties, including, among others, the risk that our product candidates will not demonstrate the hypothesized or expected benefits, the risk of delays in our expected clinical trials, the risk that new developments in the rapidly evolving cancer therapy landscape require changes in our clinical trial plans or limit the potential benefits of our product, the risk that we are unable to complete enrollment in our clinical trials in the expected timeframe and the other factors described in our risk factors set forth in our filings with the Securities and Exchange Commission from time to time, including the Company’s Annual Report on Form 10-K and Quarterly Reports on Form 10-Q. The Company undertakes no obligation to update the forward-looking statements contained herein or to reflect events or circumstances occurring after the date hereof, other than as may be required by applicable law.