OncoGenex Pharmaceuticals, Inc. Reports Financial Results for Second Quarter 2016 Pivotal Phase 3 Prostate Trial Results Expected in Third Quarter 2016 BOTHELL, WA, and VANCOUVER, British Columbia

OncoGenex Pharmaceuticals, Inc. Reports Financial Results for Second Quarter 2016

Pivotal Phase 3 Prostate Trial Results Expected in Third Quarter 2016

BOTHELL, WA, and VANCOUVER, British Columbia, Aug. 4, 2016 - OncoGenex Pharmaceuticals, Inc. (NASDAQ: OGXI) today announced its second quarter 2016 financial results and provided a summary of anticipated milestones.

Financial Results and Anticipated Near-term Milestones

As of June 30, 2016, the company's cash, cash equivalents, and short-term investments were $39.7 million compared with $55.2 million as of December 31, 2015.

Based on current expectations, OncoGenex believes that its cash, cash equivalents, and short-term investments will be sufficient to fund its currently planned operations into the third quarter of 2017. Depending on timing of enrollment or event-driven final analyses, the expected key milestones and activities are as follows:

Revenue for the three and six months ended June 30, 2016 was $2.1 million and $5.1 million, respectively, compared to $4.0 million and $5.4 million for the three and six months ended June 30, 2015, respectively. Revenue consists of recognition of deferred collaboration revenue representing our efforts in the development of custirsen. As of June 30, 2016, the full amount of the deferred collaboration revenue has been fully recognized.

Total operating expenses for the three and six months ended June 30, 2016 were $8.5 million and $15.9 million, respectively, compared to $9.6 million and $16.0 million for the three and six months ended June 30, 2015, respectively. Net loss for the three and six months ended June 30, 2016 was $6.9 million

and $10.6 million, respectively, compared to $6.0 million and $10.5 million for the three and six months ended June 30, 2015, respectively.

As of Aug. 4, 2016 OncoGenex had 30,009,730 shares outstanding.

Conference Call Details

OncoGenex will host a conference call at 4:30 p.m. Eastern Time today, Thursday, Aug. 4, 2016, to provide a business update and discuss the second quarter 2016 financial results. A live event will be available on the Investor Relations section of the OncoGenex website at www.OncoGenex.com. Alternatively, the live conference call may be accessed by dialing (877) 606-1416 (U.S. & Canada) or (707) 287-9313 (International). A webcast replay will be available approximately two hours after the call and will be archived on www.OncoGenex.com for 90 days.

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. 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 regarding the company's anticipated product development activities, such as expected clinical trial enrollment, completion and design, statements regarding the potential benefits and potential development of its product candidates and statements regarding its expected financial results, use and adequacy of cash reserves and expected future cash requirements. 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 the company's expected clinical trials may result in delays or may not demonstrate a clinical benefit for its product candidates, the risk that its product candidates may not receive regulatory approval or be successfully commercialized, the risk in the company's ability to complete required regulatory filings and requirements and/or future clinical trials, the risk of delayed future contractual payments and product revenue, the risk that new data from its product candidates or new developments in the rapidly evolving cancer therapy landscape require changes in its clinical trial plans or limit the potential benefits of its products, the risk that its products' market acceptance and potential size may differ materially from those projected, the risk that its cash resources are insufficient to fund its planned activities for the time period expected and the other factors described in the company's risk factors set forth in its 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.

Borealis-2 is a registered trademark of OncoGenex Pharmaceuticals, Inc.