OncoGenex Expands Clinical Development of OGX-427 with a Phase 1 Clinical Trial in Bladder Cancer BOTHELL, WA, and VANCOUVER

OncoGenex Expands Clinical Development of OGX-427

with a Phase 1 Clinical Trial in Bladder Cancer

BOTHELL, WA, and VANCOUVER August 13, 2009 OncoGenex Pharmaceuticals, Inc. (NASDAQ: OGXI), today announced that the

first patient has been dosed in an open label, dose-escalation, Phase 1 clinical trial evaluating OGX-427 when

administered directly into the bladder in patients with bladder cancer. This trial is separate from an ongoing Phase 1

trial of OGX-427 administered systemically in patients with various solid tumors. OGX-427 is a second-generation

antisense drug that is designed to reduce production of Heat Shock Protein 27 (Hsp27), a cell-survival protein that

inhibits apoptotic cell death through multiple pathways.

The study, which will enroll up to 36 patients with bladder cancer, is designed to determine the safety and potential

benefit of OGX-427 administered directly into the bladder using a catheter, which is called intravesical instillation.

In addition, the study will measure the direct effect of OGX-427 on expression of Hsp27 in bladder tumor cells as well

as determine the pharmacokinetics and pharmacodynamics of OGX-427 when delivered by intravesical instillation. The

study is sponsored by the National Cancer Institute of Canada (NCIC). Dr. Alan So, an Assistant Professor in the

Department of Urologic Sciences at the University of British Columbia and Research Scientist at the Vancouver Prostate

Centre, is the study s principal investigator.

The current treatment for superficial bladder cancer is local resection with immunotherapy, which often has

significant local and systemic side effects, said Dr. So. Because of the limitations of current adjuvant options, a

treatment option like intravesical delivery of OGX-427 that is specifically targeted to the tumor would be desirable.

This Phase 1 trial of OGX-427 is an attractive trial design as removal of bladder tumor samples after treatment allows

us to demonstrate inhibition of Hsp27 expression at the cellular level in the tumor, said Scott Cormack, President and

Chief Executive Officer of OncoGenex.

By conducting this trial through an investigator-sponsored trial with leading clinical researchers at the Vancouver

Prostate Centre allows us to advance the development of OGX-427 without a significant commitment of our financial

resources, Cormack added.

In preclinical studies conducted by the Vancouver Prostate Centre, OGX-427 had single-agent activity in multiple

cancers. In preclinical models of bladder cancer, the investigators observed that bladder cancer tumors were

significantly smaller six weeks after OGX-427 administration compared to the control group.

OGX-427 is designed to reduce production of Hsp27, a protein that is over-produced in response to many cancer

treatments including hormone ablation therapy, chemotherapy and radiation therapy. Hsp27 production has been shown to

inhibit cell death in tumor cells through a variety of mechanisms.

OGX-427 is being evaluated in another Phase 1 clinical trial for the systemic (intravenous) treatment of solid tumors

including prostate, non-small cell lung, breast, ovarian, and bladder cancers. OncoGenex Pharmaceuticals, Inc. recently

announced preliminary results of this Phase 1 trial presented during an oral presentation at the 2009 American Society

of Clinical Oncology (ASCO) Annual Meeting. Results as of May 2009 showed that OGX-427 was well tolerated as a

monotherapy. In addition, after treatment with OGX-427 patients experienced declines in circulating tumor cells at all

doses evaluated as well as evidence of reduction in tumor markers. Reductions in circulating tumor cells and tumor

markers both suggest single-agent activity warranting further clinical investigation.

Similar to OGX-011, OGX-427 has potential as a treatment in a broad number of cancers.

OncoGenex is a biopharmaceutical company committed to the development and commercialization of new therapies that

address unmet needs in the treatment of cancer. OncoGenex has a deep oncology pipeline, with each product candidate

having a distinct mechanism of action and representing a unique opportunity for cancer drug development. OGX-011, the

lead candidate that has completed five Phase 2 clinical studies in prostate, lung and breast cancers, is designed to

inhibit the production of a specific protein associated with treatment resistance; OGX-427 is in Phase 1 clinical

development; SN2310 has completed the Phase 1 clinical trial; and CSP-9222 and OGX-225 are currently in pre-clinical

OGX-011, OGX-427 and OGX-225 utilize second-generation antisense technology, licensed from Isis Pharmaceuticals

(NASDAQ: ISIS), to effectively target and inhibit production of specific proteins in tumor cells. OncoGenex and Isis

partnered in the successful discovery of OGX-011, OGX-427 and OGX-225 and with respect to OGX-011, in its initial

development. In 2008, OncoGenex and Isis amended their OGX-011 agreement to provide OncoGenex with sole rights to

OGX-011 and sole responsibility for development and related costs and partnering decisions, subject to financial

obligations to Isis. OncoGenex is also solely responsible for development and related costs and partnering decisions

regarding OGX-427 and OGX-225. Key intellectual property related to OGX-011, OGX-427 and OGX-225 were discovered by the

University of British Columbia and the Vancouver Prostate Centre, and were exclusively licensed to OncoGenex.

More information about OncoGenex is available at www.oncogenex.com.

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 the potential

activity and clinical benefit of OGX-427 and the anticipated clinical development activities and timing of these

activities. Such forward-looking statements are subject to risks and uncertainties, including, among others: the risk

factors set forth in the Company s filings with the Securities and Exchange Commission, including the Company s Annual

Report on Form 10-K for fiscal year 2008. 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

Media and Investor Contact:

Porter Novelli Life Sciences