FDA Agrees with OncoGenex' Phase 3 AFFINITY Protocol Amendment

BOTHELL, Wash. and VANCOUVER, June 10, 2015 /PRNewswire/ -- OncoGenex Pharmaceuticals, Inc. (NASDAQ: OGXI) announced today that the U.S. Food and Drug Administration (FDA) has agreed to the Company's proposed amendment to the Phase 3 AFFINITY protocol and statistical analysis plan. The amendment includes the addition of a co-primary endpoint designed to prospectively evaluate the survival benefit of custirsen in men who are at increased risk for poor outcomes when treated with cabazitaxel for metastatic castrate-resistant prostate cancer (CRPC).

"There are limited effective treatment options for men with metastatic CRPC who have risk factors for poor outcomes and who fall into a poor prognosis category. Recent findings from the SYNERGY trial showed a significant survival benefit in this group of patients," said Cindy Jacobs, PhD, MD, Chief Medical Officer and Executive Vice President of OncoGenex. "We have applied this key insight from the SYNERGY trial to the AFFINITY protocol to better evaluate this vulnerable subpopulation of men who have poor prognosis and shorter survival time."

The FDA is in agreement with plans for prospectively defining a poor prognostic subpopulation in the Phase 3 AFFINITY trial. OncoGenex, in collaboration with study investigators, has defined a simple 5-criteria characterization for poor prognosis in prostate cancer based on the Phase 3 SYNERGY trial, which includes: poor performance status, elevated prostate specific antigen (PSA), elevated lactate dehyrdogenase (LDH), decreased hemoglobin, and the presence of liver metastasis. Patients with poor prognosis will be identified as having 2 or more of these 5 well-recognized high-risk criteria. The proposed change for AFFINITY is also consistent with custirsen's mechanism of action, since custirsen was designed to address treatment resistance which may be more prevalent in this subpopulation.

In the revised statistical analysis plan for the AFFINITY trial, the hypothesized hazard ratio (HR) for the poor prognosis subpopulation is specified to be 0.69 with the critical HR ≤ 0.778. The hypothesized HR for the intent-to-treat patients (ITT population) remains unchanged as 0.75 with the critical HR ≤ 0.820.

Timing for the final analysis of the poor prognosis subpopulation is projected to occur by the end of 2015, while the final analysis for the ITT population is projected to occur in the second half of 2016. FDA and OncoGenex have further agreed that an interim analysis will occur for the ITT population when the final analysis for the poor prognosis subpopulation occurs. This interim analysis will have both futility and early efficacy criteria defined for the ITT population. If the earlier final analysis on the poor prognostic subpopulation shows a survival benefit for custirsen, OncoGenex could initiate a regulatory submission. The entire trial could also be stopped early due to efficacy based on the interim assessment for the ITT population by the Independent Data Monitoring Committee (IDMC).

"Findings from the SYNERGY trial recently presented at ASCO have provided important insight into the patient population in whom custirsen treatment is most relevant," said Scott Cormack, President and CEO of OncoGenex. "We are pleased that the FDA has agreed with our amendment and look forward to announcing top-line results at the end of this year and in 2016." 

OncoGenex has also initiated a review with the European Medicines Agency (EMA) for the proposed amendment to the Phase 3 AFFINITY protocol and statistical analysis plan, and expects to have this completed in the second half of 2015.

A retrospective analysis of data from the Phase 3 SYNERGY trial recently presented at the 51st Annual Meeting of the American Society of Clinical Oncology (ASCO) showed a benefit with custirsen therapy when added to first-line docetaxel chemotherapy in men with metastatic CRPC who had a poor prognosis. The analysis showed that over 40 percent of men in the trial had at least 2 of the 5 common risk factors for poor prognosis as stated above.  In these men, the analysis found a 27 percent lower risk of death when custirsen was used in combination with first-line docetaxel compared to docetaxel alone.

AFFINITY is being conducted at 95 global clinical trial sites and earlier this year, the IDMC recommended the trial continue following the completion of an interim futility analysis. The trial is fully accrued, and the protocol amendment does not affect the conduct of the study.

Conference Call Details 

OncoGenex will host a webcast today, Wednesday, June 10, 2015, at 9:00 AM PT / 12:00 PM ET to recap key data presented at ASCO and discuss today's announcement. Access to this live event will be available on the Investor Relations section of the OncoGenex website at www.OncoGenex.com. Alternatively, the event 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.

About CustirsenCustirsen 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 in patients. 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.

Custirsen has Fast Track designation by the FDA for NSCLC and metastatic CRPC.

About OncoGenexOncoGenex 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 potential benefits and potential development of our product candidates and statements regarding our clinical trial plans and timelines. 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 do not demonstrate the hypothesized or expected benefits, the risk of delays in our expected clinical trials, the risk that the EMA does not approve our proposed amendments to our 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 our cash resources are insufficient to fund our planned activities for the time period expected 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.

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SOURCE OncoGenex Pharmaceuticals, Inc.