OncoGenex reports that low serum clusterin levels were predictive of survival in preliminary analyses of Phase 2 study of lead drug candidate OGX-011

    Encouraging survival duration continues with OGX-011 plus second-line
    chemotherapy for the treatment of prostate cancer;

    Data presented at the 2008 Annual Meeting of the American Society of
    Clinical Oncology

    VANCOUVER, June 2 /CNW/ - OncoGenex Technologies Inc. announced today
that the Company's lead cancer drug candidate, OGX-011, continues to show
better than expected survival results in patients with hormone refractory
prostate cancer (HRPC) when compared to published results. OGX-011, also
referred to as custirsen sodium, is a second-generation antisense
oligonucleotide designed to facilitate tumor cell death induced by
chemotherapy by decreasing production of clusterin, a cell survival protein
linked to treatment resistance. Preliminary analyses have shown that low-
average levels of serum clusterin were predictive of the survival benefit.
Additionally, patients treated with second-line chemotherapy plus OGX-011
experienced a reduction in pain that was durable as well as a decline in PSA.
These data were presented by Dr. Fred Saad, Professor of Surgery/Urology at
the University of Montreal, on June 1 at the 2008 Annual Meeting of the
American Society of Clinical Oncology. OncoGenex and Isis Pharmaceuticals,
Inc. (NASDAQ:   ISIS) are collaborating on development of OGX-011.
    The Phase 2 study evaluated 42 patients: 22 patients were treated with
mitoxantrone plus OGX-011 and 20 patients with docetaxel plus OGX-011. While
follow up on surviving patients is still ongoing, the following preliminary
findings were reported:

    -   Survival continued to be better than expected based on previously
        published reports: With a median follow-up of 17.2 months following
        the start of second-line chemotherapy, approximately 38% of the
        42 patients remain alive with a median survival of 12.1 months.
        Median survival has been estimated at 11.4 months in the mitoxantrone
        plus OGX-011 group and 14.7 months in the docetaxel plus OGX-011
        group. These data compare favorably with published results reporting
        median survivals at approximately 10 months for HRPC patients
        receiving second-line chemotherapy.

    -   Post-treatment serum clusterin levels were lower compared to baseline
        levels and the average serum clusterin levels were predictive of
        survival in preliminary analyses: Comparison of baseline serum
        clusterin levels to the post-treatment average levels showed a
        significant reduction (p (less than) 0.0001). In addition, average
        serum clusterin levels were predictive of survival, with low-average
        levels predicting median survival time of 14.7 months compared to
        high-average levels predicting median survival time of 5.5 months.
        These data suggest that a reduction in clusterin levels may improve

    -   Durable reductions in pain or analgesic use were achieved in patients
        who entered the study with pain: Reductions in pain or analgesic use
        were seen in 46% of evaluable patients treated with mitoxantrone plus
        OGX-011 with a median duration of 5.8 months and in 61% of evaluable
        patients retreated with docetaxel plus OGX-011 with a median duration
        of 6.2 months. These data are better than expected when compared to
        the 22-35% of patients receiving first-line chemotherapy who reported
        a reduction in pain in the primary Phase 3 study resulting in the
        approval of docetaxel (TAX 327 study) that was published in the
        October 7th, 2004 issue of the New England Journal of Medicine.

    -   Both treatment groups achieved PSA declines of at least 50%: 27% of
        patients treated with mitoxantrone plus OGX-011 achieved at least a
        50% PSA decline; 40% of patients treated with docetaxel plus OGX-011
        also achieved at least a 50% PSA decline. Decreasing PSA levels are
        used by physicians as a measure of a patient's response to therapy in
        prostate cancer.

    -   More chemotherapy than expected was safely administered to and
        tolerated by patients when OGX-011 was combined with second-line
        chemotherapy: Patients received a median of 6 cycles of mitoxantrone
        plus OGX-011 or 8 cycles of docetaxel plus OGX-011 as second-line
        chemotherapy. These data compare favorably with published results
        where the median number of cycles that could be administered for
        second-line chemotherapy alone was 3 to 4 cycles. Thus OGX-011
        treatment was well tolerated and allowed administration of more
        chemotherapy for longer treatment duration of metastatic HRPC.

    This Phase 2 study was designed as an open-label, randomized, multicenter
study evaluating weekly administration of OGX-011 in combination with
second-line chemotherapy in patients with metastatic hormone refractory
prostate cancer who were previously treated with a minimum of 2 cycles of
docetaxel-based first-line chemotherapy. Patients in this study represented a
poor prognostic population due to rapid disease progression during or within
6 months of completion of first-line docetaxel therapy, with a median of
0.7 months in the OGX-011 plus mitoxantrone treated group and 1.8 months in
the OGX-011 plus docetaxel retreatment group. Because OGX-011 has been shown
to enhance chemotherapy and reverse chemotherapy resistance in preclinical in
vitro and in vivo models, the primary objective of this study was to assess
the safety and tolerability of OGX-011 in combination with either mitoxantrone
or docetaxel retreatment as second-line chemotherapy. The secondary objectives
were to determine the efficacy of OGX-011 in combination with second-line
chemotherapy in terms of PSA response, pain progression and survival as well
as exploring the relationship between serum clusterin levels with those
parameters. Registration studies are planned utilizing chemotherapy plus
OGX-011 as second-line therapy in patients whose disease is progressing after
a first-line docetaxel regimen.
    "These data showed that low serum clusterin levels were predictive of
survival," said Dr. Fred Saad, who is also the primary investigator in the
study. "The data also suggests that the combination of OGX-011 with docetaxel
or mitoxantrone may improve survival outcomes and may lead to durable pain
palliation in second-line prostate cancer. Survival and durable pain
palliation are key endpoints for planned clinical trials that will lead to the
approval of new therapeutic alternatives."

    About OGX-011

    OGX-011 is designed to block production of clusterin, a cell survival
protein that is over-produced in several cancer indications and in response to
many cancer treatments, including hormone ablation therapy, chemotherapy and
radiation therapy. Increased clusterin production is observed in many human
cancers, including prostate, non-small cell lung, breast, ovarian, bladder,
renal, pancreatic, anaplastic large cell lymphoma and colon cancers and
melanoma. Increased clusterin production is linked to faster rates of cancer
progression, treatment resistance and shorter survival duration. Clusterin
levels may be further increased in response to standard cancer therapies,
including hormone ablation therapy, chemotherapy and radiation therapy.
Clusterin expression is linked to disease progression, treatment resistance,
poor prognosis and survival in scientific publications. For example, increased
expression of clusterin in prostate cancer is closely correlated with
increasing Gleason score, which is a strong prognostic factor for poor
survival of patients with prostate cancer.

    About OncoGenex

    OncoGenex is a private biopharmaceutical company committed to the
development and commercialization of new cancer therapies that address
treatment resistance in cancer patients. The company's three product
candidates are designed to inhibit the production of specific proteins
associated with treatment resistance and which are over-produced in response
to a variety of cancer treatments. OGX-011 is completing evaluation in five
Phase 2 clinical studies in prostate, lung, and breast cancers. OGX-427 has
begun evaluation in Phase 1 clinical studies, while the third product
candidate, OGX-225, has completed preclinical pharmacology studies. More
information is available at www.oncogenex.ca.

    Definitive Agreement to Merge

    On May 28, 2008, Sonus Pharmaceuticals, Inc. (NASDAQ:   SNUS) and OncoGenex
Technologies Inc., jointly announced the signing of a definitive agreement to
merge the two companies. The combined company will operate as OncoGenex
Pharmaceuticals, Inc. The proposed transaction received unanimous approval
from the Boards of Directors of Sonus and OncoGenex, and is expected to be
completed in the third quarter of 2008, subject to regulatory approval, the
approval of Sonus' and OncoGenex' shareholders and in the case of OncoGenex,
court approval under the arrangement provisions of the Canada Business
Corporations Act.

    Safe Harbor

    This press release contains forward-looking statements, including
statements concerning clinical trial results and the proposed merger between
Sonus and OncoGenex. 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. All statements other than
statements of historical fact are statements that could be deemed
forward-looking statements. For example, statements of the results of clinical
studies, the timing of clinical trials and development efforts and the timing
of closing the proposed merger are all forward-looking statements. The
potential risks and uncertainties include, among others, that clinical results
will not be maintained in final data analysis, that current or future clinical
trials will not be successful or confirm the results of earlier studies, risks
related to the timing and costs of clinical trials and regulatory approvals,
risks associated with obtaining funding from third parties or completing a
financing necessary to support the costs and expenses of clinical studies,
risks relating to the development, safety and efficacy of therapeutic drugs
and potential applications for these products and the possibility that the
merger with Sonus does not close or that the closing may be delayed. No
assurances can be given that any of the events anticipated by the
forward-looking statements will transpire or occur, or if any of them do so,
what impact they will have on the results of operations or financial condition
of OncoGenex. The Company undertakes no obligation to update the
forward-looking statements contained herein or to reflect events or
circumstances occurring after the date hereof.

    Proxy Solicitation

    In connection with the proposed merger, Sonus intends to file with the
SEC a Proxy Statement and related materials and to mail to its stockholders
the final Proxy Statement containing information about Sonus, OncoGenex and
    Sonus and OncoGenex, and certain of their directors, executive officers
and other members of management and employees may be deemed to be participants
in the solicitation of proxies in connection with the proposed transaction.
Information about the directors and executive officers of Sonus, including
their respective security holdings, is set forth in Sonus' Amendment No. 1 to
Form 10-K for the fiscal year ended December 31, 2007, filed with the
Securities and Exchange Commission on April 29, 2008. As of May 27, 2008,
OncoGenex' directors and executive officers beneficially owned approximately
1,755,000 shares, or 14.5%, of OncoGenex' capital stock. Investors may obtain
additional information regarding the interests of OncoGenex, Sonus and their
respective executive officers and directors in the merger by reading the Proxy
Statement for such proposed transaction when it becomes available.
    The Proxy Statement and other relevant materials, when they become
available, and any other documents filed by Sonus with the SEC, may be
obtained free of charge at the SEC's web site at www.sec.gov. In addition,
investors and security holders may obtain free copies of the documents, when
they are available, filed with the SEC by Sonus by directing a request to:
Sonus Pharmaceuticals, Inc., 1522 217th Place SE, Suite 100, Bothell, WA
98021, Phone (425) 686-1500, Fax (425) 686-1600, Attention: Investor

For further information:

For further information: OncoGenex Media and Investor Contact: Jason I.
Spark, Porter Novelli Life Sciences, (619) 849-6005,

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