Oncogenex Presented Study Showing Preliminary Results for Phase II Trial of OGX-011 in Advanced Prostate Cancer
OncoGenex Technologies Inc. and Isis Pharmaceuticals, Inc. announced preliminary data from a Phase II clinical trial of OGX-011 in combination with docetaxel and prednisone in patients with metastatic hormone refractory prostate cancer (HRPC). Data were presented by Dr. Kim Chi, Study Chair and a medical oncologist at BC Cancer Agency - Vancouver Centre, representing the National Cancer Institute of Canada - clinical trials Group at the Annual Meeting of the American Society of Clinical oncology (ASCO) in Chicago.
Eighty-one patients with metastatic or locally recurrent prostate cancer refractory to hormone therapy were randomized to one of two treatment arms to receive either 640 mg OGX-011 per week in combination with docetaxel and prednisone or docetaxel and prednisone alone. As of May 14, 2007 all 81 patients had been followed for a minimum of 4.8 months. Currently, 22 percent of patients are still receiving study treatment and all patients continue to be followed.
The median duration of progression-free survival was 7.3 months in patients who received OGX-011 plus docetaxel and 5.8 months in patients who received docetaxel. Disease progression occurred in fewer patients who received OGX-011 plus docetaxel: Progressive measurable disease as the best response occurred in 4 percent of patients in the OGX-011 plus docetaxel arm and in 22 percent of patients in the docetaxel arm. PSA progression as the best response occurred in no patients in the OGX-011 plus docetaxel arm and in 10 percent of patients in the docetaxel arm. While response rates for both measurable disease and PSA assessments in the study arms were similar, disease stabilization, by both assessments, occurred in more patients in the OGX-011 plus docetaxel arm. The primary endpoint of PSA response was seen in 20 of 40 patients who received OGX-011 plus docetaxel. This number of responses met the criterion for declaring this combination of interest to explore further. PSA response was seen in 21 of 40 patients who received docetaxel, indicating this arm also met the same criterion.
OGX-011 is designed to specifically inhibit the production of the cell-survival protein, clusterin. Clusterin production is associated with treatment resistance in many cancers and in response to various cancer treatments, including hormone ablation therapy, chemotherapy and radiation therapy. Preclinical studies have shown that inhibition of clusterin can disable the tumor cell's adaptive defences, render the tumor cells susceptible to attack with a variety of cancer therapies, including chemotherapy, and facilitate tumor-cell death. OncoGenex and Isis are collaborating on development of OGX-011, which is the subject of five ongoing Phase II studies evaluating the safety and activity of OGX-011 in patients with prostate cancer, non-small cell lung cancer and breast cancer.
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