Phase 2 Trial of OGX-427 for Metastatic Castrate-Resistant Prostate Cancer
OncoGenex announced preliminary results from a Phase 2 study of OGX-427 in chemotherapy-naive patients with metastatic castrate-resistant prostate cancer (mCRPC). More patients treated with OGX-427 plus prednisone were without disease progression at 12 weeks versus those treated with prednisone alone. Additionally, there were greater declines in prostate-specific antigen (PSA) and circulating tumor cells (CTC) with OGX-427 plus prednisone treatment compared to prednisone alone.
In the first 32 patients randomized to the study, 17 patients received OGX-427 plus prednisone and 15 patients received prednisone alone. In the OGX-427 plus prednisone arm, 71% of patients were progression-free at 12 weeks, compared to 33% in the prednisone alone arm. Among patients who received OGX-427 plus prednisone, 76% experienced an overall decline in PSA compared to 53% in the prednisone alone arm.
Forty-one percent of patients who received OGX-427 plus prednisone experienced a >50% decline in PSA, versus 20% of patients who received prednisone alone. CTC declines from ≥5 to <5 occurred in 50% of patients receiving OGX-427 plus prednisone compared to 31% of those treated with prednisone alone. Among the 17 patients with baseline measurable disease, 38% of patients who received OGX-427 plus prednisone (n=8) had a partial response compared to 0% in the prednisone alone arm (n=9).
OGX-427 is a second-generation antisense drug that is designed to reduce production of Heat Shock Protein 27 (Hsp27), a cell-survival protein. Hsp27 is expressed in prostate cancer and a variety of other malignancies and can be induced by cell stress through chemotherapy, radiation therapy, and hormone therapy. Overexpression of Hsp27 confers broad resistance to commonly used anti-cancer therapies.
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