OncoGenex Pharmaceuticals, Inc. (NASDAQ: OGXI) announced the publication of results from their randomized Phase 2 trial of custirsen for men with advanced prostate cancer in the September 20, 2010 Journal of Clinical Oncology.

According to their announcement, the trial results showed a survival benefit with their investigational agent OGX-011/TV1011 (custirsen) in men with advanced prostate cancer.  The median overall survival for men who were treated with custirsen plus first-line docetaxel plus prednisone was 23.8 months compared to 16.9 months for men treated with docetaxelplus prednisone alone, the current standard of care.  This is almost a seven month increase in life extension.

In addition to the survival benefit, the study investigators concluded custirsen in combination with docetaxel was well tolerated by the men.

Analysis of trial results also showed:

1-          The observed survival benefit was attributed to the custirsen treatment rather than duration of docetaxel treatment or administration of subsequent therapies;

2-           Fewer men discontinued study therapy because of disease progression when custirsen was given (18% in custirsen plus docetaxel arm versus 39% in docetaxel arm), resulting in a greater number of treatment cycles administered (median of 9 cycles in custirsen plus docetaxel arm versus 7 cycles in docetaxel arm);

3-          Statistically significant declines in serum custirsen levels occurred within the first cycle of  custirsen treatment when compared to levels in the docetaxel arm, indicating on-target biological activity of custirsen;

4-           Measurable stable disease was higher (77% in custirsen plus docetaxel arm versus 50% in the docetaxel  arm) and disease progression, without any response to therapy, was lower (4% in custirsen plus docetaxel arm versus 17% in the docetaxel arm). The incidence of overall objective response was comparable;

5-           Because the primary endpoint of the study was achieved and survival benefit was observed, custirsen warrants further study in Phase 3 trials.

“Custirsen has the potential to reduce treatment resistance thereby increasing the efficacy  of various therapeutic agents such as docetaxel, and are hopeful this will be confirmed through the Phase 3 development program,” said Scott Cormack, president and CEO of OncoGenex.

“The survival analysis provides a strong suggestion of clinical benefit with a hazard ratio consistent with a 50% reduction in the rate of death favoring custirsen treatment,” said Dr. Kim Chi, Principal Investigator and medical oncologist at BC Cancer Agency. “These data provide the foundation and rationale for the upcoming SYNERGY Phase 3 trial evaluating custirsen in approximately 800 men with metastatic CRPC.”

Randomized Phase 2 Study of  Docetaxel and Prednisone With or Without OGX-011 in Patients With Metastatic Castration-Resistant Prostate Cancer. Chi K.N., et al. JCO Sep 20, 2010: 4247-4254

Joel T Nowak, M.A., M.S.W.