Results of custirsen Phase 2 trial for advanced prostate cancer published in Journal of Clinical Oncology

Sep 22 2010

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

OncoGenex Pharmaceuticals, Inc. (NASDAQ: OGXI) announced today publication of results from a randomized Phase 2 trial in the Journal of Clinical Oncology. The trial results showed a survival benefit with the investigational agent OGX-011/TV1011 (custirsen) in patients with advanced prostate cancer. The median overall survival for patients who were treated with custirsen plus first-line docetaxel/prednisone was 23.8 months compared to 16.9 months for patients treated with docetaxel/prednisone alone. The manuscript was published in the September 20, 2010 issue of the journal.

"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."

The study investigators concluded custirsen in combination with docetaxel was well tolerated. Furthermore, they noted that adverse events associated with custirsen, including lymphopenia, rigors and fever have been reported with other antisense therapeutics.

Analysis of trial results also showed:

- The observed survival benefit was attributed to the custirsen treatment rather than duration of docetaxel treatment or administration of subsequent therapies; - Fewer patients 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); - Statistically significant declines in serum clusterin levels occurred within the first cycle of custirsen treatment when compared to levels in the docetaxel arm, indicating on-target biological activity of custirsen; - Measurable stable disease was higher (77% in custirsen plus docetaxel arm versus 50% in docetaxel arm) and disease progression, without any response to therapy, was lower (4% in custirsen plus docetaxel arm versus 17% in docetaxel arm). The incidence of overall objective response was comparable; - Because the primary endpoint of the study was achieved and survival benefit was observed, custirsen warrants further study in Phase 3 trials.

"Despite the number of new treatment options for patients with advanced prostate cancer, many patients will eventually experience disease progression. We believe 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.

In 2009, Teva Pharmaceutical Industries Ltd. and OncoGenex Pharmaceuticals, Inc. entered into a global license and collaboration agreement to develop and commercialize custirsen.