Oncothyreon Inc. announced enrollment of the first patient in a phase II trial of PX-866 in patients with recurrent or metastatic castration-resistant prostate cancer. PX-866 is a small molecule compound designed to inhibit the activity of phosphatidylinositol-3-kinase (PI-3K), a component of an important cell survival signalling pathway.

The open label phase II trial is being conducted by the NCIC Clinical Trials Group (NCIC CTG), Queen's University in Kingston, Canada.  The trial will enroll approximately 40 patients with castration-resistant prostate cancer who have received no prior chemotherapy. The primary endpoint of this single-arm screening trial is the proportion of patients with lack of disease progression at 12 weeks from the initiation of therapy with PX-866.

“We look forward to evaluating PX-866 in this group of prostate cancer patients who no longer respond to hormone therapy and for which new treatment agents are needed,” said Kim Chi, MD, co-chair of the NCIC CTG study. “We believe PX-866 is an interesting therapeutic target for evaluation given that deregulation of the PI3K pathway has been widely implicated in castration-resistant prostate cancer.”

“We appreciate the support and interest of the NCIC CTG in initiating the second single-agent Phase 2 clinical trial evaluating PX-866, our novel, irreversible PI-3K inhibitor,” said Robert L Kirkman, MD, president and CEO of Oncothyreon. “We now have four clinical trials of PX-866 underway, evaluating this agent in a variety of treatment settings and tumour types. We believe this broad phase II programme will provide significant information to guide later stage development of this product candidate.”

PX-866 is a pan inhibitor of the PI-3K/PTEN/AKT pathway, a critical cell signalling pathway that is activated in many types of human cancer. Aberrant activation and regulation of PI-3K is implicated in a large proportion of human cancers, where it leads to increased proliferation and inhibition of apoptosis (programmed cell death).

Oncothyreon is conducting a broad development programme of PX-866 as a single agent and in combination with other agents in multiple cancer types. Current trials include a phase I/II trial of PX-866 in combination with cetuximab (Erbitux) in patients with metastatic colorectal carcinoma or progressive, recurrent or metastatic squamous cell carcinoma of the head and neck (SCCHN) and a phase I/II trial of PX-866 in combination with the chemotherapeutic agent docetaxel in patients with locally advanced, recurrent or metastatic non-small cell lung cancer or SCCHN. In addition, the NCIC Clinical Trials Group is conducting two phase II trials, the trial in patients with recurrent or metastatic castration- resistant prostate cancer described above and a trial in patients with glioblastoma multiforme that has recurred during or following primary therapy.

The NCIC Clinical Trials Group (NCIC CTG) is a cancer clinical trials cooperative group that conducts phase I-III trials testing anti-cancer and supportive therapies across Canada and internationally. It is one of the national programmes and networks of the Canadian Cancer Society Research Institute (CCSRI), and is supported by the CCSRI with funds raised by the Canadian Cancer Society (CCS).  The NCIC CTG's Central Office is located at Queen's University in Kingston, Ontario, Canada.

Oncothyreon is a biotechnology company specializing in the development of innovative therapeutic products for the treatment of cancer.