Adding a third clinical-stage drug to its oncology pipeline, Cougar Biotechnology Inc. licensed seocalcitol, a synthetic vitamin D analogue, from Danish company LEO Pharma A/S to develop in prostate cancer.

The deal calls for Cougar to pay an undisclosed licensing fee, as well as milestone and royalty payments to LEO Pharma. In exchange, the privately held Los Angeles-based company gains a product that has shown a great deal of promise in several preclinical and clinical studies, said Alan Auerbach, president and CEO of Cougar.

"The role of vitamin D [1-alpha, 25(OH2)D3] in the treatment of cancer has been extensively studied," he said. Data from one of those studies were presented just last month by another firm at the American Society of Clinical Oncology meeting in Orlando, Fla. That study evaluated calcitriol, the metabolite of vitamin D, in combination with chemotherapy for advanced prostate cancer patients.

"The group that got chemotherapy plus calcitriol had a statistically significant increase in their median survival over the patients that just received chemotherapy," Auerbach said.

During the ASCO conference, South San Francisco-based Novacea Inc. presented results from the 250-patient ASCENT (AIPC Study of Calcitriol-Enhancing Taxotere) study of its DN-101 plus Taxotere vs. Taxotere alone. Data showed that DN-101 plus Taxotere resulted in improved survival without adding toxicity, although the primary endpoint of prostate-specific antigen response was not statistically significant. (See BioWorld Today, May 17, 2005.)

As an analogue of vitamin D, seocalcitol has shown in preclinical models to "be a much more potent anticancer drug than calcitriol," Auerbach told BioWorld Today, due to an "intensification of all the mechanisms of vitamin D," which include differentiation-inducing activities and anti-proliferation, as well the ability to induce apoptosis.

In all of those mechanisms of action, analogues have shown a tendency to have a higher degree of activity than vitamin D itself, he added.

The analogue also negates some of the limitations researchers have faced with the naturally occurring vitamin D, specifically the risk of hypercalcemia.

Because of the amount of Phase I data generated from seocalcitol, Auerbach said Cougar likely will begin with Phase II trials in prostate cancer. There already is an investigational new drug application on file for seocalcitol.

"We have a strong advisory board in the prostate cancer area, so we'll be consulting them before embarking [on clinical studies] to find the best strategy to take," he said.

Auerbach, who spent six years as a biotech analyst for Wall Street, founded Cougar in May 2003 with the help of a New York venture capital firm. The goal was to license clinical-stage drugs for further development, a strategy that allows Cougar to avoid some of the early stage safety issues.

The addition of seocalcitol gives Cougar two investigational products for prostate cancer. The company recently completed a Phase I study of CB7630 (abiraterone acetate), a drug licensed from BTG, of West Conshohocken, Pa. in April.

Cougar licensed a noscapine portfolio from Emory University in June, and has an ongoing Phase I trial of CB3304 in non-Hodgkin's lymphoma. Preclinical studies are investigating noscapine as an extended-release product and as an analogue.

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