BioWorld International Correspondent

Algeta ASA raised €23 million (US$28.8 million) in a Series A funding to continue development of its lead product, Alpharadin, a cancer therapeutic based on radium-223 (Ra-223), which is undergoing Phase II studies in skeletal metastases arising from prostate cancer.

The Oslo, Norway-based firm, founded in 1997 as Anti-Cancer Therapeutic Inventions AS, previously raised €8 million, CEO Thomas Ramdahl told BioWorld International, but called the new funding a Series A round because it represents the company's first international investment.

New investors include Stockholm, Sweden-based HealthCap; London-based Advent Venture Partners; and SR One, of West Conshohocken, Pa., a subsidiary of London-based GlaxoSmithKline plc. Existing investors Selvaag Venture Capital, NorgesInvestor, Marlin Verdi AS and several smaller investors also participated.

Algeta is attempting to establish alpha radiation as a new option in cancer treatment - existing radiotherapy is based on beta emitters. Ramdahl says there has been a 20-year academic research effort focused on alpha radiation-emitting radioisotopes such as actinium-225, astatine-211, bismuth-212 and bismuth-213. However, none have been commercially feasible.

"They have been very difficult to scale up and get a hold of," he said. Some have half-lives that are impractical for use in clinical settings, while attempts to conjugate alpha emitters to tumor-targeting monoclonal antibodies have been "a blind alley," he said.

Algeta has established a production system in-house for Ra-223, which has a half-life of 11.4 days. The isotope cannot easily bind to an antibody, Ramdahl said, but it has a natural, built-in targeting mechanism as it homes to actively dividing bone tissue. As it is an alpha emitter, it penetrates tissue less deeply than the beta emitters that are being used in radiotherapy. That allows high doses of radiation to be delivered to bone surface and skeletal metastases, he said, without risk of causing bone marrow damage. The company has a use patent on the application of Ra-223 in skeletal metastases. "That patent has been issued in the U.S.," Ramdahl said.

In a Phase I trial of Alpharadin, company researchers and colleagues reported a mean reduction of the biomarker serum alkaline phosphatase of 52.1 percent in 15 men with prostate cancer. In 10 women with breast cancer, the mean reduction was 29.5 percent. Reductions in pain were reported for both groups. The full data were reported in the June 15, 2005, issue of Clinical Cancer Research in a paper titled "First Clinical Experience with Alpha-Emitting Radium-223 in the Treatment of Skeletal Metastases."

Recruitment for a Phase II trial evaluating Alpharadin in 64 men has been completed, Ramdahl said, while enrollment for a dose-finding, pain palliation study involving 100 subjects is under way. The company aims to move the program into pivotal trials by 2007 or 2008. It has not yet decided on partnering plans.

The new funding also will enable Algeta to continue its preclinical programs. OC-3, which is in development for ovarian cancer, comprises the alpha emitter lead-212 encapsulated in an undisclosed biodegradable material. RV-1, in development for gynecological cancers and soft-tissue tumors, is based on Ra-223 encapsulated in a liposome carrier. TH-1 involves the use of thorium-227 conjugated to a targeting antibody.

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