BioWorld International Correspondent

LONDON - Onyvax Ltd. raised £8 million (US$15.1 million) from existing investors in a third-round funding that will enable the company to commence a Phase IIb study of its prostate cancer vaccine.

"We have been talking about the round for a while: We are pleased that we have completed it and that all the investors followed on," CEO Anthony Walker told BioWorld International.

The round was co-led by 3i plc and SR One, with funds from Barrie Haigh, Merlin Biosciences, MB Venture Capital Fund 1 NV, Alta Berkley Venture Partners and Alberville Ltd.

The Phase IIb trial of Onyvax-P will begin later this year. Seventy-five patients will be recruited at centers in the UK and Eastern Europe. Walker said it will take six months to recruit the patients, with the first results due six months after that and full results 12 months after recruitment closes.

Walker said that "nothing is set in stone" in terms of onward development once the trial is completed. "We are starting up 12 to 16 centers with this Phase IIb trial, which is more than we need to get 75 patients. This will lay the groundwork, if we decide to do the pivotal trial of 300 to 500 patients, which we could manage ourselves."

Onyvax-P comprises a mixture of cancer antigens derived from different stages in the development of prostate tumors. In the Phase II proof-of-principle study, in patients who had failed hormone therapy, the median progression-free survival was 58 weeks, compared to 26 to 29 weeks in historical controls. Forty-two percent of patients experienced a prolonged, statistically significant reduction is prostate specific antigen velocity, which is a predictor of overall survival.

In addition, patients who had a slowing in the progression of disease exhibited evidence of an immunological response, including T-cell proliferation and enhanced cytokine responses. Treatment was well tolerated with minimal side effects.

Onyvax's second product, Onyvax-O, for ovarian cancer, is based on antigens licensed from the Mayo Clinic. The company recently reached an agreement with Eden Biodesign Ltd. to develop a GMP manufacturing process for the vaccine, and was awarded £2.7 million for the work through the UK's new National Biomanufacturing Centre. Walker said he expects it to be two years before the product is ready for clinical testing.

Investigator-led trials of Onyvax-105, a human monoclonal antibody that induces immune responses against CD55, a target found on many tumors, are ongoing in colorectal cancer and pediatric osteosarcoma.

Walker said the funding round would last two to three years, depending on how the clinical expenditure ramps up. All options are open on fund raising beyond that point. "Our job is to make sure we add value to the project, and we hope to be in the position of choosing between different options at the time," he said.