New Zealand scientists Bill Denny and Bill Wilson came up with an idea that not only resulted in a way to kill cancer while leaving healthy cells intact, but also provided the platform for multinational company Proacta.

Proacta’s science is founded on two underpinnings: prodrugs are inactive until they go through a metabolic conversion; and hypoxia (a lack of oxygen) affects tumours in approximately 65 percent of people diagnosed with cancer. Hypoxia results when tumours grow more quickly than their ability to develop blood vessels. Not only can oxygen not get through, but neither can chemotherapeutic drugs. That makes hypoxic regions particularly deadly and difficult to treat.

Chemist Denny and biochemist Wilson’s inspiration was based on using the lack of oxygen to switch on anti-cancer drugs. They came up with some extremely potent cytotoxic prodrugs that are activated when oxygen is absent (normal cells, because they are oxygen-rich, are spared the destructive effects of the treatment). The team then developed methods to introduce the drugs into the vessel-free hypoxic regions.

The result was Proacta’s lead compound, PR-104, which, in January 2006, entered into a Phase I study at Waikato Hospital in Hamilton, New Zealand, and at the Peter McCallum Cancer Centre in Melbourne, Australia.

In February 2007, Proacta announced that it had raised a further US$35m in funding, which will allow the company to take PR-104 through the next phase of clinical development and support the discovery and development of new compounds.

"Our motivation in founding Proacta was to provide a vehicle that would maximise ACSRC and more broadly New Zealand's participation in all aspects of the drug discovery and development process, and thus help build infrastructure locally. The new US funding is helping to make that a reality,” said Dr Wilson.

"While New Zealand investors maintain a sizeable holding in Proacta, we couldn't do what we are doing without US venture capital, and that's maximising the local opportunities both scientifically and clinically."

Proacta's San Francisco-based Chief Medical Officer and Senior Vice-President of Clinical Affairs, John Gutheil, has been impressed with the quality of clinical research in New Zealand.

"It would be fair to say that working in New Zealand is new for most US companies and I've been delighted with the standard of collaboration and working relationships.

"Drug discovery and development is an expensive and risky business requiring huge demands on time and resources.

"This would not have been possible without wide support from many organisations, including the Auckland Cancer Society and the Health Research Council of New Zealand. We look forward to commercialising a cancer treatment that was discovered in New Zealand," said Dr Gutheil.

The funding brings two new US life sciences venture capital firms to Proacta. Clarus Ventures, which led the round, and Delphi Ventures join existing investors Alta Partners (US), GBS Venture Partners (Australia) and New Zealand Venture Investment Fund-backed No 8 Ventures (NZ) and Endeavour iCap (NZ), as well as international pharmaceutical companies Genentech and Roche.

Proacta has also been supported with grants from TechNZ and the Australia New Zealand Biotechnology Partnership Fund administered by NZTE.

Economic Development Minister Hon Trevor Mallard said that the fact New Zealand science has attracted such significant funding from such high level US investors is an enormous endorsement of the calibre of our scientists.

"It shows New Zealand can take our biotechnology and medical science ideas and convert them into global success.

"It is also very satisfying to see that the public investment in Proacta, via the New Zealand Venture Investment Fund (NZVIF), is also paying off, with this strong endorsement by the international commercial community.”

Proacta Inc has its headquarters in San Diego, California,with a wholly-owned subsidiary, Proacta Therapeutics Ltd, in Auckland, New Zealand.

www.proactatherapeutics.com

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