KEY POINTS:
New Zealand scientists have won overseas backing to expand trials of an experimental cancer drug that fights a variety of advanced tumours.
The $51.5 million cash injection from United States investors will allow New Zealand trials to expand beyond the current 12 Waikato Hospital participants, to include about
20 new people selected by Auckland University professors.
Human testing of the drug PR-104 began at Waikato Hospital a year ago, complemented by other trials done in Melbourne and California.
The drug could be released globally within the next five years if progress goes to plan.
The men behind the compound's development are Auckland professors Bill Denning and Bill Wilson, who are the founding scientists of drug company Proacta.
The pair have researched the behaviour of tumours and new ways of treating core cancer cells for the past 20 years.
The groundbreaking drug they have created is described as "a unique anticancer drug that is converted to a DNA-damaging agent in the hypoxic [oxygen deficient] regions of tumours."
Until now, the drug's development has been supported by $12.7 million in venture capital.
But overnight Proacta chief executive Paul Cossum said that a further $51.5 million had been raised, which would ensure the drug was taken to the next phase of clinical development.
Another benefit of the extra money would be the chance to discover and develop other new compounds, he said.
Dr Michael Jameson, medical oncology specialist at Waikato Hospital, has been overseeing patients in the New Zealand-based trials.
He told the Herald that participants included people for whom other treatments were no longer having an effect and whose cancers were at an advanced stage.
Triallists had a variety of cancer types, such as bowel, stomach, pancreatic and lung.
To date, the point of the testing had been to get dosages correct, although "slim chances" of benefits were offered to patients, Dr Jameson said.
"The drug appears to be better tolerated than many chemotherapy drugs. Several patients on a particularly higher dosage felt better and the symptoms have improved. There are two or three people whose tumours have clearly shrunken a bit, but not dramatically."
Although results were encouraging, Dr Jameson warned there was a long way to go before a possible global release in about five years' time.
"The hints are there that [the drug] is active, but by itself it's not going to knock off a tumour."
However, combining the drug with chemotherapy would make for a "very potent combination" and he was excited at the prospect of the new phase in testing.
One advantage of PR-104 is that it does not "activate" until it reaches certain enzymes inside tumours, thereby localising the drug's effect on the human body.
The research and trials aim to exploit the abnormality of blood supply in tumours as a basis for treatment.
Relapse of previously treated cancer is thought to be often due to the ability of cancer cells in hypoxic regions to survive existing treatments such as chemotherapy.
Professor Wilson said the company was reliant on United States-based investment.
"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."
"It means we can submit an Investigational New Drug application to the Food and Drug Administration for clinical development of a second compound."
Economic Development Minister Trevor Mallard said the capital injection was a major international endorsement of the work New Zealand scientists and oncologists were doing.
"It shows New Zealand can take our biotechnology and medical science ideas and convert them into global success."
