By Phil Mercer
BBC News, Sydney
Some shark antibodies can survive the harsh environment of the human gut
Australian scientists have found that antibodies in shark blood could potentially be a potent weapon in the fight against cancer.
Sharks have immune systems similar to humans, but their antibodies - the molecules which actually fight disease - are exceptionally resilient.
Researchers believe this quality could be harnessed to help slow the spread of diseases such as cancer.
Potentially, it could lead to a new generation of drug treatments.
The Australian team found that shark antibodies can withstand high temperatures as well as extremely acidic or alkaline conditions.
This means they would potentially be able to survive in the harsh environment of the human gut, which is crucial to the development of a cancer-fighting pill.
Associate Prof Mick Foley from Melbourne's La Trobe University said the shark molecules can also attach themselves to cancer cells and stop them spreading.
"The cells actually grow less than where we don't add a shark antibody or we add a completely irrelevant shark antibody," he said.
"So this indicates the shark antibody that we have is binding to those cancer cells and for some reason causing them to grow more slowly and perhaps even killing them."
Sharks were chosen for the project because they have robust immune systems and rarely succumb to infections.
There is already evidence that their antibodies can slow the spread of breast cancer.
But it is also hoped that they could eventually be used to treat other conditions, such as malaria and rheumatoid arthritis.