Shark antibodies show potential as lifesaver from cancer

Oct 14 2008

Australian scientists have discovered a potentially potent weapon in the fight against cancer in antibodies taken from shark blood.

The researchers at Melbourne's La Trobe University are pioneering an unconventional new technology that uses modified shark antibodies in therapeutic interventions against disease.

They say sharks have immune systems which are similar to humans, but their antibodies, the molecules which actually fight disease, are exceptionally resilient - they believe this quality could be harnessed to help slow the spread of diseases such as cancer and lead to a new generation of drug treatments.

The Australian team discovered that shark antibodies are able to withstand high temperatures as well as extremely acidic or alkaline conditions and are possibly able to survive in the harsh environment of the human gut, which is crucial to the development of cancer-fighting drugs.

Associate Professor Mick Foley says the shark molecules can also attach themselves to cancer cells and stop them spreading and also inhibit their growth.

Professor Foley says the cells actually grow less than when a shark antibody is not added - the shark antibody binds to cancer cells and for some reason causes them to grow more slowly and possibly even kills them.

Sharks were chosen for the project because they have robust immune systems and rarely succumb to infections and there is already evidence that their antibodies can slow the spread of breast cancer.

The process involves taking genes from sharks and modifying them in a laboratory by adding proteins that cause random mutations, which mimics the way the human immune system works, developing antibodies capable of a repertoire of defensive responses.

According to the scientists, because shark antibodies are much smaller, chemically more robust and biologically more stable than conventional antibodies, they are uniquely well suited for targeted therapy - raising the prospect of new therapies that can be taken orally instead of injected.

The researchers say besides giving sharks a better press in their new role as lifesavers, the technology offers prospects for new and better therapies against such human diseases as malaria, cancers and rheumatoid arthritis.

Professor Mick Foley, an international leader in malarial research, and his CSIRO colleague Dr. Stewart Nuttall, have built the world's first 'library' of disease-targeting antibodies based on modified shark antibodies, which they say is a "library of potential new therapies in a test-tube".

The scientists are not the first to recognise the potential of shark antibodies as a new line of defence against disease, but existing technologies require shark handlers immunising the shark and letting the shark develop the antibodies.

This technology uses the shark blood, has been patented and promises to be the next generation of antibody-based diagnostic and therapeutic treatments.

According to the scientists shark antibodies are also highly effective in killing malarial parasites in vitro, through a unique protein-binding process that blocks molecular function.

The La Trobe scientists have conducted many studies showing that if a shark antibody selected from the library binds to a malaria protein and is then put into a malaria parasite in culture, it kills the parasite.

Recognition of the therapeutic potential of shark antibodies however means other biotechnology companies are also working on this topic.

Professor Foley says the aim is to use these shark antibodies as a way of finding high-affinity binding agents to bind to anything they want - such as a molecule on cancer cells, or inflammatory proteins that can then be used in therapy.