This pack of camels smokes cancer

Teensy nanobodies from camels have lots of tumour-fighting potential

By Brian Hoyle

Hair loss, fatigue, nausea... there's no doubt that chemotherapy is nasty. It's toxic not only to tumour cells but to the whole body. For a number of years, researchers have been trying to develop more targeted therapies, which zap the offensive cancer cells while sparing the rest of the body.

So far attention has been focused on antibodies produced against tumour cell-specific molecules. There are already 10 antibody-based medications available for use.

Unfortunately, conventional antibodies are pretty big beasts. This means that squeezing their way to tumour cells to close in on the kill can be a tricky proposition. In addition, their intricate structure complicates large-scale production. It's enough to make researchers wish that antibodies could somehow be simpler and smaller.

Somebody picked the right star to wish on because Hilde Revets and Patrick De Baetselier at the Flanders Interuniversity Institute for Biotechnology in Brussels, Belgium are experimenting with the use of teeny antibodies to smote tumours. These so-called 'nanobodies' exist in, of all places, the ships of the desert: camels.

The distinctiveness of camel antibodies was discovered serendipitously only three years ago. Keen medical researchers have been quick to spot their potential. Camel antibodies are really small � about one-tenth the size of a typical antibody. This is what allows them to penetrate more easily into a tumour. Further, their structure makes them very hardy and able to withstand the assaults of acidic pH and gastric enzymes in the gut. Finally, as an added bonus, the camel antibodies are easier to produce on a large scale.

When attached to an antitumour agent, nanobodies "are neither an antibody anymore nor a small chemical but something in between," said Dr Mark Vaeck, Chief Executive Officer of Ablynx, the company formed in 2001 to market the new technology. "[Their structure] allows us to go after specific targets that are inaccessible to conventional antibodies... and so in this way develop novel markets for therapeutics."

The researchers and their collaborators have already put together a roster of 16 different nanobody-based drugs directed against different targets. Two drugs, targeted towards inflammation and thrombosis, are in preclinical testing in animal models. If all pans out, they could be ready for phase II and III clinical trials in 2005.

Nanobodies have many potential applications, including the treatment of various cancers and inflammatory, heart and vascular diseases. These recent results are a step towards fully realizing the tumour-fighting potential of camel antibodies.