DRUG: Xen2174
SOURCE: Cone snail
CONDITION: Severe pain
Divers beware 鈥� not all pretty seashells are harmless. Pick up one containing a live cone snail and it will defend itself with its sting. The result can be fatal. Nevertheless, venom researcher Richard Lewis and his team at the University of Queensland in Brisbane, Australia, seek out these creatures along the Great Barrier Reef. 鈥淭hey鈥檙e a challenge to get,鈥� he says. 鈥淒uring the day they hide, and you can turn hundreds of pieces of dead coral over before you find a cone snail.鈥�
It is worth the hunt. Cone snails are one of the youngsters of the venom world, developing their poisonous sting just a few tens of millions of years ago. As a result, their venoms are still an evolutionary work in progress. Members of the same species can deploy very different mixtures of chemicals. 鈥淓ven individuals collected from the same place may only have a 25 per cent overlap in the venoms they produce,鈥� says Lewis. That means they produce a vast array of potential medicines.
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Cone snail venom is providing a complementary hunting ground to the more traditional snake venom research. Whereas snake venoms tend to target the cardiovascular system, cone snails prefer to shut down the nervous system of their prey. This means they have great potential as pain medications.
鈥淐one snail venoms shut down the nervous system, making them potential painkillers鈥�
One cone snail venom compound discovered by Lewis and his team is about to go into phase II clinical trials. Code-named Xen2174, it works by boosting the signal along the body鈥檚 natural painkilling nerves that run along the spine. 鈥淚n our initial safety study, we tested the drug in over 30 people with severe cancer pain, and the compound was able to produce a really quite profound reversal of pain in many of these patients, an effect that could last for many days with a single injection into the spine,鈥� says Lewis. Buoyed by their success, the researchers are also starting to develop a painkilling venom-based compound to be given orally.
