One basketball-sized haul of sea squirts from Antarctica yields about one-thousandth of the toxin researchers need to test a possible melanoma drug. That is the figure that drives the next stage of the work.
Bill Baker, professor of chemistry at the University of South Florida, said his team needs “hundreds of milligrams to grams” of the compound. “Obviously we cannot collect 1,000 basketball quantities from the Antarctic – that would destroy the ecology – so one of the things we have to do is figure out how to make this stuff in the lab,” he said, according to The Guardian.
What the team found
Researchers from USF, the Desert Research Institute and the Scripps Institution of Oceanography recently came back from a six-week expedition to one of the remotest places on Earth. They collected ascidians, invertebrates known as sea squirts that live in the icy water. The animals produce toxins to protect themselves from predators, and Baker says those toxins can be “repurposed”.
Earlier work by his team showed that the compound killed melanoma cells in mice. Melanoma is the deadliest form of skin cancer. “The good news is it didn’t kill the mice,” Baker said. “It did kill their cancer, so we know it has the physiological properties to act like a drug.”
The trip also taught the group how the melanoma-killing bacterium lives inside the sea squirt and how the two relate ecologically. Baker said that knowledge will help when animal and human models begin, because the team will have “a much better idea of the things we can do and things we shouldn’t do” in using it as a drug.
Diving in Antarctica
Teams of divers went down to depths of up to 130ft for about half an hour at a time. The National Science Foundation funded the expedition. Ben Meister, a USF diving safety officer for the trip, said cold water was only one of the problems. “In Antarctica, you’re dealing with ice, leopard seals, changing seas and sometimes very limited visibility,” he said. “Every dive must be carefully planned to balance getting the work done while keeping everyone safe.”
The long road
The work now moves into laboratories, with some already under way through partnerships with the Desert Research Institute and Scripps. The team returned “exhausted”, Baker said, but keen to start. Part of that stage will be trying to reproduce the toxin synthetically.
Baker was careful about what comes next. A safe, effective drug approved for people would need a series of strictly regulated trials of growing size, even once a drug had been formulated. “We need grams of material to do a bigger study in mice, perhaps go into other animal models, and if we can prove the safety, we can actually start some human trials,” he said.
He began his career in marine biology and chemistry in 1990 and said that “more than half of Food and Drug Administration-approved drugs originate from natural sources”. He called the melanoma finding “sort of a career pinnacle”. “Killing cancer cells in a petri dish is one thing, but going beyond that is much harder,” he said.
The results so far come from mice, and no one has tested the compound in people. Anyone concerned about a skin change or a mole should consult their doctor.
