Some send divers in speed boats, others dispatch submersible robots to search the seafloor and one team deploys a “mud missile” — all tools used by scientists to scour the world’s oceans for finding the next potent cancer treatment or antibiotic.
A medicinal molecule could be found in microbes scooped up in sediment, be produced by porous sponges or sea squirts — barrel-bodied creatures that cling to rocks or the undersides of boats — or by bacteria living symbiotically in a snail.
But once a compound reveals potential for treatment of, say, Alzheimer’s or epilepsy, developing it into a drug typically takes a decade or more, and costs hundreds of millions of dollars.
“Suppose you want to cure cancer — how do you know what to study?” said William Fenical, a professor at Scripps Institution of Oceanography, USA, considered a pioneer in the hunt for marine- derived medicines.
“You don’t.”
With tight budgets and little support from big pharma, scientists often rely on other research expeditions.
Marcel Jaspars of University of Aberdeen, Scotland, said colleagues collect samples by dropping a large metal tube on a 5,000 metre (16,400 feet) cable that “rams” the seafloor. However, a more sophisticated method uses small, remotely operated underwater vehicles.
“I say to people, all I really want is a tube of mud,” he told AFP.
This small but innovative area of marine exploration is in the spotlight at crucial UN high seas treaty negotiations, covering waters beyond national jurisdiction, which could wrap up this week with new rules governing marine protected areas which are crucial for protecting biodiversity.
Nations have long tussled over how to share benefits from marine genetic resources in the open ocean — including compounds used in medicines, bioplastics and food stabilisers, said Daniel Kachelriess, a High Seas Alliance co-lead on the issue at the negotiations.
And yet only a small number of products with marine genetic resources find their way onto the market, with just seven recorded in 2019, he said. The value of potential royalties has been estimated at $10 million to $30 million a year.
However, the huge biological diversity of the oceans means that there is likely much more to be discovered.
“The more we look, the more we find,” said Jaspars, whose lab specialises in compounds originating from the world’s extreme environments (like underwater hydrothermal vents and polar regions).
Natural origins
Since Alexander Fleming discovered a bacteria-repelling mould he called penicillin in 1928, researchers have studied and synthesised chemical compounds made mostly by land-based plants, animals, insects and microbes to treat human diseases.
“The vast majority of the antibiotics and anti-cancer drugs come from natural sources,” Fenical told AFP, adding that when he started out in 1973, people were sceptical that the oceans had something to offer.
In an early breakthrough in the mid-1980s, Fenical and his colleagues discovered a type of sea whip — a soft coral — growing on reefs in the Bahamas that produced a molecule with anti-inflammatory properties.
It caught the eye of cosmetics firm Estee Lauder, which helped to develop it for use in its product at the time.
But the quantities of sea whips needed to research and market the compound eventually led Fenical to abandon marine animals and focus on microorganisms instead.
Researchers collect sediment from the ocean floor and then grow the microbes they find in the lab.
In 1991, Fenical and his colleagues found a previously unknown marine bacterium called Salinispora in the mud off the coast of Bahamas.
Over a decade of work yielded two anti-cancer drugs, one for lung cancer and the other  for the untreatable brain tumor, glioblastoma. Both of them are in the final stages of clinical trials.
Fenical, 81, who still runs a lab at Scripps, said researchers were thrilled to have got this far, but the excitement is tempered by caution.
“You never know if something is going to be really good or not useful at all,” he said.
New frontiers for drug development
That long pipeline is no surprise to Carmen Cuevas Marchante, head of research and development at the Spanish biotech firm PharmaMar.
For their first drug, they started out by cultivating and collecting about 300 tonnes of bulbous sea squirts.
“From one tonne, we could isolate less than one gram” of the compound they needed for clinical trials, she told AFP.
The company currently has three cancer drugs which are approved, all derived from sea squirts, and has fine- tuned its methods for synthesising synthetic versions of natural compounds.
Marchante said, even if everything goes right, it can take 15 years between discovery and launch of a product.
Overall, 17 marine-derived drugs have been approved to treat human diseases since 1969, with about 40 in various stages of clinical trials around the world, according to the online tracker Marine Drug Pipeline.
Those already on the market include a herpes antiviral derived from a sponge and a powerful pain  medication derived from a cone snail, but most treat cancer.
Experts say that it is partly because the huge costs of clinical trials — potentially exceeding a  billion dollars — favours the development of more expensive drugs.
However, there is a “myriad” of early-stage research on marine-derived compounds for anything  from malaria to tuberculosis, said Alejandro Mayer, a pharmacology professor at Illinois’ Midwestern University, who runs the Marine Pipeline project and whose speciality is the  brain’s immune system.
That means there is still a huge potential to find the next antibiotic or HIV therapy, say scientists .
It might be produced by a creature buried in ocean sediment or quietly clinging to a boat’s hull.
Or it could already be in our possession: laboratories around the world hold libraries of compounds that can be tested against new diseases.
“There’s a whole new frontier out there,” said Fenical.
