As obesity expands waistlines in the Western world, a silent killer linked to the condition nicknamed "human foie gras" is spurring a potential bonanza worth billions for drugs giants.
The disease, formally known as non-alcoholic steatohepatitis (NASH), is caused by a buildup of fat in the liver. It is already the leading ailment cited in requests for liver transplants in the United States, Cecile Rabian of France's Gilead laboratory told AFP.
"We imagine that this will also be the case in Europe very soon," she added.
The GlobalData research group estimates that NASH could underpin a market worth more than $25 billion (22 billion euros) by 2026.
And the market should grow by a healthy 45 percent each year in the initial phases of the rollout of drugs to counter the disease, GlobalData says—with the main customer base in the United States, western Europe and Japan.
Epidemiological studies suggest that 12 percent of Americans and six percent of Europeans already suffer from the condition.
Abnormal fat accumulation
NASH can lead to scarring of the liver, which in turn leads to cirrhosis.
Abnormal accumulation of fat in the liver can set off the first stage of the disease, characterised by a chronic inflammation of the liver.
Fatty liver in ducks and geese produces the prized French delicacy of foie gras—a natural phenomenon with migrating birds that is controversially replicated by poultry farmers who force-feed their fowl.
In humans, the inflammation slowly eats away at the liver's cells, causing scar tissue to form known as fibrosis.
This can result in either liver cancer or what is known as non-alcoholic cirrhosis of the liver.
NASH recently hit the headlines in France when a sports journalist suffering from the disease received a double liver and kidney transplant.
The pharmaceuticals giants began ramping up their response to NASH in 2015.
US giant Allergan acquired Californian biotech firm Tobira for $1.7 billion last year, and recently hooked up with Switzerland's Novartis to carry out clinical trials.
Danish diabetes giant Novo Nordisk is also interested—among many others.
"Since NASH goes through several stages, it will probably be necessary to bring together several action mechanisms—bi-therapies or tri-therapies—to try to be even more effective," Rabian said.
Three companies are leading the pack, with candidate drugs already in the final third phase of development: Gilead, US firm Intercept and French biotech firm Genfit.
Shares in Genfit, based in the northern French city of Lille, have skyrocketed amid acquisition rumours, and the company's value now exceeds 900 million euros.
"There's still a very high probability of being acquired by a big pharmaceutical group," Genfit's CEO Jean-Francois Mouney told AFP. "But we're not idly waiting for customers to knock on our door, we're moving forward. And the more we move ahead, the more we are attracting attention."
The preliminary results of the phase-three trials are expected in mid-2019 for Genfit's drug Elafibranor, which is designed to reduce if not halt inflammation and degeneration of liver cells.
The drug targets two receptors in the cell's nucleus that regulate the genes that are key to its functioning.
Mouney hopes the green light will come for the drug to go on the market in Europe and the United States by the end of 2019 or early 2020.
For now health authorities have approved only one diagnostic tool for NASH—a biopsy of liver tissue, which is a costly procedure, difficult to implement on a large scale and not without risk for the patient.
The industry is looking to develop diagnostic tools for NASH such as blood tests or imaging techniques, without which the market will face a "bottleneck", Arnaud Guerin, an analyst with the brokerage firm Portzamparc, told AFP.
The market should eventually rival that of oral anti-diabetes drugs, which cost $13,000-15,000 annually in the United States— about half that in Europe, Mouney said.
Some laboratories have mooted an annual cost of up to $50,000 per NASH patient.
According to the New England Journal of Medicine, 30 percent of the world's population was overweight in 2015.
In view of the increase in NASH sufferers, health authorities say prevention is the best cure, and also the cheapest: a low-sugar diet accompanied by regular exercise.
Explore further: Diet and exercise can improve kidney function in patients with fatty liver disease