* Aiming for obesity drugs that can compete with surgery
* Starts next phase of key obesity study next year (Adds head of global research, background, graphic)
MÅLOV, Denmark, Nov 21 (Reuters) - Danish drugmaker Novo Nordisk is stepping up its efforts to treat obesity, seeking to tap into a potentially huge market as its established diabetes drugs come under price pressure, particularly in the United States.
The world's largest maker of diabetes drugs said on Tuesday it would aim to develop medicines that treat obesity - a major cause of diabetes - at least as effectively as surgery.
Its initial big hope is semaglutide, a once-weekly injection that is expected to be launched as a diabetes treatment next year. The new drug, in the so-called GLP-1 category, imitates an intestinal hormone that stimulates the production of insulin.
In a research and strategy update, Novo said it planned to start a final phase 3 clinical trial programme with once-weekly subcutaneous semaglutide in obesity in the first half of 2018. It will involve around 4,500 patients.
Worldwide obesity has nearly tripled since 1975 and the World Health Organization estimates that in 2016 more than 650 million adults were obese - with a body mass index (BMI) of 30 or more. However, just 2 percent are on obesity medication.
Shares in Novo are down around 14 percent over the past two years after price pressures in the United States forced it to cut its long-term operating profit growth target twice last year from 15 to 5 percent. The stock was little changed on Tuesday.
COMPETE WITH SURGERY
Novo said it hoped to achieve a weight loss that can compete with surgery by combining semaglutide with new biological drugs.
"Maybe 25 percent (weight loss) or beyond, but we start by setting the bar at 15 percent or beyond," senior vice president of global research Peter Kurtzhals told investors at the company's capital markets day near Copenhagen.
Two out of the six obesity projects currently in phase 1 trials are expected to move to phase 2 next year, Novo said.
The company's obesity pipeline mainly explores projects addressing weight loss by reducing appetite and thereby food intake, but is also looking at increasing energy consumption.
Novo launched its first obesity drug in 2015, marketed as Saxenda. Other prescription drugs on the U.S. market are Roche's Xenical, Vivus' Qsymia, Eisai's Belviq and Orexigen's Contrave.
Brokerage Nordea sees sales from Novo's obesity franchise rising to $4 billion in 2025, fuelled by semaglutide.
Semaglutide is expected to be approved as a diabetes treatment in December and is - in addition to obesity - also being tested on non-alcoholic steatohepatitis (NASH), known as fatty liver, and cardiovascular and chronic kidney diseases.
Semaglutide will be launched under the brand name Ozempic, Novo said. It will take aim at Eli Lilly's Trulicity, to which Novo's once-daily Victoza drug is currently losing market share.
(Reporting by Stine Jacobsen; Editing by Louise Heavens and Mark Potter)