U.S. health regulators have approved ThromboGenics's main drug, eye treatment Jetrea, clearing the way for the Belgian biotechnology company to make sustainable profits.

ThromboGenics said on Thursday the U.S. Food and Drug Administration (FDA) had cleared use of the drug, also known as ocriplasmin, for treatment of symptomatic vitreomacular adhesion - an aging-related pulling on the retina that can cause loss or distortion of vision.

Jetrea is the first drug for this disorder, which until now has been treated with surgery. ThromboGenics plans to launch it in the United States in January 2013.

They have gained 96% in the year to date and by 61% in the last three months alone, helped by an FDA panel's recommendation in July that Jetrea be approved.

"This was expected, but it's massively important," said KBC Securities analyst Jan De Kerpel. "Some institutions, because of their statutes, are not allowed to invest in companies without approved products. This brings ThromboGenics to the next level."

He and other analysts added it was important that the approval was broad, with no exclusions.

Chief Executive Patrik De Haes told Reuters the launch would cost about $25 million, spread over the final quarter of 2012 and the first of 2013. ThromboGenics still had a cash position in excess of €150 million ($197 million), he added.

De Haes declined to say how much the firm would charge for an injection, but was "comfortable" with analysts' estimates of €2,500 in Europe and $4,000 in the United States.

Patient insurance claims indicate there are some 250,000 patients with the disorder per year in the United States. Jetrea is designed to treat patients with earlier symptoms.

Brokers estimate worldwide peak sales of some $900 million. De Haes declined to comment, saying only that peak sales should come about five years after launch.

The drug is still awaiting clearance for use in Europe. De Haes said he expected a recommendation in December or January. Further trials are required for Japan and Korea.

In March, ThromboGenics sold the rights to the drug outside the United States to Novartis's ophthalmic division, leading to potential milestone payments of €375 million plus royalties.

Belgian biotech shares have surged in recent months on hopes of drug breakthroughs and speculation they might become acquisition targets.

ThromboGenics last made a profit in 2008, after an upfront payment by Roche for an antibody to fight cancer.

The company is investigating ocriplasmin for use in other eye-related indications and has a further drug candidate at a pre-clinical stage of tests in ophthalmology and oncology.