The approval from the Food and Drug Administration makes Afinitor the first drug available specifically for non-cancerous tumors that do not require immediate surgery.

Shares of Swiss-based Novartis closed 0.2 percent higher in Europe earlier on Thursday.

Tuberous sclerosis complex, or TSC, causes multiple tumors in both kidneys that compress normal tissue, leading to kidney failure and bleeding.

The disorder affects about 40,000 people in the United States, 70-80 percent of whom develop kidney problems.

Novartis' treatment, known generically as everolimus, is a pill taken once daily that blocks the activity of a protein that plays a critical role in the development and growth of non-cancerous tumors.

"This approval underscores the FDA's commitment to the development of drugs for rare diseases with significant unmet medical needs," said Dr. Richard Pazdur, director of hematology and oncology products within FDA's Center for Drug Evaluation and Research.

"It also represents another example of where an understanding of a disease's underlying biology can lead to more selective drug development."

Novartis released data from a late-stage study last September showing that Afinitor helps some people with the non-cancerous kidney tumors.

The 118-patient study found that 42 percent of TSC sufferers can experience responses including reduced tumor size and an absence of new tumors after taking the drug.

The Swiss drugmaker is increasingly focusing on specialist drugs to help protect its profitability, at a time when top-selling drugs such as the blood-pressure treatment Diovan face generic competition.

(Reporting by David Morgan; Editing by Philip Barbara, Bernard Orr)

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