March 31 (Bloomberg) -- Novartis AG’s cancer pill Afinitor, approved yesterday by U.S. regulators, has the potential to generate several billion dollars in annual sales, according to the company’s head of oncology, David Epstein.

Afinitor “could be a multi- or mega-blockbuster, in time,” Epstein said in a telephone interview.

Novartis won clearance to sell the medicine for patients with advanced kidney cancer who weren’t helped by Pfizer Inc.’s Sutent or Bayer AG’s Nexavar. The disease, also known as renal cell carcinoma, killed more than 13,000 Americans last year. The treatment may help the Swiss drugmaker to weather looming patent losses on its best-sellers, the hypertension drug Diovan and its cancer treatment Gleevec, which lose patent protection starting in 2012 and 2015.

“The first two indications, renal cell carcinoma and neuroendrocrine tumors, could make Afinitor a blockbuster,” Epstein said. Additional uses may add to the sales potential, he said. A blockbuster drug has annual sales of more than $1 billion.

Afinitor is also being tested in lymphoma, breast, gastric, lung and other cancers, as well as tuberous sclerosis, an inherited disease that causes benign tumors to grow in the brain and other vital organs. Its active ingredient is everolimus, which is already sold to block rejection of transplanted hearts or kidneys.

The medication is a so-called targeted therapy, a type of drug doctors say has fewer side effects than conventional chemotherapy. It blocks mTOR, a protein that controls cell growth and metabolism.

Renal cell carcinoma is the most common kidney cancer, with 32,000 new cases in the U.S. every year, according to U.S. government data. Patients with advanced disease such as those in the study have few treatment options.

Novartis gained 1.38 Swiss francs, or 3.3 percent, to close at 43.08 Swiss francs in Zurich.

To contact the reporter on this story: Eva von Schaper in Munich at evonschaper@bloomberg.net.

Last Updated: March 31, 2009 12:17 EDT