On Thursday, biotechnology companies Genentech Inc. and OSI Pharmaceuticals Inc. said U.S. regulators have approved their drug Tarceva for treating the most common form of lung cancer.

The once-daily pill is designed to target human epidermal growth factor receptors and block them from allowing cancer cell growth.

The FDA decision comes more than two months ahead of the agency’s scheduled deadline.

Analysts have estimated that Tarceva, one of a new class of targeted therapies offering hope to cancer patients for whom more traditional treatments have failed, could generate annual sales of some $1.6 billion by 2009 for joint developers OSI and Genentech, as well as Genentech’s majority-owner Roche.

The U.S. regulatory approval applies to patients with locally advanced or metastatic non-small cell lung cancer who have failed at least one previous round of chemotherapy.

Lung cancer is the most common form of cancer, accounting for 1.2 million cases a year worldwide, while non-small cell lung cancer accounts for almost 80 percent of all types of lung cancer.

In the United States, about 41,000 patients with advanced lung cancer are being treated, according to Genentech spokeswoman Colleen Sweeney.

Colin Goddard, OSI’s chief executive, said Tarceva’s wholesale price will be $2,026 for a 30-day supply, which is more expensive that Iressa, a targeted lung cancer drug sold by AstraZeneca Plc.

“Ours is the only targeted epidermal growth factor receptor therapy to show a survival benefit,” Goddard said.

In a pivotal-stage trial, patients receiving Tarceva had a median survival of 6.7 months compared to 4.7 months in patients who received placebo. In addition, 31.2 percent of patients receiving Tarceva in the study were alive at one year versus 21.5 percent in the placebo arm.

Side effects included rash and diarrhea.

Goddard said the companies plan to file early next year for FDA approval of Tarceva as a treatment for pancreatic cancer. The drug is also being studied for a range of other cancers including ovarian and head and neck.

South San Francisco, California-based Genentech and OSI, which is headquartered in Melville, New York, said Tarceva will be made available within five shipping days.

Genentech said it does not expect Tarceva’s approval to change its previously stated forecast for adjusted 2004 earnings of 80 cents to 83 cents a share.