(Reuters) - U.S. health regulators on Friday said they have granted accelerated approval to Roche Holding's drug for advanced lung cancer in patients with a specific genetic mutation.

The drug, alectinib, to be sold under the brand name Alecensa, was approved to treat patients with advanced ALK-positive non-small cell lung cancer (NSCLC) whose disease has worsened after, or who could not tolerate, treatment with Pfizer's Xalkori.

"Today's approval provides a new therapy for a group of patients who would have few treatment options once their disease no longer responds to treatment with Xalkori," Richard Pazdur, head of the Food and Drug Administration's Hematology and Oncology Products division, said in a statement.

Xalkori was seen as an advance in the field of personalized medicine as it was designed to treat only patients with the ALK genetic mutation, which account for about 4 percent of NSCLC patients. Pfizer is also developing a drug for ALK positive patients who have stopped responding to Xalkori.

The FDA's Accelerated Approval Program allows conditional approval of a medicine that fills an unmet medical need for a serious condition based on early evidence of clinical benefit.

A confirmatory study is required to verify the benefit of Alecensa for it to gain full approval, the agency said.

(Reporting by Bill Berkrot; Editing by David Gregorio)