* Maintenance therapy seen as lucrative addition
* Rituxan received similar European approval in October
* Showed delays worsening of disease in trials
NEW YORK, Jan 28 (Reuters) - U.S. health regulators have approved cancer drug Rituxan as a maintenance therapy for patients with advanced follicular lymphoma, adding a potentially lucrative new use for the multibillion-dollar medicine for Roche Holding AG (ROG.VX) and Biogen Idec Inc (BIIB.O).
Rituxan, which is widely used to treat non-Hodgkin's lymphoma and chronic lymphocytic leukemia, as well as for treating rheumatoid arthritis, is now approved by the Food and Drug Administration to prevent or delay relapses of follicular lymphoma in patients who responded to initial treatment with Rituxan plus chemotherapy.
The drug, which is made by Roche's Genentech unit, received a similar maintenance therapy approval in Europe in October.
In clinical trials, Rituxan given every two months for two years to patients who responded to initial treatment nearly doubled the likelihood of them living without the disease worsening.
Several companies have been exploring the use of cancer drugs as maintenance therapy, meaning it would be given to help prevent relapses rather than not until cancer returns or progresses, potentially adding many months or years of use for the expensive medicines.
"Maintenance use of Rituxan offers people with this incurable disease the opportunity to live longer without their disease getting worse, a primary goal of treatment," Hal Barron, Roche's chief medical officer said in a statement.