UPDATE 1-Roche's Lucentis found to curb retinal occlusion

* Six monthly doses of Lucentis evaluated

* Lucentis already approved for macular degeneration

LOS ANGELES, July 2 (Reuters) - Monthly injections of Roche Holding AG's (ROG.VX) Lucentis can significantly improve sight in people with retinal vein occlusion, which leads to vision loss, according to research released by the company's Genentech unit on Thursday.

The condition, known as RVO for short, occurs when blood clots obstruct the flow of veins that drain blood from the retina, causing fluid to build up and vision to cloud.

Lucentis, which had sales of $875 million last year, is currently approved for treating age-related macular degeneration, the leading cause of blindness in older adults.

The study evaluated six monthly injections of Lucentis compared with monthly placebo injections in 397 patients with branch RVO, meaning there is blockage in one of the four veins attached to the retina. The study achieved its main goal of improvement in vision at six months.

The safety profile of Lucentis was consistent with previous experience with the drug, Genentech said.

"RVO is a devastating disease and there are no FDA-approved medicines shown to improve vision for six months," Hal Barron, Genentech's chief medical officer, said in a statement.

Lucentis, or ranibizumab, is designed to block a protein that is believed to play a role in the formation of new blood vessels. It has the same mechanism of action as Genentech's blockbuster cancer drug Avastin.

By eliminating macular edema, Lucentis enables the retina "to remain essentially viable, preserving the retina and preserving vision, so the body can dissolve the thrombus," or clot, according to Dr. Roman Rubio, associate medical director of ophthalmology at Genentech.

He said that in about 30 percent of cases, occlusions eventually resolve on their own.

The company is also testing Lucentis in patients with central RVO -- a condition in which blockage is in the central retinal vein that returns blood to the heart.

Genentech estimates that there are about 144,000 new cases of branch RVO in the U.S. each year and about 36,000 new cases of central RVO, far less than age-related macular degeneration.

Full results of the study will be presented at the Retina Congress in New York, which runs from Sept. 30 to Oct. 4.