UPDATE 1-FDA panel to discuss Roche arthritis drug July 29

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LONDON, June 5 (Reuters) - Roche Holding AG's (ROG.VX) experimental arthritis drug Actemra will be considered for approval by a U.S. Food and Drug Administration panel on July 29.

The new drug, which Roche views as a potential blockbuster, will be discussed by the watchdog's Arthritis Advisory Committee, according to the agency's telephone information line.

Actemra is the first of a new class of drug designed to suppress the action of interleukin-6, a protein that acts as a trigger for the body's inflammatory process. It had been widely expected to go before an FDA panel of experts prior to approval.

The medicine was approved in April for treating rheumatoid arthritis in Japan -- where it is sold by Roche's partner Chugai Pharmaceutical Co Ltd (4519.T) -- but it has yet to reach the market in Europe or the United States.

Roche believes it will become an important alternative treatment to established anti-TNF drugs, helping the company diversify its business and to reduce its reliance on cancer medicines.

Drugs that target another protein called tumour necrosis factor, or TNF, have helped revolutionise treatment for rheumatoid arthritis, but up to 40 percent of patients do not get an adequate response.

Roche participation certificates, its most widely traded form of equity, gained 0.5 percent to 184.50 Swiss francs by 1045 GMT. (Reporting by Ben Hirschler; editing by Rory Channing)