UPDATE 3-Two drugs don't boost lung cancer survival -Roche

(Adds analysts' comments, Roche share price)

By Emma Thomasson and Ben Hirschler

ZURICH/LONDON, Oct 6 (Reuters) - Roche Holding AG (ROG.VX) and Genentech Inc DNA.N said on Monday a study into the benefits of combining their Tarceva and Avastin drugs for lung cancer patients did not show an increase in overall survival.

Both drugs are targeted therapies -- modern medicines which act as "smart bombs" by crippling cancer cells while leaving healthy cells intact. It had been hoped that adding them together would extend patients' lives.

Roche and Genentech said on Monday a Phase III study investigated the addition of Avastin to Tarceva compared with Tarceva alone for the treatment of patients with advanced non-small cell lung cancer, the most common form of lung cancer.

The study did not show a significant increase in overall survival with the Avastin-Tarceva combination compared with Tarceva alone.

But there was evidence of an increase in the time patients lived without their disease getting worse as well as the response rate when Avastin was added to Tarceva compared with Tarceva alone.

Deutsche Bank analysts said the result was "somewhat disappointing" as combining the two drugs was an attractive treatment option, with the potential to increase efficacy without undue side effects.

But the high cost -- around $12,000 a month -- meant using both drugs would only be considered if there was convincing clinical data.

Roche said further analysis was needed and the full results of the study would be submitted for presentation at a conference on thoracic oncology in Chicago next month.

Both Avastin and Tarceva are already available for the treatment of patients with advanced lung cancer in the United States and Europe.

"We are disappointed this study did not show an improvement in survival for patients with advanced lung cancer who have a poor prognosis and a disease that is extremely difficult to treat," said Genentech chief medical officer Hal Barron.

"We are, however, encouraged to see the combination of Avastin and Tarceva had clear evidence of biological activity, and will fully analyse the data so that we can apply the insights to our ongoing lung cancer research."

Panmure analysts said the result was a boost for AstraZeneca Plc (AZN.L), whose drug Zactima is in Phase III clinical trials in lung cancer. A strong result for the Tarceva/Avastin combination could have undermined the market for Zactima.

Roche, the world's largest maker of cancer drugs, wants to buy Genentech, which is already majority-owned by Roche. Genentech rejected a $89 per share bid from Roche in mid-August -- valuing the remainder of Genentech at $43.7 billion -- but Roche has said it is committed to its takeover proposal.

Roche stock was down 3 percent by 0930 GMT, underperforming a European health sector .SXDP that lost 1.8 percent. (Editing by David Holmes, Greg Mahlich)