(Adds details, analyst comment)
By John Miller
ZURICH, June 25 (Reuters) - Swiss drugmaker Roche's hopes of having the first immunotherapy cocktail to be approved as an initial treatment for an aggressive form of lung cancer remained intact on Monday after a trial showed positive survival data.
The company said Tecentriq, combined with chemotherapy, significantly boosted overall survival of patients with previously untreated extensive-stage small cell lung cancer compared with chemotherapy alone.
The mixture also helped patients survive longer without their disease getting worse, Sandra Horning, Roche's chief medical officer, said in a statement.
With rival medicine Keytruda from Merck beating Roche's immunotherapy alternative to the punch in other, more common forms lung cancer, the Swiss company is continuing efforts to prove Tecentriq's merits in hopes of being first in rarer types of the disease.
Small cell lung cancers account for 10-15 percent of all lung cancers, according to the American Cancer Society.
"These are the first positive Phase III survival results for any immunotherapy-based combination in the initial treatment of extensive-stage small cell lung cancer," Horning said.
Roche shares were seen rising 1.1 percent, according to pre-market indications.
Specific survival data from the IMpower 133 study were not given, with the company planning to release the numbers at a medical conference. Still, it emphasised the results were "clinically meaningful".
Baader Helvea analysts said winning a "first mover advantage" in the indication would likely eventually add $1.5 billion to Roche's Tecentriq sales.
"We see Tecentriq gaining momentum in lung cancer," said Baader analyst Bruno Bulic.
So far, results have been lacklustre.
Tecentriq had 139 million Swiss francs ($140.6 million) in revenue in the first quarter, just a tenth of that posted by Keytruda and Bristol-Myers Squibb's Opdivo, similar immunotherapies that work by helping the body's own defense mechanisms better detect and attack tumours.
Tecentriq is a key part of Roche's strategy of introducing newer drugs to help make up for falling sales of its $21 billion oncology trio of Rituxan, Herceptin and Avastin that is going through patent losses that expose them to cheaper copies, grabbing a big share of the market.
$1 = 0.9885 Swiss francs Reporting by John Miller; Editing by Michael Shields