A study showed Boehringer's afatinib drug prolonged the time lung cancer patients survived without a worsening of their condition by 4.2 months on average when compared with a control group on standard chemotherapy.

Results of the study were presented at the annual congress of the American Society for Clinical Oncology in Chicago on Sunday.

"This definitely meets our expectations. It's very encouraging," said Dr. Lecia Sequist, an oncologist at Massachusetts General Hospital Cancer Center and one of the lead researchers of the study.

The trial involved only patients with non-small cell lung tumors that had undergone the so-called EGFR gene mutation.

"In the U.S., this is important because this study may lead FDA approval of the first drug specifically for the EGFR mutation," she said in an interview.

Lung cancer is the most common and one of the most difficult to treat types of cancer, and targeted therapies are currently only available for patients with this type of mutation.

Cancer drugs are referred to as targeted when they interfere with cancer cell growth, unlike the shotgun approach of chemotherapy, which slows or stops any cell growth.

Boehringer, the world's largest private drugmaker, is now recruiting patients to directly compare afatinib with AstraZeneca's Iressa and Roche's Tarceva.

Iressa, a once-daily pill, was approved for certain lung cancer patients in Europe in 2009, and its sales rose 32 percent last year to $554 million.

It falls into the category of so-called personalized medicine, in which patients undergo genetic tests before treatment to determine whether they are likely to benefit from the drug in question.

Boehringer plans to take the concept further and narrow down the targeted group even within the EGFR-mutated patients.

The drug trial showed that a sub-group that accounts for 90 percent of EGFR patients had a particular benefit from afatinib. For them, survival without tumor progression was 6.7 months longer on average than in the control group on chemotherapy.

One problem with the drug is that many people develop resistance to it after about a year, Sequist said.

"Delaying resistance will be a focus of future research," she said.

Boehringer said it was planning to market a test kit to identify the genetic mutation.

(Reporting By Debra Sherman in Chicago and Ludwig Burger in Frankfurt; Editing by David Brunnstrom and Maureen Bavdek)

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