RIDGEFIELD, Conn. — An investigational treatment for lung cancer made by Boehringer Ingelheim Pharmaceuticals extended patients’ survival by more than four months, according to results of a late-stage clinical trial announced Thursday.

BI said the phase 2b/3 “LUX-Lung 1” trial of BIBW 2992 (afatinib) showed a fourfold increase in survival among advanced non-small cell lung cancer patients taking the drug versus those taking placebo, whose survival was extended by one month.

The trial enrolled 585 patients whose disease had gotten worse after they received chemotherapy and Tarceva (erlotinib), made by Genentech and OSI Pharmaceuticals, or AstraZeneca’s Iressa (gefitinib).

Trial data will be presented at the Chicago Multidisciplinary Symposium in Thoracic Oncology.