a drug used to treat certain types of non-small cell lung cancer. it is also used together with gemcitabine to treat pancreatic cancer and is being studied in the treatment of other types of cancer. tarceva is a type of epidermal growth factor receptor (egfr) tyrosine kinase inhibitor. also called erlotinib, erlotinib hydrochloride, cp-358,774, and osi-774.