- A drug used alone to treat certain types of non-small cell lung cancer and with gemcitabine hydrochloride to treat certain types of pancreatic cancer. It is also being studied in the treatment of other types of cancer. Erlotinib hydrochloride blocks a protein called EGFR, which may help keep cancer cells from growing. It is a type of EGFR tyrosine kinase inhibitor. Also called CP-358,774, OSI-774, and Tarceva.