erbB-2 is known to be overexpressed in several human malignancies including lung cancer. Because of its role in neoplastic transformation as well as its association with poor prognosis, this oncogene has been targeted through various anti-cancer methodologies. In this regard, we have recently demonstrated that erbB-2-overexpressing ovarian tumor cell lines transfected with an endoplasmic reticulum form of an anti-erbB-2 single-chain antibody undergo a specific cytotoxicity through the induction of apoptosis. Since certain forms of lung cancer are also associated with overexpression of erbB-2, we evaluated the use of this novel therapeutic in this context. For these studies, several human lung adenocarcinoma cell lines were stably and transiently transfected with the anti-erbB-2 sFv gene. We demonstrate here that the anti-erbB-2 sFv can cause specific cytotoxicity in lung cancer cells. As a first step toward clinical translation of this strategy, we constructed a replication-deficient recombinant adenoviral vector expressing the anti-erbB-2 sFv construct. We further demonstrate that our anti-erbB-2 sFv-encoding adenoviral vector can accomplish high levels of cytotoxicity in lung cancer cells. Based on these results, it is proposed that this strategy of oncoprotein ablation may have use in the treatment of some forms of human lung cancer.