['Therapy failures have been reported for retroviral gene transfer of herpes simplex virus thymidine kinase (HSV-TK) gene followed by systemic ganciclovir application in human lung cancer. Use of the HSV-TK mutant TK30 in combination with a VSV-G pseudotyped retroviral vector was found to enhance the efficacy of prodrug therapy. The present study evaluated this therapeutic strategy in human non-small cell lung cancer cell lines in a preclinical murine xenotransplant model.', 'Intrathoracally induced by HSV-TK30 transduced non-small cell lung cancer cell lines Colo 699 (adenocarcinoma) and KNS 62 (squamous cell carcinoma) were monitored for local tumor growth, survival, and metastases. So-called bystander effects were investigated in tumors consisting of as little as 25% TK30 transfected cells and by analysis of gap junctional protein connexin-43 expression.', 'Survival was significantly prolonged, and tumor growth and pleural metastases were reduced in HSV-TK30-positive tumors of both cell lines. A significant therapeutic effect in bystander experiments was observed in squamous cell carcinoma. This was correlated with higher expression of connexin-43.'] Is ganciclovir prodrug therapy effective in a murine xenotransplant model of human lung cancer?