PEGylation of Ad5 with high molecular weight PEG (20 kD) resulted in improved efficacy of intravenously applied therapy for HCC, with reduced transduction of hepatocytes and KCs and a reduction of hepatotoxicity (117), making this an attractive approach for improving the specificity of OV therapies targeted to liver tumors. The gene discussed is TBCE; the disease is hepatocellular carcinoma.