Contusugene ladenovec (Advexin; INGN-201; Introgen Therapeutics Inc) is a replication-impaired, non-integrating, serotype 5 adenoviral vector that carries the p53 gene under the control of the CMV promoter. Deletion or mutation of the p53 gene has been observed in approximately half of malignancies in patients with cancer and p53 pathway dysfunction was observed in the majority of others, thereby providing the rationale for p53 restoration in the treatment of cancer. Advexin has demonstrated a consistent safety profile and clinical efficacy as a monotherapy, as well as in combined modality regimens with chemotherapy and radiation. Additive or synergistic effects have been observed in a variety of tumor types, including NSCLC, squamous cell carcinoma of the head and neck, hepatocellular carcinoma, glioma, and breast, prostate and colorectal cancers. The identification of biomarkers may help direct research in tumor-specific therapeutics.