Thus, A4 carries TRAIL on its surface and is able to target tumor cells.15 TRAIL induces apoptosis by binding the death receptors (DR4 and DR5) that are highly expressed on the surfaces of tumor cells.16,17 A4 showed significant tumor-targeting capability, reduced liver tropism, and potent antitumor activity.15 However, we also found that the amount of TRAIL coupled with the capsid protein on the viral particle surface was less than expected, indicating that A4 needs to be further improved to ensure better efficacy. The gene discussed is TNFRSF10A; the disease is neoplasm.