Intratumoral Administration of Adenoviral Interleukin 7 Gene-Modified Dendritic Cells Augments Specific Antitumor Immunity and Achieves Tumor Eradication

Abstract

In two murine lung cancer models adenoviral interleukin 7-transduced dendritic cells (DC-AdIL-7) were administered intratumorally, resulting in complete tumor regression. Intratumoral DC-AdIL-7 therapy was as effective as DCs pulsed with specific tumor peptide antigens. Comparison with other intratumoral therapies including recombinant IL-7, AdIL-7 vector alone, unmodified DCs, IL-7-transduced fibroblasts, or DCs pulsed with tumor lysates revealed DC-AdIL-7 therapy to be superior in achieving antitumor responses and augmenting immunogenicity. Mice with complete tumor eradication as a result of either DC-AdIL-7 or AdIL-7 therapy were rechallenged with parental tumor cells 30 days or more after complete tumor eradication. All the DC-AdIL-7-treated mice completely rejected a secondary rechallenge, whereas the AdIL-7-treated mice had sustained antitumor effects in only 20-25% of the mice. DC-AdIL-7 therapy was more effective than AdIL-7 in achieving systemic antitumor responses and enhancing immunogenicity. After complete tumor eradication, those mice treated with DC-AdIL-7 evidenced significantly greater release of splenocyte GM-CSF and IFN-gamma than did controls or AdIL-7-treated mice. After intratumoral injection, gene-modified DCs trafficked from the tumor to lymph node sites and spleen. DCs were detected in nodal tissues for up to 7 days after intratumoral injection. We report that intratumoral DC-AdIL-7 leads to significant systemic immune responses and potent antitumor effects in murine lung cancer models.