1130. A Single-Component CD40-Targeted Adenoviral Vector for Efficient Transduction and Activation of Cutaneous Dendritic Cells

Dendritic cell (DC)-based tumor vaccination usually involves the administration of ex vivo generated autologous DC. Transduction of DC by viral vectors in vivo has been proposed as a more standardized, and easily clinically applicable approach. Previously, we have employed retargeting approaches to route adenoviral (Ad) vectors via the CD40 pathway as a means to circumvent the paucity of the Ad5 virus's primary receptor (CAR), on the surface of DC and to selectively target DC in situ. CD40-targeted Ad-mediated transduction of DC has been successfully realized through the use of bispecific adapter proteins. With these CD40-targeted Ad complexes we have shown an enhanced and more selective transduction as well as a simultaneous CD40-dependent maturation of DC. However, these approaches required the production of several components followed by physical association to form targeted vector complexes. Evidently for those techniques the presence of an excess of free targeting ligands in analyzed samples leaves open questions about the causal component of DC activation and the ability of targeting ligands as integral components of viral particles to induce this process with similar efficiency. Direct incorporation of the TNF-like domain of human CD40L into the Ad capsid, preserving the targeting ability of the genetically modified Ad vector, now allows us to answer these questions and offers a single-component targeted vector for direct clinical application. In the present study, we evaluate the ability of this vector to deliver transgenes in a stringent human substrate system. We report the capacity of this CD40-targeted vector to infect, with high efficiency, cutaneous DC resident in human skin explants, while simultaneously inducing their activation and maturation. This latest generation of single-component, fully targeted vectors should make feasible the clinical testing of in vivo DC-targeted vaccines.