Adenovirus-mediated interleukin 3β gene transfer by isolated limb perfusion inhibits growth of limb sarcoma in rats

Cytokine gene transfer using (multiple) intratumoral injections can induce tumor regression in several animal models, but this administration technique limits the use for human gene therapy. In the present studies we describe tumor growth inhibition of established limb sarcomas after a single isolated limb perfusion (ILP) with recombinant adenoviral vectors harboring the rat IL-3β gene (IG.Ad.CMV.rIL-3β). In contrast, a single intratumoral injection or intravenous administration did not affect tumor growth. Dose-finding studies demonstrated a dose-dependent response with a loss of antitumor effect below 1 × 10⁹ IU of IG.Ad.CMV.rIL-3β. Perfusions with adenoviral vectors bearing a weaker promoter (MLP promoter) driving the rIL-3β gene did not result in antitumor responses, suggesting that the rIL-3β-mediated antitumor effect depends on the amount of rIL-3β protein expressed by the infected cells. Furthermore, it was shown by direct comparison that ILP with IG.Ad.CMV.rIL-3β in the ROS-1 osteosarcoma model is at least as efficient as the established therapy with the combination of TNF-α and melphalan. Treatment with IG.Ad.CMV.rIL-3β induced a transient dose-dependent leukocytosis accompanied by an increase in peripheral blood levels of histamine. Leukocyte infiltrations were also histopathologically demonstrated in tumors after perfusion. These results demonstrate that ILP with recombinant adenoviral vectors carrying the IL-3β transgene inhibits tumor growth in rats and suggest that cytokine gene therapy using this administration technique might be beneficial for clinical cancer treatment.