Cancer immunotherapies are revolutionizing cancer treatment. Unfortunately, a large proportion of patients with solid tumors do not respond to currently available immune-therapeutics. The lack of response is due to a variety of mechanisms tumors adopt to avoid immune mediated clearance. The multiplicity of immunosuppressive mechanisms operational in the tumor microenvironment may not be overcome by single agents and require interventions at multiple control points. However, systemic exposure to combinations of immunoregulators may result in severe, dose limiting, acute and chronic toxicities that might be prevented if the effect of these agents is focused to the tumor microenvironment.
We are engaged in the discovery of a novel class of immuno-oncology drugs aimed at maximizing the effect of immunoregulatory molecules in the tumor microenvironment and minimizing systemic adverse effects. These drugs incorporate plasmids, engineered to program tumor cells to produce and secrete immune-regulatory proteins, within hyaluronic acid (HA) coated lipid nanoparticles, called GAGomers, which specifically target tumor cells that overexpress activated HA receptors (GAG-pDNA). GAG-pDNA based therapeutics promise highly potent but localized activation of the immune system exclusively in the tumor microenvironment following systemic administration, leading to the destruction of tumor cells by activated immune cells without debilitating toxic side effects.
To demonstrate the feasibility of the GAG-pDNA approach we have incorporated a plasmid directing the expression of murine IL-2 into GAGomers (GAG-pIL2) and assessed the anti-tumor activity of the construct after systemic delivery into tumor bearing mice. GAG-pIL2 administration resulted in statistically significant inhibition of tumor growth, which correlated with elevated IL-2 levels in the tumor and increased infiltration of T-cells into the tumor microenvironment.
These experiments demonstrate the feasibility of programming tumor cells using GAG-pDNA to produce and secrete immunoregulatory molecules into the tumor microenvironment and trigger robust anti-tumor immune responses.
Citation Format: Genia Alpert, David Altreuter, Sunil Anamandla, Arlyssa Birt, Guy Cinamon, Keren Cohen Merimi, Orli Even Or, Nir Gefen, Nadia Gurvich, Jeno Gyuris, Lorena Lerner, Adi Mondshine, Hong Wang. Anti-tumor effect of GAGomer-mediated intra-tumoral IL-2 expression following systemic administration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1601. doi:10.1158/1538-7445.AM2017-1601