Transfection of tumor-reactive T-cells with RNA -loaded nanocapsules

(Project B9 of the SFB 1066 " Nanodimensional polymer therapeutics for tumor therapy " of the German Research Foundation)

Project coordination: PD Dr. V. Mailänder with Prof. Dr. Th Woelfel

Multiple clinical studies have demonstrated that metastatic tumors can regress after adoptive transfer of tumor- reactive T cells. In most cases however, these tumor regressions were of short term and occurred preferably in immunologically easily accessible organs. A major reason for the inadequate efficacy of T cell therapy is replicative senescence, which leads to a gradual loss of important in vivo functions such as proliferation, homing and effector functions. The long term goal of this project is to develop a method of non-viral RNA transfection of tumor- reactive T cells, which opposes their ageing-related loss of function, optimizes the efficiency, accuracy and sustainability of the T-cell therapy and can be used clinically, both in vitro and in vivo. The vehicles for RNA transport are polymeric nanocapsules, which are effectively absorbed by activated T cells and have a biodegradable shell substance. This novel RNA transfection, as compared with conventional transfection methods, has the advantages that it is very gentle to cells and that the nucleic acids release can be delayed for a longer duration of action. Further, the uptake of the nanocapsules into tumor- reactive T cells is to be accurately controlled by suitable surface functionalization, so that the method can be used clinically, both in vitro and later in vivo. This is followed up by detailed studies on cellular uptake, release and toxicity of the RNA - loaded nanocapsules, in order to be able to specifically modify the intracellular transport and release of the encapsulated cargo. For an effective exit from the endolysosome, the nanocapsules are coated with appropriate peptidic escape molecules (e.g. GALA). siRNA and mRNA formats are tested as nanocapsule cargo. The targets for siRNA are the negative immunoregulatory molecules Cbl-b or PD- 1, whose switch-off in the tumor - reactive CD4+ and CD8+ T cells enhances the effector functions. Candidates for the transfer of the mRNA are the lymphatic homing molecules CCR7 and CD62L , to be re -expressed in long-term cultured tumor-reactive T cells.

Partners: Prof. DR. Th Woelfel (III Medical Clinic, University of Mainz )