Abstract 5645: Lentiviral-mediated cell-specific RNA interference in regulatory T cells

Regulatory T cells (TRegs) constrain anti-tumour immunity and remain the most significant obstacle to successful immunotherapy of cancer. The immunosuppressive influence of these cells can be abrogated by depletion strategies, modulation of T cell plasticity and inhibition of function or migration. A novel and attractive strategy for inhibiting TReg function is RNA interference directed against their crucial transcription factor, FOXP3. RNA interference (RNAi) is still in its infancy as a therapeutic modality but holds great promise in terms of specificity and potency. Foremost within the TReg microRNA signature is micro-RNA 31 (miR-31) which specifically silences FOXP3, abolishing the suppressor capability of these cells. Translation of this promising therapeutic into the clinic hinges on surmounting an obstacle common to all gene therapy strategies - delivery. Cognisant of the dangers of off-target effects, our aim was to mediate cell-specific delivery of RNA interference. This would greatly enhance the clinical utility of this treatment modality. To achieve this objective we used a lentiviral vector, pseudotyped with mutated measles virus glycoproteins bearing an antibody single chain fragment variable. This strategy circumvents the native tropism of the measles virus potentially allowing for cell-specific RNA interference. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5645. doi:1538-7445.AM2012-5645