Co-delivery of nucleoside-modified mRNA and TLR agonists for cancer immunotherapy: Restoring the immunogenicity of immunosilent mRNA.

This study reports on the design of mRNA and adjuvant-loaded lipid nanoparticles for therapeutic cancer vaccination. The use of nucleoside-modified mRNA has previously been shown to improve the translational capacity and safety of mRNA-therapeutics, as it prevents the induction of type I interferons (IFNs). However, type I IFNs were identified as the key molecules that trigger the activation of antigen presenting cells, and as such drive T cell immunity. We demonstrate that nucleoside-modified mRNA can be co-delivered with the clinically approved TLR agonist monophosphoryl lipid A (MPLA). As such, we simultaneously allow high antigen expression in vivo while substituting the type I IFN response by a more controllable adjuvant. This strategy shows promise to induce effective antigen-specific T cell immunity and may be useful to enhance the safety of mRNA vaccines.

Comparing photoporation and nucleofection for delivery of small interfering RNA to cytotoxic T cells.

The success of cancer immunotherapy through the adoptive transfer of cytotoxic T lymphocytes (CTLs) is highly dependent on the potency of the elicited anti-tumor responses generated by the transferred cells, which can be hindered by a variety of upregulated immunosuppressive pathways. Downregulation of these pathways in the T cells via RNA interference (RNAi) could significantly boost their capacity to infiltrate tumors, proliferate, persist, and eradicate tumor cells, thus leading to a durable anti-tumor response. Unfortunately, it is well known that primary T cells are hard-to-transfect and conventional non-viral transfection agents are generally ineffective. Viral transduction and electroporation are more efficient but their use is restricted by high cost, safety issues, and cytotoxicity. Photoporation has recently gained interest as a more gentle alternative physical approach to deliver membrane-impermeable macromolecules into cells. By attaching gold nanoparticles (AuNPs) to the cell surface followed by pulsed laser illumination, transient membrane pores can be generated that allow the diffusion of macromolecules directly into the cell cytosol. Here, we evaluated this technique for the non-toxic and effective delivery of small interfering RNA (siRNA) and subsequent silencing of target genes in activated CTLs. We compared photoporation with nucleofection, the current standard physical technique for T cell transfection, and demonstrated a significantly reduced cytotoxicity and higher average dose per cell for the photoporation technique.

Hitchhiking nanoparticles: Reversible coupling of lipid-based nanoparticles to cytotoxic T lymphocytes.

Following intravenous injection of anti-cancer nanomedicines, many barriers need to be overcome en route to the tumor. Cell-mediated delivery of nanoparticles (NPs) is promising in terms of overcoming several of these barriers based on the tumoritropic migratory properties of particular cell types. This guided transport aims to enhance the NP accumulation in the tumor and moreover enhance the infiltration of regions that are typically inaccessible for free NPs. Within this study, cytotoxic CD8(+) T cells were selected as carriers based on both their ability to migrate to the tumor and their intrinsic cytolytic activity against tumor cells. Many anti-cancer nanomedicines require tumor cell internalization to mediate cytosolic drug delivery and enhance the anti-cancer effect. This proof-of-concept therefore reports on the reversible attachment of liposomes to the surface of cytotoxic T lymphocytes via a reduction sensitive coupling. The activation status of the T cells and the liposome composition are shown to strongly influence the loading efficiency. Loading the cells with liposomes does not compromise T cell functionalities like proliferation and cytolytic function. Additionally, the triggered liposome release is demonstrated upon the addition of glutathione. Based on this optimization using liposomes as model NPs, a small interfering RNA (siRNA)-loaded NP was developed that can be coupled to the surface of CD8(+) T cells.

A personalized view on cancer immunotherapy.

Recent progress in cancer immunotherapy has resulted in complete responses in patients refractory to current standard cancer therapies. However, due to tumor heterogeneity and inter-individual variations in anti-tumor immunity, only subsets of patients experience clinical benefit. This review highlights the implementation of a personalized approach to enhance treatment efficacy and reduce side effects, including the identification of tumor-specific antigens for cancer vaccination and adoptive T cell therapies. Furthermore, together with the current advances and promising clinical outcomes of combination cancer (immuno-)therapies, the screening for predictive biomarkers in a patient-specific manner is emphasized.