Engineering Receptor Expression on Natural Killer Cells Through Trogocytosis

Non-viral engineering of NK cells

The last decade has witnessed great progress in the field of adoptive cell therapies, with the authorization of Kymriah (tisagenlecleucel) in 2017 by the Food and Drug Administration (FDA) as a crucial stepstone. Since then, five more CAR-T therapies have been approved for the treatment of hematological malignancies. While this is a great step forward to treating several types of blood cancers, CAR-T cell therapies are still associated with severe side-effects such as Graft-versus-Host Disease (GvHD), cytokine release syndrome (CRS) and neurotoxicity. Because of this, there has been continued interest in Natural Killer cells which avoid these side-effects while offering the possibility to generate allogeneic cell therapies. Similar to T-cells, NK cells can be genetically modified to improve their therapeutic efficacy in a variety of ways. In contrast to T cells, viral transduction of NK cells remains inefficient and induces cytotoxic effects. Viral vectors also require a lengthy and expensive product development process and are accompanied by certain risks such as insertional mutagenesis. Therefore, non-viral transfection technologies are avidly being developed aimed at addressing these shortcomings of viral vectors. In this review we will present an overview of the potential of NK cells in cancer immunotherapies and the non-viral transfection technologies that have been explored to engineer them.

Delivery technologies to engineer natural killer cells for cancer immunotherapy

In recent years, immune cell-based cancer therapeutics have been utilized broadly in the clinic. Through advances in cellular engineering, chimeric antigen receptor (CAR) T-cell therapies have demonstrated substantial success in treating hematological tumors and have become the most prominent cell-based therapy with three commercialized products in the market. However, T-cell-based immunotherapies have certain limitations, including a restriction to autologous cell sources to avoid severe side-effects caused by human leukocyte antigen (HLA) mismatch. This necessity for personalized treatment inevitably results in tremendous manufacturing and time costs, reducing accessibility for many patients. As an alternative strategy, natural killer (NK) cells have emerged as potential candidates for improved cell-based immunotherapies. NK cells are capable of killing cancer cells directly without requiring HLA matching. Furthermore, NK cell-based therapies can use various allogeneic cell sources, allowing for the possibility of "off-the-shelf" immunotherapies with reduced side-effects and shortened manufacturing times. Here we provide an overview of the use of NK cells in cancer immunotherapy, their current status in clinical trials, as well as the design and implementation of delivery technologies-including viral, non-viral, and nanoparticle-based approaches-for engineering NK cell-based immunotherapies.