Engineering NK Cells for CAR Therapy—Recent Advances in Gene Transfer Methodology

Abstract

The development of chimeric antigen receptor (CAR) T cell therapy has introduced a new and effective strategy to guide and promote the immune response against tumors in the clinic. More recently, in an attempt to enhance its utility, this method has been expanded to novel cell types. One of the more successful variants has proven to be the expression of CARs in Natural Killer (NK) cells (CAR-NK). Gene engineering NK cells to express an exogenous CAR receptor allows the innate anti-tumor ability of NK cells to be harnessed and directed against a target tumor antigen. In addition, the biology of NK cells allows the development of an allogeneic cell therapeutic product useable with most or all patient haplotypes. NK cells cause little or no graft versus host disease (GvHD) and are therefore suitable for development of an “off the shelf” therapeutic product. Initial trials have also shown that CAR-NK cells rarely cause cytokine release syndrome. However, despite their potential NK cells have proven to be difficult to engineer, with high sensitivity to apoptosis and low levels of gene expression. The creation of optimized methods to introduce genes into NK cells will promote the widespread application of CAR-NK in research laboratories and the clinics.

RETRACTED: CAR-NK Cell: A New Paradigm in Tumor Immunotherapy

“…Vectors constructed by these pathogens possess some benefits, which make it comparatively simple to form complex vectors and then insert them into the target cells. Normally, these vectors are up to 10 kb in size without experiencing substantial loss of titer throughout manufacture, permitting the introduction of up to 7–8 kb ( 59 ). Besides, these vector’s integration support cell’s prolonged alteration in the lack of antibiotic resistance markers, and then altered cells typically are upheld in the host during a long duration ( 60 ).…”

“…Besides, these vector’s integration support cell’s prolonged alteration in the lack of antibiotic resistance markers, and then altered cells typically are upheld in the host during a long duration ( 60 ). Rendering reports, NK cell susceptibilities to external genetic material accompanying the demanding procedure of transduction usually leads to low rates of transduction along with high apoptosis, making the NK cells transduction efficiency lower than T-cells ( 59 ). It is because of the resistance to viral transduction exerted by the innate immune system directed by pattern recognition receptors identifying foreign genetic material ( 61 ).…”

Expanded human NK cells armed with CAR uncouple potent anti-tumor activity from off-tumor toxicity against solid tumors

“…This was despite the lower fluorescence intensity of the HER2 CAR construct in expanded NK cells compared to the donor-matched T cells. It has been shown that NK cells typically have lower transduction efficiencies than T cells due to NK cells resistance to viral transduction and higher sensitivity to the insertion of genetic material (Schmidt et al, 2021;Sutlu et al, 2012). Thus, the resistance to transduction and large CAR vector used in our study could account for these differences in HER2 CAR expression.…”

From CAR-T Cells to CAR-NK Cells: A Developing Immunotherapy Method for Hematological Malignancies

“…RNA transfection methods are cost-effective approaches with higher gene transfer efficiency; however, the CAR constructs expression is transient through this method, approximately 3-5 days. On the one hand, the narrow therapeutic time window is a limitation; on the other hand, the incidence of CAR-associated side effects, such as on-target off-tumor effects, may be reduced due to its transient nature (39,66,67). Combining transfection methods with DNA integration techniques through transposon systems, such as PiggyBac (PB) and sleeping beauty (SB), has been developed as an attractive approach to generate safer and more stable transgene-expressing cells (68,69).…”