Table 2 Site-specific integration in CAR-T/NK cell therapy

A better defined T cell product

Safer therapeutic T cells

Functional improvement of CAR T cell therapy

Enhancement of some desirable genes

Avoiding position-effect variegation

Controlled integration of the foreign DNA in the genome

Target site selection and sgRNA design

Cas9 activity

Delivery methods

Simultaneous DSBs can lead to cytotoxicity

Gene disruption in CAR T cells can cause unintended innate immune responses

DSBs are toxic and can drive genomic instability and cell death

Continuous CAR expression (random integration into the genome causes substantial variations in CAR expression levels in a batch of CAR T cells because of different transgene copy numbers per cell)

Unpredicted translocations (may occur between double-strand breaks when multiple genes are edited)

Disrupting tumor microenvironment (TME)-driving immunosuppressors

Knocking out of genes targeted by immunosuppressive drugs

Knocking out of genes targeted by radiotheapeutic or chemotherapeutic agents

Knocking out of genes responsible for T cell apoptosis to enhance cell survival

Off-target effects (introduction of random mutations, thus impacting tumor-suppressor genes or activating oncogenes)

Minimizing the risks of insertional oncogenesis

Allowing allogeneic CAR T therapies (due to the disruption of genes involved in Graft-versus-Host Disease)

Effective against solid tumors (due to the disruption of genes involved in immunosuppressive pathways)

Reversing T cell exhaustion

Ablating Fas-induced cell death (using site specific gene-editing methods might lead to an enhancement of CAR T cell function)