Table 2.

Applications of CRISPR/Cas9 technology in T‐cell therapy

Application	Generate off‐the‐shelf CAR‐T	Knock‐in CAR or TCR	Knock‐out checkpoint molecules	Generation of CAR‐T cells expressing exogenous cytokines
Summary	TCR, B2M and PD‐1 molecules were eliminated simultaneously to enhance the antitumor activity. Other genes such as CTLA‐4 and Fas were also disrupted together with TCR and B2M	CAR or TCR cassette is knocked into endogenous TCR gene locus to mitigate GvHD	PD‐1, CTLA‐4, and LAG‐3 genes were knocked out separately or in combination	Beneficial cell cytokines (‐IL‐12, IL‐15, IL‐18, IL‐17, etc) can be knocked in designed gene locus
Advantages	Cheaper and faster, more potent	Avoid random integration; uniform CAR expression	Higher efficacy, less side effects, durable	More natural, less side effects
Disadvantages	The elimination of HLA‐class I could increase the attack from NK cells	Low knock‐in efficiency	Potential off‐target effects	Limited knock‐in efficiency
References	28, 29, 30, 31	33, 34	35, 36, 37, 40, 41, 42, 45	46, 47, 48, 49, 50

Abbreviations: CRISPR/Cas9, clustered, regularly interspaced, short palindromic repeats/ CRISPR‐associated protein 9. CAR, chimeric antigen receptor; TCR, T cell receptor; PD‐1, programmed cell death protein 1; CTLA‐4, cytotoxic T‐lymphocyte–associated antigen 4; GvHD, graft‐vs‐host disease; LAG‐3, lymphocyte activation gene 3; IL, interleukin.