Table 2.

Strengths and weaknesses of in vitro and in vivo screening systems

In vitro screens	In vivo screens
Whole-genome scale sgRNA libraries	Focused sgRNA libraries
Limited number of cell types involved in immune selection	Complex and rich mixture of cell types that drive the immune selection
Easily scalable, allows for high-quality, high-coverage screens	Poorly scalable, generally poor(er) sensitivity
Allows only for the addition of locally acting (immuno)therapies	Allows for the addition of locally and systemically acting (immuno)therapies
Reductionistic	Holistic, allows for the discovery of emergent traits
Flexible; enables highly defined (genetic) screening setting	More difficult to establish highly defined (genetic) screening setting

sgRNA, single guide RNA.