Critical cancer vulnerabilities identified by unbiased CRISPR/Cas9 screens inform on efficient cancer Immunotherapy

Abstract

The mutational landscape of human cancers is highly complex. While next generation sequencing aims to comprehensively catalogue somatic alterations in tumor cells, it fails to delineate driver from passenger mutations. Functional genomic approaches, particularly CRISPR/Cas9, enable both gene discovery, and annotation of gene function. Indeed, recent CRISPR/Cas9 technologies have flourished with the development of more sophisticated and versatile platforms capable of gene knockouts to high throughput genome wide editing of a single nucleotide base. With new platforms constantly emerging, it can be challenging to navigate what CRISPR tools are available and how they can be effectively applied to understand cancer biology. This review provides an overview of current and emerging CRISPR technologies and their power to model cancer and identify novel treatments. Specifically, how CRISPR screening approaches have been exploited to enhance immunotherapies through the identification of tumor intrinsic and extrinsic mechanisms to escape immune recognition will be discussed.

Generation of a CRISPR activation mouse that enables modelling of aggressive lymphoma and interrogation of venetoclax resistance

“…Cancer is a highly heterogenous disease with many different signalling pathways deregulated within the same cancer type 12 . The ability to create pre-clinical disease models that faithfully reflect the hallmarks of human disease is critical for the identification of specific cancer drivers and/or therapy resistance factors 13 . However, mouse models that accurately mimic aggressive lymphomas, such as double hit lymphoma (DHL), an aggressive subset (~10%) of diffuse large B cell lymphomas (DLBCLs) that express high levels of both c-MYC and BCL-2 due to chromosomal translocations, are lacking 14 , 15 .…”

Exploiting the CRISPR‐Cas9 gene‐editing system for human cancers and immunotherapy

“…Besides the above described, the CRISPR genome screens offer many advantages that when it is applied in vivo , for example, it is possible to model the complex interaction and replicate the dynamic TME. Therefore, in vivo CRISPR‐Cas9 genome screens now identify regulators of immune evasion by cancer cells, including immune cell inhibitors 124 …”

“…However, the in vivo CRISPR genome screening is somewhat similar to in vitro approaches in which sgRNA is used to modify and generate mutant tumor cells, which are then transplanted via different routes and allowed to develop. Harvested tumors are then compared with unmodified tumors from immune‐competent mice to find any genetic hits that may play a role in the antitumor response 124 …”

A novel CRISPR activation mouse enables modelling of aggressive lymphoma and interrogation of venetoclax resistance.

“…12 The ability to create pre-clinical disease models that faithfully re ect the hallmarks of human disease is critical for the identi cation of speci c cancer drivers and/or therapy resistance factors. 13 However, mouse models that accurately mimic aggressive lymphomas, such as double hit lymphoma (DHL), an aggressive subset (~ 10%) of diffuse large B cell lymphomas that express high levels of both MYC and BCL-2 due to chromosomal translocations, are lacking. 14,15 Previous attempts to model this disease using Eµ-MYC/Eµ-BCL-2 double transgenic approaches 16 or ectopic expression of BCL-2 in a Eµ-MYC transgenic background 17 failed to recapitulate DHL, instead giving rise to progenitor tumours; probably due to unnaturally high expression of both gene products.…”