Abstract 5111: Gene editing in the NSG mouse strain and its genetic derivatives

Abstract

Abstract Mouse models continue to be powerful tools in preclinical oncology and immuno-oncology studies. The development of the inbred highly immunocompromised mouse strain NSG (NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ) has dramatically improved the ability to work with human tumors in an organismal context using xenograft approaches. Furthermore, technical innovations have expanded the utility of this personalized tumor platform via the reconstitution of parts of the human immune system. An example of this is the NSG-SGM3 inbred mouse strain, in which transgenes expressing human IL3, GMCSF and SCF have been stably integrated into the NSG background. This NSG “derivative” strain can effectively support the stable engraftment of human myeloid lineages and the regulatory T cell populations. Direct genetic modification of the NSG genome in mouse embryos was a key technical capability to attain this NSG “derivative” strain rapidly and avoid extensive breeding. Modification of NSG and derivative strains represent an opportunity to optimize the engraftment of other human lineages. The ability to apply modern genome modification technology to different inbred mouse strains is highly desirable but must overcome two major technical hurdles - 1) Reproductive biology constraints that prevent live born progeny after reagent delivery methods such as microinjection or electroporation and 2) Cell intrinsic DNA-repair processes that are a prerequisite enabling gene editing tools. Given the SCID mutation (Prkdcscid) in the NSG background compromises some DNA repair pathways, it was not clear whether nuclease assisted recombination technologies would be a robust tool to modify NSG (and derivatives) genomes at the zygote stage. Here, we demonstrate that CRISPR-Cas9 is an effective tool for introducing genome modifications in NSG and present a specific example using the Hprt locus. Furthermore, we will present general experience with genomic modifications using NSG, and its derivatives, to emphasize direct modification of these genomes is technically feasible and is enabling the rapid sequential genetic tailoring in this high value cancer model strain. Citation Format: David S. Grass, F William Buaas, Michael V. Wiles, Benjamin E. Low, Peter Kutny. Gene editing in the NSG mouse strain and its genetic derivatives [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5111.