Abstract 5713
Background
Historically, immunotherapies have been tested in syngeneic mouse models and until now only limited CRC syngeneic cells are available. Animal models with functioning human immune systems are critically needed to more accurately evaluate checkpoint blockers delivery, therapeutic response, and to better define biomarker expression in the presence of a competent immune system.
Methods
To better address the efficacy of immune checkpoint therapy specifically in relation to presence of a BRAFmutation, we developed a novel platform for the generation of somatic mosaic models of CRC enabling (i) high-throughput generation of genetically complex syngeneic models of cancer, (ii) tracing studies through fluorescence reporters.
Results
Cdx2Cre/+ mice, expressing the Cre recombinaseunder the control of a human Cdx2 promoter/enhancer sequence have been crossed with the R26LSL-Cas9-Gfp strain to generate models allowing for tissue specific activation of Cas9 and Gfpreporter only in CDX2 positive cells. This strain has been crossed with BRAFFSF-V600E mice to generate the final model. 6-8 weeks old mice have then been transduced with AAV constructs expressing the FLPO recombinasethat can be activated by Cre recombinase and sgRNAs targeting APC, TP53, MLH1, MSH2and ARID1Aalone or combined, in order to model MSI CRC (APC-TP53-MLH1and ARID1A-MLH1conditional mosaic knock-outs) and MSS CRC (APC-TP53 conditional mosaic knock-out). Viral particles have been surgically delivered via subserosal cecal injection and mice monitored for tumor formation by IVIS imaging. 35 mice injected with 3 combinations of tumor suppressors provide a diverse immunology repetoire. Cell lines isolated from genetically modified mice will provide a physiologic relevant and feasible means to study the mechanisms of response and resistance to immunotherapies and to understand biological and molecular differences between BRAFmutated MSI and MSS tumors.
Conclusions
This project focuses on the identification and characterization of the functional drivers of CMS1CRC tumors leveraging in vivomosaic genome editing technologies and functional genetic labeling of malignant sub-populations emerging during disease progression and in response to therapy.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
MD Anderson Cancer Center.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
5877 - Efficacy of anti-PD(L)1 treatment in patients with metastatic urothelial cancer based on mRNA- and protein- based PD-L1 determination: Results from the multicentric, retrospective FOsMIC trial
Presenter: Jonas Jarczyk
Session: Poster Display session 3
Resources:
Abstract
5204 - A differential bladder microbiota composition is associated with tumor grade in bladder cancer.
Presenter: Monica Parra-Grande
Session: Poster Display session 3
Resources:
Abstract
4904 - Molecular characterization of metastatic urothelial carcinoma (mUC) in prior or current smokers (PCS) vs non-smokers (NS)
Presenter: Victor Sacristan Santos
Session: Poster Display session 3
Resources:
Abstract
5370 - Evaluation of different diagnostic methods for identification of FGFR alteration in advanced urothelial carcinomas: Proficiency Results based on multiple RNA extraction kits and mutation detection methods
Presenter: Veronika Weyerer
Session: Poster Display session 3
Resources:
Abstract
2579 - Title: Genomic characterization of non-schistosomiasis-related squamous cell carcinoma (NSR-SCC) of the urinary bladder: a retrospective study of potential prognostic and predictive biomarkers
Presenter: Esmail Al-ezzi
Session: Poster Display session 3
Resources:
Abstract
2203 - TiNivo: Tivozanib combined with nivolumab results in prolonged progression free survival in patients with metastatic renal cell carcinoma (mRCC). Final Results.
Presenter: Philippe Barthelemy
Session: Poster Display session 3
Resources:
Abstract
4712 - First-Line Pembrolizumab (pembro) Monotherapy for Advanced Non‒Clear Cell Renal Cell Carcinoma (nccRCC): Updated Follow-Up for KEYNOTE-427 Cohort B
Presenter: Cristina Suárez
Session: Poster Display session 3
Resources:
Abstract
2091 - First-Line Pembrolizumab (pembro) Monotherapy in Advanced Clear Cell Renal Cell Carcinoma (ccRCC): Updated Follow-Up For KEYNOTE-427 Cohort A
Presenter: James Larkin
Session: Poster Display session 3
Resources:
Abstract
2368 - Association Between Depth of Response and Overall Survival: Exploratory Analysis in Patients With Previously Untreated Advanced Renal Cell Carcinoma (aRCC) in CheckMate 214
Presenter: Viktor Grünwald
Session: Poster Display session 3
Resources:
Abstract
6008 - Quality of life in previously untreated patients with advanced renal cell carcinoma (aRCC) in CheckMate 214: updated results
Presenter: David Cella
Session: Poster Display session 3
Resources:
Abstract