Abstract B007: Leveraging HIF2α expression in the kidney epithelium to generate a genetically engineered mouse model for clear-cell renal cell carcinoma (ccRCC)

Abstract Clear cell renal cell carcinoma is the most common and aggressive form of kidney cancer. A hallmark of ccRCC is a defect in the VHL gene, which leads to the upregulation of oncogenic transcription factor HIF2α. While HIF2α inhibitors and immunotherapies have shown initial clinical promise, response rates are generally less than 50%, and most patients relapse. Preclinical ccRCC drug development is hindered by a lack of tractable, immunocompetent ccRCC mouse models that faithfully recapitulate human ccRCC (e. g. are dependent on HIF2α for activity). My colleagues and I recently demonstrated the use of an adeno-associated virus (AAV) -based system to somatically edit genes in kidneys of adult immunocompetent mice, which resulted in the formation of macroscopic ccRCCs with low latency and high penetrance. The AAVs contained CRISPR sgRNAs targeting Vhl, and other ccRCC tumor suppressor genes - Keap1, Pbrm1 and Tsc1, and was injected into the kidneys of mice expressing Cre recombinase in Pax8+ cells, leading to the expression of Cas9 (due to excision of a lox-Stop-lox cassette). While this served as a proof-of-principle for the use of CRISPR to generate a somatic mouse model of kidney cancer, ccRCCs generated were HIF2α-independent, similar to previous genetically engineered ccRCC mouse models. In thinking about this, I confirmed that HIF2α gene Epas1, is expressed sparsely throughout the kidney epithelium, while Pax8 is expressed abundantly. Thus, it is possible in the study described above those tumors formed by Pax8+ve, Epas1-ve cells simply outcompete nascent tumors formed by Pax8+, Epas1+ cells. Therefore, I hypothesized that restricting Cre expression to cells expressing Epas1 increase the possibility of generating tumors that are HIF2α-dependent upon Vhl loss. As a first step toward this goal, I have already generated an Epas1-Cre mouse, by knocking in Cre recombinase into the endogenous mouse Epas1 locus. I showed Cre-recombination to occur in a subset of kidney epithelial cells and glomerular cells. I propose to 1) Define the cellular identity and consequences of Vhl loss in Epas1 expressing mouse kidney cells ex vivo and in vivo, and 2) Apply our CRISPR-based AAV platform to Epas1 expressing cells to test the HIF2α dependency of tumors. This work will strongly benefit preclinical ccRCC drug development efforts including those involving HIF2α inhibitors and immunotherapies. Citation Format: Vijyendra Ramesh, Gregory Wyant, Berkay Simsek, Gabriel R. De Oliveira, Maxwell D. Seager, Sabina Signoretti, William G. Kaelin. Leveraging HIF2α expression in the kidney epithelium to generate a genetically engineered mouse model for clear-cell renal cell carcinoma (ccRCC) abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Innovations in Kidney Cancer Research: From Molecular Insights to Therapeutic Breakthroughs; 2026 Mar 13-16; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2026;86 (5Suppl₂): Abstract nr B007.