Project 4 Treatment of Advanced Ovarian Cancer Using Gene-Edited NK CAR Cells

ABSTRACT – PROJECT 4 Women diagnosed with advanced epithelial ovarian cancer (EOC) have a median 5-year survival rate of ~20%, and recurrent EOC remains essentially incurable. Novel immunotherapies, including immune checkpoint blockade and chimeric antigen receptor (CAR) T cell therapies have had some success, but response rates have been typically below 20%. Similarly, the response rates to molecularly targeted therapies have been limited, partly due to the lack of recurrently mutated targets and the high level of chromosomal instability characteristic of EOC. Synthetic lethality via PARP inhibition and VEGF blockade have demonstrated some benefit, but mechanisms of resistance have already surfaced for these new therapies. The long-term goal of our research program is to develop highly effective immune cell-based therapies capable of eliminating recurrent EOC. In Project 4, we will use advanced gene editing techniques that we have developed to produce hyperfunctional Natural Killer (NK) cells for treating advanced EOC. We focus on NK cells because i) they do not require antigen priming and ii) side effects, such as graft versus host disease and cytokine release syndrome, are minimal compared to T cell therapy. We propose to make two fundamental alterations to human NK cells obtained from healthy donors. The first genetic alteration removes an intracellular signaling protein that dampens NK activation (the CISH gene) using a modified CRISPR/Cas9 protocol we have developed that is highly effective in primary human NK cells. The second genetic alteration is to site-specifically integrate a chimeric antigen receptor (CAR) gene that we have developed specifically for NK cells. This CAR NK targets the mesothelin protein, a prevalent EOC tumor antigen. Our central hypothesis is that gene editing can be used to overcome signaling inhibition and improve NK cell targeting, persistence and function, resulting in improved therapeutic outcomes for women with advanced EOC. The work proposed in this project includes generating and testing the gene edited NK cells for enhanced function by co-culturing with ovarian cancer cells in vitro and testing in both cell line- and patient-derived xenograft models of EOC in vivo. The data from these preclinical tests will be used to guide the design of the Phase I clinical trial using these gene-edited NK cells. This project will determine whether gene-edited CAR NK cell immunotherapy in humans is safe and has the potential to improve outcomes in the setting of recurrent EOC. In addition, what we learn from this study will have the broader impact of potential future application to other malignancies, as the engineering techniques can be quickly adapted to remove different negative regulators and to target other tumor antigens with NK- specific CARs.