Advancing CRISPR Gene Editing for Solid Tumors Toward Clinical Application

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), when complexed with their CRISPR-associated nucleases (Cas), create a genetic engineering tool that has revolutionized the gene editing world. It is now believed that molecular medicine could support, or augment, standard of care therapy for a variety of genetic diseases including cancer. We are developing CRISPR-directed gene editing for squamous cell carcinoma of the lung, in which the NRF2 gene, the master regulator responsible for resistance to chemotherapy and other stress factors, is disabled at a frequency that enables a reduction in the levels of treatment. Our efficacy studies have provided foundational support for advancing this technology, and now expand our analyses to examine genetic rearrangements and off-target effects induced by such activity in normal and tumor cells. Our lead biomolecule, R34G, cleaves the NRF2 gene in cancer cells but not in normal cells, providing the foundational support for a novel genetic tool that acts only on tumor cells. We discovered that CRISPR-directed gene editing of the NRF2 gene can induce exon skipping, but this genetic rearrangement does not appear to negatively influence the consistent observations of increased sensitivity to chemotherapy. Our extensive molecular analyses for off-target activity support R34G as a safe biomolecule as we currently do not see elevated levels of secondary activity. While we are cautiously optimistic as we design parallel experimental tracks in which we will continue to examine R34G for both safety and efficacy with increasing scrutiny.