Development of a gene edited platform to enable human allogeneic cell replacement therapy

SUMMARY Stem cell-based therapies have the potential to regenerate cells, tissues, and organs damaged by injury, age, and autoimmunity. Pluripotent stem cell (PSC)-based clinical trials have begun in which retinal pigmental epithelial cells, dopaminergic neurons, and insulin-producing beta cells are used to treat macular degeneration, Parkinson’s disease, and type 1 diabetes (T1D), respectively. The initial results have been quite promising, and clearly the future of this avenue of investigation and treatment is bright. The case for using this approach to treat T1D is perhaps the strongest, given that mature beta cell transplants from cadavers have long been shown to be curative, and initial PSC-derived beta cell transplants have also led to independence from exogenous insulin. Aleutian Therapeutics is focused on this line of treatment for curing T1D. Nonetheless, there are major barriers to be overcome to make these types of PSC-based therapies practical and accessible. Autologous iPSC-based approaches, for instance, are costly and unscalable. Allogeneic PSC-based approaches, on the other hand, require administration of toxic immunosuppressive drugs to avoid destruction of transplanted cells by the host immune system. To overcome these limitations, Aleutian Therapeutics (Aleutian) is developing a novel gene editing-based platform to enable allogeneic PSCs and their progeny to evade recognition by the host immune system. Aleutian’s innovative approach has successfully demonstrated survival of PSC grafts in mice with a fully functional immune system. In contrast, others developing similar technologies have relied on in vitro studies or humanized mice, which may not represent the complexity of a native immune system. In fact, Aleutian’s technology has been shown to enable human PSC to survive for nearly 6 months in immunocompetent mice, effectively overcoming the xenogeneic barrier, often regarded as even higher than the allogeneic barrier. Having used this approach to successfully identify the key immune recognition pathways that must be evaded, the goals of this Phase 1 study are to now 1) adapt our system in which mouse immune evasion genes are swapped with the functionally equivalent human orthologs; 2) define the minimum required combinations of these human immune evasion factors through functional assays; 3) confirm that these edits do not impact beta cell differentiation and allow beta cells to evade the key arms of the host immune system. Successful completion of this study will inform the design and generation of a CRISPR-Cas9 edited cell line that can be further evaluated in in vivo pre-clinical studies during a Phase II program.