Somatic cell genome editing (SCGE) has remarkable promise to transform our therapeutic toolbox for heart
failure due to Titin truncation variants (TTNtvs). However, despite having the knowledge of the pathogenic
TTNtvs, their molecular consequences, and SCGE technologies including CRISPR genome editing and
transcriptional activation to target TTNtvs, the lack of in vivo studies using humanized TTNtv animal models has
hindered clinical development. There remain key knowledge gaps limiting SCGE development for TTNtvs
including the lack of a systematic examination of the proportion of TTNtv alleles and cardiomyocytes that need
to be corrected for clinical benefit, and the toxicology profile of SCGE enzymes and delivery systems including
genotoxicity and immunogenicity. Our long-term goal is to develop SCGE for heart failure patients. While in vitro
studies to evaluate the efficacy and safety of SCGE editors and delivery systems such as by utilizing human
engineered heart tissues (EHTs) are important, they do not replace the need for animal model studies that
recapitulate the complex pathophysiology of heart failure. Guided by our comprehensive preliminary data and
unique reagents including SCGE components functionally validated in TTNtv EHTs, humanized Ttntv mice and
cardiotropic adeno-associated viruses; our 1-year study will include two Specific Aims to determine efficacy and
safety of 1) TTNtv reading frame repair and 2) TTN transcriptional activation in a humanized Ttntv mouse.
Execution of these Aims will provide editing thresholds, safety, and toxicity for two SCGE approaches to treat
TTNtvs that we expect will serve as a resource for the broader scientific community.