Abstract Body (Do not enter title and authors here): Introduction

Heart failure with reduced ejection fraction (HFrEF) remains a significant clinical challenge, evidenced by high hospitalization rates and five-year mortality. Current treatments are limited by side effects, poor patient compliance, and the necessity for gradual drug titration. These challenges highlight the need for new therapies that are both safe and effective in targeting the structural remodeling pivotal to disease progression post-myocardial infarction (MI). e-therapeutics (ETX) uniquely combines computation and RNAi to discover life-transforming medicines. ETX’s RNAi platform, GalOmic™, enables generation of specific, potent, and long-acting siRNA therapies that effectively silence novel gene targets in hepatocytes. This highly specific mechanism of action limits unwanted side effects, positioning it as a promising approach to HFrEF treatment.

Methods

Potent siRNAs against a hepatic target with cardioprotective potential were designed in silico. Candidate siRNAs were screened in vitro in HEK293 cells and in vivo in C57BL/6J mice to select the lead GalOmic™ siRNA, ETX-258. MI was induced by ligation of the left anterior descending artery in C57BL/6J mice after which ETX-258 was injected subcutaneously weekly for 6 weeks. Eplerenone, a mineralocorticoid receptor antagonist which is part of the current treatment regimen for HFrEF, was used as a comparator. Cardiac function was assessed by echocardiography at 2-, 4- and 6-weeks post-MI. Cardiac damage and structural remodeling were evaluated using circulating biomarkers of cardiac function and histological assessment.

Results

ETX-258 was selected as a highly active siRNA for the treatment of heart failure with a long duration of action. Post-MI treatment with ETX-258 significantly improved key echocardiographic parameters of cardiac function, including ejection fraction and total cardiac output, achieving results comparable to eplerenone. Additionally, both structural cardiac parameters and markers of damage and remodeling showed significant improvements, reaching similar levels in both ETX-258 and eplerenone-treated mice.

Conclusions

High unmet need remains for HFrEF patients despite existing therapies. These results highlight the potential of ETX-258 to improve cardiac function and pathogenic structural remodeling post-MI. This, paired with the long duration of action and favorable safety profile of GalOmic™ siRNAs, makes ETX-258 a promising candidate for further clinical development.