Molecular design and application of splice-switching antibody-oligonucleotide conjugate for hypertrophic cardiomyopathy-related MYBPC3 splice modulation.

Familial hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease and is predominately caused by mutations in genes that encode proteins associated with cardiac sarcomeres, the functional unit critical for basic contractile heart function.

Nearly two-thirds of individuals with HCM experience mild to no symptoms, whereas the remaining one-third experience dyspnea, chest pain, or arrythmias that can progress into heart failure, causing sudden cardiac death, particularly in young competitive athletes.

Current strategies to treat HCM include invasive procedures such as septal or left ventricular reduction therapies or cardiac implantation.

Such methods are not curative, but rather aimed to treat symptoms and not the pathophysiological cause of the disease, thus highlighting the importance of new molecular therapies that can prevent HCM.

One potential method to correct HCM mutations is through the use of antisense oligonucleotides (ASOs), short polymeric nucleic acid biomolecules, that can correct aberrant RNA splicing, a fundamental biological process for gene expression, by binding to pre-mRNA splice sites and block recognition by the spliceosome.

However, delivery of ASOs to cardiac cell models, including cardiomyocytes differentiated from human induced pluripotent stem cells (iPSC-CMs), remains to be one of the biggest challenges in ASO efficacy.

Herein, this project proposes to design and test the effects of chemically-modified, splice-switching antisense oligonucleotides conjugated to an antibody, an antibody-oligonucleotide conjugate (AOC), using a unique traceless linker strategy that has the potential to not only treat splicing defects in HCM, but also provide proof-of-concept of improved cell delivery of ASOs.

AOCs will be tested in iPSC-CMs bearing cryptic splice mutations in MYBPC3 (myosin binding protein C), a gene whose mutations are commonly associated with HCM.