Abstract
Chemical optimization of ribose has significantly advanced nucleic acid therapeutics (NATs) by improving the stability, specificity, and safety of therapies like small interfering RNAs, CRISPR-Cas9 guide RNAs, and GAPmers. Recent research has extended this approach to splice-switching oligonucleotides (SSOs), which target splicing events. Our study identifies a set of mixed-modification patterns-combining 2'-O-Methyl, 2'-MethOxyEthyl, 2'-Locked Nucleic Acid, and 2'-Constrained Ethyl ribose moieties (2'OMe, 2'MOE, LNA, and cET)-that enhance SSO potency. We term this strategy lateral mixed positional configuration, which improves SSO efficacy across various sequences and could reduce the trial-and-error process in SSO development. This advancement is supported by NAT Unlabeled Reporter Assay (NATURA), a novel platform for high-throughput quantification of NATs' functional delivery and potency. NATURA uses a reporter gene system and a comprehensive sequence library to test modifications and delivery methods, validated in a transgenic mouse model. This approach aims to accelerate NAT development and address challenges in delivering these therapies to patients.