An antisense oligonucleotide (ASO) is a single-stranded, synthetic RNA (or DNA) sequence. ASOs are designed to selectively bind via complementary base-pairing to messenger RNA (mRNA) and are the basis for one type of RNA-based therapeutics being explored to treat cancer and genetic disorders. RNA-based therapeutics are catagorized as a type of gene therapy.
The binding of an ASO to precursor-mRNA (pre-mRNA) can alter splicing to either include a skipped exon or exclude an exon. In either case, the therapeutic goal is to form a mature mRNA that will be made (translated) into a functional protein. Alternatively, the binding of an ASO to mature mRNA (after processing) can either prevent a ribosome from attaching to the mRNA or can attract a special type of cellular enzyme that breaks down mRNA. In either of these cases, the therapeutic goal is to prevent the mature mRNA from being made into a protein, or, in other words, to prevent translation.