Antisense oligonucleotides (ASOs) are short, synthetic, single-stranded oligodeoxynucleotides that can alter RNA and reduce, restore, or modify protein expression through several distinct mechanisms. ASO technology has become an important drug discovery platform for most major pharmaceutical companies. To date, six antisense drugs have been approved by regulatory agencies to treat diseases spanning viral infections, hyperlipidemias, and neurological diseases. More than 50 additional ASO drugs are in clinical trials. For an ASO drug product, an assay of its active pharmaceutical ingredient…