Controlling the controls: On the importance of validated negative control ASOs

Antisense oligonucleotide (ASO) therapeutics have moved from a niche modality to a validated class of drugs, with more than a dozen agents now approved and many more advancing through preclinical and clinical pipelines. Each of these programs depends on a deceptively simple ingredient: a negative control ASO that separates the sequence-specific activity of a candidate oligonucleotide from the effects of its chemistry and delivery. In practice, researchers usually improvise a scrambled or mismatched control for each new candidate, an approach that is rarely well characterized and can involve unpredictable biological activity.