Pharmaceuticals Targeting Nonsense Mutations in Genetic DiseasesProgress in Development

Premature termination codons (PTCs) are a cause of numerous genetic disorders spanning diseases that affect children and adults, and are produced by base pair substitutions that create abnormal stop codons within the open reading frame. Several ribosome-binding drugs, including select aminoglycosides and synthetic novel small molecules, induce ‘translational readthrough’ of PTCs, restoring full-length functional protein in a number of preclinical and clinical settings. In this review, we examine the mechanistic underpinnings of PTC suppression, including the nature of the interactions between agents that suppress PTCs and the eukaryotic ribosome regulation of transcript levels in eukaryotic cells, and the importance of the mRNA context in suppression of PTCs. We also examine results from proof-of-concept studies in preclinical model systems and clinical trials (with a focus on PTC124). Several of the published studies in cystic fibrosis have reported improvements in cystic fibrosis transmembrane conductance regulator (CFTR) biomarkers during short-term evaluation, including topical and systemic aminoglycoside treatment, and oral dosing with PTC124. These results, coupled with our improved understanding of how translation termination is regulated at PTCs, will help guide future directions of research involving this innovative treatment strategy for genetic diseases.