Strategies for in vivo screening and mitigation of hepatotoxicity associated with antisense drugs

In this study we tested and modeled the hepatotoxic potential of locked nucleic acid-containing phosphorothioated antisense oligonucleotide (ASOs) gapmers designed to target human BACH1 and PAR-2 transcripts. Using RNA extracted from mouse livers we compared expression profiles of off-target (i.e. genes other than the intended target that were predicted by RNArcher software to fully or partially interact with a given ASO) and ‘background’ genes (not identified as potential targets). The analysis revealed a correlation between the number of potent unintended interactions (fold change = -0.5 with an associated p-value = 0.01) and the severity of liver phenotype. A subsequent pathway analysis has not shown any common patterns, suggesting that the adverse effects emerged through divergent mechanisms. We propose that efforts should be focussed on designing and progressing ASOs with lowest number of putative off-target genes, which will minimize the chances of encountering potent interactions and hence adverse liver phenotypes.