LAUSR

&NA; Non‐human primates (NHPs) are currently considered to be the non‐rodent species of choice for the preclinical safety assessment of single‐stranded oligonucleotide (SSO) drugs. We evaluated minipigs as a potential alternative to NHPs to test the safety of this class of compounds. Four different phosphorothioated locked nucleic acid‐based SSOs (3 antisense and 1 anti‐miR), all with known safety profiles, were administered to minipigs using similar study designs and read‐outs as in earlier NHP studies with the same compounds. The studies included toxicokinetic investigations, in‐life monitoring, clinical and anatomic pathology. In the minipig, we demonstrated target engagement by the SSOs where relevant, and a similar toxicokinetic behavior in plasma, kidney, and liver when compared with NHPs. Clinical tolerability was similar between minipig and NHPs. For the first time, we showed similar and dose‐dependent effects on the coagulation and complement cascade after intravenous dosing similar to those observed in NHPs. Similar to NHPs, morphological changes were seen in proximal tubular epithelial cells of the kidney, Kupffer cells, hepatocytes, and lymph nodes. Minipigs appeared more sensitive to the high‐dose kidney toxicity of most of the selected SSOs than NHPs. No new target organ or off‐target toxicities were identified in the minipig. The minipig did not predict the clinical features of human injection site reactions better than the NHPs, but histopathological similarities were observed between minipigs and NHPs. We conclude that there is no impediment, as default, to the use of minipigs as the non‐rodent species in SSO candidate non‐clinical safety packages.