"The clinical advantage of PEG-IFNa-2B results from the fact that it is very slowly cleared after administration, resulting in a longer terminal elimination half-life (t 1/2 ) and a higher systemic exposure (both AUC and C max ) in both preclinical and clinical studies conferring an increased efficacy compared to IFNa-2B. The pegylation of IFNa- 2B also renders the molecule less immunogenic; Pegasys ® (pegylated Interferon a) is less immunogenic than Roferon ® (native Interferon a). The toxicokinetic profile of PEG-IFNa-2B obtained in a GLP preclinical toxicology study involving the repeated administration of the biopharmaceutical for 13 weeks by the subcutaneous route in Macaca fascicularis.