Four mono-PEGylated therapeutic proteins

with a PEG molecule of 30 kDa or larger have been approved and are on the market [25]. These include, Cimzia® (PEG-anti-TNFα-Fab’) for treatment of rheumatoid arthritis and Crohn’s disease with GDC-0068 clinical trial a 40 kDa branched PEG; Macugen® (PEG-anti-VEGF-aptamer) for treatment of macular degeneration with 40 kDa PEG; Mircera® (PEG-epoetin beta) for treatment of anaemia in chronic renal failure (CRF) with a 30 kDa PEG and PEGASYS® (PEG-INF α-2a) for treatment of chronic hepatitis C with a 40 kDa branched PEG (Table 1). Cimzia®, Mircera® and PEGASYS® are reviewed further due to their large high molecular weight PEG sizes, while Macugen® is excluded due to its intravitreal

administration route. Table 2 summarizes the available preclinical studies relevant for long-term safety and, provides approximate PEG doses and publicly available safety information available from FDA and EMA regulatory summaries that are relevant to assess long-term safety of PEG molecules. Mircera® (Roche) is a long-acting erythropoiesis stimulating agent, approved in 2007 for chronic iv and subcutaneous (sc) treatment for anaemia associated with CRF. It is obtained by adding a PEG moiety to epoetin beta, giving CDK inhibitor it a higher molecular weight and a longer half-life than the non-PEGylated form. Four, 13 and 26 week toxicity studies of Mircera® were conducted in rats. No PEG-related changes were observed in these toxicity studies. In rats, both the parent protein and the 30-kDa PEG were shown to be excreted in urine [17, 18]. Clinical doses of Mircera® (initially named CERA for Continuous Erythropoetin Receptor Activator) are approximately 0.6 μg kg−1 once every 2 weeks of which approximately 50% is PEG. Many clinical studies have reported the safety of CERA therapy [26]. The adverse events reported for Mircera® in the EMA EPAR summary (hypertension, diarrhoea, headache and upper

respiratory tract effects) were similar to the reference group (epoetin α or β) and to those expected in the CRF population. In a single-arm, open-label, multicenter MCE study, conversion of a large population of haemodialysis patients from epoetin or darbepoetin to monthly CERA administration was shown to be efficacious and safe, regardless of the previous type of therapy. Adverse events reported were those expected in patients with CRF [27]. In a paediatric study evaluating the efficacy and safety of CERA therapy in peritoneal dialysis (PD) patients, stable PD children on twice-a-week, erythropoietin (EPO) were converted to sc CERA, scheduled every 2 weeks. The follow-up was for 6 months, and CERA was found to be an effective and safe therapy [28].