Impact of anti-PEG IgM antibodies on the pharmacokinetics of pegylated asparaginase preparations in mice

The potential impact of pre-existing anti-PEG antibodies on the asparaginase activity kinetics of two pegylated L-asparaginase preparations - pegylated recombinant L-asparaginase (PEG-rASNase MC0609) and pegaspargase (pegylated Escherichia coli L-asparaginase) - was investigated in immune competent, naive B6D2F1-hybrid mice. To generate anti-PEG antibodies, mice were pre-sensitised by repeated injections of 40 kDa PEG-Diol without being conjugated to a carrier. Successful PEG-Diol pre-sensitisation was verified by analysis of anti-PEG antibody titers in serum. 88-100% of animals developed PEG-specific anti-PEG IgM antibodies after PEG-Diol presensitisation. All animals positive for anti-PEG IgM antibodies and control animals (without prior PEG-Diol pre-sensitisation) were treated once with PEG-rASNase MC0609 or pegaspargase, and asparaginase enzyme activity levels and immunogenicity of both preparations were analysed. Known serum asparaginase activity profiles were measured after treatment with PEG-rASNase MC0609 or pegaspargase in all treatment groups. No rapid decrease of asparaginase activity was observed - irrespective of successful PEG-Diol pre-sensitisation and presence of acquired anti-drug-IgG and/or anti-PEG IgM antibodies. In conclusion, the pharmacokinetics of pegylated L-asparaginase was unaffected by the presence of pre-existing anti-PEG IgM antibodies in immune competent B6D2F1-hybrid mice Probably the titre or affinity of these anti-PEG IgM antibodies were too low to influence the pharmacokinetics of PEG-rASNase MC0609 or pegaspargase or anti-PEG IgM antibodies bound to PEG-ASNase without neutralising capabilities. Thus, early loss of asparaginase activity as observed in serum of ALL patients is a complex process and cannot be explained solely by the existence of pre-existing anti-PEG antibodies. (C) 2016 Elsevier B.V. All rights reserved.