EVIDENCE FOR THE PRESENCE OF GLYCATION ADDUCTS IN PROTEIN THERAPEUTICS

Glycation is a non-emzymatic reaction between free amino groups and reducing sugars (16), which was shown to take place also in human (13). It causes severe complications in diabetic and uremic patients, whereas in normal subjects contributes to senescence and aging. This study points to another negative aspect of glycation concerning the quality of protein therapeutics. Although therapeutic proteins are designed to be equivalent to their natural human counterparts, the development of anti-drug antibodies in patients treated with proteins appears to be a rule rather than the exception (5, 21, 23). The anti-drug antibodies may sometimes cause serious complications such as allergic reactions and anaphylaxis (15). In addition, severe clinical consequences might be expected with those therapeutic proteins, whose endogenous counterparts are endowed with essential biologic functions. For example, neutralizing antibodies to megakaryocyte-derived growth factor and recombinant human erythropoietin have been found to cause severe thrombocytopenia (30) and pure red cell aplasia (14), respectively. The reasons for the immunogenicity of protein therapeutics still remain unresolved. This study provides evidence for the presence of potentially immunogenic glycation adducts in widely used protein drugs that could compromise therapeutic efficacy and patient safety.