Protein therapeutics in sports drug testing: past, present and future

The detection of protein drugs in doping control samples is associated with numerous challenges as not only a sufficient analytical sensitivity but also unambiguous identification and differentiation from endogenous analogues have to be ensured. Moreover, the structural complexity of proteins in general and, especially, when post-translational modifications such as glycosylations are present, necessitates the use of sophisticated technologies as for instance immunoassays and liquid chromatography interfaced with high-resolution tandem mass spectrometry. Consequently, it is of utmost importance to continuously improve the existing sports drug testing assays and also search for novel/improved biomarkers indicative of protein doping.