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

Introduction: Protein drugs comprising - among Others - recombinantly produced analogues of endogenous Hormones as well as genetically or chemically modified long-acting derivatives, therapeutic antibodies, and recombinant fusion proteins are not only promising therapeutic means for the treatment of numerous diseases but can also be relevant as performance-enhancing agents in sports.

Areas covered: Within this review, classical and emerging protein-therapeutics with (presumed) effects on muscle growth and erythropoiesis will be described and both established and potential strategies for their detection in doping control samples will be discussed.

Expert opinion: 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.