cancers Review Integrins as Therapeutic Targets: Successes and Cancers Sabine Raab-Westphal 1, John F. Marshall 2 and Simon L. Goodman 3,* 1 Translational In Vivo Pharmacology, Translational Innovation Platform Oncology, Merck KGaA, Frankfurter Str. 250, 64293 Darmstadt, Germany;
[email protected] 2 Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK;
[email protected] 3 Translational and Biomarkers Research, Translational Innovation Platform Oncology, Merck KGaA, 64293 Darmstadt, Germany * Correspondence:
[email protected]; Tel.: +49-6155-831931 Academic Editor: Helen M. Sheldrake Received: 22 July 2017; Accepted: 14 August 2017; Published: 23 August 2017 Abstract: Integrins are transmembrane receptors that are central to the biology of many human pathologies. Classically mediating cell-extracellular matrix and cell-cell interaction, and with an emerging role as local activators of TGFβ, they influence cancer, fibrosis, thrombosis and inflammation. Their ligand binding and some regulatory sites are extracellular and sensitive to pharmacological intervention, as proven by the clinical success of seven drugs targeting them. The six drugs on the market in 2016 generated revenues of some US$3.5 billion, mainly from inhibitors of α4-series integrins. In this review we examine the current developments in integrin therapeutics, especially in cancer, and comment on the health economic implications of these developments. Keywords: integrin; therapy; clinical trial; efficacy; health care economics 1. Introduction Integrins are heterodimeric cell-surface adhesion molecules found on all nucleated cells. They integrate processes in the intracellular compartment with the extracellular environment. The 18 α- and 8 β-subunits form 24 different heterodimers each having functional and tissue specificity (reviewed in [1,2]).