Reflections on 'older' drugs: learning new lessons in rheumatology.

The management of rheumatic and musculoskeletal diseases has transformed over two decades of exciting discoveries regarding pathogenesis and innovative drug development. The introduction of sophisticated immunomodulatory therapies has given renewed hope to many patients, but notable challenges remain within the field of rheumatology. Before the advent of biologic therapies, conventional synthetic DMARDs (csDMARDs) provided effective disease control for some patients, although a comprehensive understanding of the mechanisms by which these drugs exert their effects remained elusive. Reflecting upon the efficacy and mechanisms of action of csDMARDs can provide intriguing insights. First, contemplating past approaches brings our remarkable current approaches concerning pathogenesis-driven discovery and drug development into sharper focus. Second, increased understanding of the mode of action of these older drugs might in turn provide exciting opportunities for the understanding of disease and for the development of future therapies.