Clinical Trials in Spinal and Bulbar Muscular Atrophy—Past, Present, and Future

Spinal and Bulbar Muscular Atrophy (SBMA), also known as Kennedy's disease, is a rare adult-onset lower motor neuron disorder with a classic X-linked inheritance pattern. It is caused by the abnormal expansion of the CAG-repeat tract in the androgen receptor gene. Despite important progress in the understanding of the molecular pathogenesis and the availability of a broad set of model organisms, successful translation of these insights into clinical interventions remains elusive. Here we review the available information on clinical trials in SBMA and discuss the challenges and pitfalls that impede therapy development. Two important factors are the variability of the complex neuro-endocrinological phenotype and the comparatively low incidence of the disease that renders recruitment for clinical trials demanding. We propose that these challenges can be and need to be overcome by fostering closer collaborations between clinical research centers, the patient communities and the industry and non-industry sponsors of clinical trials.