According to GlobalData’s Clinical Trials Database, the most popular neurology indication for clinical trials is pain, which currently has 265 ongoing trials in Phase I, II, and III collectively. Of these, the most significant contribution is from post-operative pain trials. As shown in the figure below, the other fields are at a notable distance from pain, despite the fact that these also have high unmet needs.

Figure 1: Number of Ongoing Clinical Trials in Neurology, July 2017

The large number of trials for pain-related indications can be attributed to the inadequate efficacy and safety profiles for the existing medications. Only 40% of these patients have about 30% pain relief, meaning that 60% of patients have no pain relief at all. This is largely due to the challenge in identifying the most appropriate targets for investigation, as multiple contributing factors are involved in this complex—and often subjective—physiological phenomenon.

Until recently, pain was traditionally seen as a symptom accompanying another disease, and thus therapies for pain were targeted at symptom reduction, rather than at treating the underlying cause of the pain. Advances in the understanding of the pathophysiological and molecular mechanisms of pain have resulted in its redefinition and reclassification, particularly with the recognition that chronic pain is a disease within itself. It is surprising to find Alzheimer’s disease as one of the most frequently researched indications, currently with 40 ongoing clinical trials, considering that Alzheimer’s has the highest attrition rate within neurology: 72% of agents fail in Phase I, 92% fail in Phase II, and 98% fail in Phase III.

However, this is indicative that the industry is keen to find a drug that can halt or slow down disease progression, given that the few available drugs are aimed at treating the symptoms of the disease. As with the other indications shown in the figure above, the common denominator is the significant challenges that pharma companies are facing. An ongoing hurdle is the lack of concrete biomarkers for disease progression, meaning that all drug trials are designed around symptomatic changes. Although the understanding of these diseases at the genetic and molecular level has increased over the past 20 years, the progress in knowledge has not easily translated in the clinic.