Domenico Merante, George Skouteris and Rayaz Malik
Randomised, double blind, placebo controlled studies are necessary in neuropathic pain clinical research arena. Few drugs are approved for the indication of painful Diabetic Peripheral Neuropathy (DPN): typically these drugs lose their therapeutic response over time and have far from an ideal tolerability risk profile. In addition to that, the response to placebo continues to represent a significant challenge in clinical trials of painful DPN, as well as any other neuropathic pain condition. Hence to date few molecules have progressed to phase 3 in painful DPN and even fewer have gained approval. Thus several studies failed because the primary endpoint of statistical superiority to placebo and a clinically relevant reduction of ADPS (Average Daily Pain Score) were not achieved. Any attempt to mitigate the placebo response in this condition may allow future new drugs to successfully progress from Proof of Concept to phase 3 of clinical development and hopefully to their approval. As of today this remains a relevant challenge in a therapeutic area of a well-recognized unmet medical need. The dangers of treating acute and chronic pain with opioids, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) or acetaminophen are considerable. By mitigating the placebo response in neuropathic pain clinical trials, this may expedite the discovery, selection and development of improved analgesic treatments for the benefit of public health. In addition, a better understanding of subjects’ typology would be of great help to identify those who really need a more specific pharmacological treatment approach from those subjects who don`t and might benefit instead from alternative non-pharmacological approaches.