For the first time, the UK’s National Institute for Health and Care Excellence (NICE) granted approval for two cannabis-based medicines, Epidyolex (cannabidiol) for Lennox-Gastaut syndrome and Dravet syndrome, as well as Sativex (delta-9 tetrahydrocannabinol cannabidiol) for multiple sclerosis.
While charities and campaigners welcome the new legislation, they argue the new regulations are not extensive enough where the recommendation of cannabis-based medicine for pain is concerned.
Current NICE guidelines do not support the use of cannabis-based medicines for chronic pain, citing that current clinical research evidence is not substantial enough to warrant a NICE recommendation. In this paper, we analyse the effectiveness of cannabis-based medicines for pain relief in Phase III clinical trials in the UK.
All clinical trials were in completed status and company-sponsored. The majority of trials (95%) were sponsored by the UK-based biopharmaceutical company GW Pharmaceuticals, the developers of Sativex, which was also involved in 95% of the clinical trials. Furthermore, clinical trials in this analysis had a 90% completion rate with 10% of trials undergoing early termination. Single-country trials (55%) narrowly outnumbered multinational trials (45%).
With regards to endpoint status, the largest proportion of clinical trials achieved their primary endpoint (45%) with 25% of trials producing inconclusive results, while 15% of trials had failed to achieve their endpoints, with 10% of trials undergoing early termination and 5% of trials partially achieving their endpoints. In clinical trials with inconclusive endpoints, there is a lack of conclusive inferences that can be drawn, with cannabis-based medicines displaying moderate to no additional effects where efficacy is concerned. In trials failing to achieve their endpoints, the inability to exhibit superiority over placebo comparators served as the primary cause of failure.
Trials that achieved their endpoint only narrowly outnumber the combined number of trials with either a failed or inconclusive endpoint, by 5%. Therefore, cannabis-based medicines fail to adequately demonstrate their efficacy when indicated for pain relief, thereby justifying the current NICE stance particularly when factors such as effectiveness are considered. Nevertheless, greater research is required before absolute conclusions on the efficacy of cannabis-based medicine indicated for pain can be made. As highlighted by the lack of clinical trials in active statuses, the research space is somewhat limited.