Neuroimmunology Unit, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London, E1 2AT, UK, [email protected]
Multiple sclerosis (MS) is the major immune-mediated, demyelinating, neurodegenerative disease of the central nervous system. Compounds within cannabis, notably Δ9-tetrahydrocannabinol (Δ9-THC) can limit the inappropriate neurotransmissions that cause MS-related problems and medicinal cannabis is now licenced for the treatment of MS symptoms. However, the biology indicates that the endocannabinoid system may offer the potential to control other aspects of disease. Although there is limited evidence that the cannabinoids from cannabis are having significant immunosuppressive activities that will influence relapsing autoimmunity, we and others can experimentally demonstrate that they may limit neurodegeneration that drives progressive disability. Here we show that synthetic cannabidiol can slow down the accumulation of disability from the inflammatory penumbra during relapsing experimental autoimmune encephalomyelitis (EAE) in ABH mice, possibly via blockade of voltage-gated sodium channels. In addition, whilst non-sedating doses of Δ9-THC do not inhibit relapsing autoimmunity, they dose-dependently inhibit the accumulation of disability during EAE. They also appear to slow down clinical progression during MS in humans. Although a 3 year, phase III clinical trial did not detect a beneficial effect of oral Δ9-THC in progressive MS, a planned subgroup analysis of people with less disability who progressed more rapidly, demonstrated a significant slowing of progression by oral Δ9-THC compared to placebo. Whilst this may support the experimental and biological evidence for a neuroprotective effect by the endocannabinoid system in MS, it remains to be established whether this will be formally demonstrated in further trials of Δ9-THC/cannabis in progressive MS.
THC:CBD spray and MS spasticity symptoms: data from latest studies.
- Bergen Hospital and University of Bergen, Bergen, Norway.
New clinical experience with 9-delta-tetrahydocannabinol (THC) and cannabidiol (CBD) oromucosal spray (Sativex®) involving more than an additional 1,000 patients with MS spasticity (approximately 150 in clinical studies and 900 in post-marketing surveillance studies) have become available in 2013 and are reviewed. A randomized, placebo controlled long-term follow-up clinical trial with THC:CBD spray versus placebo demonstrated that it was not associated with cognitive decline, depression or significant mood changes after 12 months of treatment. Furthermore, in a prospective observational pilot study involving 33 patients (60% female) aged 33-68 years and a mean disease duration of 6.6 years, THC:CBD oromucosal spray did not adversely influence standard driving ability in patients with moderate to severe MS spasticity. Other new long term observational data about the use of THC:CBD oromucosal spray in clinical practice are available from patient registries in the UK, Germany and Spain. Findings to date reinforce the efficacy and safety observed in Phase III clinical trials. It is of interest that in practice average dosages used by patients tended to be lower than those reported in clinical studies (5-6.4 vs. >8 sprays/day), and effectiveness was maintained in the majority of patients. Importantly, no additional safety concerns were identified in the registry studies which included findings from patients who have been treated for prolonged periods (in the German/UK registry 45% of patients had >2 years exposure). Thus, these new data support a positive benefit-risk relationship for THC:CBD oromucosal spray during longer-term use.