Cannabis-based drug relieves symptoms of motor neuron disease

Chemical compounds derived from the cannabis sativa plant, used as an add-on treatment, may help ease symptoms of spasticity (tight or stiff muscles), a major cause of disability and reduced quality of life in people with motor neuron disease.

That’s according to a phase 2 trial of 60 adults recently conducted by Italian researchers and published in The Lancet Neurology.

Spasticity is a common symptom in motor neuron disease, a rapidly progressive, fatal neurodegenerative disorder affecting the nerve cells that control muscle movement (motor neurons). While there are several drugs to relieve spasticity, evidence for their effectiveness is scant and they do not sufficiently improve symptoms in all patients. Moreover, they can have undesirable side effects, such as increasing muscle weakness and fatigue.

“There is no cure for motor neuron disease, so improved symptom control and quality of life are important for patients,” said Dr Nilo Riva from the San Raffaele Scientific Institute.

Previous research has found possible therapeutic benefits of cannabinoids (components of the cannabis plant) to include muscle relaxation, appetite stimulation and pain-relieving, anticonvulsant and anti-inflammatory effects in patients with other neurological conditions. Cannabinoids have been licensed in several countries for symptomatic treatment of spasticity in multiple sclerosis, and are increasingly recognised as a valuable option for the management of pain.

To investigate whether cannabinoids might also reduce spasticity in motor neuron disease, Dr Riva and colleagues recruited 60 adults from four tertiary motor neuron disease centres in Italy. To participate in the study, patients had to have experienced spasticity symptoms for at least three months and be taking a stable dose of any anti-spasticity medication for 30 days before enrolment and throughout the study.

Participants were randomised to receive an oral spray (nabiximols) containing either a placebo or delta-9 tetrahydrocannabinol THC and cannabidiol (THC-CBD) for six weeks. A physician rated the spasticity of each participant’s joints on the Modified Ashworth Scale (MAS) — an objective tool to evaluate intensity of muscle tone. Participants were also asked to keep a daily symptom diary on spasticity levels, pain, spasm frequency and sleep disruption.

At the end of treatment, spasticity was significantly improved in the THC-CBD spray group compared with the placebo group (mean MAS scores improved by an average 0.11 vs deteriorated by an average 0.16). Additionally, the number of participants treated with THC-CBD spray reporting an improvement was significantly higher compared with participants receiving placebo (55% vs 13%). Finally, pain scores were significantly improved in the THC-CBD spray group compared with placebo on a 0–10 scale (-0.97 vs -0.06).

Overall, THC-CBD spray was well tolerated and adverse events were mild to moderate and typical of cannabinoids, including loss of energy and fatigue, sleepiness, vertigo and nausea. There were no serious adverse events and no participants permanently discontinued treatment. The authors did, however, note an important limitation of the study, in that MAS has lacked sensitivity in studies assessing cannabinoids efficacy in multiple-sclerosis-related spasticity.

“Our proof-of-concept trial showed a beneficial effect of THC-CBD spray in people on treatment-resistant spasticity and pain,” Dr Riva said. “Despite these encouraging findings, we must first confirm that THC-CBD spray is effective and safe in larger, longer term phase 3 trials.”

Writing in a linked Comment, Dr Marianne de Visser from Amsterdam University Medical Centre said the study results were “encouraging”.

“Before asking for approval of cannabinoids for symptomatic treatment of spasticity in patients with amyotrophic lateral sclerosis, further studies are needed to establish the frequency of spasticity in the various presentations of motor neuron disease, and also whether reductions in spasticity improve quality of life,” she said.

“Larger multicentre randomised controlled trials should be done to identify which subgroups of patients derive clinically significant benefits from nabiximols.”

Image credit: ©stock.adobe.com/au/ChiccoDodiFC

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