A drug used for rheumatoid arthritis could be a promising new treatment option for patients with difficult-to-treat depression, according to a study.
Researchers investigated for the first time whether tocilizumab, an existing anti-inflammatory drug, could improve symptoms of depression in people who have not responded to standard antidepressant treatments.
The trial involved 30 people with moderate-to-severe depression, and it provides early evidence that tocilizumab may reduce depression symptoms, fatigue, anxiety and increase overall quality of life.
Current drug treatments for depression are solely based on targeting chemicals in the brain, such as serotonin, norepinephrine and dopamine.
Around one in three people with depression do not get better with these treatments.
Recent research shows that about a third of people with depression have signs of inflammation in their blood, indicating their symptoms may be linked to an overactive immune system.
Other studies point to higher levels of inflammatory proteins called cytokines in depression, including interleukin 6 (IL-6).
Researchers at the University of Bristol wanted to see whether symptoms could improve in people with inflammation-related depression by blocking the IL-6 pathway.
The trial split the participants into two with half given tocilizumab and the rest a placebo.
The findings suggest the participants who received tocilizumab seemed to experience greater improvements over time compared to those given a placebo.
"This work represents an important milestone in the development of new treatments for depression, especially difficult-to-treat depression," senior author Professor Golam Khandakar, from the University of Bristol, said.
"This is one of the first randomised controlled trials to test immunotherapy for depression, the first to test IL-6R as the treatment target, and the first to use a targeted approach to select patients most likely to benefit, and to show that it works."
Lead author Dr Eimear Foley added: “Depression is estimated to affect around 10% to 20% of people worldwide during their lifetime, yet for many patients current treatments do not work well enough.
“Our study moves us closer to more tailored depression care, where treatments are chosen to better fit a person’s biology.
“This will help us to provide the right treatment to the right patients at the right time.”
The next step will be to conduct a large-scale phase III randomised control trial that will provide definitive evidence to enable doctors to prescribe immunotherapy for depression.
The study, Interleukin 6 as a treatment target for depression: a proof-of-concept randomised clinical trial’, is published in the journal JAMA Psychiatry.
