A depression trial has taken an unusual turn, away from brain chemicals and toward the immune system.
A University of Bristol-led clinical trial found early signs that tocilizumab, a drug used for inflammatory conditions such as rheumatoid arthritis, may help people with difficult-to-treat depression.
The study was published in JAMA Psychiatry on May 20.
Researchers tested the drug in 30 people with moderate-to-severe depression who had not improved with standard antidepressants and who showed signs of low-grade inflammation in blood tests.
The four-week randomized controlled trial recruited participants through the University of Cambridge and the Cambridgeshire and Peterborough NHS Foundation Trust.
Fourteen participants received tocilizumab and 16 received a saltwater placebo.
Researchers said the study was small, so there was limited statistical evidence of major differences between the groups.
Still, people who received tocilizumab generally showed greater improvement over time in depression severity, fatigue, anxiety and overall quality of life.
The remission rate was also higher in the treatment group. Researchers said 54 percent of participants taking tocilizumab achieved depression remission, compared with 31 percent in the placebo group.
The Number Needed to Treat was calculated at 5, meaning five people would need treatment for one additional person to benefit. The summary said the Number Needed to Treat for SSRIs, the most commonly prescribed antidepressants for moderate-to-severe depression, is around 7.
The work builds on research into inflammation and depression. According to the summary, about one in three people with depression have elevated inflammatory markers in their blood, and previous studies have linked higher levels of the inflammatory protein interleukin 6, or IL-6, to depression.
Golam Khandakar, professor of psychiatry and immunology from the MRC Integrative Epidemiology Unit at the University of Bristol and NIHR Biomedical Research Centre: Bristol, and the study’s senior author and chief investigator, said: “This work represents an important milestone in the development of new treatments for depression especially difficult-to-treat depression, which affects millions of people in the UK alone.”
He said: “This is one of the first randomized 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.”
Dr Éimear Foley, senior research associate in immunopsychiatry at Bristol’s MRC Integrative Epidemiology Unit and the NIHR Biomedical Research Centre: Bristol, and the study’s lead author, said: “Depression is estimated to affect around 10-20% of people worldwide during their lifetime, yet for many patients current treatments do not work well enough.”
She said: “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.”
Researchers said larger studies are still needed before immunotherapy could become a standard treatment for depression.
The next step will be a large phase III randomized controlled trial to determine whether doctors should begin prescribing immunotherapy for depression more broadly.
One participant in the study said: “I was happy to take part. Without research, advancements in medicine cannot be made.”
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