In a nutshell
The study examined predictors of treatment success with anti-TNF drugs for rheumatoid arthritis (RA). The authors concluded that immune response and the presence of a protein in the blood can predict treatment outcomes with anti-TNF drugs.
Some background
In rheumatoid arthritis (RA), the immune system attacks the healthy joints the way it would a virus or bacteria. Anti-tumour necrosis factor (TNF) inhibitors such as adalimumab (Humira) or infliximab (Remicade) are biological drugs. They work by blocking the activity of a protein called TNF that can increase inflammation in RA. It has been estimated that only about one third of patients respond well to this treatment. Finding predictors of treatment success is therefore important to help identify patients that would benefit from anti-TNF therapy.
Typically, the immune system produces antibodies to clear infections from viruses or bacteria. If a patient with RA is treated with a biological drug, sometimes the immune system responds by producing antibodies that will clear the drug. These are called anti-drug antibodies (ADAbs). If this happens then these patients will have less of the drug in their system and may not respond as well to treatment.
Methods & findings
26 patients with RA were included in this study. 15 patients were treated with adalimumab and 11 patients were treated with infliximab. Blood samples were taken at the beginning of the study and after 6 months of treatment. Levels of proteins associated with RA, ADAbs, and disease activity were measured in both groups.
Both groups showed a significant improvement in disease activity after 6 months of treatment. Levels of interleukin-6 and sTNF-R2 (two proteins associated with inflammation) decreased significantly in both groups.
23% of patients had ADAbs in their blood. These patients had lower levels of adalimumab or infliximab in their system than patients with no ADAbs. Lower anti-TNF drug levels were associated with smaller improvements in disease activity. Patients who had lower levels of anti-TNF drugs in their system at 6 months had higher levels of interleukin-6 in their blood at the start of the study.
The bottom line
This study concluded that anti-TNF drugs are less effective at decreasing disease activity in patients who develop ADAbs. Patients with higher levels of the protein called interleukin-6 may not respond as well to anti-TNF therapy.
The fine print
Larger studies are needed to confirm these findings. Some of the authors received funding from the manufacturers of the drugs studied.
Published By :
PLOS ONE
Date :
Sep 08, 2016
