Biological Agents in Rheumatoid Arthritis: A Cross-Link Between Immune Tolerance and Immune Surveillance

The biological drugs have all been successfully used to treat rheumatoid arthritis (RA) and have led to fair rates of clinical remission; however, the possible occurrence of adverse events such as infectious diseases or cancers means that the patients undergoing treatment need to be closely monitored. Anti-TNF agents, first appeared in the pharmacological algorithm of RA in the early 2000s, seem to lead to a higher risk of reactivated tubercular infection than the biological agents with different mechanism of action (abatacept or rituximab). Although the data on anti-TNF agents and cancer are controversial, their use is currently not recommended in neoplastic patients because of their uncertain effects on immune-surveillance. The safety profile of abatacept is similar to that of other biological agents, while rituximab is used to treat non-Hodgkin lymphomas and is also considered in the case of RA patients with previous hematological or non-hematological malignancies. The risk of infections and new-onset cancers during tocilizumab treatment is similar to that associated with other biological therapies. Finally, under particular circumstances, such as in the presence of infections or malignancies, blocking a specific immunological pathway may be simultaneously successful and detrimental. The only thing that can be done at the moment is to continue to look for adverse events in order to discover these complications as soon as possible, and then develop the most appropriate means of treating (and even preventing) them.