Is there a real risk of bacterial infection in patients receiving targeted and biological therapies?

Over the past decades, the advent of targeted and biological therapies has revolutionized the management of cancer and autoimmune, hematological and inflammatory conditions. Although a large amount of information is now available on the risk of opportunistic infections associated with some of these agents, the evidence regarding the susceptibility to bacterial infections is more limited. Biological agents have been shown to entail a variable risk of bacterial infections in pivotal randomized clinical trials and post-marketing studies. Recommendations on risk minimization strategies and therapeutic interventions are therefore scarce and often based on expert opinion, with only a few clear statements for some particular agents (i.e. meningococcal vaccination for patients receiving eculizumab). In the present review the available information regarding the incidence of and risk factors for bacterial infection associated with the use of different groups of biological agents is summarized according to their mechanisms of action, and recommendations based on this evidence are provided. Additional information coming from clinical research and real-world studies is required to address unmet questions in this emerging field.