Assessment of latent infections in patients receiving biological therapies.

The use of biological (or targeted) therapies constitutes a major advance in the management of autoinflammatory and malignant diseases. However, due to the selective effect of these agents on the host's immune response, reactivation of certain pathogens that cause latent infection is to be expected. The most relevant concern is the risk of reactivation of latent tuberculosis infection (LTBI) and progression to active tuberculosis among patients treated with agents targeting tumor necrosis factor (TNF)-α. Systematic screening for LTBI at base-line with appropriate initiation of antituberculous treatment, if needed, is mandatory in this patient population as risk minimization strategy. In addition, reactivation of hepatitis B virus induced by B-cell-depleting (anti-CD20) and anti-TNF-α agents should be also prevented among HBsAg-positive patients and those with isolated anti-HBc IgG positivity (risk of "occult HBV infection"). The present review summarizes available evidence regarding the risk of reactivation of these latent infections induced by newer biological agents, as well as the recommendations included in the most recent guidelines.