The pooled prevalence of infective complications in patients with multiple sclerosis (MS) treated with alemtuzumab is 24%, found a new study published in the journal Expert Opinion on Drug Safety. It also found first-time reported cases of invasive aspergillosis, hepatitis E virus infection, EBV hepatitis, and cerebral toxoplasmosis among these patients.

“Clinicians should be aware that the prevalence of serious infections during alemtuzumab treatment can be higher than expected from [randomized controlled trials]”, concluded the authors of the study. They added: “Peculiar opportunistic infections should be considered when evaluating a patient treated with alemtuzumab who develops signs of infection.”

Alemtuzumab is an MS treatment that was approved in 2014. It is a humanized monoclonal antibody that induces long-lasting and significant circulating T and B lymphocyte depletion. Results of clinical trials testing the safety and efficacy of alemtuzumab suggested that the treatment rarely causes serious infections. However, a number of serious opportunistic infections, such as cytomegalovirus (CMV) disease, nocardiosis, Pneumocystis jirovecii pneumonia, and Listeria monocytogenes have been reported in clinical practice.

Continue Reading

Read more about alemtuzumab.

A team of researchers led by Ivan Gentile, PhD, assessed the pooled prevalence of infections in MS patients treated with alemtuzumab as part of randomized controlled trials and real-world studies. They also assessed selected infections and their severity.

The researchers found that the pooled prevalence of infective complications was 24%. The most commonly reported infections (47%) were respiratory tract infections. Most infections (85%) were mild to moderate and severe infections accounted for 6% of the total estimate. The researchers also found that the prevalence of infections was higher in studies conducted before 2009 and in studies that had a higher proportion of male participants.

Clinicians should account for new and rare opportunistic infections like invasive aspergillosis, EBV reactivation, and cerebral toxoplasmosis, the researchers said, adding “prevention, early detection, and treatment can improve infection outcomes to let the balance tip toward benefits rather than [the] risk of severe infections.”


Buonomo AR, Viceconte G, Zappulo E, et al. Update on infective complications in patients treated with alemtuzumab for multiple sclerosis: review and meta-analysis of real-world and randomized studies. Expert Opin Drug Saf. 2021;26:1-10. doi:10.1080/14740338.2021.1942454