Side Effects of Rituxan for MS Treatment May Carry Increased Infection Risks: Study

Patients taking Rituxan to treat multiple sclerosis may face a higher risk of suffering a serious infection than those taking other types of treatments, according to the findings of a new study that raises concerns about side effects of the MS treatment conducted in Sweden.

In findings published last week in the medical journal JAMA Neurology, Swedish researchers found that many new MS medications carried a risk of infection, with the highest risk linked to Rituxan.

Researchers focused on the risk of infection for various treatments for multiple sclerosis (MS). Those included interferon beta glatiramer acetate, as well as newer treatments including Gilenya, Tysabri, and Rituxan. All three drugs weaken the immune system, making patients more susceptible to infection.

The study used data from a national cohort involving patients with multiple sclerosis in Sweden from January 1, 2011, to December 31, 2017. This included national registers with prospective data collection from the public health care system among Swedish patients with relapsing-remitting MS whose data were recorded in the Swedish MS register as beginning treatment with one of four treatments.

A control group was matched by age and sex to compare risk factors. There was a total of 6,400 patients taking MS medications compared to a control group of 42,000 patients.

The infection rate was higher in patients with MS taking interferon beta than the control group. However, the infection rate was even higher among patients taking any of the three newer drugs studied, Rituxan, Gilenya, and Tysabri, compared to the control group.

After adjusting for other risk factors, researchers concluded the infection rate remained high for Rituxan, but not for Gilenya and Tysabri.

Additionally, the researchers found that patients using herpes antiviral drugs while taking Rituxan treatment had a similar risk of infection as those taking only interferon beta, but that risk was lower if they were taking either of the other two drugs Gilenya or Tysabri.

The research indicated the rate of infection was lowest among injectable therapies, but among new treatments like Rituxan, the risk of serious infection was the highest.

Infection data is largely unavailable for Rituxan, known as an anti-CD20 antibody. Rituxan was originally a cancer drug, but is approved for rheumatoid arthritis and other immune-mediated diseases, but not MS. However, it is often used off-label to treat MS, which is why there isn’t much information regarding how it affects MS patients.