The Rarity of Adverse Events With Natalizumab Infusion for MS

Yujie Wang, MD

Natalizumab (Tysabri; Biogen) infusion-related adverse events (AEs) are rare, generally mild, and occur within the first few infusions in patients with relapsing-remitting multiple sclerosis (RRMS), according to data from a recent study.

Researchers, including Yujie Wang, MD, University of Washington Medical Center, found that in a dataset that included almost 10,000 infusions, a total of only 33 infusion-related AEs (0.34% of infusions), all mild in severity, were recorded in 26 patients (7.8%). The majority of AEs occurred during infusion (77%) rather than throughout the 1-hour post-infusion monitoring, and 92% of AEs occurred within the first 6 months of treatments.

Wang recently presented these findings virtually at the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2021, February 25-27. NeurologyLive spoke with Wang to learn more about the 1-hour post monitoring period and how the study came about. She also spoke about how she would like to analyze prospective data in addition to retrospective.

NeurologyLive: Can you tell me about the 1-hour post monitoring period instituted for infusions and the downsides of this protocol during the COVID-19 pandemic?

Yujie Wang, MD: That’s a protocol that we are currently using for analysis and monitoring for our patients. It is really to monitor for any sort of infusion reactions, for example, itchiness or headache or nausea. We often monitor patients after other infusions as well.

The downsides of the monitoring period during the COVID-19 pandemic recently came to light and that prompted our study. Many of our patients voiced some concerns about sticking around a healthcare facility for over an hour after its infusion had completed. As you can imagine, our fusion suite was not really set up for 6 feet distancing. Usually, we’ve got chairs next to each other, our patients like to chat during the infusions, it can be quite boring to just sit there and get your infusion. Now people are very cognizant; they’re wearing masks, practicing social distancing. So, we’ve had to cut down on how many patients we are able to provide these infusions for with social distancing.

Our patients are rightfully concerned about their exposure, because they’re indoors and so COVID exposure really increases if you’re in a location for a prolonged period of time where people are going in and out, whether its staff or other patients. So, we have had, especially in the beginning of the pandemic, when masking wasn’t universal, multiple patients who decided to skip that post-infusion monitoring. We had them sign waivers, of course, because it is a protocol for them to stay. So, they would sign a waiver and they would leave on their own accord. After a number of patients did this, we thought maybe we can take a look and see how many patients actually experience adverse events of natalizumab and whether those symptoms should prompt any change to the clinical management of their MS.

Reactions were rare, and mostly happened within the first few infusions. Do you think the monitoring period should be modified?

Yeah, I wasn’t surprised to see that reactions were rare. If you talk to other people who see and manage people with MS frequently and use these medications frequently, they wouldn’t be surprised either. We saw that they are very, very rare, and prior studies have shown they are quite rare as well.

I think more work needs to be done. I don’t think there has been a systematic look at these monitoring periods yet, so I think it would be very interesting to look at that more systematically, since this study was retrospective. We looked back into our patients’ experiences for the last several years since our center started, but I think it would be good to look at it prospectively because there are some pitfalls in looking at data retrospectively.