The correlation between rituximab dose reduction and acute relapses of neuromyelitis optica spectrum disorder, lessons from COVID-19 epidemic

Background

COVID-19 was a viral infection that led to a global pandemic in March 2020. At the beginning of the pandemic, clinicians encountered the challenge of how immunosuppressive treatments would affect the course of COVID-19 infection in people with autoimmune diseases. Neuromyelitis optica spectrum disorder is an autoimmune astrocytopathy that is caused by an inflammation in the CNS. Major treatments to prevent acute relapses include immunosuppressive drugs. Rituximab is a well-established immunosuppressive agent in NMOSD maintenance therapy. Some reports suggested that treatment with Rituximab might increase the risk of COVID-19 infection and its mortality in NMOSD. On the other hand, dose reduction or extended interval treatment might lead to acute relapses of NMOSD and permanent disability.

Methods

In this study, we evaluated the correlation between the dose of rituximab and the relapse rate of NMOSD during an epidemic. This was an observational study on 171 patients among whom 55 cases were seropositive. Some patients received full dose rituximab routinely (1000 mg/dose, every 6 months), but others were treated with half dose (500 mg/dose) during the epidemic. Also, some doses were prescribed with a delay, based on the level of CD19 and CD20.

Results

The Pearson correlation coefficient (r) showed a negative and significant relation (r: - 0.19, p: 0.022) between the amount of drug and the number of relapses in the seropositive group, so low dosage of the drug was related to more acute relapses. In seronegative cases, there was not any valuable relationship. (p: 0.367).

Conclusion

Lower dose of rituximab, especially in seropositive NMOSD patients, can potentially lead to acute relapses. So, the more frequent evaluation of the CD19, CD20, and, CD27 levels, and the general clinical condition of the patients should be considered.