Objective:

To review patients with relapsing forms of multiple sclerosis (MS) who had a clinical or/and radiologic relapse while on a B cell therapy (rituximab, ocrelizumab, or ofatumumab) with low (CD19 <15) or suppressed (CD19 of 0) B cells, with a few exceptions, evaluating for any commonalities or extenuating circumstances leading to relapse.

Background:

B cell therapies are highly effective treatments for relapsing forms of MS; nevertheless, clinical or MRI relapses occur in a minority of patients. The risk factors and severity of MS relapse while on B cell therapy have not been fully characterized. 

Design/Methods:

Retrospective chart review.

Results:

Out of 601 patients on B cell therapies (42 on rituximab, 475 on ocrelizumab, 84 on ofatumumab), 12 patients (1.99%) experienced a clinical and/or MRI relapse (2 on RTX, 8 on OCR, 2 on OFA). Seven patients had breakthrough disease by imaging, 3 had clinical relapses (2 optic neuritis and 1 transverse myelitis), and 2 had clinical and radiologic findings. It is important to note the radiologic relapse lesions were compelling for interval demyelination and not ischemia or alternate etiologies. We will present a detailed summary of each case, including patient's demographics, age at MS diagnosis, relapse and disease modifying treatment history, relapse severity, CD19 count coinciding with the relapse, and the number of infusions/injections prior to disease breakthrough.

Conclusions:

MS relapse while on B cell therapies is a rare but thought -provoking phenomenon. While the reasons for relapses remain elusive, potential causes we have encountered in our cohort include fertility treatment, viral infections, alternative diagnoses, early MRIs after medication initiation, transient increase in B Cell Activating Factor, extended dosing intervals, body mass index and early B cell repopulation. We will review the literature for other potential factors.