Trends and Predictors of Peripheral CD19+ B-cell Repopulation in Patients Treated with Ocrelizumab during COVID-19 Pandemic (P7-3.014)

Abstract

<h3>Objective:</h3> To assess the predictors of B-cell repopulation in patients treated with ocrelizumab during COVID-19 pandemic. <h3>Background:</h3> Ocrelizumab (OCR) is used for multiple sclerosis (MS) administered every 6 months (SID). Peripheral CD19+ lymphocyte (CD19L) count is a surrogate marker of efficacy of OCR. B-cell repopulation (≥1% CD19L of total lymphocytes) is a potential biomarker to guide OCR extended interval dosing (EID) beyond 6 months. During COVID-19 pandemic, adjusted OCR treatment-cycle based on CD19L repopulation has been a strategy to minimize the risk of prolonged B-cell depletion associated higher potential complications of COVID. We studied the predictors of B-cell repopulation in patients treated with OCR. <h3>Design/Methods:</h3> Retrospective study of patients receiving OCR between 2020–2022 in whom CD19L counts were available &lt;30 days prior to next infusion. Data collected included age, gender, race, body mass index (BMI), MS subtype, prior immunosuppressive therapy, time-to-repopulation. Multiple linear regression was used to look for predictors of B-cell repopulation. <h3>Results:</h3> Total 248 patients (mean age 48±12.8 years; 172 female, 76 male) studied. Forty-five percent (111 patients) had CD19L repopulation, fifty-five percent (137 patients) had persistently low (&lt;1%) counts. Mean number of infusion cycles prior to CD19L repopulation was significantly longer in extended interval group (4.36±2.16 days vs. 2.33±2.04; p&lt;0.05). BMI and inter-infusion interval were predictors of repopulation (p&lt;0.001); age, race, gender, disease type, prior immunosuppressive therapy did not predict repopulation. All patients remained clinically stable. <h3>Conclusions:</h3> In this observational study of MS patients treated with OCR with standard or extended interval dosing, BMI and inter-infusion dosing interval were the only predictors of B-cell repopulation. The number of infusions prior to repopulation was higher in the extended dosing group. In the future, these data can be used to provide guidance on extending OCR dosing interval. <b>Disclosure:</b> Dr. Padron has nothing to disclose. Ms. Jimsheleishvili has nothing to disclose. Dr. Tornes has nothing to disclose. Dr. Delgado has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. The institution of Dr. Delgado has received research support from Novartis. The institution of Dr. Delgado has received research support from EMD Serono. The institution of Dr. Delgado has received research support from NIH/NINDS. Dr. Garg has nothing to disclose.