Ocrelizumab B-cell repopulation-guided extended interval dosing versus standard dosing - similar clinical efficacy with decreased immunoglobulin M deficiency rates.

Background: Ocrelizumab (OCR) is a humanized anti-CD20 monoclonal antibody used in treatment of multiple sclerosis. The standard dosing (SD) regimen consists of OCR maintenance infusions every 6 months. In B-cell repopulation-guided extended interval dosing (EID), repeat infusions are delayed until there is evidence for B-cell repopulation.

Objectives: To compare frequencies of 'no evidence of disease activity' (NEDA-3) and immunoglobulin G (hypo-IgG; <600 mg/dL) and M (hypo-IgM; <40 mg/dL) deficiencies in persons with multiple sclerosis (PwMS) treated with OCR B-cell repopulation-guided EID versus SD.

Methods: Two-center retrospective study comparing frequencies of NEDA-3 and hypo-IgG and hypo-IgM in PwMS treated with OCR B-cell repopulation-guided EID versus SD using a multivariate generalized linear model adjusted for age, sex, and treatment duration.

Results: A total of 112 OCR-treated PwMS were included (B-cell repopulation-guided EID n = 52; SD n = 60) with average infusion intervals of 319 (246-485) days (EID) and 184 (170-218) days (SD). There was no significant difference in NEDA-3 (EID: 47/52 [90.4 %]; SD: 50/60 [83.3 %]; p = 0.161) or hypo-IgG (EID: 1/52 [1.9 %]; SD: 4/60 [6.7 %]; p = 0.298) rates. Hypo-IgM was significantly less common in EID (EID: 9/52 [17.3 %] vs. SD: 34/60 [55 %]; p<0.001) upon assessment 1099 (475-1436) days (EID) and 980 (409-1846) days (SD) post-initiation of OCR. Hypo-IgM was associated with average infusion interval length (p = 0.005) and total number of OCR cycles (p = 0.003).

Conclusions: OCR B-cell repopulation-guided EID may be a safe alternative to traditional SD with similar efficacy and significantly less hypo-IgM rates.