Ocrelizumab-induced neutropenia in people with multiple sclerosis: a single-centre study

Treatment with CD20 depleting agents can be complicated by the development of neutropenia; its exact prevalence remains poorly understood. The aim of our study was to determine the frequency of neutropenia associated with ocrelizumab (OCR) in people with multiple sclerosis (pwMS).

Consecutive pwMS receiving OCR treatment were enrolled. Clinical and paraclinical data were collected, with a focus on white blood cells (WBC) and neutrophil counts at baseline and at the 1st, 3rd, and 6th months following infusions. Neutropenia was defined as a decrease in the absolute neutrophil count (ANC) to below 2 × 10^3/μL.

74 pwMS were enrolled; 65 had a relapsing disease course, 20.3 % were treatment-naïve, 40.5 % had switched from a first-line treatment, and 39.2 % from a second-line treatment. WBC counts were available for 73 patients; neutropenia developed in 16 patients (21.9 %), with 7 experiencing grade 2 to 4 neutropenia (<1.5 × 10^3/μL). Neutropenia was most commonly observed after the second treatment cycle. No bacterial infections occurred during neutropenia. G-CSF was administered to two patients with grade 4 neutropenia, with no neutropenia recurrence and no MS relapses. Neutropenia recurrence (grade 1 and 2) was observed in 6 patients. Baseline ANC and WBC counts were the only variables predicting neutropenia development.

OCR-related neutropenia was observed in >20 % of patients. Higher degrees of neutropenia (3-4) were observed in 3 cases. In our cohort, all patients were asymptomatic, without concomitant bacterial infections. Baseline WBC and in particular ANC count could help identify patients at risk for neutropenia.