Influenza Vaccine Triggers Immune Response in Patients With RMS on Ofatumumab

Patients with relapsing multiple sclerosis (RMS) who receive ofatumumab can mount an adequate immune response to the inactivated influenza vaccine, according to study results presented at the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2024, held from February 29 to March 2, in West Palm Beach, Florida.

There is lack of data on the efficacy of vaccines in patients with RMS who receive ofatumumab. Researchers reported results of a phase 4 study (ClinicalTrials.gov Identifier: NCT04667117) to determine the impact of ofatumumab on humoral immune response to the inactivated influenza vaccine in RMS.

The inactivated influenza vaccines included in the study were those from 2020 to 2021, 2021 to 2022, and 2022 to 2023. The researchers assessed hemagglutination inhibition (HI) titer among patients before and 4 weeks after vaccination.

Eligible participants had RMS, were aged between 18 and 55, and had available data regarding antibody titers before and after vaccination. Participants were categorized into 3 groups based on timing of influenza vaccine before ofatumumab treatment.

• Cohort 1: 2 or more weeks before initiation of treatment
• Cohort 2: 4 or more weeks before initiation of treatment
• Cohort 3/control group: Treatment with interferon or glatiramer acetate and influenza vaccine administered 4 or more weeks after study enrollment

Primary endpoint was achieving an immune response to the influenza vaccine 4 weeks postvaccination, with an antibody titer of 40 or more. Secondary endpoints were achieving an immune response after vaccination — with more than a 4-fold increase in HI titers or at least 40 among those with prevaccination titers of 10 and greater or less than 10, respectively — and the occurrence of adverse events (AEs).

A total of 63 patients (mean age, 41.4; 76.2% women; 85.7% White) were included in the study.

The percentage of patients who achieved seroprotection/seroconversion at week 4 was reported.

Strain	Cohort 1	Cohort 2	Cohort 3
Influenza A Cambodia	100%/84.6%	80%/20%	85.7%/42.9%
Influenza A Victoria	100%/92.3%	100%/20%	100%/42.9%
Influenza A Wisconsin	61.5%/46.2%	40%/10%	68.8%/37.5%
Influenza B Phuket	77.8%/50%	68.2%/18.2%	76.5%/41.2%
Influenza B Washington	76.9%/38.5%	20%/0%	71.4%/42.9%

The researchers found that 72.7%, 27.3%, and 10.5% of patients in cohorts 1, 2, 3, respectively, had at least 1 AE; however, except 1 patient, none of the patients had serious AEs. None of the AEs resulted in discontinuation in participation.

“Findings from this study suggest that OMB [ofatumumab]-treated patients with RMS are able to mount an immune response following inactivated influenza vaccination,” the researchers stated. They concluded, “These results will help to inform the coordination of vaccination and OMB treatment in patients with RMS.”