Drug Eruption After Subcutaneous Ofatumumab Exposure in Two Patients with Relapsing Multiple Sclerosis
Sarah Bou Reslan1, Raissa Aoun1, Nada Abou-Fayssal2
1NYU Grossman School of Medicine, 2Neurology, NYU Grossman School of Medicine
Objective:
To report and illustrate adverse skin reactions related to ofatumumab use. 
Background:
Ongoing safety reporting of ofatumumab is crucial to understand its long-term benefit–risk profile. Currently, there are no case reports demonstrating drug eruptions as complications of its use in Relapsing Multiple Sclerosis (RMS) patients outside of the ASCLEPIOS I/II core studies and ALITHIOS open-label extension study. 
Design/Methods:
A case series 
Results:

Case 1: A 35-year-old treatment-naive woman with RMS was started on subcutaneous ofatumumab in October 2021 shortly after diagnosis. She developed a scattered red raised scaly pruritic rash on her arms after completing her second loading dose. It spread to involve the legs, waistline, back, and chest after each monthly dosing. The face, palm, and soles were not involved. Skin biopsy was consistent with lichenoid psoriasiform spongiotic dermatitis. Rash resolved with drug discontinuation in January 2022 leading to a diagnosis of psoriasiform drug eruption.

Case 2: A 38-year-old woman with history RMS and eczema was started on ofatumumab in March 2023 after breakthrough disease on glatiramer acetate. She developed a widespread pruritic maculopapular rash on her chest, back, legs after completing her third loading dose. A skin biopsy showed spongiotic dermatitis consistent with eczematous drug eruption for which she was prescribed steroids ointment with improvement. Ofatumumab was felt to be the culprit as rash did not recur after its discontinuation.

Conclusions:
Ofatumumab has established effectiveness with a favorable benefit–risk profile in RMS. This case series is the first to illustrate drug eruptions as systemic injection-related reactions leading to cessation of drug use.  
10.1212/WNL.0000000000205457