Ofatumumab on the PBS

From 1 October 2021, ofatumumab (Kesimpta®) is available on the Pharmaceutical Benefits Scheme (PBS) for the treatment of relapsing-remitting multiple sclerosis (MS). This is the most common form of MS, accounting for around 85% of all cases.

Ofatumumab is a fully human anti-CD20 monoclonal antibody. The CD20 molecule is expressed on B cells at all points of differentiation as well as a small fraction of activated T cells. B cells are an important therapeutic target in the treatment of MS as they are responsible for the release of pro-inflammatory cytokines and auto-reactive antibodies and for the activation of pathogenic T cells.

A double-blind, double-dummy trial compared subcutaneous ofatumumab and oral teriflunomide. The primary end point of annualised relapse rate was 0.11 in the ofatumumab group and 0.22 in the teriflunomide group. Disability worsening in the ofatumumab group was 10.9% at three months and 8.1% at six months, compared to 15.0% and 12.0%, respectively, in the teriflunomide group. However, there was no significant difference in confirmed disability improvement between the two groups.

Ocrelizumab is another anti-CD20 monoclonal antibody approved for the treatment of MS in Australia. One of the major differences between the two therapies is that ocrelizumab is administered as an intravenous infusion every six months, while ofatumumab can be self-administered as a monthly subcutaneous injection (following the initial dosing periods).