Ofatumumab (also known as Arzerra and HuMax-CD20) is an anti-CD20 monoclonal antibody that targets antigenic determinants (epitopes) on the surface of CD20 cells (responsible for early stage division, proliferation, and maturation of B-cells) to alter their behavior. It is manufactured by the Danish biotech company Genmab in partnership with GlaxoSmithKline and Novartis AG.
In August 2015, Novartis purchased all remaining rights to ofatumumab from GSK to develop treatments for multiple sclerosis (MS) and other diseases, including cancer, marketing it under the brand name Arzerra.
The drug is mainly prescribed for patients with leukemia and similar types of blood-borne malignancies — it was approved by the U.S. FDA for treating chronic lymphocytic leukemia — but clinical trials are taking place by the manufacturers for treating pemphigus vulgaris (PV) and relapsing and remitting forms of multiple sclerosis (RRMS).
How Ofatumumab Works
Known to alter the growth and proliferative properties of B-cells, ofatumumab is believed to affect the immune system in such a way that it reduces immune-mediated damage to myelin sheaths of neurones spanning the central nervous system. The exact mode of action by which it alters relapse and remission in MS patients is still uncertain, but previous studies indicate that complement dependent cytotoxicity (CDC) and antibody-dependent cytotoxicity (ADCC) are its main modes of action against immune cells.
Preclinical trials with the drug in animal models provided suitable results, which helped developers proceed with Phase 1 clinical trials in healthy human participants. With proven safety and toxicity profiles, the companies moved forward with Phase 2 clinical trials, which started in November 2011.
A pilot Phase 2 trial with a small cohort of 38 patients was carried out in 2011, where patients with RRMS were given different doses of the drug for 48 weeks. A considerable reduction in the formation of brain plaques was seen along with a reduction in the number of (autoimmune) B-cells. Also, the formation of new plaques was suppressed.
This paved the way for a second, larger Phase 2 trial of ofatumumab called MIRROR, with 232 patients with RRMS in a multicenter, double-blind, placebo-controlled study. The study participants were divided into eight groups to receive ofatumumab injections over six months in varying dosages.
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