Namilumab is an investigational treatment being developed for rheumatoid arthritis (RA) and ankylosing spondylitis (AS).

Germany’s Micromet originally developed the treatment. Japan’s Takeda Pharmaceuticals, which conducted Phase 2 clinical trials in patients with RA, continued working on namilumab. Takeda recently granted a license to Izana Bioscience to develop and market namilumab worldwide for any indication. Izana will initially focus on AS.

Takeda was also investigating namilumab to treat plaque psoriasis but discontinued that program after a Phase 2 trial (NCT02129777) failed to meet its primary endpoint.

How namilumab works

It is a monoclonal antibody that binds and neutralizes a cell signaling molecule that stimulates the growth and differentiation of blood cells called granulocyte macrophage-colony stimulating factor (GM-CSF). GM-CSF is produced by several cell types such as T-cells, macrophages and smooth muscle cells. It induces production of inflammatory molecules and activates the immune system.

In patients with RA, GM-CSF is overproduced, so namilumab-mediated blocking of GM-CSF may neutralize the effects of high levels of GM-CSF. A recently published study indicated that levels of GM-CSF are also elevated in patients with AS. This makes an anti-GM-CSF antibody a promising therapeutic for AS.

Namilumab in clinical trials

A Phase 1b, randomized, double-blind study (NCT01317797) assessed the safety and tolerability of namilumab in patients with mild to moderate RA. The study showed that namilumab was generally well tolerated, with preliminary evidence of efficacy.

A Phase 2 study (NCT02379091) aimed to identify the optimal dose for namilumab in patients with moderate to severe RA who responded inadequately to treatment with methotrexate or tumor necrosis factor (TNF) inhibitors. The study has been completed but no results have been published yet.

Another Phase 2 study (NCT02393378) evaluated the safety and efficacy of namilumab in combination with methotrexate over 24 weeks in patients with moderate to severe early RA, diagnosed within six months and responding inadequately to methotrexate alone. The results of this study have not yet been published either.

Other information

Izana plans to initiate a Phase 2 proof-of-concept study this year, thanks to a £1.35 million U.K. government grant. The trial — a randomized, double-blind, placebo-controlled study in 30 British patients with moderate-to-severe active AS — aims to prove its efficacy as measured by changes in clinical symptoms, markers of inflammation and appearance of the spine.

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