Thursday, September 19, 2013

Mavrilimumab in Rheumatoid Arthritis

There’s news on mavrilimumab!
G.R. Burmester and colleagues published the following study in Annals of the Rheumatic diseases: “Efficacy and safety of mavrilimumab in subjects with rheumatoid arthritis.” They concluded: “Mavrilimumab induced rapid clinically significant responses in RA subjects, suggesting that inhibiting the mononuclear phagocyte pathway may provide a novel therapeutic approach for RA.”
No so quickly, you might say.
Mavrilimumab is a human monoclonal antibody (MAB) targeting granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor. The authors evaluated mavrilimumab in a randomised, double-blind, placebo-controlled phase 2 study. In results we find: “55.7% of mavrilimumab-treated subjects met the primary endpoint versus 34.7% placebo (p=0.003) at week 12; for the 10 mg, 30 mg, 50 mg, and 100 mg groups, responses were 41.0% (p=0.543), 61.0% (p=0.011), 53.8% (p=0.071), and 66.7% (p=0.001) respectively.” And there’s where we have to talk. 10 and 50 mg do not show significant effects, while 30 and 100 mg do. It is unclear, why 30 mg should be better than 50 mg; most probably the effect is due to the still small size of the different groups. So this has to be checked in a larger group of active RA patients.
Link to the Abstract: and you can open a Free Full Text there.
The article ends: “This hypothesis will be evaluated in future larger, appropriately powered clinical studies.” And these studies must show a reduction of radiographic progress. The approval of xeljanz in Europe for instance has been postponed because EMEA wants more date on radiographic progression.
Let’s sum it up: mavrilimumab is doing better than I expected from the data being published during the past year. I hope we’ll get a new targeted therapy, but I still think it’s to early to celebrate.

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