Adalimumab responders demonstrated early downregulation of chemokine ( C-C motif ) ligand 20 ( CCL20 ) mRNA ( mean [ SE ] at week 2 , -1.83 [ 0.52 ] , P < .001 ; week 16 , -3.55 [ 0.54 ] , P < .001 ) compared with late downregulation for methotrexate responders ( week 2 , 0.02 [ 0.51 ] , P = .96 ; week 16 , -2.96 [ 0.51 ] , P < .001 ) .