MMP9 and colitis: In addition to the initial colitis animal model results being misleading, the lack of success of GS-5745/andecaliximab in the UC clinical trial may also have been due to the antibody having higher affinity for proMMP-9 (KD = 0.008–0.043 nM) compared with active MMP-9 (KD = 2.0–6.6 nM) [76], and thus much of the applied inhibitor may not have been bound to the active form of the enzyme.