XL-784 free base is a selective inhibitor of matrix metalloproteinases (MMP), (IC50s of ~1900, 0.81, 120, 10.8, 18, 0.56 nM for MMP-1,MMP-2,MMP-3,MMP-8,MMP-9,MMP-13,respectively).

XL-784 is a low-molecular-weight (1,122 g/mol) MMPs inhibitor. XL-784 potently inhibits MMP-2, MMP-13, and ADAM10 [TNF-α-converting enzyme (TACE)] activity in vitro(IC50 values in the range of 1-2 nM). XL-784 also inhibits MMP-9 (IC50 ~20 nM) activity and ADAM17 (IC50 ~70 nM) also known as TACE. However, XL-784 exhibits low potency for inhibition of MMP-1 (IC50 ~2,000 nM)[1].

Treatment with all doses of XL-784 and doxycycline are effective in inhibiting aortic dilatation. There is a clear dose-response relationship between XL-784 and reductions in aortic dilatation at harvest (50 mg/kg 140.4% ±3.2%; 125 mg/kg 129.3% ±5.1%; 250 mg/kg 119.2%±3.5%; all Ps<0.01 compared to control). This continues with the higher doses (375 mg/kg 88.6%±4.4%; 500 mg/kg 76.0%±3.5%). The two doses of the highest dose of XL-784 tested were more effective than doxycycline in inhibiting the maximum expansion of the aorta after elastase infusion (112.2%±2.0%, P<0.05) [2].