<p>Pirfenidone is an orally active, small molecule that shows a wide range of biologic activity. In vitro evidence has shown that pirfenidone inhibits collagen synthesis, down-regulates profibrotic cytokines and decreases fibroblast proliferation. Pirfenidone leads to a reduction of TGF-beta2 mRNA levels and of the mature TGF-beta2 protein due to decreased expression and direct inhibition of the TGF-beta pro-protein convertase furin. In addition, pirfenidone reduces the protein levels of the matrix metalloproteinase (MMP)-11, a TGF-beta target gene and furin substrate involved in carcinogenesis.</p>