Inhibition of the epidermal growth factor receptor tyrosine kinase activity by leflunomide

Abstract
The active metabolite of leflunomide, A77 1726 inhibits the proliferation of a variety of mammalian cell lines in culture. Epidermal growth factor (EGF)‐dependent proliferation is inhibited by A77 1726 at an effective dose of 30–40 μM. A77 1726 appears to directly inhibit the EGF receptor tyrosine‐specific kinase activity both in intact cells and purified EGF receptors at the same effective dose. These data suggest that leflunomide inhibits cellular proliferation by the inhibition of tyrosine‐specific kinase activities.