A new series of indazole-containing αvβ3 integrin antagonists is described. Starting with lead compound 18a, variations in a number of structural features were explored with respect to inhibition of the binding of β3-transfected 293 cells to fibrinogen and to selectivity for αvβ3 over GPIIbIIIa, another RGD-binding integrin. Indazoles attached to a 2-aminopyridine or 2- aminoimidazole by a propylene linker at the indazole 1-position and to a ...