Discovery of small molecule integrin alphavbeta3 antagonists as novel anticancer agents.

Integrin alphavbeta3 has been implicated in multiple aspects of tumor progression and metastasis. Many tumors have high expression of alphavbeta3 that correlates with tumor progression. Therefore, alphavbeta3 receptor is an excellent target for drug design and delivery. We have discovered a series of novel alphavbeta3 antagonists utilizing common feature pharmacophore models. Upon validation using a database of known alphavbeta3 receptor antagonists, a highly discriminative pharmacophore model was used as a 3D query. A search of a database of 600 000 compounds using the pharmacophore Hypo5 yielded 832 compounds. On the basis of structural novelty, 29 compounds were tested in alphavbeta3 receptor specific binding assay and four compounds showed excellent binding affinity. A limited SAR analysis on the active compound 26 resulted in the discovery of two compounds with nanomolar to subnanomolar binding affinity. These small-molecule compounds could be conjugated to paclitaxel for selective delivery to alphavbeta3 positive metastatic cancer cells.