Tyrphostin AG 879 potently inhibits HER2/ErbB2 with IC50 of 1 μM, 100- and 500-fold higher selective to ErbB2 than PDGFR and EGFR.

AG879 inhibits growth of FET6αS26X cells in a concentration-dependent manner.AG879(10 nM) blocks the activation of PAK1 and suppresses RAS-induced malignant transformation of NIH 3T3 cells. AG879(<1 μM) inhibits the Tyr-phosphorylation of ERK and its association with PAK1 in v-Ha-RAS-transformed NIH 3T3 fibroblasts.AG 879 dose-dependently reduce MCF-7 cell numbers and show already a significant effect at 0.4 mM through inhibiting DNA synthesis and mitotic. AG 879(<20 μM) inhibits activation of ERK-1/2 in MCF-7 cell. AG 879(5 μM) decreases expression of Hsp90 client proteins RAF-1 and HER-2.AG879(20 μM) dramatically decreases proliferation with a variable increase in apoptosis in Cell lines from human leiomyosarcoma (HTB-114, HTB-115, HTB-88), rhabdomyosarcoma (HTB-82, TE-671), prostatic adenocarcinoma (PC-3), acute promyelocytic leukemia (HL-60) and histiocytic lymphoma (U-937).

AG879(2 mg) induces a decrease in cancer growth in athymic NOD/SCID mice grafted with HTB-114 or HL-60.AG 879(20 mg/kg) treatment keeps 50% of mice absolutely free of RAS-induced sarcomas, and dramatically reduces the size of the growing sarcomas in the nude mice carrying v-Ha-RAS transformed NIH 3T3 cells.