BBT594 is a potent receptor tyrosine kinase RET inhibitor , used for cancer treatment. In Vitro NVP-BBT594 blocks the GDNF-mediated enhancement of MCF7-LTED cell viability in 2D culture and 3D colony formation. The addition of 10 pM E2, to mimic the E2 level in post-menopausal patients that have relapsed on AI treatment and ceased AI therapy, increases 3D colony formation of both MCF7 and MCF7-LTED cells, and this effect is efficiently reverted by NVP-BBT594. Parental T47D cells cultured in presence of low level E2, GFRα1/GDNF stimulation results in increased 3D colony formation, which is significantly reverted by NVP-BBT594. NVP-BBT594 targets GDNF-RET signaling and sensitizes MCF7-2A cells to letrozole treatment. NVP-BBT594 impairs GDNF-mediated RET downstream signaling and significantly enhances the antiproliferative effects of letrozole. NVP-BBT594 shows the highest suppression of GDNF-induced RET signaling, as assessed by RET, ERK1/2, AKT and ER phosphorylation. NVP-AST487 and NVP-BBT594 have comparable RET inhibitory activity in wild-type MCF7 cells. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid