Figure 4.

Ponatinib is the most potent KIF5B-RET inhibitors and the vandetanib resistant RET^G810A mutation is hypersensitive to ponatinib. A, growth curve of parental, vector control (B/V) and stable BaF3 cells expressing KIF5B-RET (B/KR) without IL-3. B, cells were grown in medium without IL-3 for 6, 16, 24 hours. The cell lysates were immunoblotted with anti-cleaved PARP or anti-β actin. P, parental; V, vector control; KR, KIF5B-RET. C, vector control and KIF5B-RET cells were treated with or without 1 µM cabozantinib (CBT) for 3 hours. The cell lysates were immunoblotted with anti-RET-pY905, anti-Flag, anti-cleaved PARP or anti-beta actin. D, Ba/F3 expressing KIF5B-RET, KIF5B-RET^V804L, or KIF5B-RET^G810A were seeded on 96-well plates and treated with indicated concentration of ponatinib (PNT), cabozantinib (CBT), vandetanib (VDT) or lenvatinib (LVT) for 5 days. Cell viability was measured using the CellTiter-Glo assay and IC_50s were determined. The data were from two triplicate experiments (n = 6).