HRAS and thyroid cancer: AZD6244 could also enhance the efficiency of the selective RTK inhibitor tipifarnib in HRAS-driven dedifferentiated thyroid cancers in vivo.346 In PDX models of thyroid cancer with different KRAS, BRAF, and NRAS mutations, the MEK inhibitor selumetinib combined with the MDM2 inhibitor KRT-232 showed a remarkable effect.