KIF5B and medullary thyroid gland carcinoma: Consistent with these findings, vepafestinib suppressed growth of allograft tumors harboring the RETG810R mutation (Ba/F3 KIF5B–RETG810R) and displayed substantial efficacy against Ba/F3 cells expressing CCDC6-RET fusions (RETWT and RETS904F) or the RETM918T mutation found in MTC.