In preclinical models, pralsetinib has shown activity both against KIF5B–RET Ba/F3 and KIF5B–RETV804L Ba/F3 allograft tumors, and in the same work, the first proof of clinical activity towards 4 patients enrolled in the phase I/II trial ARROW was presented (two patients with medullary thyroid carcinoma and two patients with NSCLC, the first TKI-naïve and the second previously pretreated with vandetanib plus everolimus) [60]. The gene discussed is KIF5B; the disease is medullary thyroid gland carcinoma.