INS and Hyperglycemia: Hyperglycaemia is a known class effect of anti-IGF-1R mAbs and TKIs, despite their lack of interference with insulin binding.1 The finding that drug-related hyperglycaemia was rare with xentuzumab (no patients in study 1280.1 and two patients in study 1280.2 [grade 1 and grade 3]) is consistent with clinical studies of another IGF-ligand blocking mAb, dusigitumab (MEDI-573).9,10 The low incidence of hyperglycaemia with xentuzumab suggests that the anti-ligand mechanism of action may be more favourable than IGF-1R-targeted therapies with regard to hyperglycaemia.