SLC16A1 and neoplasm: Non-invasive metabolic studies are a powerful tool for longitudinal assessment of metabolism at the tumour site, with methods such MRS (single voxel and spectroscopic imaging methods) enabling the steady state as well as dynamic assessment of several key metabolic pathways in pre-clinical models and patients.31,32 If validated in other MCT1-dependent models, our data support exploring the use of the clinically applicable 1H NMR spectroscopy of choline/water as a biomarker for monitoring the action of AZD3965 and potentially other MCT1 inhibitors in patient tumours.