PDCD1 and neoplasm: Mice were exposed to a physiologically equivalent dosage of sucralose (0.09 mg/mL, ∼0.45 mg/day) based on their increased basal metabolic rates compared with humans (30) in the drinking water starting 2 weeks before tumor injection and were maintained on sucralose-containing water for the duration of treatment with anti–PD-1 (days 9, 12, and 15; Fig. 2A).