Interestingly, although ampicillin had no impact on tumor growth during sucralose consumption (complete response: 20%), vancomycin, a bacteriostatic antibiotic that targets Gram-positive bacteria (complete response: 44%), increased overall response rates in mice consuming sucralose and receiving anti–PD-1 (Fig. 4B), suggesting that the gut microbiome may be associated with sucralose-driven resistance to anti–PD-1. The gene discussed is PDCD1; the disease is neoplasm.