IDO1 and neoplasm: One potential mechanism for the failure of the IDO1 inhibitor epacadostat in clinical trials is that IDO1 inhibition leads to an effective blockade of the Kyn pathway and is accompanied by metabolic adaptation, which promotes the NAD biosynthesis pathway and inhibits T cell proliferation and function.[23] To further explore the regulatory role of lacidipine‐induced downstream adaptive metabolism in tumor immunity, we investigated the effects of lacidipine on key metabolites in the Trp and energy metabolism pathways using metabolomic analysis (Figure 4A and Figure S4A, Supporting Information).