found that indole‐3‐aldehyde (I3A) derived from L. reuteri could induce aryl hydrocarbon receptor‐dependent CREB activity, and promote ICI response and survival in melanoma patients.[57] Similarly, indole‐3‐lactic acid (ILA) from L. reuteri could suppress colorectal tumorigenesis by inhibiting T helper 17 cell differentiation to promote the atorvastatin treatment effect.[58] The SynCom in this study increased indole‐3‐acetamide, 3‐indolepropionic acid, indole‐3‐lactic acid, and 5‐hydroxyindole‐3 acetic acid, and all of them showed a negative correlation with tumor number. Here, CREB1 is linked to neoplasm.