CD8A and colorectal carcinoma: Additionally, Lactobacillus‐derived ICA can inhibit the differentiation of CD4+ Tregs by modulating the IDO1/Kyn/AHR axis, thereby enhancing CD8+ T cell function and improving the efficacy of anti‐PD1 therapy in CRC, highlighting the potential of Lactobacillus as an adjuvant to enhance anti‐PD1 treatment [59].