CD28 and colorectal carcinoma: In recent years, as immunotherapy has come to the forefront, ICB strategies have been applied to CRC treatment.18,19 For instance, PD-1, PD-L1, and members of the CD28 superfamily of T cell regulatory factors have been identified as potential targets for immunotherapy in CRC.20 Recently, research has shown that the microbiome can influence the effectiveness of cancer immunotherapy.