CTLA4 and neoplasm: Also CTLA-4 is an inhibitory immune checkpoint that can be accentuated in tumor-infiltrating lymphocytes and colorectal cancer (CRC) cells, facilitating tumor growth and metastasis [16]; in addition, anticancer immunotherapy by CTLA-4 blockade is accentuated by outgrowth of Bacteroides fragilis with its anticancer properties [17].