A native cyclotide (MCoTI-II), on the other hand, has been tested for action against the BCR-ABL fusion protein (found as a product of the BCR/ABL gene fusion in leukemias) or the anti-CTLA-4 immune checkpoint, whose blockade with monoclonal antibodies is an immunotherapy registered and successfully used in immunogenic tumors [34,35]. Here, BCR is linked to leukemia.