D1 is a peptide containing the 81-WKTIITKN-88 conserved sequence from the IL13Ralpha2 binding site, the full sequence being that which interacts directly with IL-13 in site III. IL13Ralpha2 is a cancer/testis-like tumour antigen that is overexpressed in various tumours, and in colorectal cancer, IL13Ralpha2 expression is associated with late stage disease and lower overall survival. D1 blocks IL-13 binding to IL13Ralpha2 with near complete inhibition at 50µg/ml, and in metastatic colorectal and glioblastoma cancer cells treated with IL-13, D1 peptide inhibits migration, invasion, and proliferation. In vivo, D1 peptide causes a modest increase in survival of mice innoculated with KM12SM colonic cancer cells preincubated with D1, but in contrast, the more stable D1 enantiomer consisting of all D amino acids, D-D1, causes a remarkable increase in survival in animal models, with 40% of mice surviving the experimental endpoint without metastatic lesions in liver. In glioblastoma xenografts, D-D1 peptide administration causes significant growth arrest accompanied by a regression in tumour size. Please contact us for the D-D1 peptide
