The monofunctionalizationof the mutant did not dampen its affinity vs PD-L1 and the immunomodulatingproperties of the derivatives obtained were investigated in vitro vs two different types of breast cancer (BC) cell lines.The HACTR-PD-1 rhamnosyl derivatives successfully prepared, namely, 1-HACTR-PD-1 and 2-HACTR-PD-1, are characterizedby two different spacers and different types of glycosidic bonds usedto link the rhamnosyl moiety to the mutant. The gene discussed is PDCD1; the disease is breast cancer.