Therapeutic MUC1-Based Cancer Vaccine Expressed in Flagella-Efficacy in an Aggressive Model of Breast Cancer

MUC1, a tumor-associated antigen overexpressed in many carcinomas, represents a candidate of choice for cancer immunotherapy. Flagella-based MUC1 vaccines were tested in therapeutic setting in two aggressive breast cancer models, comprising the implantation of the 4T1-MUC1 cell line in either Balb/c, or Human MUC1 transgenic mice in which spontaneous metastases occurs. Recombinant flagella carrying only 7 amino acid of MUC1 elicited therapeutic activity, affecting both the growth of established growing tumors and the number of metastases. Higher therapeutic activity was achieved with an additional recombinant flagella designed with the SYFPEITHI algorithm. The vaccines triggered a Th1 response against MUC1 with no evident autoimmune response towards healthy MUC1-expressing tissues. Recombinant flagella carrying a 25-residue fragment of MUC1, induced the most effective response, as evidenced by a significant reduction of both the size and growth rate of the tumor as well as by the lower number of metastases, and expanding life span of vaccinated mice.