Anti-tumor immune responses and tumor regression induced with mimotopes of a tumor-associated T cell epitope.

Mimotopes provide an alternative to natural T cell epitopes for cancer immune therapy, as they can recruit and stimulate T cell repertoires that deviate from the repertoires engaged with the tumor and exposed to disease-related immune suppression. Here, mimotopes of a shared tumor-associated T cell epitope in cutaneous lymphoma were tested for their capacities to induce clinical and immunological responses in cancer patients. The mimotope sequences had been determined by a combinatorial peptide library approach without knowledge of the corresponding natural tumor-associated antigen. Vaccination with these mimotopes together with helper T cell-inducing antigens led to complete tumor remission in the two patients tested. After each booster vaccination, enhanced frequencies of mimotope-specific CD8+ T cells were detected in the peripheral blood of the patients, and the CTL proved to be cytotoxic and tumoricidal when tested in vitro. These data provide a first indication of clinical efficacy of mimotopes in cancer patients.