Microbial HSP70 peptide epitope 407-426 as adjuvant in tumor-derived autophagosome vaccine therapy of mouse lung cancer.

Tumor-derived autophagome (DRibble) is an effective therapeutic cancer vaccine inducing T cell recognition and death of tumor cells in mice. However, the potential for improved anti-tumor response still remains. Our previous study demonstrated that two repeats of a mycobacterial HSP70407-426 (M2) peptide acted as adjuvant in improving anti-tumor efficacy of human umbilical vein endothelial cell (HUVEC) vaccine. Here, a DRibble vaccine conjugated with M2 (DRibble-M2) was designed as a novel vaccine to enhance anti-tumor activity. Compared with DRibble alone, DRibble-M2 vaccination more significantly inhibited the growth of mouse Lewis lung cancer both in a subcutaneous tumor model and in a lung metastasis model. Higher expression of antigen-specific CTL was induced by DRibble-M2. DRibble-M2 induced higher CD83 and CD86 expression in DC2.4 and also improved the internalization of DRibble antigen into DC2.4. Our data indicated that DRibble-M2 is a potential vaccine for clinical cancer therapy.