Definition

A therapeutic peptide vaccine consisting of two highly immunogenic synthetic long peptides (SLPs), which are 25-35 amino acids in size, derived from the human papillomavirus (HPV)-type 16 oncoprotein E6, and conjugated to a proprietary toll-like receptor 2 (TLR2) ligand (TLR2-L) immunoadjuvant, with potential immunostimulating and antitumor activities. Upon administration, the TLR2-L moiety of the synthetic long E6 peptides TLR ligand conjugate vaccine targets and binds to TLRs expressed on antigen-presenting cells (APCs), particularly dendritic cells (DCs). This increases the direct targeting of, binding to, uptake by, and processing of the SLPs into small pieces by the DCs. The processed viral epitopes are presented by DCs, which activate and stimulate the host immune system to mount specific cytotoxic T lymphocyte (CTL) and helper T (Th) cell responses against HPV E6-expressing tumor cells. This results in the destruction of tumor cells and leads to decreased growth of HPV E6-expressing tumor cells. The E6 oncoprotein is implicated in tumorigenesis in a variety of cancers. The TLR2-L improves antigen processing and presentation by, and activation of APCs, thereby improving the immunostimulatory effect of the vaccine. The two peptides cover the most immunodominant regions of the HPV16 E6 oncogenic protein and contain both Th and CTL epitopes.