The present status and future prospects of peptide-based cancer vaccines

Abstract

Tumor cells commonly express several antigens, such as tumor-associated antigens (TAAs) or mutation-derived antigens (neoantigens), that can be regarded as foreign antigens and elicit anti-tumor immune responses in cancer patients. Various TAAs or neoantigens expressed in cancer cells have been identified and utilized as targets for cancer vaccines. One approach to elicit tumor-specific immune responses is termed peptide-based cancer vaccination; it involves administrating TAAs or neoantigen-derived peptide for treatment of cancers. There have been several forms of peptide-based cancer vaccines depending on which effector cells, such as CTLs or CD4(+) T-helper cells, are targeted to be activated. Many phase I and II clinical trials of peptide-based cancer vaccines using TAA-derived CTL epitopes, T-helper cell epitopes or dendritic cells loaded with TAA-derived peptides for various malignant tumors have been conducted and provide clinical benefits in a small fraction of patients. Nowadays, to improve the efficiency of peptide-based cancer vaccines, combination immunotherapy of peptide-based cancer vaccines with the immune-checkpoint blockade therapies using mAbs specific for CTLA-4, programmed cell death 1 (PD-1), or PD-1 ligand 1 (PD-L1) have been developed for clinical application. Furthermore, along with the recent technological progress in genetic and bioinformatic analysis, it has become easier to identify neoantigens from individual cancer patients. It is expected that peptide-based cancer vaccines targeting neoantigens as a personalized cancer immunotherapy will be developed.

Trial watch: Peptide-based vaccines in anticancer therapy

“…267-269 In line with this notion, the vast majority of peptide-based vaccines tested in the clinic so far mediated limited, if any, therapeutic activity, despite being able to elicit tumor-targeting immune responses, at least to some degree. 118 The field is therefore moving along three non-mutually exclusive directions: (1) combining peptide-based vaccination with additional forms of (immuno)therapy, with the specific aim of reverting immunosuppression and enabling therapeutically relevant immune responses, 270-272 (2) targeting private antigenic epitopes that originate from mutations affecting only malignant cells (or sub-populations thereof), with PPV, 167,272-275 and (3) identifying specific patient populations that may obtain clinical benefit from the use of peptide-based vaccination. 174,254 Although the feasibility of PPV on a large scale remains unclear, we surmise combining some variants of peptide-based vaccination with potent immunostimulatory agents including immune checkpoint blockers and oncolytic viruses may be the key to unlock the true potential of this hitherto unrealized therapeutic modality.…”

Nanomaterials for cancer immunotherapy

“…Typically, CD8 + T cells recognize peptides associated with MHCI molecules, which are 8 to 10 amino acids long. MHCII molecules can present much larger peptides, often 13 to 18 amino acids long, but generally stimulate CD4 + T cells [104]. Due to ease of synthesis and stable formulation, peptide vaccines are widely studied in research and clinic [65].…”

Cancer vaccine therapy based on peptides

“…To overcome this problem, extended long peptides were developed. Long peptides do not bind to HLA directly and only professional APCs, such as DCs, can take it up [76] . However, it was reported that some long peptides might induce peptide-specific regulatory T cells (Tregs) and Th2 cells to limit the clinical efficacy of long peptides [77,78] .…”