Table 1.
Vaccine platforms (Table adapted from multiple sources6-12).
| Platform | Rationale | Immunogenicity | Toxicity | HLA Restriction | Pros | Cons |
|---|---|---|---|---|---|---|
| Peptide – Based | Elicit immunity to tumor associated self-antigens or tumor specific antigens | Low | Low | Yes | • Easy to produce with high purity in large amounts (e.g., cost effective) | • Only target one or a few epitopes – needs multiple peptides to prevent immune escape |
| • High specificity through use of defined epitopes | ||||||
| • Immunological compatibility only in patients with a specific HLA subtype. | ||||||
| • No additional treatments/procedures for patients | ||||||
| • Not pharmacologically active (little toxicity) | • Peptides with low affinity for MHC may be poorly immunogenic | |||||
| • Repeated booster vaccines to help with sustained immune response | ||||||
| • Immune responses may be transient or of low magnitude | ||||||
| • Often requires that it is given with immunoadjuvant to enhance immunogenicity | ||||||
| Protein – Based | Elicit immunity to tumor associated self-antigens or tumor specific antigens | Moderate | Low | No | • Multiple epitopes | • Give with immunoadjuvant to enhance immunogenicity |
| • More costly than peptide-based vaccines | ||||||
| • Higher antigen load | ||||||
| Viral – Based | Use natural ability to trigger immune responses and carry genetic material into cells for production of antigens | High | High | No | • Introduce target antigen into immune cells | • Immune response against priming virus requires different virus for a booster |
| • Easy to produce on large scale | ||||||
| Bacteria – Based | Use natural ability to trigger immune responses and carry genetic material into cells for production of antigens | High | High | No | • Effective antigen delivery – express foreign antigens | • Risk of undesired infections (but may be treated with antibiotics) |
| • Stimulate mucosal and systemic responses | ||||||
| • Easy to produce on large scale | ||||||
| Dendritic Cells/ Antigen Presenting Cells | DC's are the body's most effective APCs Can have protein, peptide or viral infected cells | High | Low | Yes | • More control over APC stimulation and antigen presentation | • Logistically difficult (APC selection, ex vivo maturation) |
| • HLA restricted but autologous cells | • Expensive – collection and manipulation | |||||
| • Need for a leukapheresis facility | ||||||
| • Risk of leukapheresis (central line insertion, hypotension, electrolyte imbalances, vascular injury) | ||||||
| • Difficult to ensure consistent vaccine production (varying leukapheresis yields, varying activated APCs, possible bacterial contamination) | ||||||
| Whole Tumor Cells | Deliver multiple relevant tumor antigens | Moderate | Low | No | • Broad array of antigens represented (minimizes immune escape) | • Cancer cells themselves are not that immunogenic |
| • Autologous cell vaccines are labor-intensive and difficult to standardize | ||||||
| • Readily produce allogenic cell lines on larger scale | ||||||
| • Not HLA restricted due to whole proteins present |
HLA Restriction – Different HLA subtypes present different antigens. Antigen is only immunological comparable in patients with a specific HLA subtype (i.e., HLA-A2+)