restriction. The need for MHC profile selection can be overcome by using longer peptides (“synthetic long peptides”) or purified protein, which are then processed into epitopes by APCs. Gene-based vaccines are composed of the nucleic acid (DNA/RNA) encoding for the gene. The gene is then expressed in APCs and the resulting protein product is processed into epitopes. Delivery of the gene is particularly challenging for this type of vaccine. Clinical trials The clinicaltrials.gov website lists over 1900 trials associated with the term “cancer vaccine”. Of these, 186 are Phase 3 trials. In a Phase III trial of follicular lymphoma (a type of non-Hodgkin's lymphoma), investigators reported that the BiovaxID (on average) prolonged remission by 44.2 months, versus 30.6 months for the control. On April 14, 2009, Dendreon Corporation announced that their Phase III clinical trial of sipuleucel-T, a cancer vaccine designed to treat prostate cancer, had demonstrated an increase in survival. It received U.S. Food and Drug Administration (FDA) approval for use in the treatment of advanced prostate cancer patients on April 29, 2010. Interim results from a phase III trial of talimogene laherparepvec in melanoma showed a significant tumour response compared to administration of GM-CSF alone. A recent Trial Watch review (2015) of peptide-based vaccines summarized the results of more than 60 trials that were published in the 13 months preceding the article. These trials targeted hematological malignancies (cancers of the blood), melanoma (skin cancer), breast cancer, head and neck cancer, gastroesophageal cancer, lung cancer, pancreatic cancer, prostate cancer, ovarian cancer, and colorectal cancers. The antigens included peptides from HER2, telomerase (TERT), survivin (BIRC5), and Wilms’ tumor 1 (WT1). Several trials also used “personalized” mixtures of 12-15 distinct peptides. That is, they contain a mixture of peptides from the patient’s tumor that the patient exhibits an immune response against. The results of these studies indicate that these peptide vaccines have minimal side effects and suggest that they induce targeted immune responses in patients treated with the vaccines. The article also discusses 19 clinical trials that were initiated in the same time period. These trials are targeting solid tumors, glioma, glioblastoma, melanoma, and breast, cervical, ovarian, colorectal, and non-small lung cell cancers and include antigens from MUC1, IDO1 (Indoleamine 2,3-dioxygenase), CTAG1B, and two VEGF receptors, FLT1 and KDR. Notably, the IDO1 vaccine is being tested in patients with melanoma in combination with the immune checkpoint inhibitor ipilimumab and the BRAF