Purpose Peptide antigens have been administered by different approaches as cancer vaccine therapy, including direct injection or pulsed onto dendritic cells; however, the optimal delivery method is still debatable. In this study, we describe the immune response elicited by two vaccine approaches using the wild-type (wt) p53 vaccine. Experimental design Twenty-one HLA-A2.1 patients with stage III, IV, or recurrent ovarian cancer over-expressing the p53 protein with no evidence of disease were treated in two cohorts. Arm A received SC wt p53:264-272 peptide admixed with Montanide and GM-CSF. Arm B received wt p53:264-272 peptide-pulsed dendritic cells IV. Interleukin-2 (IL-2) was administered to both cohorts in alternative cycles. Results Nine of 13 patients (69%) in arm A and 5 of 6 patients (83%) in arm B developed an immunologic response as determined by ELISPOT and tetramer assays. The vaccine caused no serious systemic side effects. IL-2 administration resulted in grade 3 and 4 toxicities in both arms and directly induced the expansion of T regulatory cells. The median overall survival was 40.8 and 29.6 months for arm A and B, respectively; the median progression-free survival was 4.2 and. 8.7 months, respectively. Conclusion We found that using either vaccination approach generates comparable specific immune responses against the p53 peptide with minimal toxicity. Accordingly, our findings suggest that the use of less demanding SC approach may be as effective. Furthermore, the use of low-dose SC IL-2 as an adjuvant might have interfered with the immune response. Therefore, it may not be needed in future trials.

BackgroundDue to the lack of specific tumor antigens, the majority of tested cancer vaccines for renal cell carcinoma (RCC) are based on tumor cell lysate. The identification of the von Hippel-Lindau (VHL) gene mutations in RCC patients provided the potential for developing a novel targeted vaccine for RCC. In this pilot study, we tested the feasibility of vaccinating advanced RCC patients with the corresponding mutant VHL peptides.MethodsSix patients with advanced RCC and mutated VHL genes were vaccinated with the relevant VHL peptides. Patients were injected with the peptide mixed with Montanide subcutaneously (SQ) every 4 weeks until disease progression or until the utilization of all available peptide stock.ResultsFour out of five evaluable patients (80%) generated specific immune responses against the corresponding mutant VHL peptides. The vaccine was well tolerated. No grade III or IV toxicities occurred. The median overall survival (OS) and median progression-free survival (PFS) were 30.5 and 6.5 months, respectively.ConclusionsThe vaccine demonstrated safety and proved efficacy in generating specific immune response to the mutant VHL peptide. Despite the fact that the preparation of these custom-made vaccines is time consuming, the utilization of VHL as a vaccine target presents a promising approach because of the lack of other specific targets for RCC. Accordingly, developing mutant VHL peptides as vaccines for RCC warrants further investigation in larger trials. Trial registration: 98C0139