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Datasets  >  clinical study dataset  >  Phase I/II clinical trial ...

Phase I/II clinical trial on the use of long peptides plus adjuvant for end-stage cervical cancer or VIN patients

clinical study dataset

We have obtained data from a phase I/II clinical trial of patients with end stage cervical cancer and of patients with vulvar intraepithelial neoplasia (VIN) grade III. Preclinical animal studies have shown that long peptides of 25-35 amino acids in length upon injection are only processed efficiently for MHC class I by dendritic cells in vivo. Long peptide injection is followed by appropriate cognate interactions between such DC, CD4+ T helper cells and CD8+ CTL precursors.

Three groups of end stage cervical cancer patients (in total N=35) were subcutaneously vaccinated with HPV16 E6 combined with or separated from HPV16 E7 overlapping long peptides in Montanide ISA-51 adjuvant, 4 times at three week intervals. Group 1 received 300 microgram per peptide at a single site, group 2 received 100 microgram per peptide of the E6 peptides in one limb, and 300 microgram per peptide of the E7 peptides in a second limb. Group 3 received separate injections of E6 and E7 peptides, each at a dose of 50 micrograms per peptide. The primary endpoint was to determine safety and toxicity of the HPV16 long peptide vaccine. In addition, the vaccine-induced T-cell response was assessed by IFN gamma-ELISPOT. No toxicity beyond grade II was observed during and after 4 vaccinations. In a few patients transient flu-like symptoms were observed. ELISPOT analysis of the vaccine-induced immune response revealed that co-injection of the E6 and E7 peptides resulted in a strong and broad T-cell response dominated by immunity against E6. Injection of the E6 and E7 peptides at two different sites increased the E7-response but did not affect the magnitude of the E6-induced immune response.

The HPV16 E6 and E7 long-peptide based vaccine is well tolerated and capable of inducing a broad IFN gamma-associated T-cell response, even in end stage cervical cancer patients. 5 out of 20 patients showed complete clearance of all VIN III disease and in 4 of these this was also associated with complete clearance of HPV16 virus. In conclusion, our peptide based vaccine is safe, elicits a strong and broad HPV16 specific T cell response, even under sub-optimal clinical conditions. We have now observed 9 months later, without further vaccination, that another 4 patients have achieved complete remission of all disease, confirmed by microscopy. Sustained benefit was observed in all 9 patients with complete remission of disease. This is also expected, because the 5 complete responders at 3 months after the last vaccination were also shown to be free of HPV16 at the site of the original vaccination. We conclude that this therapeutic vaccine trial caused complete disease regression in 9 out of 20 patients (45%), whereas spontaneous complete regression of VIN3 lesions occurs in less than 1.5% of patients. Another 6 patients had objective partial regressions of lesions 12 months after the last vaccination. At three months after vaccination there was a highly significant positive correlation between the strength of the interferon gamma and proliferative T cell response and the clinical response. In summary, clinical benefit was observed in 15 out of 20 patients (75%). A paper describing these results has been submitted for publication. Preclinical evidence has shown that these long peptides act so well as a therapeutic vaccine, because only dendritic cells can efficiently process all potential epitopes from the long peptides and because concentrated antigen is offered to the immune system in the absence of antigenic competition.

Additionally tissue biopsies of the last vaccination site and of the VIN lesion prior to the first vaccination and 3 months after the last vaccination were analysed for the presence of HPV16-specific T cells. The IFN?-ELISPOT analysis and proliferation with its accompanying cytokine production revealed a strong and broad vaccine-induced T cell response. The strength of the immune response (defined as breath and magnitude of the response) was significantly higher in the patients with a complete remission (CR) than in the patients with no changes (NC) in the lesion size. Phenotypical anlaysis revealed a strong induction of CD4+ T-cells specifically against HPV16 E6 and E7, whereas CD8+ T cells were found merely against HPV16 E6 and to a less broad array of epitopes within each patient. This analysis was done after one in vitro restimulation, however, by directly ex vivo flow cytometric analysis hardly any CD8+ T cell response could be detected.

The T cell cultures obtained from the biopsies taken of the last vaccination site were found to be HPV16 peptides specific in 3/5 tested NR patients and in 4/5 tested CR. However, recognition of the recombinant HPV16 E6 and/or E7 protein was observed in 1/5 cultures from NR patients and 4/5 cultures of the CR patients, suggesting the differences in vaccine-induced T-cell reactivity. Tissue biopsies of the VIN lesion before and after vaccination showed only in one patient a HPV16-specific T-cell response, which was against HPV16 E6 and merely of the type 2 cytokine producing T cells. Notably, no T-cell cultures could be obtained from VIN biopsies taken from the CR patients.

In conclusion, the HPV16 E6 and E7 synthetic long peptides vaccine is highly immunogenic, in that it increases the number and activity of HPV16-specific CD4+ and CD8+ T-cells to a broad array of epitopes in all patients. The expansion of CD4+ and CD8+ tumor-specific T-cells, both considered to be important in the anti-tumor response indicates the immunotherapeutic potential of this vaccine. Addition of a strong toll-like receptor ligand might increase the CD8 response in frequency and to a broader set of epitopes.

Conducting a new clinical trial in which the peptide vaccination is combined with the application of Aldara? on the vaccination site in order to induce a strong CD4+ but more importantly a CD8+ T cell response, which can be detected directly ex vivo.

N.B. information relevant to design of one arm of proposed DC-THERA trial

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