Introduction

Clearance of HPV and related cervical lesions is associated with the development of a robust T cell response. Therapeutic vaccination is a promising approach to restore T cell immunity, treat infections and malignancies. A two-dose heterologous vaccination strategy using non-replicating viral vectors, Chimpanzee Adenovirus Oxford 1 (ChAdOx1) and Modified Vaccinia virus Ankara (MVA), has been safe and immunogenic in clinical studies across various indications. This is the first study to evaluate the safety, tolerability, immunogenicity and efficacy of ChAdOx1 and MVA in participants with persistent cervical high-risk HPV (hrHPV) infection and low-grade cervical lesions.

Methods

MVA boosts and prolongs the T cells induced by ChAdOx1. Doses of ChAdOx1 up to 5 x 10¹⁰ vp and MVA doses up to 2.5 x 10⁸ pfu have been evaluated in various indications. We will investigate different doses of ChAdOx1 and MVA to deliver sequences from high risk HPV strains (16, 18, 31, 52, 53 and 58). The study will be conducted sequentially under an umbrella protocol design (Fig 1):

- An open label dose escalation study investigating 3 varying doses of ChAdOx1 (baseline) and a fixed dose of MVA (Day 28) with a 3-months follow-up period (n=9).

- A blinded, randomised (2:1), placebo-controlled study investigating 3 varying doses of ChAdOx1 (baseline) and 2 doses of MVA (Day 28) with a 12-month follow-up period (n=96).

Results

105 participants will be enrolled. The primary objective is to evaluate safety of both vaccines. The secondary objectives will include dose determination for further development, clearance of hrHPV infection and resolution of associated cervical lesions.

Conclusions

The success of therapeutic vaccination depends on an appropriate prime-boost vaccination strategy. This study evaluates the impact of a heterologous prime boost therapeutic vaccination strategy to clear persistent cervical hrHPV infection and revert low-grade cervical lesions. Available study results will be presented at the meeting.

Introduction

The conventional prophylactic vaccines for human papillomavirus (HPV) efficiently prevent infection with high-risk HPV types, but they do not promote therapeutic effects against cervical cancer. Previously, we developed HPV16 E7-expressing Lactobacillus casei (L. casei-E7) as a therapeutic vaccine candidate for cervical cancer, which induces antitumor therapeutic effects in a TC-1 murine cancer model. To improve the therapeutic effect of L. casei-E7, we performed co-treatment with poly-gamma-glutamic acid (γ-PGA), a safe and edible biomaterial naturally secreted by Bacillus subtilis. We investigated their synergistic effect to improve antitumor efficacy in a murine cancer model. The treatment with γ-PGA did not show in vitro cytotoxicity against TC-1 tumor cells; however, an enhanced innate immune response including activation of dendritic cells was observed. Mice co-administered with γ-PGA and L. casei-E7 showed significantly suppressed growth of TC-1 tumor cells and an increased survival rate in TC-1 mouse models compared to those of mice vaccinated with L. casei-E7 alone. The administration of γ-PGA markedly enhanced the activation of natural killer (NK) cells but did not increase the E7-specific cytolytic activity of CD8⁺ T lymphocytes in mice vaccinated with L. casei-E7. Overall, our results suggest that oral administration of γ-PGA induces a synergistic antitumor effect in combination with L. casei-E7.

Methods

We did experiments as above figures.

Results

Fig. 1. The effect of γ-PGA on the viability of tumor cells and the activation of immune cells in vitro.

Fig. 2. The antitumor efficacy of oral administration with L. casei-E7 and γ-PGA.

Fig. 3. Antigen-specific CTL responses to oral administration of L. casei-E7 and γ-PGA.

Fig. 4. The increases in NK cells and CD107a-expressing NK cells in response to oral administration of L. casei-E7 and γ-PGA.

Conclusions

Taken together, γ-PGA may be a potential adjuvant for a L. casei-E7 therapeutic vaccine to improve the antitumor effect in TC-1 tumor mouse model.

Introduction

Bovine papillomaviruses types 1 and 2 (BPV1, BPV2) induce semi-malignant skin tumours termed sarcoids in horses. Sarcoids seriously compromise the health and welfare of affected individuals due to their high propensity to progress upon accidental or iatrogenic trauma, and to reoccur in a more severe, multiple form following ineffective treatment.

Methods

We have developed live-attenuated influenza (Flu) A and B viruses co-expressing shuffled BPV1 E6 and E7 antigens as potential sarcoid immunotherapeutic.

Results

In a phase I trial involving 12 sarcoid- and BPV1/2-free horses, intradermal administration of vaccine candidates was well tolerated with the only transient side effect being mild fever in four horses for < 8 hours following first administration of the Flu A BPV1-E6E7 virus. Importantly, vaccine candidates also proved biologically safe: repeated screening of secretions and faeces by RT-PCR and focus forming assay in the course of the trial demonstrated the absence of virus shedding.

In an ongoing patient trial involving 30 horses bearing multiple, partly recurrent sarcoids, one lesion per horse was injected three times (days 1, 3, 5) with the influenza A virus, and then boosted three times with the influenza B virus (days 8, 10 and 12). Treatment led to significant tumour regression in five, and stable disease in three patients subjected to this therapeutic regimen thus far. In two patients, tumours recurred 5 months post treatment, indicating that the viral vaccines and/or treatment schedule need to be further optimized as to induce a long-lasting therapeutic effect in all the patients. Immunotherapy is currently repeated in these horses.

Intriguingly, treatment also had a systemic effect in all individuals as revealed by synchronous regression or growth arrest of non-injected lesions located at different sites of the horses’ integument

Conclusions

To our knowledge, this is the first immunotherapeutic approach showing significant reduction of tumour burden in equine sarcoid patients.

Introduction

Cell-mediated immune responses play a crucial role in regression of HPV lesions and clearance of infections. However, studies evaluating the role of T cell responses to specific proteins have produced conflicting results, likely reflecting the diverse methods used and predominance of cross-sectional analyses.

Methods

We established a prospective longitudinal cohort of women aged 16-55 years to study the relationship between detection of T-cell responses to early proteins and detection of hrHPV DNA. Cohort 1 comprises asymptomatic sexually active women aged 16-24. Cohort 2 comprises women aged 25-55 undergoing colposcopy, with mild, moderate or severe dyskaryosis. Women are followed for 12 months and provide a blood sample and self-taken vaginal swab at 4-monthly (Cohort 1) or 6-monthly (Cohort 2) intervals. T cell responses to all hrHPV early proteins are quantified by IFNγ Elispot and flow cytometry using overlapping 15-mer peptides based on HPV16, HPV52 and selected conserved sequences across 5 hrHPV genotypes.

Results

144 women were enrolled in the study: 107 in Cohort, mean age 21y; 37 in Cohort 2, mean age 32y. Baseline data are reported. Prior prophylactic vaccination was reported in 88% Cohort 1 and 21% Cohort 2. HPV DNA was detected in 27 (25%) Cohort 1 and 31 (91%) Cohort 2. hrHPV isolates were non-16/18 types in 100% Cohort 1 and 82% Cohort 2. HPV16/18 were also detected in 21% Cohort 2. T-cell responses to E1/E2 or E6/E7 peptides (HPV52 > HPV16) were detected in 22/103 (21%) Cohort 1 and 15/31 (48%) Cohort 2. Overall, E1/E2 was most frequently targeted.

Conclusions

There was no consistent relationship between baseline hrHPV DNA prevalence and T-cell reactivity. Our data suggest that transient infections infrequently elicit T-cell responses. Longitudinal analysis is directed at determining the phenotype and duration of T-cell responses that are associated with hrHPV clearance or persistence.