Phase I trial to determine safety and immunogenicity of amplivant, a synthetic toll-like receptor 2 ligand, conjugated to two HPV16 E6 synthetic long peptides

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Background: Therapeutic vaccines based on synthetic long peptides (SLPs) have a great potential for immunotherapy of cancer patients as these SLPs include both human leukocyte antigen (HLA) class I and II epitopes and no patient selection for HLA types is required. The antigen-induced immune response can be strengthened with immune stimulating additives. Amplivant (AV) is a synthetic Toll-like receptor 2 ligand which can be directly conjugated to tumor peptide antigens. In preclinical studies, AV-conjugation to antigens led to both enhanced antigen presentation by dendritic cells and T-cell priming and caused superior induction of effective anti-tumor responses. Moreover, AV-conjugated SLPs showed a 100 times higher immune response compared to unconjugated SLP. The current study is a first-in-human trial to investigate safety and immunogenicity of AV-conjugated human papillomavirus (HPV)16-SLPs. Methods: A dose escalation phase I trial was performed in 24 patients with HPV16 positive (pre-) malignant lesions. AV was conjugated to two SLPs derived from the most immunodominant regions of the HPV16 E6 oncoprotein. Four dose groups (1, 5, 20 or 50 μg of each peptide) in 6 patients each were studied. The vaccine was injected three times intradermally in DMSO / water with a three-week interval. Adverse events (AE) were collected according to CTCAE v4.0 up to 26 weeks. Peptide-specific T-cell immune responses were determined in blood samples taken before and after vaccination using complementary immunological assays (proliferation assay, IFNγ-ELISPOT and cytokine bead array). Results: Toxicity after three AV-conjugated HPV16-SLP vaccinations was limited to CTCAE grade 1 or 2, with predominantly inflammation at the vaccination site and sometimes flu-like symptoms, which generally resolved within one day. Dose increase resulted from no AE in the lowest dose group to mild/moderate AE in all vaccinated persons in the highest dose group. In the lowest dose group, minor vaccine-induced T-cell responses were observed in three of six vaccinated persons. In the highest dose group, all patients displayed a strong HPV16-specific T-cell response after vaccination. The induced T-cell response against HPV16 lasted until the end of the trial. Conclusions: This first-in-human study showed that AV conjugated to SLPs can safely be used as an intradermal therapeutic vaccine. AV-conjugated HPV16-SLP was able to induce robust HPV16-specific T-cell immunity in patients treated for HPV16 positive (pre-) malignancies without any other vaccine adjuvant or formulation. Increase in dose resulted in both a higher number of mild adverse events as well as stronger T-cell immunity. Clinical trial information: NCT02821494.

Abstract 1254: Tumor infiltrating M1 macrophages work side by side with T cells to prolong the survival in patients with cervical carcinoma

One of the hallmarks of cancer is the influx of myeloid cells. In this study we exploited a cohort of 86 patients with cervical carcinoma to investigate the constitution of cervical cancer infiltrating myeloid cells and their relationship to other tumor infiltrating immune cells, tumor characteristics and the survival of patients. Triple color immunofluorescent confocal microscopy was used to locate, identify and quantify macrophages (CD14), their maturation status (CD33) and their polarization (CD163). Quantification of the numbers of populations of myeloid cells based on the expression of these three markers revealed that a strong intraepithelial infiltration of CD14+ cells, more specifically the population of CD14+CD33-CD163- M1 macrophages, is associated with a large general influx of intraepithelial T lymphocytes (p=0.008) and improved survival (p=0.007) as well as forms an independent prognostic factor for survival (p=0.033). The ratio of intraepithelial CD8+ T-cells / Tregs also formed an independent prognostic factor (p=0.010). Combination of these two factors revealed a dramatic difference in survival between the group of patients whose tumor was well infiltrated with intraepithelial M1 macrophages and relatively high numbers of CD8+ T-cells compared to Tregs (100%) and the group of patients whose tumor displayed a low infiltration with M1 macrophages and a low CD8+ T-cell / Treg ratio (50%), indicating that these two populations of immune cells work side by side to improve survival. Our data suggests that reinforcement and activation of the intratumoral M1 macrophages may form an attractive immunotherapeutic option in cervical cancer.

Citation Format: Sjoerd H. Van Der Burg, Peggy de Vos van Steenwijk, Thorbald van Hall, Ekaterina S. Jordanova. Tumor infiltrating M1 macrophages work side by side with T cells to prolong the survival in patients with cervical carcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1254. doi:10.1158/1538-7445.AM2013-1254