Immunoprotective effect of an in silico designed multiepitope cancer vaccine with BORIS cancer-testis antigen target in a murine mammary carcinoma model

In our previous study, immunoinformatic tools were used to design a novel multiepitope cancer vaccine based on the most immunodominant regions of BORIS cancer-testis antigen. The final vaccine construct was an immunogenic, non-allergenic, and stable protein consisted of multiple cytotoxic T lymphocytes epitopes, IFN-γ inducing epitopes, and B cell epitopes according to bioinformatic analyzes. Herein, the DNA sequence of the final vaccine construct was placed into the pcDNA3.1 vector as a DNA vaccine (pcDNA3.1-VAC). Also, the recombinant multiepitope peptide vaccine (MPV) was produced by a transfected BL21 E. coli strain using a recombinant pET-28a vector and then, purified and screened by Fast protein liquid chromatography technique (FPLC) and Western blot, respectively. The anti-tumor effects of prophylactic co-immunization with these DNA and protein cancer vaccines were evaluated in the metastatic non-immunogenic 4T1 mammary carcinoma in BALB/c mice. Co-immunization with the pcDNA3.1-VAC and MPV significantly (P < 0.001) increased the serum levels of the MPV-specific IgG total, IgG2a, and IgG1. The splenocytes of co-immunized mice exhibited a significantly higher efficacy to produce interleukin-4 and interferon-γ and proliferation in response to MPV in comparison with the control. The prophylactic co-immunization regime caused significant breast tumors’ growth inhibition, tumors’ weight decrease, inhibition of metastasis formation, and enlarging tumor-bearing mice survival time, without any considerable side effects. Taking together, this cancer vaccine can evoke strong immune response against breast tumor and inhibits its growth and metastasis.

80 Cancer testis antigen burden: A novel predictive biomarker for immunotherapy in solid tumors

BackgroundWhen expressed in cancer cells, cancer testis antigens (CTAs) are highly immunogenic and have the capacity to elicit cancer-specific immune responses in diverse malignancies. With their expression limited to tumor cells, CTAs have become a prime target of natural T cell response, immune cell-based therapy, and cancer vaccines. In this study, we investigated CTA burden in real-world clinical tumors spanning multiple histologies, revealing a novel prognostic gene expression-based biomarker.MethodsTargeted RNA-seq was performed on 5450 FFPE tumors representing 39 histologic types, predominantly composed of lung cancer (40.4%) followed by colorectal cancer (10.6%) and breast cancer (8.6%). Using an amplicon-based NGS approach, expression levels of 17 CTA genes were ranked against a reference population. Cancer Testis Antigen Burden (CTAB) was calculated as the sum of the gene expression rank for each CTA gene. The median CTAB of ≥171 was used as cutoff for CTAB High versus Low classification. We estimated Pearson’s correlation for all CTA genes to discover co-expression patterns between CTAs and histologies. Overall survival (OS) analysis was performed using CoxPh regression model whereas response analysis was performed using logistic regression model with p-values reported.ResultsWithin the tumor samples, CTAB values ranged from 0–1700, with kidney cancer demonstrating overall lowest mean CTAB (110) and melanoma the highest (550). NSCLC had an average CTAB of 283. In an immune checkpoint blockade treated retrospective cohort of 110 NSCLC patients, High CTAB showed better OS compared to Low CTA (HR: 0.55, p=0.07). Additionally, when combined with tumor inflammation and cell proliferation biomarkers, highly inflamed but poorly proliferative tumors with High CTAB had improved OS (HR: 0.27, p=0.05). No significant association with response was detectedConclusionsOur studies show that co-expression of multiple CTA genes occurs in many tumor types and can be reliably detected using a targeted RNA-seq approach. Utilization of this co-expression pattern to calculate CTAB reveals tumor-type associated signatures, which in a small NSCLC cohort is associated with the overall survival. The findings suggest that these immunogenic antigens expose the tumor cells to natural or immunotherapy augmented cell-based immune response, and that CTAB is a potential predictive marker for therapeutic response to checkpoint inhibitors. Further studies are needed to establish the predictive value in other tumor types, as well as the role of CTAB in immune cell therapies and vaccinations.

A Novel HAGE/WT1-ImmunoBody® Vaccine Combination Enhances Anti-Tumour Responses When Compared to Either Vaccine Alone

Many cancers, including myeloid leukaemia express the cancer testis antigen (CTA) DDX43 (HAGE) and/or the oncogene Wilms’ tumour (WT1). Here we demonstrate that HAGE/WT1-ImmunoBody® vaccines derived T-cells can kill ex-vivo human CML cell lines expressing these antigens and significantly delay B16/HHDII+/DR1+/HAGE+/WT1+ tumour growth in the HHDII/DR1 mice and prolonged mouse survival in the prophylactic setting in comparison to non-immunised control mice. We show that immunisation of HHDII/DR1 mice with HAGE- and WT1-ImmunoBody® DNA vaccines in a prime-boost regime in two different flanks induce significant IFN-γ release by splenocytes from treated mice, and a significant level of cytotoxicity against tumour targets expressing HAGE/WT1 in vitro. More importantly, the combined HAGE/WT1 ImmunoBody® vaccine significantly delayed tumour growth in the B16/HHDII+/DR1+/HAGE+/WT1+ tumour model and prolonged mouse survival in the prophylactic setting in comparison to non-immunised control mice. Overall, this work demonstrates that combining both HAGE- and WT1-ImmunoBody® into a single vaccine is better than either vaccine alone. This combination vaccine could be given to patients whose cancer expresses HAGE and WT1 in parallel with existing therapies in order to decrease the chance of disease progression and relapse.