BioProject

This study aimed to analyse the effect of immunotherapeutic treatment with ChAdOx/MVA MAGE vaccine and anti-PD-1 on the transcriptional mRNA profiles of murine 15V4T3 tumours. 15V4T3 tumour-bearing mice were treated with either a PBS control, anti-PD-1 inhibitor (3-doses of 100 µg 3-days apart), ChAdOx/MVA P1A vaccine (10^7 IU / 10^6 PFU doses 1-week apart), or with a combination of vaccine + anti-PD-1. Following treatment, RNA was isolated from tumour tissue samples and then tumour transcriptomic gene expression profiles were analysed by RNA-sequencing. Sequenced reads were mapped to the mouse genome GRCm38. A counts matrix reporting the numbers of reads mapping to each gene was then generated, and abundance measurements performed using TMM-normalized (EdgeR) counts data to quantify gene expression levels. 14937 expressed transcripts were identified as expressed above a minimum threshold. Results from the transcriptomic analysis indicated that ChAdOx/MVA P1A vaccination had a profound effect on the gene expression profiles of 15V4T3 tumours. Approximately 1250 differentially expressed genes were identified in tumours from vaccinated compared to unvaccinated mice using a threshold for differential expression of fold change > 2 and Padj < 0.05. Furthermore, gene expression signatures corresponding to a CD8+ T-cell driven inflammatory response and an IFNg response were found to be highly enriched in tumours from vaccinated mice. Such gene expression signatures have been found in other studies to be predictive of response to immunotherapy and anti-PD-1 immune checkpoint blockade. GSVA further confirmed the enrichment of gene sets corresponding to immune activation, a pro-inflammatory response and T-cell activity in the mRNA expression data from tumours of vaccinated mice compared to unvaccinated. Taken together these findings show that a ChAdOx/MVA vaccine targeting a MAGE type antigen can generate and drive tumour gene expression patterns associated with a T-cell inflammatory response and positive response to cancer immunotherapy. Overall design: 15V4T3-tumour-bearing mice were treated with a PBS control, anti-PD-1 inhibitor, ChAdOx/MVA P1A vaccine, or with vaccine + anti-PD-1 combination. Following treatment tumours were excised and tumour-RNA isolated. Tumour mRNA expression profiles were then analyzed by RNA-sequencing. n=12 samples total, 3 from each experimental treatment group.