Transcriptomic profiling of peripheral blood cells in HPV-associated carcinoma patients receiving combined valproic acid and avelumab.

Human papillomavirus (HPV)-associated cancer continues to evade the immune system by promoting a suppressive tumor-microenvironment. Therefore, immunotherapy appears to be a promising approach for targeting HPV-associated tumors. We hypothesized that valproic acid (VA) as an epigenetic agent combined with avelumab may enhance the anti-tumor immunity in HPV-associated solid tumors. We performed bulk RNA-sequencing (RNA-seq) on total peripheral blood mononuclear cells (PBMCs) of seven non-responders (NRs) and four responders (Rs). A total of 39 samples (e.g. pre-treatment, post-VA, post-avelumab, and endpoint) were analyzed. Also, we quantified plasma analytes and performed flow cytometry. We observed a differential pattern in immune response following treatment with VA and/or avelumab in NRs vs Rs. A significant upregulation of transcripts associated with NETosis [the formation of neutrophil extracellular traps (NETs)] and neutrophil degranulation pathways was linked to the presence of a myeloid-derived suppressor cell signature in NRs. We noted the elevation of IL-8/IL-18 cytokines and a distinct transcriptome signature at the baseline and endpoint in NRs. By using the receiver operator characteristics, we identified a cut-off value for the plasma IL-8/IL-18 to discriminate NRs form Rs. We found differential therapeutic effects for VA and avelumab in NRs vs Rs. Thus, our results imply that measuring the plasma IL-8/IL-18 and bulk RNA-seq of PBMCs may serve as valuable biomarkers to predict immunotherapy outcomes.