Combined proteomics and miRNomics of a glioblastoma immunotherapy cohort reveal resistance factor candidates and potential counterstrategies

Glioblastoma is the most prevalent and aggressive brain cancer. With a median overall survival of ~15-20 months under standard therapy, novel treatment approaches are desperately needed. A recent phase II clinical trial with a personalized immunotherapy based on tumor lysate-charged dendritic cells (DCs), however, failed to prolong survival. Here, we investigated tumor tissue from patients from this trial to explore glioblastoma (immuno)resistancesurvival-related factors. and strategies to overcome them. We followed an innovative approach of combining mass spectrometry-based quantitative proteomics (n=36) with microRNA sequencing plus RT-qPCR (n=38). Protein quantification identified e.g. huntingtin interacting protein 1 (HIP1), retinol binding protein 1 (RBPP1), ferritin heavy chain (FTH1) and focal adhesion kinase 2 (FAK2) as resistance factor candidates. MicroRNA analysis identified miR-216b, miR-216a, miR-708 and let-7i as molecules potentially associated with overcoming resistancefavourable tissue characteristics as they were enriched in patients with a comparably longer survival. In silico target prediction and subsequent analyses indicated focal adhesion as a pathway of interest. Taken together, we here mapped possible drivers of glioblastoma outcome under immunotherapy's (immuno)resistance in one of the largest DC vaccination tissue analysis cohorts so far – demonstrating usefulness and feasibility of combined proteomics/miRNomics approaches. Future research should investigate agents that sensitize glioblastoma to (immuno)therapy – potentially building on insights generated here. Overall design: Examination of microRNA profiles in glioblastomas of long-term and short-term surviors under immuno- and conventional therapy