AB047. Searching for factors relating to long-term survivors of glioblastoma.

Background: There remains controversy in the observed survival of gliomas worldwide, especially for glioblastoma (GBM). The 5-year survival rate ranged wildly, but comparable higher in several Asian countries, such as China showed almost 18% from CONCORD-3 data. Are there any special factors relating to long-term survivors (LTSs)?

Methods: We reviewed our single center real-world data for the last 20 years, of 536 GBM [World Health Organization (WHO) grade 4] patients revealed 5-year overall survival (OS) of 19.1%. We analyzed our GBM patients and searched for possible factors relating to LTSs. We collected tumor samples of 13 LTSs (OS >60 months) and 19 short-term survivors (OS <24 months), and performed whole exome sequencing and transcriptome sequencing.

Results: From treatment setting, besides surgical resection, post-operational adjutant treatment (radiotherapy plus chemotherapy) are the most important factor contributing to long-term survival. Whole exome sequencing analysis revealed a higher proportion of mutation signature 19 was associated with LTSs. Analysis of copy number variation (CNV) showed that the LTSs had higher copy number variants at the chromosomal level (P=0.049). At the arm level, the proportion of 19p amplification in the LTS was significantly higher than in the short-term survivors (P=0.001). And in The Cancer Genome Atlas (TCGA) GBM dataset, GBM patients with 19p amplification also had a better prognosis (log-rank P=0.04). Based on RNA sequencing (RNAseq) and differential expression analysis, the differentially expressed genes were enriched in hypoxia-related processes, apoptosis, and immune-related processes.

Conclusions: From our single-institution data, the factors relating to GBM LTSs should be both clinical management and genomic alternation which could be potential novel targets be applied to future clinical practice.