Highly sensitive detection of TERT promoter mutations in recurrent glioblastomas using digital PCR

Telomerase reverse transcriptase promoter (TERTp) hotspot mutations are the most frequent mutations in primary glioblastomas (GBM). Previous studies have shown that the combination ofTERTpand isocitrate dehydrogenase (IDH) status may serve as a useful diagnostic marker for oligodendroglioma and glioblastoma. In oligodendrogliomas,TERTpandIDHmutations, along with the 1p/19q codeletion, usually coexist and are likely to be founder mutations. However, in contrast to oligodendroglioma, the role of theTERTpstatus in GBM remains obscure. Here, we used Sanger sequencing, pyrosequencing, and digital PCR (dPCR) to examine theTERTpstatus in 15 pairs of frozen tissue samples from primary and recurrentIDHwild-type GBM, all of which were operated in a single institute. We showed that theTERTpstatus was stable between primary and recurrent GBM but this consistency was only detected by dPCR. The results suggest that dPCR is a powerful, highly sensitive tool to detectTERTpmutations, especially in a mixed cell population (e.g., a recurrent GBM tissue) where earlier treatment may have grossly altered the tumor microenvironment.