Investigation of the relationship between immune checkpoints and mismatch repair deficiency in recurrent and nonrecurrent glioblastoma

The presence of microsatellite instability and low PD-L1 levels, which are among the causes of treatment resistance in glioblastoma, were found to be compatible with the literature in our study, with higher rates in recurrent cases. In recurrent cases with higher mutations and where immunotherapy resistance is expected less, low PD-L1 levels thought that different combinations with other immune checkpoint inhibitors can be tried as predictive and prognostic marker in GBM patients.