Immune checkpoint inhibitors have been successful across several tumor types; however, their efficacy has been uncommon and unpredictable in glioblastomas (GBM), where <10% of patients show long-term responses. To understand the molecular determinants of immunotherapeutic response in GBM, we longitudinally profiled 66 patients, including 17 long-term responders, during standard therapy and after treatment with PD-1 inhibitors (nivolumab or pembrolizumab). Genomic and transcriptomic analysis revealed a significant enrichment of PTEN mutations associated with immunosuppressive expression signatures in non-responders, and an enrichment of MAPK pathway alterations (PTPN11, BRAF) in responders. Responsive tumors were also associated with branched patterns of evolution from the elimination of neoepitopes, as well as differences in T cell clonal diversity and tumor microenvironment profiles. Our study shows that clinical response to anti-PD-1 immunotherapy in GBM is associated with specific molecular alterations, immune expression signatures, and immune infiltration that reflect the tumor’s clonal evolution during treatment.

The World Health Organization (WHO) classification of tumors of the central nervous system (CNS) was recently updated, restructuring solitary fibrous tumor (SFT) and hemangiopericytoma (HPC) into one combined entity. This is the first population-based study to examine outcomes of SFT/HPC based on the new WHO guidelines. The Surveillance, Epidemiology, and End Results (SEER) database (1998-2013) was queried to examine age-adjusted incidence and prognostic factors associated with overall survival in 416 surgically resected cases. Age-adjusted incidence was calculated to be 3.77 per 10,000,000 and was rising. Median survival was 155 months, with 5- and 10-year survival rates of 78 and 61%, respectively. Younger age, Asian/Pacific Islander versus white race, benign histology, tumor location, gross-total resection (GTR), and GTR plus radiation (RT) versus subtotal resection were significantly associated with survival. In multivariable analysis, older age (HR = 1.038, p < 0.0001), infratentorial location (HR = 2.019, p = 0.038), GTR (HR = 0.313, p = 0.041), and GTR + RT (HR = 0.215, p = 0.008) were independent prognostic factors. In the HPC and borderline/malignant subgroups, GTR + RT was associated with significantly increased survival compared with GTR alone (HR = 0.537, p = 0.039 and HR = 0.525, p = 0.038). After eliminating patients that died within 3 months of diagnosis, GTR + RT was still associated with an incremental increase in survival (HR = 0.238, p = 0.031) over GTR alone (HR = 0.280, p = 0.054). GTR + RT may be optimal in the management CNS HPC and SFT/HPC tumors with borderline/malignant features. This study, in combination with existing literature, warrants further investigation of adjuvant radiation through a prospective clinical trial.

Craniotomy is associated with increased survival over biopsy for PCNSL in 3 retrospective datasets. Prospective studies are necessary to adequately evaluate this relationship. Such studies should evaluate patients most likely to benefit from cytoreductive surgery, ie, those with favorable RPA and RC.