Molecular characterization of gliosarcoma reveals prognostic biomarkers and clinical parallels with glioblastoma.

PURPOSE

Gliosarcoma is a rare histopathological variant of glioblastoma, but it is unclear whether distinct clinical or molecular features distinguish it from other glioblastomas. The purpose of this study was to characterize common genomic alterations of gliosarcoma, compare them to that of glioblastoma, and correlate them with prognosis.

METHODS

This was a single-institution, retrospective cohort study of patients seen between 11/1/2017 to 1/28/2024. Clinical and genomic data were obtained from the medical record. Results were validated using data from AACR Project GENIE (v15.1-public).

RESULTS

We identified 87 gliosarcoma patients in the institutional cohort. Compared to a contemporary cohort of 492 glioblastoma, there was no difference in overall survival, though progression free survival was inferior for patients with gliosarcoma (p = 0.01). Several of the most-commonly altered genes in gliosarcoma were more frequently altered than in glioblastoma (NF1, PTEN, TP53), while others were less frequently altered than in glioblastoma (EGFR). CDKN2A/CDKN2B/MTAP alterations were associated with inferior survival on univariate Cox (HR = 5.4, p = 0.023). When pooled with 93 patients from the GENIE cohort, CDKN2A/B (HR = 1.75, p = 0.039), RB1 (HR = 0.51, p = 0.016), LRP1B (p = 0.050, HR = 2.0), and TSC2 (HR = 0.31, p = 0.048) alterations or loss were significantly associated with survival. These effects remained when controlled for age, sex, and cohort of origin with multivariate Cox.

CONCLUSION

Gliosarcoma has a similar overall survival but worse response to treatment and different mutational profile than glioblastoma. CDKN2A/B loss and LRP1B alterations were associated with inferior prognosis, while RB1 or TSC2 alterations were associated with improved outcomes. These findings may have implications for clinical management and therapeutic selection in this patient population.