BIOM-28. PROGNOSTIC BIOMARKERS IN GLIOBLASTOMA PATIENTS TREATED WITH TEMOZOLOMIDE

Identifying blood biomarkers that predict favorable outcomes for patients with glioblastoma treated with temozolomide (TMZ).

Glioblastoma is the most aggressive primary brain tumor. The standard of care is maximum safe resection, then radiation plus oral TMZ, followed by six months of cyclic oral TMZ. Previous studies have revealed that TMZ-induced myelosuppression is associated with improved overall survival.

Adults with glioblastoma who completed radiation therapy and received temozolomide for at least 6-months at Beth Israel Deaconess Medical Center between 2018-2021 were identified. Baseline and nadir white blood cell count, absolute neutrophil count, absolute lymphocyte count, red blood cells, and platelets were collected retrospectively. Additionally, IDH1 R132H, MGMT promoter methylation, progression free survival (PFS), and overall survival (OS) were also collected retrospectively. Data was combined with that of Vaios et al. and Ho et al. Kaplan-Meier analysis and multivariate testing were performed.

Leukopenia is associated with increased overall survival (p = 0.008) and progression free status (p = 0.02). Grade 3 thrombocytopenia is associated with decreased PFS (p = 0.0005) and OS (p = 0.0006). Grade 1 & 2 lymphopenia is associated with increased progression free survival (p = 0.01 and p = 0.03). Lower baseline absolute lymphocyte count is associated with improved OS (p = 0.007). Higher baseline absolute neutrophil count is associated with worse OS (p = 0.002).

Cytopenia may serve as a prognostic biomarker for OS and PFS. Leukopenia may reflect adequate temozolomide dosing, anti-tumor activity, or changes in the tumor micro-environment. Peripheral biomarker monitoring may improve prognostic stratification and lead to personalized treatment with improved outcomes.