Prognostic impact of PTEN status in recurrent IDH-wildtype glioblastoma receiving second-line therapy

Background Recurrent IDH-wildtype glioblastoma has a poor prognosis, and no validated molecular biomarker guides second-line treatment choices. Because PTEN alterations are frequent in glioblastoma and may influence therapy resistance, we assessed their association with outcomes in patients with recurrence of IDH-wildtype glioblastoma. Methods This is a retrospective study including consecutive adults with first recurrence of IDH-wildtype glioblastoma treated between 2019 and 2022 with regorafenib, nitrosoureas, or bevacizumab. PTEN alterations were assessed by NGS. Overall survival was analyzed using Kaplan-Meier estimates and multivariable Cox models adjusted for clinically relevant covariates. An exploratory weighted analysis compared regorafenib and nitrosoureas in PTEN wild-type tumors. Results Among 226 patients, 128 (57%) had PTEN alterations. The prevalence was higher in patients who received regorafenib (66%) than in those treated with nitrosourea (48%) or bevacizumab (55%). In univariate analyses, PTEN alteration was associated with shorter survival with regorafenib (median OS, 9.4 vs 17.0 months; HR, 2.04; P = .043) and nitrosoureas (6.9 vs 8.0 months; HR, 1.63; P = .027), but not with bevacizumab (HR, 1.23; P = .60). In multivariable analyses, PTEN alteration remained associated with worse survival with regorafenib (HR, 1.88; P = .016) and nitrosoureas (HR, 1.97; P = .020). In the overall cohort, PTEN alteration remained associated with worse survival (HR, 2.04; 95% CI, 1.26-3.30; P = .0039), independently of MGMT promoter methylation. Conclusions PTEN alteration is a clinically relevant prognostic biomarker in recurrent IDH-wildtype glioblastoma and warrants prospective validation as a stratification factor.