Impacts of genotypic variants on survival following reoperation for recurrent glioblastoma

Glioblastoma IDH-wild type: imaging independent predictors of gross total resection (GTR) using the VASARI feature set and tumoral volumetric measurements

BackgroundExtent of resection (EOR), including gross total resection (GTR), is one of the most important factors in predicting overall survival (OS) in IDH-wild type (IDH-WT) glioblastoma patients. Although GTR represents the complete resection of all visible contrast-enhancing parts of the tumor, imaging predictors of achieving this extent still need to be better understood.PurposeTo assess the impact of preoperative imaging phenotypes as defined by the VASARI feature set and tumoral volumetry to determine predictors of GTR in patients with IDH-WT glioblastoma.Material and MethodsThis retrospective, single-center study analyzed imaging characteristics based on the VASARI features in the preoperative scans of IDH-WT glioblastoma patients. Volumetric analysis was performed to determine associations with clinical outcomes. Univariate analysis was used to determine the association of VASARI features with GTR. A multivariate analysis model was used to determine predictors of GTR.ResultsGTR was achieved in 79/144 (54.8%) patients, near total resection in 15 (10.4%), and subtotal resection in 50 (34.7%) patients. Our results showed non-eloquent tumor regions (55% vs. 35%; P = 0.04) and thick margin of enhancement (56.1% vs. 43.9%; P = 0.04) were associated with GTR and ependymal extension (37% vs. 63%; P = 0.02). Deep white matter invasion (36.3% vs. 63.7%; P = 0.03) was significantly associated with non-gross total resection. Lower tumoral volumes were also associated with gross total resection (P < 0.01). After performing multivariate analysis, the thickness of the tumoral enhancing margins was correlated with GTR with an OR of 1.57 (95% CI=1.1-2.23). Furthermore, the volume of the enhancing component was significantly different according to EOR with a calculated OR of 0.95 (95% CI = 0.92-0.97; P < 0.01).ConclusionImaging characteristics on standard-of-care MRI can predict the rate of GTR in patients with IDH-WT glioblastomas. The thickness of enhancing margins predicts GTR after multivariate analysis. A diagnostic model that includes a combination of the discriminating depicted features on MRI and brain tumor volumetrics has an acceptable diagnostic performance with a specificity >90%.

Repeat Resection for Recurrent Glioblastoma in the WHO 2021 Era: A Longitudinal Matched Case-Control Study

BACKGROUND AND OBJECTIVES

This study aims to evaluate the overall survival benefits of repeat resection in patients with recurrent glioblastoma, IDH-wildtype (rGBM), and to identify factors for long-term survival, including the role of clinical, radiological, and molecular parameters.

METHODS

This longitudinal matched case-control study included 60 patients with rGBM divided into two groups: one surgery (n = 30) and repeat resection (n = 30). The baseline characteristics, preoperative and postoperative volumes, and molecular markers were assessed. Survival analyses were conducted using the Log-rank test, and associated factors with long-term survival were identified in the repeat resection cohort.

RESULTS

The patients who underwent repeat resection had a significantly longer median survival of 23.9 months compared to 9.2 months in the one-surgery group (p < 0.001). Preoperative tumor volume was found to correlate with postoperative residual volume in repeat resections. The patients with no residual contrast-enhancing tumor volume (0 cm3) after repeat resection had a median survival of 19.33 months, while those with any residual volume had a median survival of 10.13 months. The patients with lower KPS (≤70) and GCS (≤13) scores at the time of the repeat resection tended to have shorter survival, underscoring the potential clinical relevance of functional status when evaluating surgical candidacy.

CONCLUSIONS

Complete repeat resection may improve overall survival in patients with recurrent IDH-wildtype GBM and should be considered earlier as a therapeutic option rather than a diagnostic or salvage procedure. Early surgical intervention, before declines in the KPS and GCS or tumor volumes become unmanageable, may lead to better outcomes. Further studies with larger cohorts are needed to confirm these findings.

Bevacizumab exerts dose-dependent risk for intracranial hemorrhage in patients with malignant gliomas

PURPOSE

Bevacizumab, an anti-VEGF monoclonal antibody, has become a mainstay therapeutic in the management of malignant glioma. It is unknown if the risk of intracranial hemorrhage (ICH), a major complication associated with bevacizumab use, is dose-dependent.

METHODS

This was a single institution retrospective analysis of patients treated with bevacizumab for the management of gliomas between 2009 and 2022. Incidence rates of ICH between patients receiving low-dose (< 5 mg/kg/week) and conventional-dose (5 mg/kg/week) bevacizumab regimens were compared via competing risk analysis over time. We evaluated post-progression survival (PPS) as a secondary outcome using multivariate Cox regression.

RESULTS

One hundred and seventy-three patients were identified (low-dose group, n = 51, conventional-dose group, n = 122) for inclusion in our analysis. Cumulative incidence rates of all cases of ICH and clinically symptomatic cases of ICH were higher in the conventional-dose (17.2% for all cases, 13.7% for symptomatic) relative to the low-dose group (3.9% for all cases, 2.0% for symptomatic); p-value 0.0296 for all cases, p-value 0.0274 for symptomatic cases. On multivariate Fine-Gray regression, conventional-dose bevacizumab therapy remained significantly associated with increased risk for symptomatic ICH (SHR 8.0560; p-value 0.0442). No difference in PPS was observed between the low-dose versus conventional-dose groups.

CONCLUSIONS

Conventional-dose bevacizumab therapy (5 mg/kg/week) is associated with increased incidence of ICH in patients with malignant glioma compared to lower dose bevacizumab (< 5 mg/kg/week) in this single center retrospective cohort. No difference in PPS was observed between the low-dose versus conventional-dose groups.

Extent of Resection Thresholds in Molecular Subgroups of Newly Diagnosed Isocitrate Dehydrogenase-Wildtype Glioblastoma

BACKGROUND AND OBJECTIVES

Maximizing the extent of resection (EOR) improves outcomes in glioblastoma (GBM). However, previous GBM studies have not addressed the EOR impact in molecular subgroups beyond IDH1/IDH2 status. In the current article, we evaluate whether EOR confers a benefit in all GBM subtypes or only in particular molecular subgroups.

METHODS

A retrospective cohort of newly diagnosed GBM isocitrate dehydrogenase (IDH)-wildtype undergoing resection were prospectively included in a database (n = 138). EOR and residual tumor volume (RTV) were quantified with semiautomated software. Formalin-fixed paraffin-embedded tumor tissues were analyzed by targeted next-generation sequencing. The association between recurrent genomic alterations and EOR/RTV was evaluated using a recursive partitioning analysis to identify thresholds of EOR or RTV that may predict survival. The Kaplan-Meier methods and multivariable Cox proportional hazards regression methods were applied for survival analysis.

RESULTS

Patients with EOR ≥88% experienced 44% prolonged overall survival (OS) in multivariable analysis (hazard ratio: 0.56, P = .030). Patients with alterations in the TP53 pathway and EOR <89% showed reduced OS compared to TP53 pathway altered patients with EOR>89% (10.5 vs 18.8 months; HR: 2.78, P = .013); however, EOR/RTV was not associated with OS in patients without alterations in the TP53 pathway. Meanwhile, in all patients with EOR <88%, PTEN -altered had significantly worse OS than PTEN -wildtype (9.5 vs 15.4 months; HR: 4.53, P < .001).

CONCLUSION

Our results suggest that a subset of molecularly defined GBM IDH-wildtype may benefit more from aggressive resections. Re-resections to optimize EOR might be beneficial in a subset of molecularly defined GBMs. Molecular alterations should be taken into consideration for surgical treatment decisions in GBM IDH-wildtype.

Prognostic evaluation of re-resection for recurrent glioblastoma using the novel RANO classification for extent of resection: A report of the RANO resect group

BACKGROUND

The value of re-resection in recurrent glioblastoma remains controversial as a randomized trial that specifies intentional incomplete resection cannot be justified ethically. Here, we aimed to (1) explore the prognostic role of extent of re-resection using the previously proposed Response Assessment in Neuro-Oncology (RANO) classification (based upon residual contrast-enhancing (CE) and non-CE tumor), and to (2) define factors consolidating the surgical effects on outcome.

METHODS

The RANO resect group retrospectively compiled an 8-center cohort of patients with first recurrence from previously resected glioblastomas. The associations of re-resection and other clinical factors with outcome were analyzed. Propensity score-matched analyses were constructed to minimize confounding effects when comparing the different RANO classes.

RESULTS

We studied 681 patients with first recurrence of Isocitrate Dehydrogenase (IDH) wild-type glioblastomas, including 310 patients who underwent re-resection. Re-resection was associated with prolonged survival even when stratifying for molecular and clinical confounders on multivariate analysis; ≤1 cm3 residual CE tumor was associated with longer survival than non-surgical management. Accordingly, "maximal resection" (class 2) had superior survival compared to "submaximal resection" (class 3). Administration of (radio-)chemotherapy in the absence of postoperative deficits augmented the survival associations of smaller residual CE tumors. Conversely, "supramaximal resection" of non-CE tumor (class 1) was not associated with prolonged survival but was frequently accompanied by postoperative deficits. The prognostic role of residual CE tumor was confirmed in propensity score analyses.

CONCLUSIONS

The RANO resect classification serves to stratify patients with re-resection of glioblastoma. Complete resection according to RANO resect classes 1 and 2 is prognostic.

Immunotherapy in Glioblastoma: Current Approaches and Future Perspectives

Glioblastoma (GBM) is the most common malignant brain tumor. Despite multimodality treatment with surgical resection, radiation therapy, chemotherapy, and tumor treating fields, recurrence is universal, median observed survival is low at 8 months and 5-year overall survival is poor at 7%. Immunotherapy aims to generate a tumor-specific immune response to selectively eliminate tumor cells. In treatment of GBM, immunotherapy approaches including use of checkpoint inhibitors, chimeric antigen receptor (CAR) T-Cell therapy, vaccine-based approaches, viral vector therapies, and cytokine-based treatment has been studied. While there have been no major breakthroughs to date and broad implementation of immunotherapy for GBM remains elusive, multiple studies are underway. In this review, we discuss immunotherapy approaches to GBM with an emphasis on molecularly informed approaches.