Assessment of treatment response to dendritic cell vaccine in patients with glioblastoma using a multiparametric MRI-based prediction model.

PURPOSE: Autologous tumor lysate-loaded dendritic cell vaccine (DCVax-L) is a promising treatment modality for glioblastomas. The purpose of this study was to investigate the potential utility of multiparametric MRI-based prediction model in evaluating treatment response in glioblastoma patients treated with DCVax-L. METHODS: Seventeen glioblastoma patients treated with standard-of-care therapy + DCVax-L were included. When tumor progression (TP) was suspected and repeat surgery was being contemplated, we sought to ascertain the number of cases correctly classified as TP + mixed response or pseudoprogression (PsP) from multiparametric MRI-based prediction model using histopathology/mRANO criteria as ground truth. Multiparametric MRI model consisted of predictive probabilities (PP) of tumor progression computed from diffusion and perfusion MRI-derived parameters. A comparison of overall survival (OS) was performed between patients treated with standard-of-care therapy + DCVax-L and standard-of-care therapy alone (external controls). Additionally, Kaplan-Meier analyses were performed to compare OS between two groups of patients using PsP, Ki-67, and MGMT promoter methylation status as stratification variables. RESULTS: Multiparametric MRI model correctly predicted TP + mixed response in 72.7% of cases (8/11) and PsP in 83.3% (5/6) with an overall concordance rate of 76.5% with final diagnosis as determined by histopathology/mRANO criteria. There was a significant concordant correlation coefficient between PP values and histopathology/mRANO criteria (r = 0.54; p = 0.026). DCVax-L-treated patients had significantly prolonged OS than those treated with standard-of-care therapy (22.38 ± 12.8 vs. 13.8 ± 9.5 months, p = 0.040). Additionally, glioblastomas with PsP, MGMT promoter methylation status, and Ki-67 values below median had longer OS than their counterparts. CONCLUSION: Multiparametric MRI-based prediction model can assess treatment response to DCVax-L in patients with glioblastoma.

Phase 2 Study of Bortezomib Combined With Temozolomide and Regional Radiation Therapy for Upfront Treatment of Patients With Newly Diagnosed Glioblastoma Multiforme: Safety and Efficacy Assessment.

PURPOSE: To assess the safety and efficacy of upfront treatment using bortezomib combined with standard radiation therapy (RT) and temozolomide (TMZ), followed by adjuvant bortezomib and TMZ for ≤24 cycles, in patients with newly diagnosed glioblastoma multiforme (GBM). METHODS AND MATERIALS: Twenty-four patients with newly diagnosed GBM were enrolled. The patients received standard external beam regional RT with concurrent TMZ beginning 3 to 6 weeks after surgery, followed by adjuvant TMZ and bortezomib for ≤24 cycles or until tumor progression. During RT, bortezomib was given at 1.3 mg/m2 on days 1, 4, 8, 11, 29, 32, 36, and 39. After RT, bortezomib was given at 1.3 mg/m2 on days 1, 4, 8, and 11 every 4 weeks. RESULTS: No unexpected adverse events occurred from the addition of bortezomib. The efficacy analysis showed a median progression-free survival (PFS) of 6.2 months (95% confidence interval [CI] 3.7-8.8), with promising PFS rates at ≥18 months compared with historical norms (25.0% at 18 and 24 months; 16.7% at 30 months). In terms of overall survival (OS), the median OS was 19.1 months (95% CI 6.7-31.4), with improved OS rates at ≥12 months (87.5% at 12, 50.0% at 24, 34.1% at 36-60 months) compared with the historical norms. The median PFS was 24.7 months (95% CI 8.5-41.0) in 10 MGMT methylated and 5.1 months (95% CI 3.9-6.2) in 13 unmethylated patients. The estimated median OS was 61 months (95% CI upper bound not reached) in the methylated and 16.4 months (95% CI 11.8-21.0) in the unmethylated patients. CONCLUSIONS: The addition of bortezomib to current standard radiochemotherapy in newly diagnosed GBM patients was tolerable. The PFS and OS rates appeared promising, with more benefit to MGMT methylated patients. Further clinical investigation is warranted in a larger cohort of patients.

Large-scale assessment of the gliomasphere model system.

BACKGROUND: Gliomasphere cultures are widely utilized for the study of glioblastoma (GBM). However, this model system is not well characterized, and the utility of current classification methods is not clear. METHODS: We used 71 gliomasphere cultures from 68 individuals. Using gene expression-based classification, we performed unsupervised clustering and associated gene expression with gliomasphere phenotypes and patient survival. RESULTS: Some aspects of the gene expression-based classification method were robust because the gliomasphere cultures retained their classification over many passages, and IDH1 mutant gliomaspheres were all proneural. While gene expression of a subset of gliomasphere cultures was more like the parent tumor than any other tumor, gliomaspheres did not always harbor the same classification as their parent tumor. Classification was not associated with whether a sphere culture was derived from primary or recurrent GBM or associated with the presence of EGFR amplification or rearrangement. Unsupervised clustering of gliomasphere gene expression distinguished 2 general categories (mesenchymal and nonmesenchymal), while multidimensional scaling distinguished 3 main groups and a fourth minor group. Unbiased approaches revealed that PI3Kinase, protein kinase A, mTOR, ERK, Integrin, and beta-catenin pathways were associated with in vitro measures of proliferation and sphere formation. Associating gene expression with gliomasphere phenotypes and patient outcome, we identified genes not previously associated with GBM: PTGR1, which suppresses proliferation, and EFEMP2 and LGALS8, which promote cell proliferation. CONCLUSIONS: This comprehensive assessment reveals advantages and limitations of using gliomaspheres to model GBM biology, and provides a novel strategy for selecting genes for future study.