Albert Lai

Advances in organoid technology have transformed how gliomas are modeled and studied. Recent FDA and NIH initiatives further promote human-relevant organoid platforms for preclinical research. Glioma organoids can be broadly categorized into 3 main classes: Engineered organoids, which enable controlled modeling of gliomagenesis driven by specific mutations; patient-derived organoids, which preserve key molecular and histopathological features of the original tumors; and assembloids, which are designed to model tumor-microenvironment interactions. Together, these systems provide a human cell-relevant framework for investigating glioma biology, tumor-microenvironment crosstalk, and therapeutic responses and resistance. In this review, we provide a comprehensive overview of the spectrum of glioma organoid models, recognizing that different systems offer distinct and complementary strengths, and we offer practical guidance for selecting appropriate models and analytical readouts based on specific basic and translational research objectives. To address increasing methodological heterogeneity and fragmented terminology, we propose a foundational nomenclature framework for glioma organoid models to improve clarity and communication within the field. We highlight applications in technically challenging subtypes, including isocitrate dehydrogenase (IDH)-mutant gliomas and diffuse midline gliomas (DMGs). We also discuss key challenges—including scalability, standardization, microenvironment fidelity, and vascularization—and emerging innovations addressing these limitations. Finally, we call for greater collaboration and standardization within the glioma organoid community to accelerate the integration of organoid models into translational pipelines to redefine and refine preclinical modeling in neuro-oncology.

While CDKN2A loss is classically associated with cell cycle deregulation through the p16-Cdk4-Rb axis, our findings suggest an additional layer of metabolic vulnerability arising from altered NAD⁺ homeostasis in CDKN2A-deleted glioblastoma, revealing a metabolic-genetic interface for rationally revisiting NAD⁺ targeting strategies, moving beyond the broad inhibition approaches.

Background: Current standard of care for glioblastoma involves fractionated radiotherapy administered with Temozolomide (TMZ), a DNA-alkylating agent. Inhibition of the DNA repair enzyme, O⁶-methylguanine-DNA methyltransferase (MGMT), promotes sensitivity to TMZ, particularly in tumors that repress MGMT mRNA transcription through promoter methylation. Novel strategies to inhibit MGMT are a promising avenue to improve therapeutic outcomes to TMZ. We hypothesized that CRISPR-Cas13-mediated RNA regulatory silencing of MGMT mRNA enhances response of immortalized and primary patient-derived gliomaspheres to TMZ in vitro. Methods: We utilized the Cas13x and Cas13d variants to target MGMT mRNA in the MGMT-expressing LN18 glioma cell line and in two patient-derived gliomasphere lines (GS104, GS081). Cas13-guide RNA ribonucleoproteins were delivered via lipofection, and stable knockdown was achieved using a lentiviral all-in-one system. MGMT mRNA and protein downregulation were assessed by RT-PCR and Western blot, respectively. Cell viability and chemosensitivity to TMZ were evaluated using MTT assays. Results: Both Cas13x and Cas13d systems, directed by specific guide CRISPR RNAs, achieved rapid and potent knockdown of MGMT mRNA and protein in all tested cell lines. This downregulation of MGMT expression led to an increase in the cytotoxic effects of TMZ, sensitizing previously resistant glioma cells and patient-derived gliomaspheres to standard chemotherapy. The lentiviral Cas13d system established stable chemosensitization in gliomasphere models. Conclusion: CRISPR-Cas13-mediated targeting of MGMT mRNA is an effective strategy for overcoming TMZ resistance in in vitro glioblastoma models. This RNA regulatory editing approach offers a proof-of-principle for CRISPR mediated therapeutics in patients with MGMT unmethylated gliomas.

Background: While bevacizumab, an anti-angiogenic monoclonal antibody, is approved for recurrent IDH wild-type glioblastoma, reports on clinical outcomes of IDH-mutant gliomas receiving this therapy are scarce. We retrospectively evaluated prognostic variables associated with outcomes in a cohort of recurrent contrast-enhancing IDH-mutant gliomas treated with bevacizumab. Methods: Ninety-seven consecutive patients were retrospectively studied. Age, biological sex, Karnofsky performance status (KPS), number of prior recurrences, prior disease duration, 1p19q status, MGMT status, and therapy schemes were annotated as clinical variables. MRI datasets were used to quantify pre-bevacizumab contrast-enhancing tumor volume, immediate percent volumetric reduction after bevacizumab, and RANO radiographic response. Clinical and radiographic variables were evaluated as predictors of progression-free survival (PFS) and overall survival (OS) in multivariate Cox survival analyses. Results: Median PFS and OS were 3.62 and 10.49 months, respectively. A lower number of recurrences prior to bevacizumab initiation (P = .002 OS; P = .004 PFS), 1p19q codeletion (P = .005 OS; P = .0007 PFS), a higher KPS (P = .02 OS; P = ns PFS), treatment schemes including immunotherapies (P = .03 OS; P = ns PFS), a smaller baseline contrast-enhancing volume (P = .02 OS; P = ns PFS), and the achievement of RANO radiographic response (P = .004 OS; P < .0001 PFS) were independent predictors of favorable outcomes. Bevacizumab was associated with a mean corticosteroid dose reduction of 2.9 mg/day (49%) after 2 months (P = .001). Conclusion: This is one of the first studies to report prognostic factors associated with clinical outcomes in IDH-mutant gliomas treated with bevacizumab. Early radiographic changes may be used to monitor treatment effectiveness, and bevacizumab significantly aids the tapering of corticosteroids in this patient subset.

Background: Multicentric glioma (MCG) are defined radiographically as two or more tumor foci with separation of MRI T2-FLAIR (T2-weighted Fluid-attenuated Inversion Recovery) hyperintensities presenting synchronously (sMCG) and/or metachronously (mMCG). Previous studies have not stratified isocitrate dehydrogenase (IDH) wild-type and mutant gliomas by sMCG and mMCG. In this large, single-institution cohort stratified by IDH status, we evaluated MCG prevalence, prognostic implications, time to mMCG (TtM), location, and pathological concordance. Methods: We identified 836 IDH wild-type and 531 IDH mutant diffuse glioma patients treated at our institution with evaluable MRI. We inspected MRIs at presentation for sMCG and subsequent imaging for mMCG, reviewed radiology and pathology reports, and performed overall survival (OS) and TtM analyses. Results: MCG prevalence was higher in IDH wild-type cases (18%) than in IDH mutant cases (9%) (P < .0001). We found 20 sMCG and 26 mMCG in IDH mutant and 91 sMCG and 54 mMCG in IDH wild-type patients. In 7 wild-type and 1 mutant instances, mMCG arose from sMCG (smMCG). While sMCG and mMCG were associated with lower OS in IDH wild-type cases (sMCG: HR = 1.46, P = .003; mMCG: HR = 1.44, P = .02), only mMCG was associated with lower OS in IDH mutant cases (sMCG: HR = 1.22, P = .7; mMCG: HR = 2.64, P = .001). IDH wild-type cases had shorter TtM than mutant cases (P < .0001). Among double-biopsied MCG, pathology discordance occurred in 5/7 mutant but 0/28 wild-type cases. Conclusion: Results from this cohort of diffuse gliomas stratified by IDH status showed differences between IDH wild-type and mutant cohorts in prevalence, prognosis, TtM, distribution, and pathological concordance.

Background: This study explored MRI characteristics at the time of tumor progression to study pathologically confirmed MT in IDHm 1p/19q-intact astrocytomas (IDHm-A) and IDHm 1p/19q-co-deleted oligodendrogliomas (IDHm-O). Methods: N = 64 patients with initial pathological grade 2 IDH-mutant glioma diagnosis who underwent repeated tissue sampling and were classified as pathologically confirmed MT (n = 35) or non-MT (n = 29) with available presurgical anatomical (n = 64), diffusion-weighted (n = 61), and dynamic susceptibility contrast perfusion MRI (n = 53) were retrospectively studied. Measurable contrast enhancement (> 1000 mm3), tumor volume, tumor growth rate, sphericity, median apparent diffusion coefficient (ADC), and normalized relative cerebral blood volume (nrCBV) were compared between MT vs non-MT IDHm-A and IDHm-O. Results: 81% of contrast-enhancing IDHm-A and 100% of contrast-enhancing IDHm-O demonstrated MT, while 41% of IDHm-A and 62% IDHm-O exhibited both nonenhancing tumor progression and MT. Tumor volumes were significantly larger in patients with MT compared to non-MT groups for IDHm-A (P = .02) and IDHm-O (P = .04). T2/FLAIR tumor volume growth rate was significantly higher (P = .003), nrCBV was significantly higher (P = .002), and ADC trended lower (P = .06) in MT vs non-MT IDHm-A. There were no significant differences in growth rate, ADC, nrCBV, or sphericity when comparing MT vs non-MT IDHm-O (P > .05). Conclusions: Many MT IDHm gliomas remain nonenhancing. Growth rate, diffusion, and perfusion MRI show differences between MT and non-MT in IDHm-A but not IDHm-O, which may reflect the different tumor biology of these IDHm molecular subtypes and their need for separate imaging biomarkers. Tumor volumes can help determine MT for both IDHm-A and IDHm-O.

Background: Corticosteroids impact the radiographic interpretation of glioblastoma, including artificial reduction in the contrast-enhancing tumor volume and intensity (i.e., a “pseudoresponse”) and in the apparent diffusion coefficient (ADC). This study aimed to estimate the influence of corticosteroids on these measurements in treatment naïve glioblastoma before surgery. Methods: Fifty-seven pairs of MRI scans from 54 patients with presurgical treatment-naïve glioblastoma were retrospectively grouped as increased (n = 29, all corticosteroid-free at baseline), stable (n = 25), or decreased (n = 3) corticosteroid dose between scans (median interval: 15 days). Tumor size and ADC changes between timepoints were compared between lesions with increased and stable corticosteroids. Volumetric changes ascribable to increased corticosteroid dose was modeled, adjusting for the time between scans. Results: Increased corticosteroid dose showed an observed volumetric shrinkage of the contrast-enhancing tumor (median: −23.7%) and reduction in estimated growth rates (median: −2.48% per day), significantly different (P < .0001) from the control group receiving a stable dose (median: +36.0% volume; +2.08% growth rate). When adjusting for the time interval between scans, the estimated corticosteroid-induced volumetric shrinkage was 44.0% (P < .0001, 95% CI, 25.7%–62.2%). Increased corticosteroid dose also decreased ADC in the contrast-enhancing tumor (median reduction: 180, IQR = 39 − 281 × 10-6 mm2/s, P = .0005). Conclusion: Corticosteroid administration can induce a significant “pseudoresponse” in glioblastoma, with an observed reduction in contrast-enhancing tumor volume of 23.7% and a time interval adjusted reduction of 44.0% (25.7%–62.2%), and an ADC drop of 180 × 10-6 mm2/s (14.2%). These data confirm that radiographic measurements are impacted by corticosteroids and provide benchmarks for the development of adjusted response criteria accounting for corticosteroid use.