GLIOBLASTOMA · White paper
Glioblastoma Clinical Trials
Approved therapies, the pivotal-trial endpoints they were judged on, the magnitude of benefit — and the drugs that failed their endpoints, and why.
Indication overview
About glioblastoma — and why its trials are hard
Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor in adults, a WHO Grade IV astrocytic tumor with median survival typically 12 to 18 months and five-year survival under 10%. It is defined by marked intratumoral and intertumoral heterogeneity, microvascular proliferation, and pseudopalisading necrosis, with MGMT promoter methylation and IDH status as key prognostic/predictive markers. The therapeutic landscape is a graveyard of failures: standard of care still rests on maximal safe resection followed by radiotherapy plus temozolomide (the 2005 Stupp regimen, which added only about 2.5 months of median overall survival), with tumor-treating fields (Optune) extending survival in the EF-14 trial and bevacizumab approved for recurrence despite no overall-survival benefit. The blood-brain barrier, tumor heterogeneity, pseudoprogression, patient-selection bias, and underpowered designs drive frequent trial failure. Cilengitide (CENTRIC), rindopepimut (ACT IV), enzastaurin, veliparib, and cediranib all failed pivotal testing. Recent progress includes vorasidenib for IDH-mutant lower-grade glioma, though effective GBM-specific breakthroughs remain elusive.
Approved therapies & pivotal evidence
What's been approved — and by how much it moved the endpoint
| Drug (brand) | Approved | Setting | Pivotal trial | Primary endpoint | Magnitude of benefit |
|---|---|---|---|---|---|
| Temozolomide (Temodar) | 2005 (newly diagnosed GBM indication; initial approval 1999) | Newly diagnosed GBM, concurrent with radiotherapy and as maintenance (Stupp regimen) | EORTC-NCIC 26981/22981 (Stupp, NEJM 2005) | Oral alkylator; median OS 14.6 vs 12.1 months (HR 0.63, P<0.0001), +~2.5 months; 2-year survival 26.5% vs 10.4% | |
| Bevacizumab (Avastin) | 2009 | Recurrent glioblastoma (accelerated approval) | BRAIN (AVF3708g); confirmatory AVAglio / RTOG-0825 | Anti-VEGF antibody; objective response ~19.6-25.9%; improved PFS but no overall-survival benefit in AVAglio/RTOG-0825 | |
| Tumor-treating fields (Optune (NovoTTF-100A)) | 2015 (newly diagnosed GBM; initial recurrent-GBM approval 2011) | Newly diagnosed GBM with maintenance temozolomide; monotherapy for recurrence | EF-14 (newly diagnosed); EF-11 (recurrent) | Alternating electric fields disrupt mitosis; EF-14 median OS 20.9 vs 16.0 months and PFS 6.7 vs 4.0 months with adequate compliance | |
| Carmustine (BiCNU / Gliadel wafer) | 1977 (BiCNU); 1996/2003 (Gliadel wafer) | Combination chemotherapy; implantable wafer in resection cavity (Gliadel largely discontinued) | Gliadel wafer pivotal trial (newly diagnosed malignant glioma) | Alkylator cross-linking DNA; wafer median survival 13.9 vs 11.6 months, ~29% reduction in risk of death (P=0.03); Gliadel later discontinued | |
| Lomustine (Gleostine) | 1976 | Recurrent/second-line GBM, often in combination regimens | Approved on historical clinical evidence; used as comparator in modern recurrent-GBM trials | Oral nitrosourea alkylator; modest survival benefit in recurrence; delayed myelosuppression is dose-limiting | |
| Vorasidenib (Voranigo) | 2024 | Grade 2 IDH-mutant astrocytoma/oligodendroglioma after surgery (NOT approved for Grade IV GBM) | INDIGO (NCT04164901) | Brain-penetrant IDH1/2 inhibitor; significantly prolonged progression-free survival vs placebo; relevant to IDH-mutant glioma, not classic GBM |
Where trials have failed
Drugs that missed their endpoint — and what contributed
The most instructive lessons in glioblastoma development come from programmes that failed the endpoint that mattered.
| Drug / trial | Endpoint outcome | What contributed |
|---|---|---|
| Cilengitide — CENTRIC (EORTC 26071-22072, Phase III) | Did not improve overall survival when added to temozolomide/radiotherapy in MGMT-methylated newly diagnosed GBM | Integrin (alphavbeta3/alphavbeta5) inhibitor; no survival benefit; development for GBM discontinued |
| Rindopepimut — ACT IV (Phase III) | Failed to improve overall survival in EGFRvIII-positive newly diagnosed GBM; discontinued | EGFRvIII peptide vaccine; antigen loss and tumor heterogeneity undermined single-target vaccination |
| Cediranib — REGAL and combination Phase II/III (recurrent GBM) | Failed to significantly improve OS or PFS | VEGFR inhibitor; anti-angiogenesis alone insufficient given redundant angiogenic pathways and pseudoresponse |
Choosing the right endpoint
Primary endpoints that matter in glioblastoma trials
- Overall survival (OS) — Gold-standard endpoint; confounded by tumor heterogeneity and post-progression salvage therapies; addressed with molecular stratification
- Progression-free survival (PFS) — Time without progression; complicated by pseudoprogression after chemoradiation and imaging variability; RANO criteria standardize assessment
- Objective response rate (ORR) — Imaging-based tumor reduction; responses often short-lived and irregular tumors are hard to measure; benefits from centralized review
- Health-related quality of life — EORTC QLQ-C30 / FACT-Br; important given aggressive disease and treatment toxicity; subject to reporting bias
- Biomarker-based endpoints — MGMT promoter methylation and IDH status predict alkylator response and prognosis; require validation and account for heterogeneity
How iNGENū runs glioblastoma trials
Physician-led design, built for FDA submission
Endpoint & biomarker strategy
Board-certified specialists design endpoints and patient selection aligned to current FDA guidance for this indication.
FDA-ready data
Built to ICH-GCP and 21 CFR 312.120, with direct FDA submission — data accepted by the FDA, EMA and MHRA.
Faster, lower-cost delivery
~4-week ethics via the TGA CTN scheme, up to 43.5% R&D rebate, and 80–90% below US CRO cost.
The full white paper: approved-product analyses, pivotal endpoints and trial-design strategy. Open-access · no sign-in.
Frequently asked questions
Glioblastoma clinical trials — FAQs
What is the standard of care for newly diagnosed glioblastoma?
Why has glioblastoma drug development failed so often?
Does bevacizumab improve survival in glioblastoma?
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