Temozolomide

證據等級: L5

預測適應症: 2 個

Temozolomide: From Glioblastoma to Adult Astrocytic Tumour

One-Sentence Summary

Temozolomide (TMZ) is an oral alkylating agent established as the backbone of the Stupp protocol — the global standard of care for newly diagnosed glioblastoma — where it is combined with radiotherapy to significantly extend survival. The TxGNN model predicts it may be effective for the broader category of Adult Astrocytic Tumour, with 2 clinical trials and 20 publications currently supporting this direction, including multiple landmark Phase 3 RCTs. Notably, glioblastoma is itself the highest-grade adult astrocytic tumour, meaning this prediction is strongly anchored in established clinical practice.

Quick Overview

Item	Content
Original Indication	Glioblastoma / Malignant Astrocytoma (established by landmark Phase 3 RCT evidence; no Taiwan TFDA registration found)
Predicted New Indication	Adult Astrocytic Tumour
TxGNN Prediction Score	99.36%
Evidence Level	L1
Taiwan Market Status	✗ Not Marketed (未上市)
Number of Authorizations	0
Recommended Decision	Proceed with Guardrails

Why is This Prediction Reasonable?

Temozolomide belongs to the imidazotetrazine class of alkylating agents. After oral administration, it spontaneously hydrolyses to its active metabolite MTIC, which methylates DNA at the O⁶-guanine and N7-guanine positions. The O⁶-methylguanine adduct is recognised by the mismatch repair (MMR) system, ultimately triggering apoptosis. A critical pharmacological advantage is its excellent blood-brain barrier penetration (CSF-to-plasma ratio ≈ 0.4), making it uniquely suited for central nervous system tumours.

Efficacy is strongly modulated by MGMT promoter methylation status: when the MGMT gene is silenced by methylation, the tumour cell cannot repair TMZ-induced DNA damage, yielding substantially better outcomes. This biomarker-driven response has been demonstrated across multiple Phase 3 trials and is now a routine predictive test before initiating TMZ-based therapy.

Adult astrocytic tumours encompass a histological spectrum — from WHO Grade 2 diffuse astrocytoma through Grade 3 anaplastic astrocytoma to Grade 4 glioblastoma (GBM). GBM is precisely the indication for which the Stupp protocol (concurrent TMZ + radiotherapy, followed by adjuvant TMZ) was validated and globally adopted. The TxGNN model's prediction therefore reflects mechanistic and clinical continuity: TMZ's alkylating action on neuroepithelial tumour cells, combined with its CNS penetration, makes it rationally applicable across the full adult astrocytic spectrum.

Clinical Trial Evidence

Trial Number	Phase	Status	Enrollment	Key Findings
NCT00052455	Phase 3	Completed	500	Randomised trial comparing TMZ alone vs PCV (procarbazine + lomustine + vincristine) in recurrent WHO Grade III–IV astrocytic tumours. Direct head-to-head RCT evidence for TMZ in this exact disease category.
NCT00960492	Phase 1	Completed	26	Dose-finding study of XL184 (cabozantinib) added to TMZ + radiotherapy as first-line treatment for glioblastoma. TMZ serves as the standard backbone, confirming its established safety and feasibility in this setting.

Literature Evidence

PMID	Year	Type	Journal	Key Findings
15758009	2005	Phase 3 RCT	N Engl J Med	Landmark Stupp trial: RT + concomitant/adjuvant TMZ vs RT alone in newly diagnosed GBM. Established TMZ as the standard of care (median OS 14.6 vs 12.1 months; 2-year survival 26.5% vs 10.4%).
19269895	2009	Phase 3 RCT follow-up	Lancet Oncol	5-year analysis of the EORTC-NCIC Stupp trial. Confirmed sustained OS benefit of TMZ + RT; MGMT methylation identified as key predictive biomarker (5-year OS 13.8% vs 1.9% for MGMT-methylated vs unmethylated).
22578793	2012	Phase 3 RCT	Lancet Oncol	NOA-08 trial: TMZ alone vs radiotherapy alone in elderly patients with malignant astrocytoma (anaplastic astrocytoma or GBM). TMZ non-inferior to RT; MGMT methylation predicted benefit from TMZ.
24552317	2014	Phase 3 RCT	N Engl J Med	RTOG 0825: addition of bevacizumab to standard TMZ + RT in newly diagnosed GBM. TMZ-RT is the control arm reference; bevacizumab did not improve OS.
26670971	2015	Phase 3 RCT	JAMA	EF-14 trial: Tumour Treating Fields (TTFields) + TMZ vs TMZ alone for maintenance therapy in GBM. TTFields + TMZ improved median OS (20.9 vs 16.0 months) and PFS.
30782343	2019	Phase 3 RCT	Lancet	CeTeG/NOA-09 trial: Lomustine-TMZ combination vs standard TMZ in newly diagnosed GBM with MGMT methylation. Combination arm showed improved OS (48.1 vs 31.4 months) in methylated patients.
25920709	2015	Phase 2/3 RCT subset	J Neuro-oncol	RT + TMZ in anaplastic astrocytoma (AA) and anaplastic oligo-astrocytoma (AOA). Exploratory cohort; supports TMZ + RT as active regimen across the broader astrocytic tumour spectrum.
40779733	2025	Phase 2/3 RCT	J Clin Oncol	NRG BN007: Dual checkpoint blockade (ipilimumab + nivolumab) added to standard TMZ chemoradiotherapy in MGMT-unmethylated GBM. TMZ backbone again used as standard comparator arm.
36809318	2023	Systematic Review	JAMA	Comprehensive review of glioblastoma and other primary brain malignancies in adults. Confirms TMZ-based Stupp protocol as established standard; outlines unmet needs and emerging therapies.
10914698	2000	Review	Clin Cancer Res	Early clinical review of TMZ in malignant gliomas (GBM and anaplastic astrocytoma). Documents early efficacy signals that led to Phase 3 trials and eventual approval.

Taiwan Market Information

Temozolomide currently has no registered authorizations in the Taiwan TFDA database based on the data retrieved for this report (query date: 2026-03-29, result count: 0). There are no licensed products, approved indications, or dosage forms on record.

Note: This finding warrants independent verification against the current TFDA online drug licence database, as Temozolomide (Temodar®/Temodal®) holds regulatory approval in numerous major markets (USA, EU, Japan). The absence of TFDA records may reflect a data retrieval limitation or the drug being available under a different trade name or via special importation.

Cytotoxicity

Temozolomide is classified as an antineoplastic agent (oral alkylating agent, imidazotetrazine class). The following table applies.

Item	Content
Cytotoxicity Classification	Conventional cytotoxic — Alkylating agent (Imidazotetrazine / Triazene class)
Myelosuppression Risk	High — Thrombocytopenia and neutropenia are the dose-limiting toxicities; typically nadir at days 21–28 of each 28-day cycle. Grade 3/4 thrombocytopenia occurs in ~14% of patients on the standard 5-day schedule.
Emetogenicity Classification	Moderate (standard antiemetic prophylaxis recommended prior to each dose)
Monitoring Items	CBC with differential and platelet count (on Day 22 and Day 29 of each cycle before next cycle); liver function tests (ALT, AST, bilirubin); renal function; MGMT promoter methylation status (baseline, for prognosis and treatment selection)
Handling Protection	Must be handled according to cytotoxic drug handling regulations — avoid crushing capsules, use appropriate PPE during preparation and disposal

Safety Considerations

Formal safety data (TFDA package insert warnings, contraindications, and drug interactions) were not retrievable from available sources at the time of this report.

Please refer to the official package insert (Temodar®/Temodal® SmPC or FDA prescribing information) for complete safety information, including warnings regarding myelosuppression, opportunistic infections (e.g., Pneumocystis jirovecii pneumonia prophylaxis recommended during concurrent RT phase), hepatotoxicity, and use in pregnancy.

Conclusion and Next Steps

Decision: Proceed with Guardrails

Rationale: The evidence base for Temozolomide in adult astrocytic tumours is among the strongest in neuro-oncology — the landmark Stupp Phase 3 RCT and its 5-year follow-up directly established TMZ + radiotherapy as the global standard of care for glioblastoma (WHO Grade 4 astrocytic tumour), and subsequent trials have extended evidence to anaplastic astrocytoma (Grade 3). The TxGNN prediction score of 99.36% is fully concordant with this established clinical evidence, with multiple completed Phase 3 RCTs qualifying this as Level L1 evidence.

To proceed, the following is needed:

Taiwan regulatory pathway clarification: Verify whether Temozolomide is available in Taiwan under a trade name (Temodar®), via special importation, or under NHI reimbursement — TFDA query returned 0 results and needs manual confirmation.
Formal safety data: Retrieve and document the complete package insert (warnings, contraindications, DDIs) — currently not available in the Evidence Pack due to the data gap flagged as DG001 (Blocking).
MGMT biomarker testing protocol: Establish institutional workflow for MGMT promoter methylation testing to guide patient selection and expected response.
Opportunistic infection prophylaxis plan: Confirm P. jirovecii prophylaxis protocol for patients receiving concurrent TMZ + radiotherapy.
Reimbursement review: Assess NHI or institutional funding pathway for TMZ given its absence from TFDA records.
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.