temozolomide

Overview

Temozolomide (TMZ) is an oral alkylating chemotherapeutic agent widely used in the treatment of malignant brain tumors, most notably glioblastoma multiforme (GBM) and other high-grade gliomas. It belongs to the imidazotetrazine class of compounds and exerts its cytotoxic effect by methylating DNA at the O6 position of guanine, leading to DNA strand breaks, replication failure, and apoptosis in rapidly dividing tumor cells. The drug's ability to cross the blood-brain barrier makes it particularly valuable in neuro-oncology, where it remains a cornerstone of the Stupp protocol — concurrent (chemo)radiotherapy followed by adjuvant TMZ cycles — established as standard of care for newly diagnosed GBM. Beyond gliomas, temozolomide is also employed in combination regimens for pediatric solid tumors, including neuroblastoma and Ewing sarcoma, reflecting its broad alkylating activity and manageable tolerability profile.

A central challenge in temozolomide-based therapy is the development of tumor resistance, which is mechanistically linked to the expression and methylation status of the MGMT promoter. MGMT (O6-methylguanine-DNA methyltransferase) directly repairs the DNA lesions induced by TMZ; tumors with an unmethylated MGMT promoter tend to express this repair enzyme at high levels, rendering TMZ less effective. Abnormal DNA damage repair pathways — including those driven by oncogenic alterations such as EGFRvIII — further complicate treatment outcomes. As a result, understanding and overcoming TMZ resistance has become one of the most active areas of contemporary neuro-oncology research.

Focus of Latest Publications

Recent publications on temozolomide have focused largely on overcoming resistance in glioblastoma and on identifying biomarkers that may predict response to DNA-damaging therapy. Several studies examined temozolomide in combination strategies, including adjuvant use with a neuronal nitric oxide synthase inhibitor (BA-101), synergy with rutin in YANK2-overexpressing glioblastoma models, and incorporation into localized chemo-photothermal delivery systems using MXene-integrated GelMA microspheres. Across these reports, temozolomide was generally positioned as a standard cytotoxic backbone whose activity might be enhanced by targeted agents, drug delivery platforms, or biomarker-guided combinations.

Mechanistic work highlighted molecular determinants of temozolomide resistance in glioblastoma. One study reported that MET-mediated phosphorylation of YANK2 promoted glioblastoma cell proliferation and tumor growth, and that rutin directly bound YANK2 and synergized with temozolomide to suppress tumor growth and prolong survival in orthotopic models. Another study found that inhibition of miR-25-3p in patient-derived glioblastoma cells reduced β-catenin signaling, re-induced FBXW7 expression, and increased temozolomide sensitivity in a subset of cell lines, with accompanying reductions in invasiveness and a shift toward a less aggressive transcriptional and epigenetic state. A separate publication linked the cuproptosis-related protein SLC31A1 to the immune microenvironment of glioblastoma and specifically evaluated whether cuproptosis agonists could alter temozolomide sensitivity.

Temozolomide was also evaluated in other tumor contexts as a marker of sensitivity to DNA damage-based treatment. In nasopharyngeal carcinoma, SLC44A4 overexpression was associated with reduced malignant behavior and increased sensitivity to temozolomide, along with other DNA-damaging agents such as doxorubicin, cisplatin, olaparib, and etoposide. In a pediatric H3K27M-mutant diffuse intrinsic pontine glioma study, the role of adding temozolomide to radiotherapy was examined, reflecting ongoing uncertainty about the benefit of chemoradiotherapy in this disease. Additional clinical and translational reports included retrospective evaluation of adjuvant temozolomide in high-risk WHO grade 2 diffuse glioma and broader combination regimens such as capecitabine and temozolomide in neuroendocrine tumors, or bevacizumab, irinotecan, and temozolomide in relapsed/refractory neuroblastoma.

Overall, the recent literature portrays temozolomide as a central therapy whose limitations are driven by intrinsic and acquired resistance, especially in glioblastoma. Current investigations emphasize combination approaches, biomarker stratification, and resistance pathways involving MET-YANK2 signaling, miR-25-3p/β-catenin, DNA damage repair, and cuproptosis-related biology. Several studies also suggest that delivery optimization and local treatment platforms may improve the therapeutic impact of temozolomide-based regimens.