A Striking New Study from Aziz Sancar: Overcoming Resistance in Brain Cancer
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Aziz Sancar's Innovative Approach to Glioblastoma: Overcoming Resistance Through a "Futile Cycle"
Science's Answer to Despair
Glioblastoma (GBM) is the most aggressive, rapidly progressing and, unfortunately, treatment-resistant brain tumor encountered in oncology. Despite standard surgery, radiotherapy and chemotherapy with temozolomide, tumor cells adapt like chameleons, finding ways to survive, and the disease often returns. This creates profound helplessness for patients and physicians alike.
Science, however, does not accept helplessness. Our esteemed Nobel Prize in Chemistry laureate, Prof. Aziz Sancar and his team, including Turkish scientists Hümeyra Kaanoğlu and Yasemin K. Akyel, offered a ray of hope with a study published on 31 December 2025.
The study proposes more than a new drug combination: it sets a biologically elegant trap, turning cancer cells' own DNA repair machinery against them. Here are the details of this strategy, called the "futile cycle" .
1. The Clinical Problem: Why Is Glioblastoma So Difficult to Treat?
Temozolomide (TMZ), the cornerstone of glioblastoma treatment, damages DNA to kill tumor cells. Yet cancer cells are in an evolutionary race to survive:
- MGMT Enzyme: Some tumors promptly repair TMZ-induced damage like an efficient mechanic.
- Genomic Heterogeneity: Tumor cells differ; some clones are inherently treatment-resistant and initiate recurrence.
- Blood–Brain Barrier: Most potent chemotherapy drugs cannot penetrate this protective armor to reach the tumor.
2. The Strategic Tool: The Futile Cycle Mechanism
The strategy developed by Prof. Aziz Sancar and colleagues turns cancer cells' own machinery against them. EdU acts as a Trojan horse.
How Does the Mechanism Work?
Result: TMZ attacks from one side and EdU from the other, creating a two-pronged assault that kills the cell.
3. Study Findings: From the Laboratory to Living Tissue
The researchers tested the hypothesis in three challenging models and obtained statistically strong results.
The Most Striking Findings: Orthotopic Mouse Models
- Successful Barrier Crossing: EdU was shown to cross the blood–brain barrier (BBB) and accumulate directly in brain tumor tissue.
- U87 Model: Combination treatment (TMZ+EdU) increased survival compared with placebo by 130% .
- GBM8 Model (Curative Success): In this patient-derived model, tumors recurred in 60% of mice receiving TMZ alone, whereas 100% of mice receiving TMZ + EdU were alive and tumor-free at study completion. This represents a complete response, an uncommon achievement in oncology. It is essential to remember that this response occurred in a preclinical model, meaning an animal experiment.
Testing Living Patient Tissue (Ex Vivo)
Living tumor tissue obtained during surgery was maintained in the laboratory and exposed to the drugs. Tumors from 4 different patients all responded to the combination. Effects were additive in some and synergistic in others, suggesting potential for individualized treatment.
4. Safety: Is the Treatment Toxic?
Safety matters as much as efficacy. Detailed toxicity analyses in the study were encouraging:
- Target Organs: Mild, temporary damage occurred in the small intestine and spleen, which contain rapidly dividing cells.
- Reversible: Tissues fully regenerated after treatment stopped, with no permanent damage.
- Systemic Safety: No liver or kidney functional toxicity was detected. The mice's weight and blood values returned to normal.
- Kaanoglu H, Akyel YK, Adefolaju A, et al. Combinatorial treatment of glioblastoma with temozolomide (TMZ) plus 5-ethynyl-2′-deoxyuridine (EdU). Proc Natl Acad Sci U S A. 2025 Dec 31;123(1):e2532187123. doi: 10.1073/pnas.2532187123
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