Using glutamate inhibitors to treat glioblastoma

A Phase Ib/II Randomized, Open Label Drug Repurposing Trial of Glutamate Signaling Inhibitors in Combination With Chemoradiotherapy in Patients With Newly Diagnosed Glioblastoma

Phase1; Phase2 Interventional University of Zurich · NCT05664464

This study is testing if adding certain medications that block glutamate can help improve treatment outcomes for people with newly diagnosed glioblastoma when used with standard chemotherapy and radiation.

Quick facts

PhasePhase1; Phase2
Study typeInterventional
Enrollment120 (estimated)
Ages18 Years and up
SexAll
SponsorUniversity of Zurich Academic / other
Drugs / interventionsmethotrexate
Locations1 site (Zurich, Canton of Zurich)
Trial IDNCT05664464 on ClinicalTrials.gov

What this trial studies

This clinical trial investigates the effectiveness of adding anti-glutamatergic drugs—gabapentin, sulfasalazine, and memantine—to standard chemoradiotherapy with temozolomide in patients with newly diagnosed glioblastoma. The study is designed as a 1:1 randomized, multi-center, open-label phase Ib/II trial. The rationale behind this approach is based on the role of glutamate in glioblastoma progression and the potential of these drugs to inhibit glutamate synthesis and signaling, which may improve patient outcomes. Participants will receive standard treatment alongside these additional medications to assess their combined efficacy.

Who should consider this trial

Good fit: Ideal candidates are adults over 18 with newly diagnosed supratentorial glioblastoma eligible for standard chemoradiotherapy.

Not a fit: Patients scheduled for hypofractionated radiotherapy or those who are pregnant or breastfeeding may not benefit from this study.

Why it matters

Potential benefit: If successful, this approach could significantly improve survival rates and quality of life for patients with glioblastoma.

How similar studies have performed: While there is limited commercial interest, the rationale for this combined anti-glutamatergic approach is based on existing knowledge, though it remains largely untested in this specific context.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion criteria

* Diagnosis: Newly diagnosed supratentorial glioblastoma according to the 2021 World Health Organization (WHO) Classification of Central Nervous System Tumors
* Signed informed consent
* Age \>18 years
* Eligible for standard chemoradiotherapy with temozolomide (TMZ/RT-\>TMZ, hypofractionated RT regimen not allowed)
* KPS 70 or more
* Ability to judge per local investigator estimate (at least oriented to time, place and situation)
* Paraffin-embedded tissue for central pathology review
* Adequate heamatological, liver and renal function

Exclusion criteria

* Scheduled for hypofractionated radiotherapy
* Women who are pregnant or breast feeding,
* Intention to become pregnant during the course of the study or intention to father a child,
* Lack of safe contraception, defined as: Female participants of childbearing potential, not using and not willing to continue using a medically reliable method of contraception for the entire study duration, such as oral, injectable, or implantable contraceptives, or intrauterine contraceptive devices, or who are not using any other method considered sufficiently reliable by the investigator in individual cases. Female participants who are surgically sterilised / hysterectomised or post-menopausal for longer than 2 years are not considered as being of child bearing potential.
* Other clinically significant concomitant disease states (e.g., renal failure, hepatic dysfunction, cardiovascular disease),
* Known or suspected non-compliance, drug or alcohol abuse,
* Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant,
* Participation in another study with investigational drug within the 30 days preceding and during the present study,
* Previous enrolment into the current study,
* Being an investigator, his/her family members, employees and other dependent persons,
* Any prior radiotherapy of the brain or radiotherapy with potential overlap of the irradiation fields,
* Active malignancy that may interfere with the study treatment,
* Abnormal ECG with QTc \>450 ms,
* Contraindication for Gadolinium-enhanced MRI,
* Previous intolerance reactions to one of the study drugs,
* Intolerance reactions to sulfonamides or salicylates,
* Acute intermittend porphyria,
* Known glucose-6-phosphate dehydrogenase deficiency,
* Concomitant therapy with digoxin, cyclosporin, methotrexate,
* History of exfoliative dermatitis, Stevens-Johnson-Syndrome, toxic epidermal necrolysis, DRESS (Drug Rash with Eosinophilia and Systemic Symptoms) syndrome or renal tubular acidosis.

Where this trial is running

Zurich, Canton of Zurich

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions GlioblastomaIDH wild-typenewly diagnosedglutamateepilepsy
Last reviewed 2026-06-10 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.