Glioblastoma Multiforme, AdultOLFGBMNCT06954636
Prognostic Potential of Olfactory Function in Glioblastoma: a Prospective Observational Study
An observational study of Glioblastoma Multiforme, Adult and Glioblastoma or Gliosarcoma, run by Sied Kebir at 2 sites in Germany.
Trial summary
The study aims to investigate the prognostic significance of olfactory function in patients with glioblastoma. We are examining olfactory function at various points during therapy and correlating the results with survival data. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Glioblastoma Multiforme, Adult, Glioblastoma or Gliosarcoma, Glioblastoma, Adult
- What is being tested?
- olfactory testing (threshold and identification test)
- How many people
- 128 participants
- Where
- 2 sitesGermany
- Study dates
- 3 May 2023to 31 Dec 2029
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Newly-diagnosed glioblastoma
Who may be able to join
- At least 18 years of age
- Newly-diagnosed glioblastoma (IDH wild-type)
- Never received prior chemotherapy
- Never received radiotherapy to the head or neck before
- KPS ≥ 70
- No history of severe head or brain trauma requiring ICU admission or classified as Glasgow Coma Scale grade 3
- No respiratory infection at the time of inclusion
- No significant aphasia
Who cannot join
- Presence of Neurodegenerative diseases (e.g. Parkinson's disease, Alzheimer's disease, Huntington's disease, Korsakoff's syndrome, Pick's disease, Shy-Drager syndrome)
- History of invasive tumors or surgery in the head or neck area, except for surgeries for non-invasive skin tumors (e.g. basal cell carcinomas)
- Permanent olfactory impairment following infections (e.g., influenza, coronavirus)
- Conditions that, in the examiner's judgment, could interfere with the participant's study compliance (e.g., schizophrenia)
- Language barriers likely to interfere with participation or comprehension of study procedures.
Trial locations and contacts
2 sites in 1 country. Contact the study team or a site near you to ask about taking part.
Germany2 sites, 2 recruiting
- Recruiting
University Hospital Essen, Department of Neurology, Division of Clinical Neuro-Oncology
Essen, 45147
Christoph Oster, Dr. med., +49 201 723 82598, christoph.oster@uk-essen.de
- Recruiting
Department of Neurosurgery
Münster
Michael Müther, PD Dr. med., +49 251 83-47472, Michael.Muether@ukmuenster.de
About this study
The study aims to investigate the prognostic significance of olfactory function in patients with glioblastoma. We are examining olfactory function at various points during therapy and correlating the results with survival data. In addition, neurocognitive tests will be carried out to correlate the results of olfactory function with the patient's cognitive abilities. Investigations into the quality of life and psychological condition of the patients are also performed. In addition to the cohort of glioblastoma patients, there is a control cohort without tumor disease in which the olfactory testing is also carried out in order to have a comparison.
Read the detailed description
Background: Olfactory impairment is frequent in glioblastoma and is associated with poor overall survival. However, earlier studies were limited by confounding of important predictive factors and the lack of long-term olfactory assessments to evaluate treatment-related neurotoxicity.
Aim: To determine whether olfactory function is an independent prognostic marker for survival, quality of life and neurocognitive outcome in glioblastoma.
Design: Prospective, multicenter cohort study with 64 glioblastoma patients and 64 comparable controls without tumor disease. Patients were stratified by baseline olfactory status, extent of resection, radiologic involvement of olfactory regions,O6-methylguanine DNA methyltransferase (MGMT) promoter methylation, age, and Karnofsky performance status.
Methods: Olfactory function will be serially assessed from diagnosis to treatment using Sniffin' Sticks (identification and threshold tests). Psychosocial assessments, neurocognitive testing and quality of life assessments will be performed at intervals. Coronal T2- and T1-weighted MRI scans will be evaluated independently by blinded neuroradiologists to identify olfactory involvement.
Next-generation sequencing will be used to investigate molecular correlates of hyposmia. As part of a parallel translational study, blood samples will be taken to analyze extracellular vesicles.
Olfactory testing:
In the identification test, 12 sniffin sticks are presented, which the patient has to name using a selection card with four terms each. Both nostrils are tested individually at each visit during the identification test. A correct answer scores one point. A maximum of 12 points is possible.
The threshold test consists of 16 dilution levels. Each level contains one sniffin stick with odor and two blanks. All three sniffin sticks of a dilution level are presented to the patient one after the other with eyes closed. The patient must indicate which of the three sticks contains an odor. Depending on whether the patient gives the correct answer, the three sniffin sticks in the next higher or next lower level are presented next. A maximum of 16 points is possible.
- Being tested
- olfactory testing (threshold and identification test)
- Keywords
- olfactory dysfunction, threshold test, identification test, glioblastoma, prognosis, observational study, olfactory function, neurocognition, quality of life
- Medical subject headings
- Glioblastoma, Gliosarcoma
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
olfactory testing (threshold and identification test)Diagnostic test
In the identification test, 12 sniffin sticks are presented, which the patient has to name using a selection card with four terms each. Both nostrils are tested individually at each visit during the identification test. A correct answer scores one point. A maximum of 12 points is possible.
The threshold test consists of 16 dilution levels. Each level contains one sniffin stick with odor and two blanks. All three sniffin sticks of a dilution level are presented to the patient one after the other with eyes closed. The patient must indicate which of the three sticks contains an odor. Depending on whether the patient gives the correct answer, the three sniffin sticks in the next higher or next lower level are presented next. A maximum of 16 points is possible.
| Study group | Role | What they receive |
|---|---|---|
| Newly-diagnosed glioblastoma cohort | Not described Receives: Diagnostic Test: olfactory testing (threshold and identification test) | |
| Control cohort | Control group of patients with non-tumourous (neurological) diseases not primarily associated with an olfactory dysfunction Receives: Diagnostic Test: olfactory testing (threshold and identification test) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Overall survival
Overall survival in relation to olfactory function
Measured: From tumor diagnosis to death (usually 6 to 24 months)
Secondary outcomes (4)
Progression free survival
Progression free survival in relation to olfactory function
Measured: From date of first surgery until the date of first progression (MRI)
Neurocognition
Neurocognition in relation to olfactory function
The following tests are used for neurocognition testing:
- Immediate and delayed story recall from the Rivermead Behavioural Memory Test
- Number span (forward and backward) and block span (forward and backward) from the Wechsler Memory Scale
- Phonemic word fluency from the Regensburg Word Fluency Test (phonemic)
- Trail Making Test A and B
Measured: From enrollment to 2 years after the end of radiotherapy
Quality of Life (QoL)
Quality of Life in relation to olfactory function
The following questionnaires are used to assess quality of life:
- EORTC QLQ-C30 (Version 3.0; Part A with 28 questions on a Likert scale, 28 to 112 points, Higher score means lower quality of life; Part B with 2 questions on a Likert scale, 2 to 14 points, Lower score means lower quality of life )
- EORTC QLQ-BN20 (20 questions on a Likert scale; 20 to 80 points; Higher score means lower quality of life)
Measured: From enrollment to 2 years after the end of radiotherapy
Psychological condition
Psychological well-being in relation to olfactory function
The following psychiatric questionnaires are used:
- Patient Health Questionnaire-8 (PHQ-8): 8 questions on a Likert scale, score 0 to 24, higher score indicate more depression
- Generalized Anxiety Disorder 7 (GAD-7): 7 questions on a Likert scale, score 0 to 21, higher score indicate more anxiety
- National Comprehensive Cancer Network (NCCN) Distress Thermometer:
Score 1 to 10, higher score indicate more distress
Measured: From enrollment to 2 years after the end of radiotherapy
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted1 May 2025
- Study start3 May 2023
- Primary completion31 Dec 2027 (estimated)
- Study completion31 Dec 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for Glioblastoma Multiforme, AdultStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Prospective
- Enrolment
- 128 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Sied Kebir
- Sponsor type
- University, hospital or other
- Collaborators
- University Hospital Muenster
- Responsible party
- Sponsor-investigator, Sied Kebir, University Hospital, Essen
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06954636
- Sponsor's protocol ID
- 22-10501-BO
- Acronym
- OLFGBM
- Status last verified
- Aug 2026
- First submitted
- 16 Apr 2025
- Last updated
- 24 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Clinical Data from the other study centers will be transferred pseudonymously to the study headquarters in Essen. Only pseudonymized data is also used for accompanying scientific projects.
Publications
Hummel T, Sekinger B, Wolf SR, Pauli E, Kobal G. 'Sniffin' sticks': olfactory performance assessed by the combined testing of odor identification, odor discrimination and olfactory threshold. Chem Senses. 1997 Feb;22(1):39-52. doi: 10.1093/chemse/22.1.39.
PubMed 9056084Hummel T, Konnerth CG, Rosenheim K, Kobal G. Screening of olfactory function with a four-minute odor identification test: reliability, normative data, and investigations in patients with olfactory loss. Ann Otol Rhinol Laryngol. 2001 Oct;110(10):976-81. doi: 10.1177/000348940111001015.
PubMed 11642433Kebir S, Hattingen E, Niessen M, Rauschenbach L, Fimmers R, Hummel T, Schafer N, Lazaridis L, Kleinschnitz C, Herrlinger U, Scheffler B, Glas M. Olfactory function as an independent prognostic factor in glioblastoma. Neurology. 2020 Feb 4;94(5):e529-e537. doi: 10.1212/WNL.0000000000008744. Epub 2019 Dec 12.
PubMed 31831598Walker IM, Fullard ME, Morley JF, Duda JE. Olfaction as an early marker of Parkinson's disease and Alzheimer's disease. Handb Clin Neurol. 2021;182:317-329. doi: 10.1016/B978-0-12-819973-2.00030-7.
PubMed 34266602Oster C, Matyar A, Schmidt T, Hummel T, Hattingen E, Jokisch M, Jokisch D, Grieger J, Cappello G, Kizina K, Lazaridis L, Ahmadipour Y, Rauschenbach L, Stuschke M, Pottgen C, Guberina N, Tertel T, Giebel B, Dreizner GL, Barbato F, Skoda EM, Scheffler B, Muther M, Herrmann K, Kleinschnitz C, Sure U, Deuschl C, Glas M, Kebir S. Decoding glioblastoma survival: unraveling the prognostic potential of olfactory function in a prospective observational study. Neurol Res Pract. 2025 Jul 24;7(1):51. doi: 10.1186/s42466-025-00410-2.
PubMed 40708059
Study at a glance
From the registry record, last updated by the sponsor on 24 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Prognostic Potential of Olfactory Function in Glioblastoma: a Prospective Observational Study
- ClinicalTrials.gov ID
- NCT06954636
- Acronym / sponsor ID
- OLFGBM / 22-10501-BO
- Keywords
- olfactory dysfunction, threshold test, identification test, glioblastoma, prognosis, observational study, olfactory function, neurocognition
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 128 participants (estimated)
- Lead sponsor
- Sied KebirUniversity, hospital or other
- Collaborators
- University Hospital Muenster
- Study start
- 3 May 2023 (actual)
- Primary completion
- 31 Dec 2027 (estimated)
- Study completion
- 31 Dec 2029 (estimated)
- First posted
- 1 May 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The study aims to investigate the prognostic significance of olfactory function in patients with glioblastoma. We are examining olfactory function at various points during therapy and correlating the results with survival data. In addition, neurocognitive tests will be carried out to correlate the results of olfactory function with the patient's cognitive abilities. Investigations into the quality of life and psychological condition of the patients are also performed. In addition to the cohort of glioblastoma patients, there is a control cohort without tumor disease in which the olfactory testing is also carried out in order to have a comparison.
Detailed description
Background: Olfactory impairment is frequent in glioblastoma and is associated with poor overall survival. However, earlier studies were limited by confounding of important predictive factors and the lack of long-term olfactory assessments to evaluate treatment-related neurotoxicity.
Aim: To determine whether olfactory function is an independent prognostic marker for survival, quality of life and neurocognitive outcome in glioblastoma.
Design: Prospective, multicenter cohort study with 64 glioblastoma patients and 64 comparable controls without tumor disease. Patients were stratified by baseline olfactory status, extent of resection, radiologic involvement of olfactory regions,O6-methylguanine DNA methyltransferase (MGMT) promoter methylation, age, and Karnofsky performance status.
Methods: Olfactory function will be serially assessed from diagnosis to treatment using Sniffin' Sticks (identification and threshold tests). Psychosocial assessments, neurocognitive testing and quality of life assessments will be performed at intervals. Coronal T2- and T1-weighted MRI scans will be evaluated independently by blinded neuroradiologists to identify olfactory involvement.
Next-generation sequencing will be used to investigate molecular correlates of hyposmia. As part of a parallel translational study, blood samples will be taken to analyze extracellular vesicles.
Olfactory testing:
In the identification test, 12 sniffin sticks are presented, which the patient has to name using a selection card with four terms each. Both nostrils are tested individually at each visit during the identification test. A correct answer scores one point. A maximum of 12 points is possible.
The threshold test consists of 16 dilution levels. Each level contains one sniffin stick with odor and two blanks. All three sniffin sticks of a dilution level are presented to the patient one after the other with eyes closed. The patient must indicate which of the three sticks contains an odor. Depending on whether the patient gives the correct answer, the three sniffin sticks in the next higher or next lower level are presented next. A maximum of 16 points is possible.
Study design
- Observational model
- Case-control
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Newly-diagnosed glioblastoma cohort | – | Diagnostic Test: olfactory testing (threshold and identification test) |
| Control cohort | – | Diagnostic Test: olfactory testing (threshold and identification test)Control group of patients with non-tumourous (neurological) diseases not primarily associated with an olfactory dysfunction |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Newly-diagnosed glioblastoma
Key inclusion criteria (8 listed)
- At least 18 years of age
- Newly-diagnosed glioblastoma (IDH wild-type)
- Never received prior chemotherapy
- Never received radiotherapy to the head or neck before
- KPS ≥ 70
Key exclusion criteria (5 listed)
- Presence of Neurodegenerative diseases (e.g. Parkinson's disease, Alzheimer's disease, Huntington's disease, Korsakoff's syndrome, Pick's disease, Shy-Drager syndrome)
- History of invasive tumors or surgery in the head or neck area, except for surgeries for non-invasive skin tumors (e.g. basal cell carcinomas)
- Permanent olfactory impairment following infections (e.g., influenza, coronavirus)
- Conditions that, in the examiner's judgment, could interfere with the participant's study compliance (e.g., schizophrenia)
- Language barriers likely to interfere with participation or comprehension of study procedures.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| olfactory testing (threshold and identification test)In the identification test, 12 sniffin sticks are presented, which the patient has to name using a selection card with four terms each. Both nostrils are tested individually at each visit during the identification test. A correct answer scores one point. A maximum of 12 points is possible. The threshold test consists of 16 dilution levels. Each level contains one sniffin stick with odor and two blanks. All three sniffin sticks of a dilution level are presented to the patient one after the other with eyes closed. The patient must indicate which of the three sticks contains an odor. Depending on whether the patient gives the correct answer, the three sniffin sticks in the next higher or next lower level are presented next. A maximum of 16 points is possible. | Diagnostic test | Control cohort, Newly-diagnosed glioblastoma cohort |
Primary outcome
Overall survival
Time frame: From tumor diagnosis to death (usually 6 to 24 months)
Overall survival in relation to olfactory function
4 secondary outcomes
Progression free survival
Time frame: From date of first surgery until the date of first progression (MRI)
Neurocognition
Time frame: From enrollment to 2 years after the end of radiotherapy
Quality of Life (QoL)
Time frame: From enrollment to 2 years after the end of radiotherapy
Psychological condition
Time frame: From enrollment to 2 years after the end of radiotherapy
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Aug 2026.
- Background: PubMed 9056084Hummel T, Sekinger B, Wolf SR, Pauli E, Kobal G. 'Sniffin' sticks': olfactory performance assessed by the combined testing of odor identification, odor discrimination and olfactory threshold. Chem Senses. 1997 Feb;22(1):39-52. doi: 10.1093/chemse/22.1.39.
- Background: PubMed 11642433Hummel T, Konnerth CG, Rosenheim K, Kobal G. Screening of olfactory function with a four-minute odor identification test: reliability, normative data, and investigations in patients with olfactory loss. Ann Otol Rhinol Laryngol. 2001 Oct;110(10):976-81. doi: 10.1177/000348940111001015.
- Background: PubMed 31831598Kebir S, Hattingen E, Niessen M, Rauschenbach L, Fimmers R, Hummel T, Schafer N, Lazaridis L, Kleinschnitz C, Herrlinger U, Scheffler B, Glas M. Olfactory function as an independent prognostic factor in glioblastoma. Neurology. 2020 Feb 4;94(5):e529-e537. doi: 10.1212/WNL.0000000000008744. Epub 2019 Dec 12.
- Background: PubMed 34266602Walker IM, Fullard ME, Morley JF, Duda JE. Olfaction as an early marker of Parkinson's disease and Alzheimer's disease. Handb Clin Neurol. 2021;182:317-329. doi: 10.1016/B978-0-12-819973-2.00030-7.
- Derived from this study: PubMed 40708059Oster C, Matyar A, Schmidt T, Hummel T, Hattingen E, Jokisch M, Jokisch D, Grieger J, Cappello G, Kizina K, Lazaridis L, Ahmadipour Y, Rauschenbach L, Stuschke M, Pottgen C, Guberina N, Tertel T, Giebel B, Dreizner GL, Barbato F, Skoda EM, Scheffler B, Muther M, Herrmann K, Kleinschnitz C, Sure U, Deuschl C, Glas M, Kebir S. Decoding glioblastoma survival: unraveling the prognostic potential of olfactory function in a prospective observational study. Neurol Res Pract. 2025 Jul 24;7(1):51. doi: 10.1186/s42466-025-00410-2.
- Individual participant dataSharing planned: Yes. Clinical Data from the other study centers will be transferred pseudonymously to the study headquarters in Essen. Only pseudonymized data is also used for accompanying scientific projects.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Glioblastoma Multiforme, Adult and Glioblastoma or Gliosarcoma, run by Sied Kebir at 2 sites in Germany.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 8 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 24 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Germany. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Christoph Oster, Dr. med. (+49201-723-82598, christoph.oster@uk-essen.de), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Overall survival (time frame: From tumor diagnosis to death (usually 6 to 24 months)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06954636, which also lists 5 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Aug 2026.