Glioma Glioblastoma MultiformePhase 1CITADEL-123NCT06650605
Phase 1 Open-label Study of 123I-ATT001 in Subjects With Relapsed Glioblastoma
A Phase 1 study testing 123I-ATT001 in people with Glioma Glioblastoma Multiforme, run by Theragnostics Ltd at 2 sites in United Kingdom.
Trial summary
Phase I open-label trial of 123I-ATT001 monotherapy and in combination with treatment therapies in subjects with relapsed glioblastoma. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Glioma Glioblastoma Multiforme
- What is being tested?
- 123I-ATT001
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 7 participants
- Where
- 2 sitesUnited Kingdom
- Study dates
- 4 Jul 2024to 1 Mar 2026
- Phase
- Phase 1
- Are there results?
- None posted in the registry
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
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- written informed consent
- Men and women over 18 years of age.
- Histologically confirmed recurrent glioblastoma (grade IV) as per WHO criteria 2021 (IDH- wild type only) where the subjects have an Ommaya reservoir in an intralesional cavity of at least 5 mL volume.
- Documented recurrent disease (radiological, based on RANO v.1.0) within 3 months prior to first study drug administration with no suitable standard of care options available.
- Eastern Cooperative Oncology Group Performance status of 0 or 1.
- Adequate organ function
- Women of childbearing potential must use two forms of reliable contraception before starting 123I-ATT001 treatment, during therapy and for 6 months after receiving the last dose of 123I-ATT001. All male subjects must agree to not donate sperm during the study and for 6 months after the last dose of study drug.
- Be able to understand and comply with the requirements of the study, as judged by the Investigator.
Who cannot join
- Is currently participating and receiving study therapy or has participated in a study of an investigational agent and received study therapy or used an investigational device within 4 weeks of the first dose of treatment.
- Diagnosis of immunodeficiency or receiving systemic steroid therapy of up to 4 mg/ day dexamethasone or equivalent or any other form of immunosuppressive therapy within 7 days prior to the first dose of study treatment.
- Prior anticancer treatments within the following time periods:
- Chemotherapy within 4 weeks of enrolment or 5 half-lives, whichever is shorter.
- Targeted small molecule therapy within 4 weeks of enrolment or 5 half-lives, whichever is shorter.
- Immunotherapy (including monoclonal antibody therapy) or radiation therapy within 4 weeks prior to study day 1.
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- Unresolved NCI-CTCAE grade 2 or higher toxicity (except stable neurological toxicities/deficits related to disease process, alopecia).
- Patients with a known allergy to Olaparib or Iodine.
- Known additional malignancy that is progressing or requires active treatment excepting basal cell carcinoma of the skin, squamous cell carcinoma of the skin that has undergone potentially curative therapy, or in situ cervical cancer.
- Any condition that precludes the proper performance of SPECT and/or MRI scan
- Any clinically significant abnormalities in resting ECG at the time of screening including prolonged QTcF (>450 ms for males; >470 ms for females) and cardiac arrhythmias, as judged by the Investigator or designee.
- Unstable systemic disease (including but not limited to active infection, uncontrolled hypertension, unstable angina, congestive heart failure, myocardial infarction within the previous year, serious cardiac arrhythmia requiring medication, hepatic, renal, or metabolic disease).
- Psychiatric, substance misuse or functional disorders that prevent subjects from providing informed consent, following protocol instructions or cooperating with the requirements of the study.
- Active infection requiring systemic therapy.
- Pregnant, breastfeeding, or expecting to conceive or father children within the projected duration of the study, starting with the pre-screening or screening visit through 3 months after the last dose of study treatment.
- Subject that has a condition or is in a situation, which in the Investigators opinion may put the subject at significant risk, may confound the study results, or may interfere significantly with the subject's participation in the study.
- History of non- infectious pneumonitis within the last 3 years.
Trial locations and contacts
2 sites in 1 country.
United Kingdom2 sites
University College London Hosptial
London
University Hospital Southampton
Southampton
About this study
Official title: Citadel-123: A Phase I Clinical Trial to Assess the Activity of I-123 Poly Adenosine Diphosphate Ribose Polymerase I Inhibitor (123I-ATT001) Directly Administered in Subjects With Relapsed Glioblastoma.
Phase I open-label trial of 123I-ATT001 monotherapy and in combination with treatment therapies in subjects with relapsed glioblastoma.
Read the detailed description
The main goals of this study are to understand if 123I-ATT001 is safe and tolerable to treat participants with relapsed glioblastoma and to determine the maximum tolerated dose that can be given to participants without any unacceptable side effects.
The study consists of two parts:
- Part 1 is a dose escalation study where three doses of 123I-ATT001 will be tested, starting with the lowest dose. When a recommended dose (RD) has been declared, a monotherapy expansion cohort will be open at that dose level.
In Part 1 participants will receive a 123I-ATT001 dose, once per week, for four weeks (+ two optional extra cycles).
- Part 2 is a dose expansion study where one dose of 123I-AT001 will be tested in combination with other therapies. Part 2 will begin after the Part 1 has completed and a recommended part 2 dose has been chosen.
The specific details and combination therapies for Part 2 of the study will be added via a protocol amendment at a later date.
- Conditions
- Glioma Glioblastoma Multiforme
- Being tested
- 123I-ATT001
- Medical subject headings
- Glioblastoma
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
123I-ATT001Drug
123I-ATT001
| Study group | Role | What they receive |
|---|---|---|
| Part 1 Dose Escalation & Dose Expansion | Experimental | Dose Escalation:
123I-ATT001 Dose Level 1 123I-ATT001 Dose Level 2 123I-ATT001 Dose Level 3
Dose Expansion:
123I-ATT001 Recommended Dose from Dose Escalation Receives: Drug: 123I-ATT001 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Part 1 - Dose Escalation: Frequency and severity of treatment emergent adverse events (TEAEs) and serious adverse events (SAEs)
To assess safety and tolerability of 123I-ATT001
Measured: Screening to end of treatment visit (28 days after last dose of 123I-ATT001)
Part 1- Dose Escalation: Incidence of Dose Limiting Toxicity (DLT)
Evaluated by monitoring of Adverse Events.
Measured: Day 1 to Day 14 of 123I-ATT001 administration
Secondary outcomes (6)
Part 1 - Dose Escalation: biodistribution and pharmacokinetics of 123I-ATT001 in blood
Blood samples will be collected from the first 6 patients in Part 1.
Measured: Collected 1 hour, 4 hours and 24 hours post each dose and optionally at 48 hours post first dose.
Part 1- Dose Escalation: biodistribution and pharmacokinetics of 123I-ATT001 in urine.
Urine samples will be collected from the first 6 patients in Part 1.
Measured: Collected 24 hours post first dose
Part 1 - Dose Escalation: radiation dosimetry of 123I-ATT001 (exposure of each organ to radiation)
SPECT/CT and or whole body planar imaging
Measured: 1 and 4 and 24 hours post first dose and 4 hours post fourth dose.
Part 1- Dose Escalation: preliminary assessment of the antitumour activity of 123I-ATT001
Efficacy will be assessed according to the RANO response criteria using MRI Scans
Measured: Screening, Day 14 post each dose, 28 days after last dose, then a further 3 times every 8 weeks at follow up.
Part 1 - Dose Escalation: effect of 123I-ATT001 on neurological function
Neurological function will be assessed by the principal investigator according to NANO criteria.
Measured: Screening, the day of the 1st, 3rd and 5th (if given) dose, may also be performed within 48 hours prior to dose administration. It will also be performed on the End of Treatment visit which takes place 28 days post last dose.
Part 1 - Dose Escalation: effect of 123I-ATT001 on neurological function
Patients will complete the MDASI-BT questionnaire
Measured: Screening, the day of the 1st, 3rd and 5th (if given) dose, may also be performed within 48 hours prior to dose administration. It will also be performed on the End of Treatment visit which takes place 28 days post last dose.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Oct 2024
- Study start4 Jul 2024
- Primary completion1 Mar 2026
- Study completion1 Mar 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Glioma Glioblastoma MultiformeStudies 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
- Interventional
- Phase
- Phase 1
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 7 participants (actual)
Sponsor and investigators
- Lead sponsor
- Theragnostics Ltd
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Paul Mulholland, Principal investigator, University College London Hospitals
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06650605
- Sponsor's protocol ID
- PIL101
- Other IDs
- 1006521
- Acronym
- CITADEL-123
- Status last verified
- Mar 2026
- First submitted
- 16 Jul 2024
- Last updated
- 31 Mar 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: no current plans to share any data with other researcheers
Study at a glance
From the registry record, last updated by the sponsor on 31 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Citadel-123: A Phase I Clinical Trial to Assess the Activity of I-123 Poly Adenosine Diphosphate Ribose Polymerase I Inhibitor (123I-ATT001) Directly Administered in Subjects With Relapsed Glioblastoma.
- ClinicalTrials.gov ID
- NCT06650605
- Acronym / sponsor ID
- CITADEL-123 / PIL101
- Conditions
- Glioma Glioblastoma Multiforme
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 7 participants (actual)
- Lead sponsor
- Theragnostics LtdIndustry (pharma, biotech, devices)
- Study start
- 4 Jul 2024 (actual)
- Primary completion
- 1 Mar 2026 (actual)
- Study completion
- 1 Mar 2026 (actual)
- First posted
- 21 Oct 2024 (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.
Phase I open-label trial of 123I-ATT001 monotherapy and in combination with treatment therapies in subjects with relapsed glioblastoma.
Detailed description
The main goals of this study are to understand if 123I-ATT001 is safe and tolerable to treat participants with relapsed glioblastoma and to determine the maximum tolerated dose that can be given to participants without any unacceptable side effects.
The study consists of two parts:
- Part 1 is a dose escalation study where three doses of 123I-ATT001 will be tested, starting with the lowest dose. When a recommended dose (RD) has been declared, a monotherapy expansion cohort will be open at that dose level.
In Part 1 participants will receive a 123I-ATT001 dose, once per week, for four weeks (+ two optional extra cycles).
- Part 2 is a dose expansion study where one dose of 123I-AT001 will be tested in combination with other therapies. Part 2 will begin after the Part 1 has completed and a recommended part 2 dose has been chosen.
The specific details and combination therapies for Part 2 of the study will be added via a protocol amendment at a later date.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Part 1 Dose Escalation & Dose Expansion | Experimental | Drug: 123I-ATT001Dose Escalation: 123I-ATT001 Dose Level 1 123I-ATT001 Dose Level 2 123I-ATT001 Dose Level 3 Dose Expansion: 123I-ATT001 Recommended Dose from Dose Escalation |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (8 listed)
- written informed consent
- Men and women over 18 years of age.
- Histologically confirmed recurrent glioblastoma (grade IV) as per WHO criteria 2021 (IDH- wild type only) where the subjects have an Ommaya reservoir in an intralesional cavity of at least 5 mL volume.
- Documented recurrent disease (radiological, based on RANO v.1.0) within 3 months prior to first study drug administration with no suitable standard of care options available.
- Eastern Cooperative Oncology Group Performance status of 0 or 1.
Key exclusion criteria (17 listed)
- Is currently participating and receiving study therapy or has participated in a study of an investigational agent and received study therapy or used an investigational device within 4 weeks of the first dose of treatment.
- Diagnosis of immunodeficiency or receiving systemic steroid therapy of up to 4 mg/ day dexamethasone or equivalent or any other form of immunosuppressive therapy within 7 days prior to the first dose of study treatment.
- Prior anticancer treatments within the following time periods:
- Unresolved NCI-CTCAE grade 2 or higher toxicity (except stable neurological toxicities/deficits related to disease process, alopecia).
- Patients with a known allergy to Olaparib or Iodine.
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 |
|---|---|---|
| 123I-ATT001123I-ATT001 | Drug | Part 1 Dose Escalation & Dose Expansion |
Primary outcome
Part 1 - Dose Escalation: Frequency and severity of treatment emergent adverse events (TEAEs) and serious adverse events (SAEs)
Time frame: Screening to end of treatment visit (28 days after last dose of 123I-ATT001)
To assess safety and tolerability of 123I-ATT001
Part 1- Dose Escalation: Incidence of Dose Limiting Toxicity (DLT)
Time frame: Day 1 to Day 14 of 123I-ATT001 administration
Evaluated by monitoring of Adverse Events.
6 secondary outcomes
Part 1 - Dose Escalation: biodistribution and pharmacokinetics of 123I-ATT001 in blood
Time frame: Collected 1 hour, 4 hours and 24 hours post each dose and optionally at 48 hours post first dose.
Part 1- Dose Escalation: biodistribution and pharmacokinetics of 123I-ATT001 in urine.
Time frame: Collected 24 hours post first dose
Part 1 - Dose Escalation: radiation dosimetry of 123I-ATT001 (exposure of each organ to radiation)
Time frame: 1 and 4 and 24 hours post first dose and 4 hours post fourth dose.
Part 1- Dose Escalation: preliminary assessment of the antitumour activity of 123I-ATT001
Time frame: Screening, Day 14 post each dose, 28 days after last dose, then a further 3 times every 8 weeks at follow up.
Part 1 - Dose Escalation: effect of 123I-ATT001 on neurological function
Time frame: Screening, the day of the 1st, 3rd and 5th (if given) dose, may also be performed within 48 hours prior to dose administration. It will also be performed on the End of Treatment visit which takes place 28 days post last dose.
Part 1 - Dose Escalation: effect of 123I-ATT001 on neurological function
Time frame: Screening, the day of the 1st, 3rd and 5th (if given) dose, may also be performed within 48 hours prior to dose administration. It will also be performed on the End of Treatment visit which takes place 28 days post last dose.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 31 Mar 2026.
- Related InfoLink provided by the sponsor.
- Individual participant dataSharing planned: No. no current plans to share any data with other researcheers
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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. This study is not recruiting at the moment.
Paul Mulholland principal investigator
University College London Hospitals
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing 123I-ATT001 in people with Glioma Glioblastoma Multiforme, run by Theragnostics Ltd at 2 sites in United Kingdom.
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 17 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: finished, as of the sponsor's last update on 31 Mar 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 United Kingdom. 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.
What does this phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Part 1 - Dose Escalation: Frequency and severity of treatment emergent adverse events (TEAEs) and serious adverse events (SAEs) (time frame: Screening to end of treatment visit (28 days after last dose of 123I-ATT001)). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 31 Mar 2026.