Phase 1 Open-label Study of 123I-ATT001 in Subjects with Relapsed Glioblastoma

Inclusion Criteria:

1. written informed consent

2. Men and women over 18 years of age.

3. Histologically confirmed recurrent glioblastoma (grade IV) as per WHO criteria 2021 (IDH- wild type only) where the subjects have an Ommaya reservoir in anintralesional cavity of at least 5 mL volume.

4. Documented recurrent disease (radiological, based on RANO v.1.0) within 3 monthsprior to first study drug administration with no suitable standard of care optionsavailable.

5. Eastern Cooperative Oncology Group Performance status of 0 or 1.

6. Adequate organ function

7. Women of childbearing potential must use two forms of reliable contraception beforestarting 123I-ATT001 treatment, during therapy and for 6 months after receiving thelast dose of 123I-ATT001. All male subjects must agree to not donate sperm duringthe study and for 6 months after the last dose of study drug.

8. Be able to understand and comply with the requirements of the study, as judged bythe Investigator.

Exclusion Criteria:

1. Is currently participating and receiving study therapy or has participated in astudy of an investigational agent and received study therapy or used aninvestigational device within 4 weeks of the first dose of treatment.

2. Diagnosis of immunodeficiency or receiving systemic steroid therapy of up to 4 mg/day dexamethasone or equivalent or any other form of immunosuppressive therapywithin 7 days prior to the first dose of study treatment.

3. Prior anticancer treatments within the following time periods:

4. Chemotherapy within 4 weeks of enrolment or 5 half-lives, whichever is shorter.

5. Targeted small molecule therapy within 4 weeks of enrolment or 5 half-lives,whichever is shorter.

6. Immunotherapy (including monoclonal antibody therapy) or radiation therapywithin 4 weeks prior to study day 1.

7. Unresolved NCI-CTCAE grade 2 or higher toxicity (except stable neurologicaltoxicities/deficits related to disease process, alopecia).

8. Patients with a known allergy to Olaparib or Iodine.

9. Known additional malignancy that is progressing or requires active treatmentexcepting basal cell carcinoma of the skin, squamous cell carcinoma of the skin thathas undergone potentially curative therapy, or in situ cervical cancer.

10. Any condition that precludes the proper performance of SPECT and/or MRI scan

11. Any clinically significant abnormalities in resting ECG at the time of screeningincluding prolonged QTcF (>450 ms for males; >470 ms for females) and cardiacarrhythmias, as judged by the Investigator or designee.

12. Unstable systemic disease (including but not limited to active infection,uncontrolled hypertension, unstable angina, congestive heart failure, myocardialinfarction within the previous year, serious cardiac arrhythmia requiringmedication, hepatic, renal, or metabolic disease).

13. Psychiatric, substance misuse or functional disorders that prevent subjects fromproviding informed consent, following protocol instructions or cooperating with therequirements of the study.

14. Active infection requiring systemic therapy.

15. Pregnant, breastfeeding, or expecting to conceive or father children within theprojected duration of the study, starting with the pre-screening or screening visitthrough 3 months after the last dose of study treatment.

16. Subject that has a condition or is in a situation, which in the Investigatorsopinion may put the subject at significant risk, may confound the study results, ormay interfere significantly with the subject's participation in the study.

17. History of non- infectious pneumonitis within the last 3 years.