A Dose Finding Study of [177Lu]Lu-DOTA-TATE in Newly Diagnosed Glioblastoma in Combination With Standard of Care and in Recurrent Glioblastoma as a Single Agent.

Key Inclusion Criteria:

Common Criteria:

• Participant is >= 18 years on the day of signing informed consent form

• Histologically confirmed glioblastoma

• Adequate bone marrow, organ function and electrolyte values

Newly diagnosed glioblastoma (Group 1):

• Presence of Gadolinium enhancing tumor in pre-surgery magnetic resonance imaging (MRI)

• Karnofsky Performance Score (KPS) >= 70 %

Recurrent glioblastoma (Group 3 dose Escalation only):

• Participant has experienced first or second recurrence of their glioblastoma, after standard or experimental therapy that includes prior EBRT

Recurrent glioblastoma (Group 3 dose escalation and expansion):

• Evidence of recurrent disease demonstrated by disease progression using modifiedResponse Assessment in Neuro-Oncology (mRANO) criteria

• KPS >= 60 %

• [68Ga]Ga-DOTA-TATE uptake by positron emission tomography/computed tomography (PET/CT) or PET/MRI at the tumor region

• Presence of Gadolinium enhancement in the tumor region in MRI at the time ofdiagnosis of tumor recurrence

• A second surgery for glioblastoma is allowed provided that the following criteriaare met:

1. Residual and measurable disease post-surgery is not required but surgery musthave confirmed the diagnosis of recurrence

2. Surgery completed at least 2 weeks prior to study treatment initiation, withpost-surgery recovery without any complications related to surgical procedureRecurrent glioblastoma (Group 3 Dose Expansion only):

• Patients experiencing first recurrence of their glioblastoma, after standard orexperimental therapy that includes prior EBRT

Key Exclusion Criteria:

Common Criteria:

• Participant is receiving additional, concurrent, active therapy for glioblastomaoutside of the trial

• Extensive leptomeningeal disease

• History of another active malignancy in the previous 3 years prior to study entry

• Prior administration of a radiopharmaceutical unless 10 or more effective half-liveshave elapsed before injection of [68Ga]Ga-DOTA-TATE or [177Lu]Lu-DOTA-TATE

Newly diagnosed glioblastoma (Group 1):

• Any prior treatment for glioma of any grade

Recurrent glioblastoma (Group 3 dose escalation and expansion):

• Early disease progression prior to 3 months from the completion of radiotherapy

• Previous treatment with bevacizumab for the treatment of glioblastoma withtherapeutic intent, or with bevacizumab as supportive therapy (e.g. edema reduction)within 60 days of initiation of study treatment

Recurrent glioblastoma (Group 3 dose escalation only):

• More than 2 prior lines for systemic therapy

Recurrent glioblastoma (Group 3 dose expansion only):

• More than 1 prior line for systemic therapy