Locoregional, intracavitary radioimmunotherapy (iRIT) with a newly developed radioimmunoconjugate (Lu-177 labeled 6A10-Fab-fragments) will be used to prevent or postpone tumour recurrence in patients with GBM following standard therapy .

Following study objectives will be analyzed:

• Determining the Maximum Tolerated Dose (MTD)
• Determining safety by assessing all new neurological, hematological and other AEs CTC grade 2 or higher
• Determining absorbed dose to the 2 cm shell of the resection cavity (based on a series of SPECT/CTs of the head 2h,24h,48h, 72h p.i. and on day 5-7)
• Determining absorbed dose values for the kidneys, the liver, the active marrow (based on a series of SPECT/CTs of the abdomen 2h,24h,48h, 72h p.i. and on day 5-7)
• Determining 24 weeks Progression-Free-Survival (PFS), defined from the day of inclusion

In glioblastoma (GBM), tumour recurrence occurs adjacent to the initial tumor resection cavity in about 85% of cases (Albert et al., 1994; Bashir et al., 1988; Nestler et al., 2015). Therefore, local treatment concepts seem crucial for effective recurrence treatment strategies. We consider locoregional, intracavitary radioimmunotherapy (iRIT) to be a new therapeutic approach to delay or prevent the development of local tumour regrowth in GBM patients. By applying a radioimmunoconjugate (RIC) into the surgically created resection cavity (RC) the blood-brain barrier can effectively be by-passed, allowing the a deposit of high radiation doses locally while sparing sensitive organs like the bone marrow and the kidneys. LuCaFab (Lu-177 labeled 6A10- Fab-fragment) is a carbonic anhydrase XII-specific antibody Fab fragment developed by Helmholtz Munich, labeled with ITM's highly pure medical radioisotope, lutetium-177. (ITM IsotopeTechnologies Munich SE). Patients with GBM after standard therapy (surgery by radio-chemotherapy concomitant and adjuvant chemotherapy) Are eligible for the study. Patients will receive the calculated total doses of Lu-177-labeled 6A10-Fabs in three fractions with an interval of 4 weeks between injections, administered into the tumour cavity via an implanted reservoir. A patient specific dosing strategy will be applied and will depend on the individual RC volume. This investigator-initiated trial is sponsored by the University Hospital Münster, conducted in hospitals in Münster, Essen, Cologne, and Wuerzburg, and supported by ITM and Helmholtz Munich.

Inclusion Criteria:

• Written patient consent after comprehensive information
• Age between 18 and 80 years
• Primary supratentorial high grade glioma after standard therapy (fluorescence-guided surgery, radio-chemotherapy, concomitant + adjuvant chemotherapy), with no or stable small tumor residue (residual contrast enhancement of up to 5cm3) at earliest 6 weeks after completion of radiotherapy
• Histological verification of glioblastoma and CA 12-expression of tumor cells confirmed
• Karnofsky-score ≥ 60
• Volume of resection cavity 2,5-25 cm3
• Male and female patients with reproductive potential must use an approved contraceptive method
• Pre-menopausal female patients with childbearing potential: a negative serum pregnancy test must be obtained prior to treatment start
• Adequate bone marrow reserve: white blood cell (WBC) count ≥3000/μl, granulocyte count >1500/μl, platelets ≥100000/μl, hemoglobin ≥ 10 g/dl
• Adequate liver function: bilirubin < 1.5 times above upper limit of normal range (ULN), alanine transaminase (ALT/SGPT) and aspartate transaminase (AST/SGOT) < 3 times ULN. In the case of documented or suspected Gilbert's disease bilirubin < 3 times ULN.
• Blood clotting: INR (=PT) and PTT within acceptable limits according to the investigator
• Adequate renal function: creatinine < 3 times above ULN; eGFR > (or equal) 60 ml/min

Exclusion Criteria:

• Patient unable to undergo imaging by CT, PET or contrast-enhanced MRI for whatever reason (i.e., pacemaker)
• Resection cavity with intraventricular access
• Significant leakage of radioactivity into CSF spaces or ventricles
• Other actively treated invasive malignancy
• Breastfeeding women
• Past medical history of diseases with poor prognosis, e.g., severe coronary heart disease, heart failure (NYHA III/IV), severe and poorly controlled diabetes, immune deficiency, residual deficits after stroke, severe mental retardation, pre-existing neurological diseases except those related to glioblastoma or other serious concomitant systemic disorders incompatible with the study (at the discretion of the investigator)
• Any active infection (at the discretion of the investigator)
• Previous participation in a registered clinical trial with therapeutic intervention less than 6 weeks prior to enrolment (date of informed consent)
• Allergy against known constituents of study medication