Clinical Trial Finder

Inclusion Criteria:

• - Written consent.

• - Patients with diagnosed and metastasized secreting and non-secreting GEP-NEN (grade 1 and 2) - Absence of a curative surgical option.

• - At least 2 measurable tumours based on RECIST 1.1 (minimal tumour diameter of 1 cm) - Documentation of a positive 68Ga-DOTATOC/-TATE positron emission tomography (PET)/CT (in vivo detection of SST2 on GEP-NENs) - Indication for PRRT.

• - Patient of any gender and of age older than 18.

• - Female patients of child-bearing age (who are not surgically sterilized or are less than 2 years in their menopause) must use a medically accepted contraceptive and must agree to use it during and till 3 months after the treatment.

• - Eastern Cooperative Oncology Group (ECOG) ≤ 2.

• - Blood parameters: h) Leucocytes ≥ 3*109/L i) Haemoglobin ≥ 90 g/L j) Thrombocytes ≥ 90*109/L k) Estimated glomerular filtration rate ≥ 50 ml/min or Creatinine < 150 μmol/l l) Albumin > 25 g/L m) alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP): ≤ 5 times upper standard value n) Bilirubin ≤ 2 times upper standard value.

Exclusion Criteria:

• - Known intolerance against 177Lu, 161Tb, DOTA, TOC, LM3, SST analogues or against one of the components of 177Lu-DOTATOC or 161Tb-DOTA-LM3.

• - Bone/bone marrow metastases located in the lumbar spine if they affect the bone marrow dose estimation.

• - Ongoing infection at the screening visit or a serious infection in the past 4 weeks.

• - Administration of another investigational product in the last 60 days before Visit 1 Day 1.

• - Prior or planed administration of a therapeutic radio-pharmaceutical during 8 half-lives of the used radio-pharmaceutical's radionuclide, also during the ongoing study.

• - Any extensive radiotherapy involving bone marrow over the last 3 months before inclusion to the study.

• - Chemotherapy in the last 4 weeks before inclusion.

• - Pregnant or breastfeeding female patients.

• - Any uncontrolled significant medical, psychiatric or surgical condition (active infection, unstable angina pectoris, cardiac arrhythmia, poorly controlled hypertension, poorly controlled diabetes mellitus [HbA1c ≥ 9%], uncontrolled congestive heart disease, etc.) or laboratory findings that might jeopardize the patient's safety or that would limit compliance with the objectives and assessments of the study.

Neuroendocrine neoplasia's (NENs) are a group of neoplasms arising from neuroendocrine cells and are most commonly found in the intestine, pancreas and lung. The overexpression of somatostatin receptor subtype 2 (SST2), is a characteristic of NENs and presents an important molecular target for the management of these tumours. Peptide receptor radionuclide therapy (PRRT) targets the SST2 through the administration of radiolabelled SST2 agonists such as 177Lu-DOTATOC and 177Lu-DOTATATE (Lutathera®). Although PRRT is one of the most efficient treatments for the management of NENs, it does only stabilize but not cure the disease. There is a need to improve PRRT with more effective radiopharmaceuticals. There is evidence that terbium-161 (161Tb) is more powerful that 177Lu not only in combination with SST2 agonists but particularly with SST2 antagonists. The efficacy of PRRT can be enhanced by using a potent SST2 antagonist (DOTA-LM3) labelled with 161Tb. 161Tb-DOTA-LM3 has the following advantages compared to 177Lu-DOTATOC and 177Lu-DOTATATE: 1) SST2 antagonists bind to many more SST2-binding sites and accumulate mainly on the cellular membrane. 2) The Auger electrons of 161Tb deposit their high energy over a short distance (1-1000 nm) resulting in a high relative biological effectiveness mainly to the cell membrane which seems to be more radiosensitive than the cytoplasm. 161Tb-DOTA-LM3 does, therefore, not only deliver dose by β- radiation, but also through the emission of conversion and Auger electrons which leads to a 3

• - 4 fold increased dose to single cancer cells compared to 177Lu-DOTA-LM3.

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