Combination External Radiation and PRRT for Large GI Neuroendocrine Tumors.

PRIMARY OBJECTIVE:

I. To determine the rate of acute grade 3+ non-hematologic toxicity of PRRT after external radiation compared to historical control of PRRT alone.

SECONDARY OBJECTIVES:

I. To determine the rate of acute grade 2+ toxicity compared to historical control of PRRT alone.

II. To determine response rate of both large and small lesions at 3 months following treatment.

III. To determine progression free survival. IV. To describe patient-reported outcomes (PROs) of toxicity.

OUTLINE:

Patients undergo SBRT over 5 fractions in the absence of disease progression or unacceptable toxicity. Starting 4-10 weeks after completion of SBRT, patients receive standard of care (SOC) lutetium-177 DOTATATE (177Lu-DOTATATE) intravenously (IV) once every 8 weeks for 4 doses in the absence of disease progression or unacceptable toxicity. Patients also undergo computed tomography (CT) and/or magnetic resonance imaging (MRI) throughout the trial and undergo gallium Ga 68-DOTATATE positron emission tomography (PET)/CT before treatment.

After completion of study treatment, patients are followed up at 90 days and then every 3 months for 12 months.

Inclusion criteria

• Male or female
• Age ≥ 18 years
• Patient must be able to provide study specific informed consent
• Pathologically confirmed neuroendocrine tumor fulfilling all of the following criteria
• Well-differentiated, grade 1-2
• Unresectable (prior resection is allowable), verified by tumor board or surgical oncology (surg onc)
• Progression after one or two prior lines of systemic therapy
• Somatostatin-receptor positive disease as determined by positive radiotracer-labeled DOTATATE PET/CT scan (modified Krenning score 3+)
• One or more large lesions measuring 3 or more cm on contrast-enhanced CT or MRI
• Eastern Cooperative Oncology Group (ECOG) performance status 0-2
• Estimated glomerular filtration rate (GFR) > 30 mL/min (within 90 days prior to study registration)
• Total bilirubin ≤ 3 x upper limit of normal (within 90 days prior to study registration)
• Albumin > 30 g/L (within 90 days prior to study registration)
• White blood cell (WBC) ≥ 2,000 cells/mm^3 (within 90 days prior to study registration)
• Platelets ≥ 70000 cells/mm^3 (within 90 days prior to study registration)
• Hemoglobin ≥ 8.0 g/dl (Note: The use of transfusion or other intervention to achieve hemoglobin [Hgb] ≥ 8.0 g/dl is acceptable.) (within 90 days prior to study registration)

Exclusion criteria

• Any prior radiation therapy including prior PRRT, external radiation, or Yttrium-90 radioembolization to the same site/region
• Contraindications to radiation therapy including inflammatory bowel disease, systemic sclerosis, etc.
• Brain metastases or any metastases extending into the spinal canal
• Unable to obtain confirmation of payment coverage for any planned radiation treatment