Impact of administered amount of peptide on tumor dosimetry at the first cycle of peptide receptor radionuclide therapy (PRRT) in relation to total tumor somatostatin receptor expression.

Background: The accumulation of Lu-DOTATATE might be influenced by the amount of administered peptide in relation to the tumor somatostatin receptor expression. The effect of the administered peptide mass on the resulting absorbed dose in tumors and normal organs has not previously been assessed in relation to the patients' tumor load.

Method: Patients with small intestinal (n = 141) and pancreatic (n = 62) neuroendocrine tumors (NETs) who underwent PRRT were selected for retrospective evaluation.

Receptor depletion and recovery in small-intestinal neuroendocrine tumors and normal tissues after administration of a single intravenous dose of octreotide measured by Ga-DOTATOC PET/CT.

Background: Low-grade neuroendocrine tumors (NETs) are characterized by an abundance of somatostatin receptors (SSTR) that can be targeted with somatostatin analogs (SSA). When activated with a single dose of SSA, the receptor-ligand complex is internalized, and the receptor is by default recycled within 24 h. Ongoing medication with long-acting SSAs at Ga-DOTA-SSA-PET has been shown to increase the tumor-to-normal organ contrast.

Peptide Receptor Radionuclide Therapy (PRRT) with Lu-DOTATATE; Differences in Tumor Dosimetry, Vascularity and Lesion Metrics in Pancreatic and Small Intestinal Neuroendocrine Neoplasms.

Dosimetry during peptide receptor radionuclide therapy (PRRT) has mainly focused on normal organs and less on the tumors. The absorbed dose in one target tumor per patient and several response related factors were assessed in 23 pancreatic neuroendocrine neoplasms (P-NENs) and 25 small-intestinal NEN (SI-NENs) during PRRT with Lu-DOTATATE. The total administered activity per patient was (mean ± standard error of mean (SEM) 31.

177Lu-DOTATATE Peptide Receptor Radionuclide Therapy: Dose Response in Small Intestinal Neuroendocrine Tumors.

Introduction: Peptide receptor radionuclide therapy (PRRT) has during the last few years been frequently used in patients with progressive, disseminating, well-differentiated neuroendocrine tumors (NETs).

Objective: To study whether the absorbed dose in small intestinal NET (SI-NET) metastases from PRRT with 177Lu-DOTATATE is related to tumor shrinkage.

Materials And Methods: Dosimetry for 1 tumor was performed in each of 25 SI-NET patients based on sequential SPECT/CT 1, 4, and 7 days after 177Lu-DOTATATE infusion.