Treatment with the radiolabelled somatostatin analog Lu-DOTATATE for advanced pancreatic neuroendocrine tumors

Background: We evaluated the activity and safety profile of 177Lu-DOTATATE peptide receptor radionuclide therapy (Lu-PRRT) in patients with advanced G1-G2 pancreatic neuroendocrine tumors. Patients and Methods: Fifty-two consecutive patients were treated at two different therapeutic dosages of 18.5 or 27.8 GBq in five cycles, according to the patient's kidney function and bone marrow reserve, which are known to be the critical organs in PRRT. Results: Twenty-six patients received a mean full dosage (FD) of 25.5 GBq (range 20.7-27.8) and 26 a mean reduced dosage (RD) of 17.8 GBq (range 11.1-19.9). Both therapeutic dosages resulted in antitumor activity (disease control rate in the entire case series 81%), with 12% complete response, 27% partial response and 46% stable disease in the FD group, whereas we observed 4% complete response, 15% partial response and 58% stable disease in the RD group. Median progression-free survival was not reached in the FD group and was 20 months in the RD group. No major acute or delayed hematological toxicity occurred. Conclusion:177Lu-DOTATATE peptide receptor radionuclide therapy showed antitumor activity in advanced pancreatic neuroendocrine tumors even at a reduced total activity of 18.5 GBq. However, progression-free survival was significantly longer (p = 0.05) after a total activity of 27.8 GBq, which can thus be considered the recommended dosage in eligible patients.