First real-world experience of peptide receptor radionuclide therapy (PRRT) in neuroendocrine tumors (NET) since US FDA approval.

e15691 Background: PRRT using 177Lu-DOTATATE was US FDA approved in Jan 2018, and real world data in the US is lacking. Methods: We retrospectively reviewed medical records of patients who began PRRT 03/14/18 - 10/01/18 at our institution. 177Lu-DOTATATE was administered at a dose of 200mCi over 20-30 min every 8 weeks for 4 doses. Infusion of arginine-lysine 25gm/25gm in 1-liter normal saline was given over 4 hours starting 30 min prior to treatment, in addition to intravenous palonosetron 0.25mg. Results: 51 patients received at least 1 of 4 doses and 40/51 were no longer on active therapy. 28/40 received all 4 doses and 12/40 discontinued treatment after < 4 doses. 25/40 were evaluable for response per RECIST v1.1. 16/25 (64%) had GI NET, 3/25 (12%) pancreatic NET, 4/25 (16%) atypical lung carcinoid, 1/25 (4%) multifocal NET, and 1/25 (4%) had paraganglioma. 28% had grade 1, 56% grade 2, and 8% (2/25) had grade 3 (Ki 67: 25% and 40%) NET. 12/25 (48%) had received ≥2 prior systemic therapies not including somatostatin analogs, and 10/25 (40%) had ≥1 prior liver-directed therapy. Median follow-up from date of last PRRT was 61.5 days. Objective response (partial response) rate was 16% (4/25; table). 18/25 (72%) had stable disease and 3/25 (12%) had progressive disease. Most adverse events (AEs) were grade 1-2 and included fatigue, nausea, abdominal pain, and cytopenias. ≥Grade 3 AEs requiring treatment discontinuation included symptomatic gastric outlet obstruction (2/51), small bowel obstruction (1/51), ischemic enteritis (1/51), confusion/bone pains (1/51), liver failure (1/51), and severe neutropenia (1/51). All patients with ≥grade 3 AEs had a high tumor burden at baseline. Conclusions: 177Lu-DOTATATE is an effective and safe treatment in advanced NET, and our results are consistent with NETTER 1 data.[Table: see text]