Effectiveness and safety of retreatment with lutetium Lu 177 DOTATATE in patients with progressive neuroendocrine tumors in the United States: A retrospective real-world study.

Abstract

e16215 Background: Advanced neuroendocrine tumors (NETs) are associated with a very poor prognosis. A regimen of 4 doses of lutetium Lu 177 (177Lu)-DOTATATE has been shown to improve both progression-free survival (PFS) and overall survival (OS) in patients with advanced NETs. This is the first United States (US) study to evaluate the effectiveness and safety of additional doses in patients with progressive NETs. Methods: This was a retrospective chart review of 31 adults with advanced NETs who had undergone initial treatment with up to 4 doses of 177Lu-DOTATATE and who, following disease progression and a period of ≥6 months since the end of initial treatment, were re-treated with ≥1 additional dose at a single US center (2010–2020). Patient characteristics, treatment patterns, and clinical outcomes were evaluated descriptively. Response was evaluated according to RECIST 1.1; toxicity was defined using CTCAE 5.0 criteria. Kaplan–Meier plots were used to evaluate PFS and OS. Results: Of the 31 patients who received 177Lu-DOTATATE re-treatment, 19 (61%) were male and 29 (94%) were white. Overall, patients received a median of 6 doses (4 initial doses and 2 re-treatment doses) and the mean±sd administered activity was 41.9±4.4 GBq. Two patients also went on to receive additional re-treatment (1 and 2 doses, respectively) following a second period of ≥6 months and progression after re-treatment. Best responses of partial response and stable disease were observed in 11 patients (35%) and 20 patients (65%) after initial treatment, and 7 patients (23%) and 14 patients (45%) after re-treatment (Table). The median PFS after initial treatment was 20.2 months and after re-treatment was 9.6 months. The median OS after initial treatment was 42.6 months and after re-treatment was 12.6 months. Hematological parameters decreased significantly during both initial and re-treatment but recovered such that there was no significant difference between the values prior to initial treatment and prior to re-treatment. Clinically significant hematotoxicity occurred in 1 and 3 patients following initial and re-treatment, respectively. No grade 3/4 nephrotoxicity (based on creatinine levels) was observed. Conclusions: Re-treatment with 177Lu-DOTATATE after progression appeared to be well-tolerated and offered disease control in patients with progressive NETs following initial 177Lu-DOTATATE treatment.[Table: see text]