Final overall survival in the phase 3 NETTER-1 study of lutetium-177-DOTATATE in patients with midgut neuroendocrine tumors.
Jonathan Strosberg, Martyn Caplin, Pamela L. Kunz, Philippe Ruszniewski, Lisa Bodei, Andrew Hendifar, Erik Mittra, Edward M. Wolin, James C. Yao, Marianne Pavel, Enrique Grande, Eric Van Cutsem, Ettore Seregni, Hugo Duarte, Germo Gericke, Amy Bartalotta, Arnaud Demange, S. Mutevelic, Eric P. Krenning, on behalf of the NETTER-1 study group
Abstract
4112 Background: As demonstrated in the primary analysis of the phase 3 NETTER-1 trial, 177 Lu-DOTATATE significantly prolonged progression-free survival (PFS) versus high-dose long-acting octreotide, with a HR of 0.18 (95% CI: 0.11, 0.29; p < 0.0001), in patients with advanced, progressive, well-differentiated, somatostatin receptor-positive midgut neuroendocrine tumors (NETs). Here we report final overall survival (OS) for NETTER-1. Methods: In this international open-label trial, eligible patients were randomized to receive either four cycles of 177 Lu-DOTATATE 7.4 GBq (200 mCi) every 8 ± 1 weeks plus long-acting octreotide 30 mg or high-dose long-acting octreotide 60 mg every 4 weeks (control arm), both on top of best supportive care. After disease progression on randomized treatment or completion of an 18-month treatment period, patients in both arms entered long-term follow-up and could receive further anti-cancer treatment as recommended by their physicians. The primary endpoint was PFS per RECIST 1.1 and OS was a key secondary endpoint. Primary intention-to-treat analysis of OS was prespecified to take place after 158 deaths or 5 years after the last patient was randomized, whichever occurred first. Results: Of 231 randomized patients, 101/117 (86.3%) in the 177 Lu-DOTATATE arm and 99/114 (86.8%) in the control arm entered long-term follow-up. Final analysis occurred 5 years after the last patient was randomized, following 142 deaths, with a median follow-up of more than 76 months. During long-term follow-up, 41/114 (36%) of patients in the control arm received subsequent radioligand therapy (“cross-over”), the majority (22.8%) within 24 months. Median OS was 48.0 months (95% CI: 37.4, 55.2) in the 177 Lu-DOTATATE arm and 36.3 months (95% CI: 25.9, 51.7) in the control arm. HR was 0.84 (95% CI: 0.60, 1.17) with p = 0.30 (unstratified 2-sided log-rank test). A total of 2/112 (1.8%) 177 Lu-DOTATATE treated patients in the study developed myelodysplastic syndrome (MDS). No new cases of MDS or acute leukemia were reported in the long-term follow-up. Overall, no new safety signals emerged during long-term follow-up. Conclusions: Median OS was 48.0 months in the 177 Lu-DOTATATE arm of the NETTER-1 trial and 36.3 months in the control arm. This difference was not statistically significant, potentially impacted by a high rate (36%) of cross-over of patients in the control arm to radioligand therapy after progression. In overall conclusion, the NETTER-1 study demonstrated that 177 Lu-DOTATATE yielded a clinically and statistically significant improvement in PFS as a primary endpoint (HR: 0.18, p < 0.0001) as well as a clinically meaningful trend towards improvement in median OS of 11.7 months. No new safety signals emerged during the 5-year long-term follow-up. Clinical trial information: NCT01578239.