Background
Phase III RCT included 229 patients with well-differentiated, metastatic midgut neuroendocrine tumors that progressed on octreotide LAR, with somatostatin receptors present on all target lesions.
Interventions and follow up
Arm A: 177Lu-Dotatate 7.4 GBq (200 mCi) IV q8wk x4 with IV amino acid solution, plus octreotide LAR 30 mg IM monthly
Arm B: Octreotide LAR 60 mg IM q4wk (high-dose)
Primary endpoint: PFS
mFollow up: NR (interim analysis)
Arm B: Octreotide LAR 60 mg IM q4wk (high-dose)
Primary endpoint: PFS
mFollow up: NR (interim analysis)
Results
mPFS: not reached vs 8.4 mo, arm A vs B (HR 0.21; 95% CI 0.13-0.33; P<.001)
PFS at 20 mo: 65.2% vs 10.8%
ORR: 18% vs 3% (P<.001)
Interim OS: trend favoring arm A (P=.004 at interim, not formally significant)
PFS at 20 mo: 65.2% vs 10.8%
ORR: 18% vs 3% (P<.001)
Interim OS: trend favoring arm A (P=.004 at interim, not formally significant)
Adverse events
Non-hematologic (arm A): fatigue/asthenia, nausea, abdominal pain, diarrhea (mostly grade 1-2); serious treatment-related events 9% vs 1% (P=.01)
Hematologic (grade 3-4, arm A vs B): neutropenia 1% vs 0%, thrombocytopenia 2% vs 0%, lymphopenia 9% vs 0%; one case of MDS in arm A
Hematologic (grade 3-4, arm A vs B): neutropenia 1% vs 0%, thrombocytopenia 2% vs 0%, lymphopenia 9% vs 0%; one case of MDS in arm A
Conclusions
177Lu-Dotatate markedly improved PFS over high-dose octreotide LAR in progressive metastatic midgut neuroendocrine tumors, establishing peptide receptor radionuclide therapy in this setting.
Key Limitations
Limited to midgut (small intestine) primaries; control arm used high-dose octreotide rather than alternative active therapy. Requires specialized radionuclide facilities. Long-term myeloid neoplasm risk warrants monitoring.
Clinical Context
FDA approved 177Lu-Dotatate (Lutathera) for somatostatin receptor-positive GEP-NETs (2018). ESMO endorses PRRT for progressive, well-differentiated, somatostatin receptor-positive midgut NETs after somatostatin analog failure.