Efficacy and Safety of 177Lu-DOTATATE in Lung Neuroendocrine Tumors: A Bicenter study

To assess the efficacy and safety of ¹⁷⁷Lu-DOTATATE in patients with somatostatin receptor (SSR) positive lung neuroendocrine tumor (NET). Methods: This is a retrospective review of the outcome of patients with typical carcinoid (TC) and atypical carcinoid (AC), treated with ¹⁷⁷Lu-DOTATATE at two ENETS Centres of Excellence. Morphological imaging (RECIST 1.1) and ⁶⁸Ga-DOTATATE PET/CT responses were assessed at 3 months after completion of ¹⁷⁷Lu-DOTATATE. Concordance between two response assessment methods was evaluated by Kappa statistics. Progression-free survival (PFS) and overall survival (OS) was estimated by Kaplan-Meier analysis and compared by Log-rank test. Treatment-related adverse events (AEs) were graded based on CTCAE version 5. Results: Of 48 patients (median age, 63 years, 13 female), 43 (90%) had AC and 5 (10%) TC. Almost all patients (47, 98%) were treated due to progression. Majority (40, 83%) received somatostatin analogs and 10 patients (20%) had prior everolimus, chemotherapy or both. All patients had high SSR expression (≥ modified Krenning score 3) on pre-treatment ⁶⁸Ga-DOTATATE PET/CT. Patients received a median 4 (range 1-4) cycles of ¹⁷⁷Lu-DOTATATE (33% with concurrent radiosensitizing chemotherapy) to a median cumulative activity of 27GBq (range 6-43GBq). At median follow-up of 42 months, the median PFS and OS were 23 months (95% CI 18-28 months) and 59 months (95% CI 50-not reached [NR]), respectively. Of 40 patients with RECIST-measurable disease and 39 patients with available ⁶⁸Ga-DOTATATE PET/CT response categories were: partial response, 20% (95% CI 10-35%) and 44% (95% CI 30-59%); stable disease, 68% (95% CI 52-80%) and 44% (95% CI 30-59%) and progressive disease 12% (95% CI 5-27%) by both, respectively. There was a moderate concordance between response categories by RECIST and ⁶⁸Ga-DOTATATE PET/CT, weighted Kappa of 0.51 (95% CI 0.21-0.68). Of patients with stable disease by RECIST, those with partial response on ⁶⁸Ga-DOTATATE PET/CT had longer OS compared to those with no response, NR vs 52 months (95% CI 28-64), HR 0.2 (95% CI 0.1-0.6), p 0.001. Most grade 3/4 AEs were reversible and the most common was lymphopenia (14%) with no incidence of myelodysplasia/leukemia. Conclusion: In patients with advanced progressive lung NET and satisfactory SSR expression, ¹⁷⁷Lu-DOTATATE is effective and safe with a high disease control rate and encouraging PFS and OS.