Ziel/Aim:
The purpose of this study was to analyze the long-term outcome, efficacy and safety of PRRT in patients with SSTR-expressing grade 3 (G3) neuroendocrine neoplasm.
Methodik/Methods:
A total of 69 patients (M = 41 males; age 28 – 81 years) received PRRT with Lu-177 and/or Y-90 labeled DOTATATE or DOTATOC. Kaplan-Meier analysis was performed to calculate progression-free survival (PFS) and overall survival (OS), defined from start of PRRT, including a subgroup analysis for patients with a Ki-67 of < 55% and > 55%. Treatment response was evaluated according to RECIST 1.1 as well as by molecular imaging criteria (EORTC). Treatment-related adverse events were graded according to the CTCAE v.5.0.
Ergebnisse/Results:
46 patients had pancreatic, 11 CUP, 6 midgut, 3 gastric, and 3 rectal NEN. Median follow-up was 94.3 months. The median PFS was 9.6 months and median OS was 19.9 months. For G3 NEN with a Ki-67 of more than 55% (n = 53), the median PFS was 11 months and median OS 22 months. Patients with a Ki-67 > 55% (n = 11), had a median PFS of 4 months and a median OS of 7 months. For those patients with positive SSTR imaging, but no FDG uptake, the median PFS was 24 months and median OS was 42 months. In the group with FDG scored as 3 – 4, the median PFS was 7.1 months and the median OS 17.2 months. For FDG scored as 0 – 2, the median PFS was 24.3 months and the median OS 41.6 months. PRRT was well-tolerated by all patients; no grade 3 or grade 4 hematotoxicity occurred and no clinically significant decline in renal function was observed. There was no hepatotoxicity.
Schlussfolgerungen/Conclusions:
PRRT was tolerated well without significant adverse effects and is efficacious in G3 NEN with promising clinical outcome, especially in patients with a Ki-67 index of < 55% and even in patients who have failed chemotherapy. Baseline FDG along with SSTR molecular imaging is useful to stratify those G3-NEN patients with high uptake on SSTR PET/CT and no or minor FDG-avidity, a mismatch pattern which is associated with a better long term prognosis.
