Survival After Somatostatin Based Radiopeptide Therapy With Y-90-Dotatoc Vs. Y-90-Dotatoc Plus Lu-177-Dotatoc In Metastasized Gastrinoma

We aimed to explore the effects of Y-90-DOTATOC and Y-90-DOTATOC plus Lu-177-DOTATOC on survival of patients with metastasized gastrinoma. Patients with progressive metastasized gastrinoma were treated with repeated cycles of Y-90-DOTATOC or with cycles alternating between Y-90-DOTATOC and Lu-177-DOTATOC until tumor progression or permanent toxicity. Multivariable Cox regression analyses were used to study predictors of survival. A total of 36 patients were enrolled; 30 patients received Y-90-DOTATOC (median activity per patient 11.8GBq; range: 6.162.2GBq) and 6 patients received Y-90-DOTATOC plus Lu-177-DOTATOC (median activity per patient: 14.8GBq; range: 7.4-14.8GBq). Response was found in 26 patients (72.2%), including morphological (n=12, 33.3%), biochemical (n=14, 38.9%) and/or clinical response (n=6, 16.2%). A total of 21 patients (58.3%) experienced hematotoxicity grade 1/2, while 1 patient (2.8%) experienced hematotoxicity grade 3; no grade 4 hematotoxicity occurred. Furthermore, 2 patients (5.6%) developed grade 4 renal toxicity; no grade 5 renal toxicity occurred. Responders had a significantly longer median survival from time of enrollment than non-responders (45.1 months, range: 37.1-53.1 months vs. 12.6 months, range: 11.0-14.2, hazard ratio: 0.12 (0.027-0.52), p=0.005). Additionally, there was a trend towards longer median survival with Y-90-DOTATOC plus Lu-177-DOTATOC as compared to Y-90-DOTATOC alone (60.2 months, range: 19.8-100.6 months vs. 27.0 months, range: 4.0-50.0, hazard ratio: 0.21 (0.01-3.98), p=0.16). Response to Y-90-DOTATOC and Y-90-DOTATOC plus Lu-177-DOTATOC therapy is associated with a longer survival in patients with metastasized gastrinoma. Both treatment regimens are promising tools for management of progressive gastrinoma.