Survival after somatostatin-based radiopeptide therapy with [⁹⁰Y-DOTA]-TOC and [⁹⁰Y-DOTA]-TOC plus [¹⁷⁷Lu-DOTA]-TOC in metastasized gastrinoma

Objectives We aimed to explore the efficacy of [⁹⁰Y-DOTA]-TOC and [⁹⁰Y-DOTA]-TOC plus [¹⁷⁷Lu-DOTA]-TOC for the treatment of metastasized gastrinoma.

Methods Patients with metastasized gastrinoma were treated with repeated cycles of [⁹⁰Y-DOTA]-TOC or with cycles alternating between [⁹⁰Y-DOTA]-TOC and [¹⁷⁷Lu-DOTA]-TOC until tumor progression or permanent toxicity. Multivariable Cox regression analyses were used to study predictors of survival.

Results A total of 36 patients were enrolled; 30 patients received [⁹⁰Y-DOTA]-TOC (median activity) and 6 patients received [⁹⁰Y-DOTA]-TOC plus [¹⁷⁷Lu-DOTA]-TOC. All patients displayed tumor uptake higher than the liver uptake. 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 survival from time of enrollment (45.1 months, range: 37.1-53.1 months vs. 12.6 months, range: 11.0-14.2, hazard ratio: 0.20 (0.05-0.81), p=0.02). Furthermore, there was a trend towards longer survival under [⁹⁰Y-DOTA]-TOC plus [¹⁷⁷Lu-DOTA]-TOC as compared to [⁹⁰Y-DOTA]-TOC 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=0.30).

Conclusions [⁹⁰Y-DOTA]-TOC and [⁹⁰Y-DOTA]-TOC plus [¹⁷⁷Lu-DOTA]-TOC are promising tools for the treatment of metastasized gastrinoma.