PET derived biomarkers prognosticate the outcome of NET patients undergoing radiopeptide therapy

Ziel/Aim Patient selection in the NETTER-1 trial was based on the degree of somatostatin receptor (SSTR) expression in the highest uptake lesion as assessed by planar ¹¹¹Indium-Pentetreotid. A recent head-to-head comparative study has shown that ¹¹¹Indium-Pentetreotid considerably underestimates the expression levels in lesions 111Indium-Pentetreotid cannot be directly translated to SSTR-PET. We retrospectively investigate pre-PRRT SSTR-PET parameters for prognostication and therapy selection.

Methodik/Methods All patients who received at least two cycles of PRRT in the department of nuclear medicine Essen between 2008 and 2019 were included in this retrospective analysis. All tumor lesions were manually segmented and SUV_max and MTV noted. MTV was quantified using 50 % of the local SUV_max as threshold. Mean SUV_max was calculated on a per-patient basis by averaging the SUV_max of all segmented metastases. Additionally, primary NET location, tumor grade, Chromogranin levels, age, metastatic pattern, alkaline phosphatase, and lactate dehydrogenase levels were tested to establish a prediction nomogram. Natural logarithm of continuous parameters was used for cox regression.

Ergebnisse/Results 209 patients were eligible. The mean SUV_max of all lesions was a statistically significant positive prognosticator in multivariate cox regression (HR = 0.61, p = 0.0046). The baseline whole-body tumor volume was a statistically independent negative prognosticator of overall (HR= 1.53, p < 0.001) and progression-free survival in a multivariate cox regression (HR= 1.18, p = 0.02). Moreover, baseline whole-body tumor volume was significantly associated with response in a multivariate logistic regression (p = 0.019).

Schlussfolgerungen/Conclusions Baseline tumor volume and mean uptake were significant prognosticators of overall and progression-free survival. These findings might lead to the identification of patients that might profit from combinational therapy or alpha emitting PRRT strategies.

Publication History

Article published online:
08 April 2021