Evaluation of [68Ga]Ga-PSMA-PET/CT in therapy response assessment of PSMA-targeted radionuclide therapy in patients with castration resistant prostate cancer

J Kurth; J Kretzschmar; M Heuschkel; G Kundt; OW Hakenberg; BJ Krause; SM Schwarzenböck

doi:10.1055/s-0039-1683739

Nuklearmedizin - NuclearMedicine, Table of Contents

Nuklearmedizin 2019; 58(02): 193-194
DOI: 10.1055/s-0039-1683739

Poster

Theranostik

Georg Thieme Verlag KG Stuttgart · New York

Evaluation of [68Ga]Ga-PSMA-PET/CT in therapy response assessment of PSMA-targeted radionuclide therapy in patients with castration resistant prostate cancer

J Kurth

¹Universitätsmedizin Rostock, Klinik und Poliklinik für Nuklearmedizin, Rostock

,

J Kretzschmar

¹Universitätsmedizin Rostock, Klinik und Poliklinik für Nuklearmedizin, Rostock

,

M Heuschkel

¹Universitätsmedizin Rostock, Klinik und Poliklinik für Nuklearmedizin, Rostock

,

G Kundt

²Universitätsmedizin Rostock, Institut für Biostatistik, Informatik in der Medizin und Altersforschung, Rostock

,

OW Hakenberg

³Universitätsmedizin Rostock, Klinik und Poliklinik für Urologie, Rostock

,

BJ Krause

¹Universitätsmedizin Rostock, Klinik und Poliklinik für Nuklearmedizin, Rostock

,

SM Schwarzenböck

¹Universitätsmedizin Rostock, Klinik und Poliklinik für Nuklearmedizin, Rostock

› Author Affiliations

Abstract

Full Text

Ziel/Aim:

The aim of this study was to retrospectively evaluate the value of [⁶⁸Ga]Ga-PSMA-PET/CT in monitoring early and late response to PSMA-targeted radionuclide therapy (Lu-177/Y-90) in castration resistant prostate cancer patients.

Methodik/Methods:

38 patients were referred for [⁶⁸Ga]Ga-PSMA-PET/CT before the first cycle (PET 1), after one/two cycles (PET 2) and after a mean of 3 cycles (range 3 to 5 cycles) (PET 3) of PSMA radioligand therapy (Lu-177/Y-90) for patient-based therapy response assessment. PET-based therapy response was assessed according to EORTC and PERCIST criteria, for PET 2 vs. 1 (early response assessment, ERA) as well as for PET 3 vs. 1 (late response assessment, LRA). PET-classified response was compared to the results of ERA and LRA based on clinical criteria and percentual change in PSA. Additionally, relationship between change of SUV_max/SUV_mean and PSA (early and late, respectively) was evaluated. Prognostic value of initial SUV_maxand SUV_mean was assessed.

Ergebnisse/Results:

About 76% of the patients were classified as SD or PR (SD: 65.2%; PR: 10.9%) by clinical criteria and 77% by change in PSA as response criterion (SD: 46.7%; PR: 31.1%). However, by PET-based response assessment approx. 95% were classified as SD or PR (PERCIST: SD 23.9%; PR: 71.7%; EORTC: SD 23.9%; PR: 69.6%). Cohens kappa analysis showed no statistically significant concordance between EORTC/PERCIST based and clinical criteria/PSA-based ERA and LRA; kappa < 0.2. No statistically significant correlation was found between change in SUV and PSA in ERA and LRA; r < 0.1, for both ERA and LRA. No statistically significant prognostic value of initial SUV_max and SUV_mean could be shown.

Schlussfolgerungen/Conclusions:

Pretherapeutic [⁶⁸Ga]Ga-PSMA-PET/CT is an essential prerequisite to detect sufficient expression of the molecular target. However, a significant correlation between [⁶⁸Ga]Ga-PSMA-PET/CT based and clinical criteria/PSA-based therapy response assessment during the early and late course of PSMA targeted therapy could not be shown. The role of [⁶⁸Ga]Ga-PSMA-PET/CT in this setting has to be evaluated in further studies.