The Impact of Baseline PSMA PET/CT Versus CT on Outcomes of 223Ra Therapy in Metastatic Castration-Resistant Prostate Cancer Patients

Dianne Bosch; Kim J M van der Velden; Irma M Oving; Dirk N J Wyndaele; Leo E Weijs; W Dick van Schelven; Wim J G Oyen; Erik T Te Beek; Addy C M van de Luijtgaarden; Diederik M Somford; James Nagarajah; Rick Hermsen; Niven Mehra; Winald R Gerritsen; Maarten J van der Doelen; Inge M van Oort

doi:10.2967/jnumed.123.266654

The Impact of Baseline PSMA PET/CT Versus CT on Outcomes of ²²³Ra Therapy in Metastatic Castration-Resistant Prostate Cancer Patients

J Nucl Med. 2024 Apr 1;65(4):541-547. doi: 10.2967/jnumed.123.266654.

Authors

Dianne Bosch¹, Kim J M van der Velden¹, Irma M Oving², Dirk N J Wyndaele³, Leo E Weijs⁴, W Dick van Schelven⁵, Wim J G Oyen^{6

7

8}, Erik T Te Beek⁹, Addy C M van de Luijtgaarden¹⁰, Diederik M Somford¹¹, James Nagarajah¹², Rick Hermsen¹³, Niven Mehra¹⁴, Winald R Gerritsen¹⁴, Maarten J van der Doelen¹⁵, Inge M van Oort¹

Affiliations

¹ Department of Urology, Radboud University Medical Center, Nijmegen, The Netherlands.
² Department of Medical Oncology, Ziekenhuisgroep Twente, Almelo, The Netherlands.
³ Department of Nuclear Medicine, Catharina Hospital, Eindhoven, The Netherlands.
⁴ Department of Radiology and Nuclear Medicine, Ziekenhuisgroep Twente, Almelo, Netherlands.
⁵ Department of Nuclear Medicine, Medical Center Leeuwarden, Leeuwarden, The Netherlands.
⁶ Department of Radiology and Nuclear Medicine, Rijnstate Hospital, Arnhem, The Netherlands.
⁷ Department of Biomedical Sciences, Humanitas University, Milan, Italy.
⁸ Department of Nuclear Medicine, Humanitas Clinical and Research Center, Milan, Italy.
⁹ Department of Nuclear Medicine, Reinier de Graaf Gasthuis, Delft, The Netherlands.
¹⁰ Department of Medical Oncology, Reinier de G raaf Gasthuis and Reinier Haga Prostate Cancer Center, Delft, The Netherlands.
¹¹ Department of Urology, Canisius-Wilhelmina Hospital, Nijmegen, The Netherlands.
¹² Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
¹³ Department of Nuclear Medicine, Canisius-Wilhelmina Hospital, Nijmegen, The Netherlands; and.
¹⁴ Department of Medical Oncology, Radboud University Medical Center, Nijmegen, The Netherlands.
¹⁵ Department of Urology, Radboud University Medical Center, Nijmegen, The Netherlands; maarten.vanderdoelen@radboudumc.nl.

PMID: 38423781
DOI: 10.2967/jnumed.123.266654

Abstract

Imaging before ²²³Ra-dichloride (²²³Ra) therapy is crucial for selecting metastatic castration-resistant prostate cancer (mCRPC) patients with bone-only disease. The purpose of this study was to evaluate if baseline prostate-specific membrane antigen (PSMA) PET/CT (bPSMA) versus CT is associated with outcomes of ²²³Ra therapy. Methods: A secondary analysis of the data of a prospective observational study (NCT04995614) was performed. Patients received a maximum of 6 ²²³Ra cycles and were retrospectively divided into the bPSMA or baseline CT (bCT) groups. All patients received baseline bone scintigraphy. Primary endpoints were alkaline phosphatase and prostate-specific antigen response. Secondary endpoints were overall survival (OS) and radiologic response. Results: Between 2017 and 2020, 122 mCRPC patients were included: 18 (14.8%) in the bPSMA group and 104 (85.2%) in the bCT group. All baseline characteristics were comparable. No significant differences in alkaline phosphatase or prostate-specific antigen response were found. The bCT group showed an OS significantly shorter than that of the bPSMA group (12.4 vs. 19.9 mo, P = 0.038). In 31 of 76 patients (40.1%) in the bCT group who also received posttherapy CT, lymph node or visceral metastases (soft-tissue involvement [STI]) were detected after ²²³Ra therapy, compared with 0 of 15 patients in the bPSMA group who received posttherapy PSMA PET/CT or CT. No significant difference in OS was found between patients in the bCT or posttherapy CT subgroup without STI (46/76) and the bPSMA group. Conclusion: bPSMA versus CT does not seem to impact biochemical response during ²²³Ra therapy in mCRPC patients. Nevertheless, patients in the bCT group had a significantly shorter OS, most likely due to underdetection of STI in this group. Therefore, replacing bCT with PSMA PET/CT appears to be a valuable screening method for identifying patients who will benefit most from ²²³Ra therapy.

Keywords: 223Ra; PSMA PET/CT; castration-resistant prostate cancer; computer tomography; overall survival.

Publication types

Observational Study

MeSH terms

Alkaline Phosphatase
Humans
Male
Positron Emission Tomography Computed Tomography*
Prostate-Specific Antigen
Prostatic Neoplasms, Castration-Resistant* / diagnostic imaging
Prostatic Neoplasms, Castration-Resistant* / radiotherapy
Radiopharmaceuticals / therapeutic use
Retrospective Studies
Treatment Outcome

Substances

Alkaline Phosphatase
Prostate-Specific Antigen
Radiopharmaceuticals