title: 68Ga-PSMA-11 PET as a Gatekeeper for the Treatment of Metastatic Prostate Cancer with223Ra: Proof of Concept.
abstract: We retrospectively evaluated the utility of68Ga-PSMA-11 PET for planning223RaCl2therapy of patients with metastatic prostate cancer and its impact on the therapeutic response as determined by prostate-specific antigen (PSA) and alkaline phosphatase (ALP), as well as the correlation of PSA changes with the results of prostate-specific membrane antigen (PSMA) PET follow-up scans.Methods:Sixty-three patients with a median age of 73 y who underwent 307 cycles of therapy with223RaCl2were analyzed. In 31 patients, bone scanning and radiologic imaging were performed for pretherapeutic imaging (group 1). In 32 patients, bone scanning and PSMA PET were performed before therapy (group 2). Patients with small lymph node metastases and local recurrence were not excluded from treatment, consistent with current guidelines. PSA and ALP were measured before each treatment cycle and 4 wk after the final cycle. Thirteen patients from group 2, who underwent a second PSMA PET scan as a follow-up, were evaluated to determine the significance of PSA changes as a follow-up marker.Results:In group 1, 4 patients (12.9%) showed a PSA decline, of whom 2 patients and 1 patient showed a PSA decline of more than 30% and more than 50%, respectively. In contrast, in group 2, 14 patients (43.8%) showed a PSA decline, of whom 10 and 8 patients showed a decline of more than 30% and more than 50%, respectively (P= 0.007). Thirty-seven patients had a high ALP level (19 from group 1 and 18 from group 2). Twelve (63.2%) and 16 (88.9%) patients in groups 1 and 2, respectively, showed an ALP decline. This difference was not significant; however, 7 (36%) and 13 (72.2%) patients in groups 1 and 2, respectively, showed an ALP decline of more than 30% (P= 0.04). Considering any ALP decline as a response, no patient with increasing ALP showed a PSA response (P= 0.036). There was a significant correlation between the PSA changes and the therapeutic response according to follow-up PSMA PET.Conclusion:When PSMA PET is used as the gatekeeper in addition to bone scanning, radionuclide therapy with223Ra may be more effective and have more success regarding changes in the PSA. An increase in PSA during therapy cycles occurs because of disease progression.
authors.affiliation: Department of Nuclear Medicine, University Hospital Bonn, Bonn, Germany Hojjat.ahmadzadehfar@ukb.uni-bonn.de.
authors.forename: Hojjat
authors.initials: H
authors.lastname: Ahmadzadehfar
authors.affiliation: Department of Nuclear Medicine, University Hospital Bonn, Bonn, Germany.
authors.forename: Kambiz
authors.initials: K
authors.lastname: Azgomi
authors.affiliation: Department of Urology, University Hospital Bonn, Bonn, Germany; and.
authors.forename: Stefan
authors.initials: S
authors.lastname: Hauser
authors.affiliation: Department of Nuclear Medicine, University Hospital Bonn, Bonn, Germany.
authors.forename: Xiao
authors.initials: X
authors.lastname: Wei
authors.affiliation: Department of Nuclear Medicine, University Hospital Bonn, Bonn, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Yordanova
authors.affiliation: Department of Nuclear Medicine, University Hospital Bonn, Bonn, Germany.
authors.forename: Florian C
authors.initials: FC
authors.lastname: Gaertner
authors.affiliation: Department of Nuclear Medicine, University Hospital Bonn, Bonn, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Kürpig
authors.affiliation: Department of Diagnostic Radiology, University Hospital Bonn, Bonn, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Strunk
authors.affiliation: Department of Nuclear Medicine, University Hospital Bonn, Bonn, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Essler
mesh_terms: D000368:Aged; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000556:secondary*; D004492:Edetic Acid / Q000031:analogs & derivatives; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D006801:Humans; D008297:Male; D009842:Oligopeptides; D009942:Organometallic Compounds; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D011868:Radioisotopes / Q000627:therapeutic use; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D061089:Radiotherapy, Image-Guided / Q000379:methods; D011883:Radium / Q000627:therapeutic use*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D009842:Oligopeptides; D009942:Organometallic Compounds; D011868:Radioisotopes; D019275:Radiopharmaceuticals; C000718244:gallium 68 PSMA-11; D004492:Edetic Acid; C581106:radium Ra 223 dichloride; D011883:Radium
keywords: 223Ra; PET; PSMA; bone metastases; bone scan; prostate cancer; radionuclide therapy