Effects of novel androgen receptor signaling inhibitors on PSMA PET signal intensity in patients with castrate-resistant prostate cancer: a prospective exploratory serial imaging study

Ida Sonni; Andrei Gafita; Lena M Unterrainer; Rejah M Alano; Stephanie Lira; John Shen; Alexandra Drakaki; Tristan Grogan; Matthew B Rettig; Johannes Czernin; Jeremie Calais

doi:10.1186/s13550-023-01048-4

Effects of novel androgen receptor signaling inhibitors on PSMA PET signal intensity in patients with castrate-resistant prostate cancer: a prospective exploratory serial imaging study

EJNMMI Res. 2023 Oct 30;13(1):95. doi: 10.1186/s13550-023-01048-4.

Authors

Ida Sonni^{1

2

3}, Andrei Gafita⁴, Lena M Unterrainer^{4

5}, Rejah M Alano⁴, Stephanie Lira⁴, John Shen⁶, Alexandra Drakaki⁶, Tristan Grogan⁷, Matthew B Rettig⁶, Johannes Czernin⁴, Jeremie Calais⁴

Affiliations

¹ Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA. isonni@mednet.ucla.edu.
² Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90095-7370, USA. isonni@mednet.ucla.edu.
³ Department of Experimental and Clinical Medicine, University Magna Graecia, Catanzaro, Italy. isonni@mednet.ucla.edu.
⁴ Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA.
⁵ Department of Nuclear Medicine, Ludwig Maximilian University of Munich LMU, Munich, Germany.
⁶ Department of Medical Oncology, University of California, Los Angeles, Los Angeles, CA, USA.
⁷ Department of Medicine Statistics Core, University of California, Los Angeles, Los Angeles, CA, USA.

Abstract

Background: PSMA expression is influenced by hormonal status. We evaluated changes in PSA and whole-body 68Ga-PSMA-11 PET/CT (WB-PSMA PET) after initiation of androgen receptor signaling inhibitors (ARSi).

Methods: Prospectively enrolled patients with metastatic castration-resistant prostate cancer (mCRPC) initiating ARSi underwent serial PSA measurements and WB-PSMA PET at baseline, 1-week, and 3-months post-ARSi. We correlated WB-PSMA PET metrics and PSA kinetics after ARSi to 1-year clinical outcome.

Results: Due to low enrollment rate, the study was closed before reaching the recruitment goal of 30 patients. Nine patients were enrolled. At 1-year, unfavorable outcome was documented in 6/9 (66%) patients. Nine/9 patients completed PSMA PET at 1-week, 5/9 at 3-months. Changes in PSA, PSMA-VOL, SUVmean and SUVmax were - 12%, + 5%, + 3%, and + 10% at 1-week, - 42%, - 16%, - 15% and - 17% at 3-months, respectively.

Conclusions: Our prospective trial involving 9 mCRPC patients initiating ARSi did not show significant modulation of PSMA expression measured on WB-PSMA PET at 1-week. This study was registered on clinicaltrials.gov (NCT04279561).

Keywords: Androgen receptor; Hormonal treatment; PSMA PET; PSMA flare; Prostate cancer.

Associated data

ClinicalTrials.gov/NCT04279561