Early changes of PSMA PET signal after initiation of androgen receptor signaling inhibitors in mCRPC: An international multicenter retrospective study.
Year: 2023
Type: conference-abstract
Abstract: 5063 Background: Androgen receptor signaling inhibitors (ARSi) play a relevant role in the treatment of prostate cancer. A potential influence of ARSi on PSMA expression has been described. We evaluated early changes of PSMA-expression by PET in mCRPC patients. Methods: This retrospective study included 5 international sites. Patients with mCRPC undergoing 68Ga-PSMA-11 PET/CT prior to (PET1) and early after ARSi (PET2 within 29 days maximum) were included. Whole-body (WB) PSMA-positive tumor volume (PSMA-TV) was evaluated using a liver-specific semi-automatically threshold (Affinity 3.0.2, Hermes Medical Solutions). WB PSMA-TV, SUVmean and SUVmax and their respective changes (%) were analyzed. PSA changes between PET 1 and PET2 were evaluated. Median values and ranges are provided. Results: 54 patients were included in the analysis. ARSi was initiated 1 day (range 0 – 28) after PET1 while PET2 was performed 14 days (range 7 – 29) after ARSi initiation. PSA at PET1 and PET2 was 9.5 ng/ml (range 0.2 – 490.0) and 8.7 ng/ml (range 0.1 – 732.0), respectively (p = 0.035): -33.0% (range -98% – +496%). The WB PSMA-TV at PET1 and PET2 was 89.9 ml (0.0 – 3097.0) and 112.2 ml (0.0 – 3133.0) ml, respectively (p = 0.016; change of +6.0% (range -88% – +260%). WB PSMA SUVmean and SUVmax at PET1 and PET2 was 9.0 (range 5.0 – 43.7) and 9.3 (range 0.0 – 42.5) and 26.5 (range 0.0 – 125.0) and 28.5 (range 0.0 – 212.0), respectively (p = 0.194 and p = 0.353): % change of +3 % (-85% – +71%) and 0% (-55% – +232%). Four of 7 patients with PSA increases at PET2 had an increasing PSMA-TV, 6/7 showed an increasing SUVmean and 5/7 presented with an increased SUVmax. Decreasing WB-PSMA-TV in 18/54 (33%) patients was accompanied by decreasing SUVs in 10 of them (56%). Percent PSA change was unrelated to changes in PSMA-TV, SUVmean and SUVmax. Conclusions: PSMA-PET performed early after ARSI revealed slight increases in the WB-PSMA-TV, stable WB-PSMA SUVs while serum PSA decreased in most of the patients. We conclude that ARSi does not have a strong effect on PSMA expression within 30 days after treatment initiation. [Table: see text]
Source: Journal of Clinical Oncology
Institutions: University of California, Los Angeles, IRCCS Azienda Ospedliero-Universitaria di Bologna Policlinico di Sant'Orsola, University of Bologna, Saarland University, University of Liège, St Vincent's Hospital Sydney, University of California, San Francisco, UCSF Helen Diller Family Comprehensive Cancer Center, National Center for Global Health and Medicine, Johns Hopkins University, Johns Hopkins Medicine, Centre Hospitalier Universitaire de Grenoble
Language: English
Subfield: Pulmonary and Respiratory Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W4379281973