PSMA PET/CT SUVmax as a prognostic biomarker in patients with metachronous metastatic hormone-sensitive prostate cancer (mHSPC).

BACKGROUND

Metastatic hormone-sensitive prostate cancer (mHSPC) is treatment-resistant and generally considered incurable. The development of prostate-specific membrane antigen positron emission-computed tomography (PSMA PET/CT) has generated immense expectations due to its diagnostic accuracy in prostate cancer (PCa). PSMA expression of the primary tumor, quantified by SUVmax, is a predictor of oncological outcomes. The role of PSMA-PET/CT SUVmax in metachronous mHSPC treated with ADT plus second-generation antiandrogens (ARSI) is unknown. The main aim of this study was to evaluate Ga-PSMA-11expression (SUVmax) as a potential prognostic biomarker in patients with metachronous mHSPC treated with ADT and first or second-generation antiandrogens. A second aim was to determine the association between PSMA SUVmax and PSA response to hormone therapy.

MATERIAL AND METHODS

Patients diagnosed with metachronous mHSPC between July 2017 and February 2023 who developed biochemical recurrence following radical surgery (with or without salvage radiotherapy and/or ADT) or external radiation therapy (with or without ADT) were included. All patients underwent  Ga-PSMA-11 PET/CT imaging and the SUVmax value was determined for all measurable locations. The SUVmax value was used for the semiquantitative analysis. The Wilcoxon method was used to compare responders (PSA reduction ≥ 50%) to non-responders (PSA reduction < 50%). The SUVmax value and hormone therapy were evaluated as independent variables relative to the PSA response rate or PSA reduction using the linear regression method. A mixed-effects model (ANOVA) was used for the comparisons.

RESULTS

A total of 82 patients were included. Median follow-up was 11.7 months. On the linear regression analysis, patients with a high SUVmax treated with ADT + ARSI showed a greater PSA response (p = 0.034) than those treated with ADT + first-generation antiandrogens. In the mixed-effects model, SUVmax was significant (p = 0.041). On the univariate analysis, PSA at recurrence (HR, 3.2; 95% CI: 1.07-13.6; p = 0.078) and the number of metastases (HR, 4.77; 95% CI 1.1-26.1: p = 0.002) were associated with the type of hormone therapy administered.

CONCLUSIONS

PSMA-PET/CT SUVmax is a prognostic biomarker that can be used to predict a PSA response to ADT + ARSI in patients with metachronous mHSPC. However, these findings need to be confirmed in larger prospective studies.