Impact of Three-Month Androgen Deprivation Therapy on [68Ga]Ga-PSMA-11 PET/CT Indices in Men with Advanced Prostate Cancer—Results from a Pilot Prospective Study

Abstract

Purpose: The purpose of this pilot prospective study is to examine the gallium-68-prostate-specific membrane antigen-11 ([68Ga]Ga-PSMA-11) positron emission tomography/computed tomography (PET/CT) imaging response in patients with advanced or metastatic hormone-naïve prostate cancer (PC) after 3 months of androgen deprivation therapy (ADT). Methods: We prospectively included men with untreated, clinical stage III or IV PC scheduled to receive ADT for at least 6 months. [68Ga]Ga-PSMA-11 PET/CT images were obtained before the start of ADT and 10–14 weeks thereafter. The following indices were examined: maximum standardized uptake value (SUVmax), mean SUV, PSMA total volume, and PSMA total lesion values of the prostate, nodes, bones, and whole-body. The therapeutic response was assessed using the modified PET response criteria in solid tumors 1.0. A subgroup analysis of patients with the International Society of Urological Pathology (ISUP) grade group 5 versus <5 was also performed. Results: A total of 30 patients were eligible. All PSMA PET/CT indices were significantly reduced (p < 0.001) after 3 months of ADT. Twenty-four (80%) patients showed partial response. Complete response, stable disease, and disease progression were observed in two patients each. Sixteen patients with ISUP grade group 5 showed a less prominent SUVmax reduction (p = 0.006), and none of them reached complete response. Conclusions: Three months of ADT in patients with untreated, advanced PC significantly reduced PSMA PET/CT indices. While most participants partially responded to ADT, patients with ISUP grade group 5 showed a less prominent SUVmax reduction. Collectively, our pilot results indicate that [68Ga]Ga-PSMA-11 PET/CT imaging holds promise to monitor treatment response after the first three months of ADT.

Diagnostic performance of 99mTc-HYNIC-PSMA SPECT/CT for biochemically recurrent prostate cancer after radical prostatectomy

“…Shortterm ADT is known to increase PSMA expression in PCa cells, thereby increasing PSMA ligand uptake (36). In contrast, it has been reported that PSMA uptake decreases with long-term ADT, decreasing the sensitivity of PSMA PET for detecting PCa lesions (37,38). Furthermore, long-term ADT also reduces tumor cell numbers.…”

68Ga-PSMA-11 PET/CT Features Extracted from Different Radiomic Zones Predict Response to Androgen Deprivation Therapy in Patients with Advanced Prostate Cancer

“…The acquisition protocol for 68 Ga-PSMA-11 PET/CT imaging has been previously described [9]. In brief, images were acquired on a GE Discovery MI PET/CT scanner (GE Healthcare, Milwaukee, WI, USA) 60 min after tracer injection (dose range: 103-182 MBq; median dose: 141 MBq).…”

“…A Bayesian penalized likelihood algorithm (Q.Clear) was used for image reconstruction. Methods for image calibration included attenuation correction, the point spread function, and the QCHD-S technique [9].…”

“…68 Ga-labeled prostate-specific membrane antigen (PSMA)-targeted PET has recently emerged as a promising imaging modality for lesion detection [3,4] and monitoring of response to androgen deprivation therapy (ADT) in patients with metastatic PCa [5,6]. There is also evidence that the percentage variations of 68 Ga-PSMA-11 PET/CT imaging parameters measured before and after three months of ADT are clinically useful in evaluating treatment response [7][8][9].…”

“…While measurements of circulating prostate specific antigen (PSA) levels may have a role in predicting response to ADT when PCa has not spread to lymph nodes or skeletal sites [36], its clinical utility in patients with disseminated disease remains limited. In this scenario, there is pilot evidence supporting the potential utility of the reduction ratios of 68 Ga-PSMA-11 PET/CT indices measured before and after 3 months of ADT [7,9]. By expanding our previous work [35], we designed this current study to investigate whether radiomic features from zone-1 may have clinical value for predicting response to ADT.…”