Can 68Ga-PSMA PET/CT-derived prostate-specific membrane antigen expression parameters predict prostate-specific antigen response to enzalutamide treatment?

The Application of Radiolabeled Targeted Molecular Probes for the Diagnosis and Treatment of Prostate Cancer

Radiopharmaceuticals targeting prostate-specific membrane antigens (PSMA) are essential for the diagnosis, evaluation, and treatment of prostate cancer (PCa), particularly metastatic castration-resistant PCa, for which conventional treatment is ineffective. These molecular probes include [⁶⁸Ga]PSMA, [¹⁸F]PSMA, [Al¹⁸F]PSMA, [^99mTc]PSMA, and [⁸⁹Zr]PSMA, which are widely used for diagnosis, and [¹⁷⁷Lu]PSMA and [²²⁵Ac]PSMA, which are used for treatment. There are also new types of radiopharmaceuticals. Due to the differentiation and heterogeneity of tumor cells, a subtype of PCa with an extremely poor prognosis, referred to as neuroendocrine prostate cancer (NEPC), has emerged, and its diagnosis and treatment present great challenges. To improve the detection rate of NEPC and prolong patient survival, many researchers have investigated the use of relevant radiopharmaceuticals as targeted molecular probes for the detection and treatment of NEPC lesions, including DOTA-TOC and DOTA-TATE for somatostatin receptors, 4A06 for CUB domain-containing protein 1, and FDG. This review focused on the specific molecular targets and various radionuclides that have been developed for PCa in recent years, including those mentioned above and several others, and aimed to provide valuable up-to-date information and research ideas for future studies.

Role of baseline 68Ga-PSMA PET/CT-derived whole-body volumetric parameters in predicting survival outcomes of metastatic castration-resistant prostate cancer patients receiving first-line treatment

OBJECTIVE

We aimed to evaluate whether baseline ⁶⁸Ga-PSMA PET/CT-derived whole-body volumetric parameters could be used as predictive biomarkers for survival in metastatic castration-resistant prostate cancer (mCRPC) patients receiving first-line treatment.

MATERIALS AND METHODS

This retrospective study included 54 mCRPC patients, who underwent baseline ⁶⁸Ga-PSMA PET/CT imaging within 1 month before starting first-line treatment. Pre-treatment prostate-specific antigen (PSA) levels and treatments were recorded. SUVmax, SUVmean, whole-body PSMA-derived tumor volume (wbPSMA-TV), and whole-body total lesion PSMA (wbTL-PSMA) were calculated for all patients. PSA response was defined as a decline of ≥ 50% from pre-treatment value at 12 weeks. Overall survival (OS) was measured from the start of the first-line treatment for mCRPC.

RESULTS

Docetaxel and abiraterone/enzalutamide were administered to 32 and 22 patients in the first-line setting, respectively. wbPSMA-TV (rho = 0.582, p = 0.004) and wbTL-PSMA (rho = 0.564, p = 0.007) showed moderate positive correlations with PSA levels. Older age (p = 0.02), higher wbPSMA-TV (p = 0.007), higher PSA (p = 0.01), higher number of bone metastases (p = 0.02), and lack of PSA response (p = 0.03) were significantly associated with an increased risk of mortality. Multivariate analysis determined wbPSMA-TV (HR: 1.003, 95% CI 1.001-1.004, p = 0.001) and PSA response (HR: 2.241, 95% CI 1.189-4.222, p = 0.01) as independent predictors of OS.

CONCLUSION

The wbPSMA-TV may be a useful tool to reflect tumor burden and predict survival outcomes in patients with mCRPC.