Prostate-specific Membrane Antigen-based Imaging of Castration-resistant Prostate Cancer

Metastases-directed local therapies (MDT) beyond genuine oligometastatic disease (OMD): Indications, endpoints and the role of imaging

To further personalise treatment in metastatic cancer, the indications for metastases-directed local therapy (MDT) and the biology of oligometastatic disease (OMD) should be kept conceptually apart. Both need to be vigorously investigated. Tumour growth dynamics - growth rate combined with metastatic seeding efficiency - is the single most important biological feature determining the likelihood of success of MDT in an individual patient, which might even be beneficial in slowly developing polymetastatic disease. This can be reasonably well assessed using appropriate clinical imaging. In the context of considering appropriate indications for MDT, detecting metastases at the edge of image resolution should therefore suggest postponing MDT. While three to five lesions are typically used to define OMD, it could be argued that countability throughout the course of metastatic disease, rather than a specific maximum number of lesions, could serve as a better parameter for guiding MDT. Here we argue that the unit of MDT as a treatment option in metastatic cancer might best be defined not as a single procedure at a single point in time, but as a series of treatments that can be delivered in a single or multiple sessions to different lesions over time. Newly emerging lesions that remain amenable to MDT without triggering the start of a new systemic treatment, a change in systemic therapy, or initiation of best supportive care, would thus not constitute a failure of MDT. This would have implications for defining endpoints in clinical trials and registries: Rather than with any disease progression, failure of MDT would only be declared when there is progression to polymetastatic disease, which then precludes further options for MDT.

Adoption of Lutetium-177 PSMA radioligand therapy for metastatic castration resistant prostate cancer: a total population analysis in Germany from 2016 to 2020

PURPOSE

This study is to investigate the adoption and current trends of Lutetium-177 PSMA RLT for mCRPC in Germany.

METHODS

We analyzed data from the reimbursement.INFO tool based on German hospitals' quality reports for Lutetium-177 PSMA RLT from 2016 to 2020 and from the nationwide German hospital billing database (Destatis) for general therapy with open radionuclides in combination with prostate cancer from 2006 to 2020. For validation of these billing data, we included the 177Lu-PSMA RLT cycles from two participating institutions from 2016 to 2020. For detection of trends over time we applied linear regression models.

RESULTS

General therapy with open radionuclides increased from 2006 to 2020. We identified a total of 12,553 177Lu-PSMA RLT cycles. The number of 177Lu-PSMA RLTs steadily increased from a total of 1026 therapies in 2016 to 3328 therapies in 2020 (+ 576 RLT/year; p < 0.005). In 2016, 25 departments of nuclear medicine offered this treatment, which increased to 44 nuclear medicine departments in 2020. In 2016, 16% of nuclear medicine departments (4/25) performed more than 100 177Lu-PSMA RLTs, which increased to 36% (16/44) in 2020 (p < 0.005). In 2016, 88% (22/25) of 177Lu-PSMA RLTs were performed at a university hospital, which decreased to 70% (31/44) in 2020. The proportion of patients older than 65 years receiving 177Lu-PSMA RLT increased from 78% in 2016 to 81% in 2020.

CONCLUSION

Treatment of mCRPC with 177Lu-PSMA RLT has been rapidly increasing in Germany in the recent years providing an additional therapy option. This development is remarkable, because of outstanding formal EMA approval.

Oligometastatic Prostate Cancer Treated with Metastasis-Directed Therapy Guided by Positron Emission Tomography: Does the Tracer Matter?

The superior diagnostic accuracy of [68Ga]Ga-prostate-specific membrane antigen-11 (PSMA) ([68Ga]Ga-PSMA-11) compared to [18F]F-Fluorocholine Positron Emission Tomography/Computed Tomography (PET/CT) in Prostate Cancer (PCa) is established. However, it is currently unclear if the added diagnostic accuracy actually translates into improved clinical outcomes in oligometastatic PCa patients treated with [68Ga]Ga-PSMA-11 PET-guided metastasis-directed therapy (MDT). The present study aimed to assess the impact of these two imaging techniques on Progression-Free Survival (PFS) in a real-world sample of oligometastatic PCa patients submitted to PET-guided MDT. Thirty-seven oligometastatic PCa patients treated with PET-guided MDT were retrospectively enrolled. MDT was guided by [18F]F-Fluorocholine PET/CT in eleven patients and by [68Ga]Ga-PSMA-11 PET/CT in twenty-six. Progression was defined as biochemical recurrence (BR), radiological progression at subsequent PET/CT imaging, clinical progression, androgen deprivation therapy initiation, or death. Clinical and imaging parameters were assessed as predictors of PFS. [18F]F-Fluorocholine PET-guided MDT was associated with significantly lower PFS compared to the [68Ga]Ga-PSMA-11 group (median PFS, mPFS 15.47 months, 95% CI: 4.13−38.00 vs. 40.93 months, 95% CI: 40.93−40.93, respectively; p < 0.05). Coherently, the radiotracer used for PET-guided MDT resulted in predictive PFS at the univariate analysis, as well as the castration-resistant status at the time of MDT and the PSA nadir after MDT. However, in the multivariate analysis, castration resistance and PSA nadir after MDT remained the sole independent predictors of PFS. In conclusion, in the present proof-of-concept study, [68Ga]Ga-PSMA-11 provided higher PFS rates than [18F]F-Fluorocholine imaging in oligometastatic PCa patients receiving PET-guided MDT. Although preliminary, this finding suggests that enlarging the “tip of the iceberg”, by detecting a major proportion of the submerged disease thanks to next-generation imaging may favourably impact the oncological outcome of oligometastatic PCa treated with MDT.

Special Issue "Prostate Cancer: Recent Advances in Diagnostics and Treatment Planning"

This editorial of the Special Issue "Prostate Cancer: Recent Advances in Diagnostics and Treatment Planning" aims to draw more attention to the broad and diverse field of prostate cancer (PCa) diagnosis and the utilization of different diagnostic means to improve clinical decision-making and treatment strategy planning [...].

A systematic review and meta-analysis on non-metastatic castration resistant prostate cancer: The radiation oncologist's perspective

Prostate cancer is the second most common cause of cancer-related mortality in men. In patients undergoing a failure after radical treatment, one of the therapeutic option is androgen deprivation: despite initial response rates, a progression to a state of castration resistance is observed in most of the patients. In the present article, we conducted a systematic review and meta-analysis of all clinical trials assessing treatment for nmCRPC with next-generation androgen receptor inhibitors. We performed a review and meta-analysis of phase III randomized controlled trials comparing new agents (apalutamide, enzalutamide, darolutamide) with placebo as control arm, in the setting of nmCRPC. Patients treated with next-generation ARIs had a 26% reduction in the risk of death compared with placebo; compared with other ARIs, darolutamide had the lowest rate of grade 3 and 4 AEs and the lowest therapy discontinuation rate due to any grade AEs. This meta-analysis shows that treatment with new ARIs is safe and significantly reduces the risk of death and of metastasis onset in nmCRPC patients. Under way studies on new biomarkers such as genomic classifiers will probably allow the stratification in more specific subsets of disease. New imaging modalities such as PSMA-PET have shown greater sensibility and specificity than conventional imaging in metastases detection. All patients were randomized in a 2:1 fashion, with a total of 2,694 who underwent next-generation ARIs (806 apalutamide, 955 darolutamide, 933 enzalutamide) and 1,423 in the placebo arm.

The role of PSMA radioligands in the diagnosis and treatment of prostate carcinoma

Prostate cancer (PC) is the most common tumor in men in the West and the fifth leading cause of cancer-related death. The use of PSMA radioligands has represented an important advance both in its diagnosis, through PET molecular imaging, and in its treatment in advanced stages of the disease. This article reviews the contribution of PET studies with PSMA radioligands in initial staging, in tumor detection in biochemical recurrence (elevation of PSA) after treatment with curative intent, and in the more advanced stages of the disease (castration resistant PC or CRPC). The contribution of PSMA radioligand therapy (PSMA-RLT) in CRPC patients who progress to standard therapy is also analyzed.

The Added Value of 18F-FDG PET/CT Compared with 68Ga-PSMA PET/CT in Patients with Castration-Resistant Prostate Cancer

⁶⁸Ga-prostate-specific membrane antigen (⁶⁸Ga-PSMA) PET/CT is a commonly used imaging modality in prostate cancers. However, few studies have compared the diagnostic efficiency between ⁶⁸Ga-PSMA and ¹⁸F-FDG PET/CT and evaluated whether a heterogeneous metabolic phenotype (especially ⁶⁸Ga-PSMA-negative [-], ¹⁸F-FDG-positive [+] lesions) exists in patients with castration-resistant prostate cancer (CRPC). We determined the added value of ¹⁸F-FDG PET/CT compared with ⁶⁸Ga-PSMA PET/CT in CRPC patients and identified CRPC patients who may benefit from additional ¹⁸F-FDG PET/CT. Methods: The data of 56 patients with CRPC who underwent both ⁶⁸Ga-PSMA and ¹⁸F-FDG PET/CT from May 2018 to February 2021 were retrospectively analyzed. The patients were classified into 2 groups: with or without ⁶⁸Ga-PSMA-, ¹⁸F-FDG+ lesions. The differences in patient characteristics between the 2 groups and predictors of patients who have at least 1 ⁶⁸Ga-PSMA-, ¹⁸F-FDG+ lesion were analyzed. Results: Although both the detection rate (75.0% vs. 51.8%, P = 0.004) and the number of positive lesions (135 vs. 95) were higher for ⁶⁸Ga-PSMA PET/CT than for ¹⁸F-FDG PET/CT, there were still 13 of 56 (23.2%) patients with at least 1 ⁶⁸Ga-PSMA-, ¹⁸F-FDG+ lesion. Prostate-specific antigen (PSA) and the Gleason score were both higher in patients with ⁶⁸Ga-PSMA-, ¹⁸F-FDG+ lesions than in those without (P = 0.04 and P < 0.001, respectively). Multivariate regression analysis showed that the Gleason score (≥8) and PSA (≥7.9 ng/mL) were associated with the detection rate of patients who had ⁶⁸Ga-PSMA-, ¹⁸F-FDG+ lesions (P = 0.01 and P = 0.04, respectively). The incidences of having ⁶⁸Ga-PSMA-, ¹⁸F-FDG+ lesions in low-probability (Gleason score < 8 and PSA < 7.9 ng/mL), medium-probability (Gleason score ≥ 8 and PSA < 7.9 ng/mL or Gleason score < 8 and PSA ≥ 7.9 ng/mL), and high-probability (Gleason score ≥ 8 and PSA ≥ 7.9 ng/mL) groups were 0%, 21.7%, and 61.5%, respectively (P < 0.001). Conclusion: Gleason score and PSA are significant predictors of ⁶⁸Ga-PSMA-, ¹⁸F-FDG+ lesions, and CRPC patients with a high Gleason score and PSA may benefit from additional ¹⁸F-FDG PET/CT.

Genetic comprehension of organophosphate flame retardants, an emerging threat to prostate cancer

In recent years, organophosphate ester flame retardants (OPFRs), which have been regarded as alternatives for brominated flame retardants (BFRs), have become widely used in building materials, textiles, and electric equipment. Elucidating the relationship between OPFRs and tumors holds great significance for the treatment and prevention of diseases. In this work, we found a new method for predicting the correlation between the interactive genes of OPFRs and tumors. Transcriptome profiles and OPFR information were obtained from The Cancer Genome Atlas and the Genotype-Tissue Expression, Comparative Toxicogenomics, and PharmMapper databases. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis showed that interactive genes were mainly enriched in prostate cancer, steroid metabolic process, and steroid hormone regulation. Furthermore, protein-protein interaction network analysis revealed 33 biological hub genes. The operating characteristic curves and survival analysis showed the role of key genes in predicting the prognosis of prostate cancer. Gene target prediction and gene set variation analysis proved that OPFRs and their metabolites exert potential effects on prostate cancer. Colony formation assay showed that the cells with AR, mTOR and DDIT3 knockdown could remarkably mitigate the cell proliferation ability in both PC-3 and LNCap cells. Transwell assay demonstrated that the silencing of AR, mTOR and DDIT3 could significantly inhibit the cell invasion capacity of prostate cells. Triphenyl phosphate (TPP) significantly increase the cell proliferation ability and promote cell invasion capacity. AR, mTOR and DDIT3 in the PC-3 and LNCap cells were significantly upregulated with 10-6 M TPP treated.

Lutetium-177 Labelled PSMA Targeted Therapy in Advanced Prostate Cancer: Current Status and Future Perspectives

Patients suffering from metastatic castration-resistant prostate cancer (mCRPC) have a poor prognosis. As a further treatment option ¹⁷⁷Lutetium (Lu) prostate-specific membrane antigen (PSMA) radioligand therapy gained a significant interest of many investigators. Several publications showed great response and prolonged survival with limited adverse events. However, to this point, it still remains unclear which patients benefit the most from ¹⁷⁷Lu-PSMA therapy, and how to improve the treatment regimen to achieve best outcome while minimizing potential adverse events. The efficacy for mCRPC patients is a given fact, and with the newly published results of the VISION trial its approval is only a matter of time. Recently, investigators started to focus on treating prostate cancer patients in earlier disease stages and in combination with other compounds. This review gives a brief overview of the current state and the future perspectives of ¹⁷⁷Lu labelled PSMA radioligand therapy.

Efficacy of PSMA PET-Guided Radiotherapy for Oligometastatic Castrate-Resistant Prostate Cancer

Purpose

To assess the outcome of radiotherapy (RT) to all PSMA ligand positive metastases for patients with castrate-resistant prostate cancer (mCRPC).

Patients and methods

A total of 42 patients developed oligometastatic mCRPC and received PSMA PET-guided RT of all metastases. The main outcome parameters were biochemical progression-free survival (bPFS), and second-line systemic treatment free survival (SST-FS).

Results

A total of 141 PSMA ligand-positive metastases were irradiated. The median follow-up time was 39.0 months (12-58 months). During the follow-up five out of 42 (11.9%) patients died of progressive mPCa. Five out of 42 (11.9%) patients showed no biochemical responses and presented with a PSA level ≥10% of the baseline PSA at first PSA level measurement after RT and were classified as non-responders. The median PSA level before RT was 4.79 ng/mL (range, 0.4-46.1), which decreased significantly to a median PSA nadir level of 0.39 ng/mL (range, <0.07-32.8; p=0.002). The median PSA level at biochemical progression after PSMA ligand-based RT was 2.75 ng/mL (range, 0.27-53.0; p=0.24) and was not significantly different (p=0.29) from the median PSA level (4.79 ng/mL, range, 0.4-46.1) before the PSMA ligand-based RT. The median bPFS was 12.0 months after PSMA ligand PET-based RT (95% CI, 11.2-15.8) and the median SST-FS was 15.0 months (95% CI, 14.0-21.5).

Conclusion

In well-informed and closely followed-up patients, PSMA PET-guided RT represents a viable treatment option for patients with oligometastatic mCRPC to delay further systemic therapies.