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

Efficacy and safety of rechallenge with [177Lu]Lu-PSMA-I&T radioligand therapy in metastatic castration resistant prostate cancer

BACKGROUND

The purpose of this study was to evaluate the safety and outcome of rechallenge [177Lu]Lu-PSMA-I&T in newly progressed mCRPC patients after response to initial [177Lu]Lu-PSMA radioligand therapy (PRLT).

METHODS

We retrospectively included 18 patients who underwent rechallenge with [177Lu]Lu-PSMA-I&T. All patients presented with (i) newly progressed disease after response to initial PRLT; (ii) a [68Ga]Ga-PSMA-11 PET/CT confirming the presence of PSMA-positive metastases; iii) ECOG performance status 0-1. Adverse events were graded according to CTCAE v5.0. Response was assessed by PSA and classified according to PCWG3 recommendations. For patients who underwent restaging with [68Ga]Ga-PSMA-11 PET/CT, imaging response was categorised according to adapted PERCIST v1.0. In patients with discordant [68Ga]Ga-PSMA-11 PET/CT and PSA, other available imaging modalities were evaluated to confirm disease status. Overall survival (OS) was calculated from the first cycle of initial PRLT and rechallenge PRLT, respectively, until last patient contact or death.

RESULTS

Patients were initially treated with a median of 5 cycles (range 4-7) and were rechallenged after a median of 9 months (range 3-13). Each patient received a median of 4 (range 2-7) rechallenge cycles (median cumulative activity 26.1 GBq). None of the patients experienced life-threatening G4 adverse events during either treatment period. Grade 3 adverse events included one case of anaemia, one case of thrombocytopenia, and one case of renal failure. In 8/18 patients long-term toxicities were evaluated. Serious toxicities (≥ Grade 3) occurred in 3/8 patients (n = 1 G4 thrombocytopenia, n = 1 G4 renal failure and n = 1 pancytopenia and G4 renal failure). Best PSA50%-response was observed in 44% of patients and PSA-disease control was confirmed in 56% of patients at the last cycle. Of the 12/18 patients restaged by imaging, 6/12 (50%) patients had disease control (partial response/stable disease), 1/12 had a mixed response, and 5/12 had progression. After a median follow-up time of 25 months (range 14-44), 10 patients had died, 7 were still alive, and one patient was lost at follow-up. The median OS was 29 months (95%CI, 14.3-43.7 months) for the initial treatment and 11 months (95%CI, 8.1-13.8 months) for the first rechallenge course.

CONCLUSION

More than half of patients benefit from rechallenge PRLT. Our analysis suggests that rechallenge may prolong survival in selected patients, with an acceptable safety profile.

Progression-directed Therapy in Oligoprogressive Castration-resistant Prostate Cancer: Final Results from the Prospective, Single-arm, Phase 2 MEDCARE Trial

BACKGROUND AND OBJECTIVE

Next-line systemic treatment (NEST) is the standard of care for patients presenting with progressive metastatic castration-resistant prostate cancer (mCRPC). Progression-directed therapy (PDT), defined as a lesion-directed approach in patients with a limited number of progressive and/or new lesions, could postpone the need for NEST in these patients with so-called oligoprogressive mCRPC. Our aim was to investigate the feasibility of postponing NEST initiation in oligoprogressive mCRPC by using PDT.

METHODS

MEDCARE was a prospective, single-arm, nonrandomized phase 2 trial. Eligible patients had oligoprogressive mCRPC and were treated with PDT while their ongoing systemic therapy was continued. The primary endpoint was NEST-free survival (NEST-FS). Secondary endpoints were prostate-specific antigen response, clinical progression-free survival (cPFS), prostate cancer-specific survival (PCSS), overall survival (OS), and PDT-induced toxicity.

KEY FINDINGS AND LIMITATIONS

Twenty patients underwent PDT for 38 oligoprogressive lesions. At median follow-up of 28 mo, median NEST-FS was 17 mo and the 2-yr NEST-FS rate was 35%. Median PCSS and median OS were not reached. The PCSS and OS rates at 2 yr were 80% and 70%, respectively. The 2-yr local control rate was 95%. No patient experienced early or late grade ≥3 toxicity. NEST-FS was longer for patients who received PDT to all lesions visible on 18F-PSMA positron emission tomography/computed tomography (30 vs 13 mo; p = 0.002).

CONCLUSIONS AND CLINICAL IMPLICATIONS

This single-center, single-arm, phase 2 trial demonstrated that PDT in oligoprogressive mCRPC resulted in median NEST-FS of 17 mo without any early or late grade ≥3 toxicity.

PATIENT SUMMARY

For patients with metastatic prostate cancer no longer responding to hormone therapy, we investigated radiotherapy targeted at progressive cancer lesions while continuing their ongoing systemic treatment. The results show that this targeted therapy had very low toxicity and delayed the need to start a new line of systemic treatment by 17 months.

[Clinical Value of Dual Tracer PET Imaging With 68Ga-PSMA and 18F-FDG in Patients With Metastatic Prostate Cancer]

Objective

In this study, we retrospectively analyzed the imaging characteristics of dual-tracer 68Ga-prostate specific membrane antigen (PSMA) and 18F-flurodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in metastatic prostate cancer (mPCa) patients. We analyzed the uptake modes of the dual tracers, explored clinical pathological parameters affecting the 18F-FDG uptake in the lesions, and evaluated their prognostic implications for prostate specific antigen progression-free survival (PSA-PFS).

Methods

A total of 41 mPCa patients who underwent dual-tracer PET/CT (68Ga-PSMA and 18F-FDG) scans between September 2021 and January 2024 were retrospectively enrolled. One patient had negative uptake of both PSMA and FDG. According to the uptake patterns of the 2 tracers, the other patients, 40 in total, were categorized in 2 groups, including group A consisting of 33 cases who showed PSMA and FDG dual and those who showed FDG only avidity, and group B consisting of 7 cases who showed PSMA avidity only. Comparative analyses of clinical pathological characteristics between group A and group B were conducted. The relationship between various parameters and PSA-PFS was analyzed by the Kaplan-Meier method.

Results

A total of 26 patients (63.4%) were diagnosed with metastatic castration-resistant prostate cancer (mCRPC), and 38 cases (92.7%) had a Gleason score of 8-9. Bone metastasis, the predominant type of distant metastasis, occurred in 36 cases (87.8%). The skeletal and distant lymph node metastases mostly showed a dual positive uptake pattern for both PSMA and FDG (85.7% [24/28] and 81.8% [9/11]). 37.5% (3/8) of the metastases to organs showed FDG only positive uptake pattern. The serum levels of prostate specific antigen (PSA) in group A were significantly higher than those in group B (P=0.013). A total of 13 patients of special pathological classification (intraductal carcinoma and neuroendocrine differentiation) were all found to be in group A. Among the 41 cases, 16 were lost to follow-up. Of the 25 patients who completed follow-up, 9 patients, with a median PSA value of 104 ng/mL, experienced PSA progression, while the 16 other patients, with a median PSA of 0.34 ng/mL, did not incur any PSA progression. There was significant difference in the median PSA between patients showing PSA progression and those who did not show PSA progression (P<0.001). Kaplan-Meier survival analysis revealed that the median PSA-PFS of patients of specific pathological classifications was 7 months, which was shorter than the 16 months of the patients with typical prostate cancer, with the difference between the two groups being statistically meaningful (P=0.043). The median PSA-PFS for group A was 30 months. With more than half of the patients in the group not experiencing any PSA progression, group B did not reach the median PSA-PFS (P=0.645).

Conclusion

Dual-tracer PET/CT imaging with 68Ga-PSMA and 18F-FDG commonly exhibits avidity for both tracers in mPCa. Serum PSA level is a reliable biomarker for predicting FDG-positive lesions. mPCa presented with intraductal carcinoma and neuroendocrine differentiation tends to exhibit FDG avidity and is more susceptible to PSA progression.

Genetically Engineered Membrane-Coated Nanoparticles for Enhanced Prostate-Specific Membrane Antigen Targeting and Ferroptosis Treatment of Castration-Resistant Prostate Cancer

Conventional androgen deprivation therapy (ADT) targets the androgen receptor (AR) inhibiting prostate cancer (PCa) progression; however, it can eventually lead to recurrence as castration-resistant PCa (CRPC), which has high mortality rates and lacks effective treatment modalities. The study confirms the presence of high glutathione peroxidase 4 (GPX4) expression, a key regulator of ferroptosis (i.e., iron-dependent program cell death) in CRPC cells. Therefore, inducing ferroptosis in CRPC cells might be an effective therapeutic modality for CRPC. However, nonspecific uptake of ferroptosis inducers can result in undesirable cytotoxicity in major organs. Thus, to precisely induce ferroptosis in CRPC cells, a genetic engineering strategy is proposed to embed a prostate-specific membrane antigen (PSMA)-targeting antibody fragment (gy1) in the macrophage membrane, which is then coated onto mesoporous polydopamine (MPDA) nanoparticles to produce a biomimetic nanoplatform. The results indicate that the membrane-coated nanoparticles (MNPs) exhibit high specificity and affinity toward CRPC cells. On further encapsulation with the ferroptosis inducers RSL3 and iron ions, MPDA/Fe/RSL3@M-gy1 demonstrates superior synergistic effects in highly targeted ferroptosis therapy eliciting significant therapeutic efficacy against CRPC tumor growth and bone metastasis without increased cytotoxicity. In conclusion, a new therapeutic strategy is reported for the PSMA-specific, CRPC-targeting platform for ferroptosis induction with increased efficacy and safety.

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.