Administering [177Lu]Lu-PSMA-617 Prior to Radical Prostatectomy in Men with High-risk Localised Prostate Cancer (LuTectomy): A Single-centre, Single-arm, Phase 1/2 Study

BACKGROUND

High-risk localised prostate cancer (HRCaP) has high rates of biochemical recurrence; [177Lu]Lu-PSMA-617 is effective in men with advanced prostate cancer.

OBJECTIVE

To investigate the dosimetry, safety, and efficacy of upfront [177Lu]Lu-PSMA-617 in men with HRCaP prior to robotic radical prostatectomy (RP).

DESIGN, SETTING, AND PARTICIPANTS

In this single-arm, phase I/II trial, we recruited men with HRCaP (any of prostate-specific antigen [PSA] >20 ng/ml, International Society of Urological Pathology (ISUP) grade group [GG] 3-5, and ≥cT2c), with high tumour uptake on [68Ga]Ga-PSMA-11 positron emission tomography/computed tomography (PSMA PET/CT), and scheduled for RP.

INTERVENTION

Cohort A (n = 10) received one cycle and cohort B (n = 10) received two cycles of [177Lu]Lu-PSMA-617 (5 GBq) followed by surgery 6 weeks later.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was tumour radiation absorbed dose. Adverse events (AEs; Common Terminology Criteria for Adverse Events (CTCAE) version 5.0), surgical safety (Clavien-Dindo), imaging, and biochemical responses were evaluated (ClinicalTrials.gov: NCT04430192).

RESULTS AND LIMITATIONS

Between May 29, 2020 and April 28, 2022, 20 patients were enrolled. The median PSA was 18 ng/ml (interquartile range [IQR] 11-35), Eighteen (90%) had GG ≥3, and six (30%) had N1 disease. The median (IQR) highest tumour radiation absorbed dose after cycle 1 for all lesions was 35.5 Gy (19.5-50.1), with 19.6 Gy (11.3-48.4) delivered to the prostate. Five patients received radiation to lymph nodes. Nine (45%) patients achieved >50% PSA decline. The most common AEs related to [177Lu]Lu-PSMA-617 were grade 1 fatigue in eight (40%), nausea in seven (35%), dry mouth in six (30%), and thrombocytopenia in four (20%) patients. No grade 3/4 toxicities or Clavien 3-5 complications occurred. Limitations include small a sample size.

CONCLUSIONS

In men with HRCaP and high prostate-specific membrane antigen (PSMA) expression, [177Lu]Lu-PSMA-617 delivered high levels of targeted radiation doses with few toxicities and without compromising surgical safety. Further studies of [177Lu]Lu-PSMA-617 in this population are worthwhile to determine whether meaningful long-term oncological benefits can be demonstrated.

PATIENT SUMMARY

In this study, we demonstrate that up to two cycles of [177Lu]Lu-PSMA-617 given prior to radical prostatectomy in patients with high-risk localised prostate cancer are safe and deliver targeted doses of radiation to tumour-affected tissues. It is tolerated well with minimal treatment-related adverse events, and surgery is safe with a low rate of complications. Activity measured through PSA reduction, repeat PSMA PET/CT, and histological response is promising.

A Novel Risk Calculator Incorporating Clinical Parameters, Multiparametric Magnetic Resonance Imaging, and Prostate-Specific Membrane Antigen Positron Emission Tomography for Prostate Cancer Risk Stratification Before Transperineal Prostate Biopsy

Background

Prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) can detect multiparametric magnetic resonance imaging (mpMRI)-invisible prostate tumours and improve the sensitivity of detection of prostate cancer (PCa) in comparison to mpMRI alone. Numerous risk calculators have been validated as tools for stratification of men at risk of being diagnosed with clinically significant (cs)PCa.

Objective

To develop a novel risk calculator using clinical parameters and imaging parameters from mpMRI and PSMA PET/CT in a cohort of patients undergoing mpMRI and PSMA PET/CT before biopsy.

Design setting and participants

A total of 291 men from the PRIMARY prospective trial underwent mpMRI and PSMA PET/CT before transperineal prostate biopsy with sampling of systematic and targeted cores.

Outcome measurements and statistical analysis

Novel risk calculators were developed using multivariable logistic regression analysis to predict detection of overall PCa (International Society of Urological Pathology grade group [GG] ≥1) and csPCa (GG ≥2). The risk calculators were then compared with the European Randomised Study of Screening for Prostate Cancer risk calculator incorporating mpMRI (ERSPC-MRI). Resampling methods were used to evaluate the discrimination and calibration of the risk calculators and to perform decision curve analysis.

Results and limitations

Age, prostate-specific antigen, prostate volume, and mpMRI Prostate Imaging-Reporting and Data System scores were included in the MRI risk calculator, resulting in area under the receiver operating characteristic curve (AUC) values of 0.791 for overall PCa (GG ≥1) and 0.812 for csPCa (GG ≥2). Addition of the maximum standardised uptake value (SUVmax) on PSMA PET/CT for the prostate lesion, and of SUVmax for the mpMRI lesions for the MRI-PSMA risk calculator resulted in AUCs of 0.831 for overall PCa and 0.876 for csPCa (≥ISUP2).The ERSPC-MRI risk calculator had AUCs of 0.758 (p = 0.02) for overall PCa and 0.805 (p = 0.001) for csPCa. Both the MRI and MRI-PSMA risk calculators were superior to the ERSPC-MRI for both overall PCa and csPCa.

Conclusions

These novel risk calculators incorporate clinical and radiological parameters for stratification of men at risk of csPCa. The risk calculator including PSMA PET/CT data is superior to a calculator incorporating mpMRI data alone.

Patient summary

We evaluated a new risk calculator that uses clinical information and results from two types of scan to predict the risk of clinically significant prostate cancer on prostate biopsy. This risk model can guide patients and clinicians in shared decision-making and may help in avoiding unnecessary prostate biopsies.

The PRIMARY Score: Using intra-prostatic PSMA PET/CT patterns to optimise prostate cancer diagnosis

Background: Multi-parametric magnetic resonance imaging (mpMRI) is validated for the diagnosis of clinically significant prostate cancer (csPCa). ⁶⁸Ga-PSMA -11 PET/CT (PSMA-PET/CT) combined with mpMRI has improved negative predictive value over mpMRI alone for csPCa. The aim of this post-hoc analysis of the PRIMARY study was to evaluate the clinical significance of patterns of intra-prostatic PSMA activity, proposing a 5- point PRIMARY score to optimise accuracy of PSMA-PET/CT for csPCa in a low prevalence population. Methods: The PRIMARY trial is a prospective multi-centre phase II imaging trial that enrolled biopsy-naïve men with suspected PCa, no prior biopsy, recent mpMRI (6 months) and planned for prostate biopsy. 291 men underwent mpMRI, PSMA-PET/CT and systematic +/- targeted biopsy. The mpMRI was read separately using PI-RADS (V2). PSMA-PET/CT (pelvic only) was acquired a minimum 60 minutes post injection. PSMA-PET/CT was centrally read for pattern (diffuse transition zone (TZ), symmetrical central zone (CZ), focal TZ or peripheral zone (PZ), and intensity (SUV_max). In this post-hoc analysis, a 5-level PRIMARY score was assigned based on analysis of the central read: 1. No pattern, 2. Diffuse TZ or CZ (no focal), 3. Focal TZ, 4. Focal PZ or 5. SUV_max ≥ 12. Two further readers independently assigned a PRIMARY score to 118 scans for inter-rater agreement. Associations between PRIMARY score and csPCa (ISUP≥2) were evaluated. Results: Of 291 men enrolled, 162 (56%) had csPCa. PRIMARY score-1 was present in 16% (47), score-2 in 19% (55), score-3 in 10% (29), score-4 in 40% (117) and score-5 in 15% (43). The proportion of patients with csPCa and PRIMARY score 1 to 5 was 8.5% (4/47), 27% (15/55), 38% (11/29), 76% (89/117) and 100% (43/43) respectively. Sensitivity, specificity, PPV and NPV for PRIMARY score 1,2 (low-risk patterns) vs PRIMARY score 3-5 (high-risk patterns) was 88%, 64%, 76% and 81%, compared to 83%, 53%, 69% and 72% for PI-RADS (2 vs 3-5) on mpMRI. The inter-rater agreements for PRIMARY score 1,2 vs. PRIMARY score 3-5 was 0.76 (CI: 0.64-0.88) and 0.64 (CI: 0.49-0.78). Conclusion: A PRIMARY score incorporating intra-prostatic pattern and intensity on PSMA-PET/CT shows potential with high diagnostic accuracy for csPCa. Further validation is warranted prior to implementation.

The Additive Diagnostic Value of Prostate-specific Membrane Antigen Positron Emission Tomography Computed Tomography to Multiparametric Magnetic Resonance Imaging Triage in the Diagnosis of Prostate Cancer (PRIMARY): A Prospective Multicentre Study

BACKGROUND

Multiparametric magnetic resonance imaging (MRI) is validated for the detection of clinically significant prostate cancer (csPCa), although patients with negative/equivocal MRI undergo biopsy for false negative concerns. In addition, ⁶⁸Ga-PSMA-11 positron emission tomography/computed tomography (prostate-specific membrane antigen [PSMA]) may also identify csPCa accurately.

OBJECTIVE

This trial aimed to determine whether the combination of PSMA + MRI was superior to MRI in diagnostic performance for detecting csPCa.

DESIGN, SETTING, AND PARTICIPANTS

A prospective multicentre phase II imaging trial was conducted. A total of 296 men were enrolled with suspected prostate cancer, with no prior biopsy or MRI, recent MRI (6 mo), and planned transperineal biopsy based on clinical risk and MRI. In all, 291 men underwent MRI, pelvic-only PSMA, and systematic ± targeted biopsy.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Sensitivity, specificity, and predictive values (negative predictive value [NPV] and positive predictive value) for csPCa were determined for MRI, PSMA, and PSMA + MRI. PSMA + MRI was defined as negative for PSMA negative Prostate Imaging Reporting and Data System (PI-RADS) 2/3 and positive for either MRI PI-RADS 4/5 or PSMA positive PI-RADS 2/3; csPCa was any International Society of Urological Pathology (ISUP) grade group ≥2 malignancy.

RESULTS AND LIMITATIONS

Of the patients, 56% (n = 162) had csPCa; 67% had PI-RADS 3-5, 73% were PSMA positive, and 81% were combined PSMA + MRI positive. Combined PSMA + MRI improved NPV compared with MRI alone (91% vs 72%, test ratio = 1.27 [1.11-1.39], p < 0.001). Sensitivity also improved (97% vs 83%, p < 0.001); however, specificity was reduced (40% vs 53%, p = 0.011). Five csPCa cases were missed with PSMA + MRI (four ISUP 2 and one ISUP 3). Of all men, 19% (56/291) were PSMA + MRI negative (38% of PI-RADS 2/3) and could potentially have avoided biopsy, risking delayed csPCa detection in 3.1% men with csPCa (5/162) or 1.7% (5/291) overall.

CONCLUSIONS

PSMA + MRI improved NPV and sensitivity for csPCa in an MRI triaged population. Further randomised studies will determine whether biopsy can safely be omitted in men with a high clinical suspicion of csPCa but negative combined imaging.

PATIENT SUMMARY

The combination of magnetic resonance imaging (MRI) + prostate-specific membrane antigen positron emission tomography reduces false negatives for clinically significant prostate cancer (csPCa) compared with MRI, potentially allowing a reduction in the number of prostate biopsies required to diagnose csPCa.

The application of theranostics in different stages of prostate cancer

Despite the remarkable achievements in treating metastatic prostate cancer over the last two decades, castrate-resistant status is still considered the lethal stage of the disease. Theranostics combines a targeting compound (ligand) with a therapeutic radioisotope (radioactive particle) injected into the blood to target the cancer cells. The most studied radioligand is ¹⁷⁷Lu-PSMA-617, which targets PSMA, a protein found in prostate cancer cells. This new approach has shown promising results in treating metastatic castration-resistant prostate cancer. Currently, many trials are using PSMA-targeting radioligands in combination with conventional therapies in advanced prostate cancer or even in the earlier stages of the disease. Other preclinical trials are exploring the possibility of using newer ligands or radioisotopes to treat prostate cancer to increase the specificity and efficacy of this treatment.

Study of the dosimetry, safety, and potential benefit of 177Lu-PSMA-617 radionuclide therapy prior to radical prostatectomy in men with high-risk localized prostate cancer (LuTectomy study)

TPS264

Background: High-risk localised prostate cancer (HRCaP) is treated by radical prostatectomy (RP) or radiotherapy. Despite curative intent, a significant number of men will progress with metastatic disease or local recurrence. Lutetium-177 radiolabelled to the small molecule PSMA-617 targeting prostate-specific membrane antigen (Lu-PSMA) has proven efficacious in men with metastatic castration-resistant prostate cancer who have progressed after standard-of-care. The LuTectomy trial evaluates whether administration of Lu-PSMA before radical prostatectomy in men with HRCaP will deliver high doses of radiation to the prostate and involved lymph nodes. It also aims to assess the feasibility, safety profile and oncological efficacy of Lu-PSMA. Methods: Lutectomy is an open-label, phase I/II non-randomised clinical trial. 20 men with HRCaP defined by European Association of Urology who are scheduled for RP and pelvic lymph node dissection (PLND) will be recruited. All men will have high PSMA-avidity with a standardised uptake value (SUVmax) of ≥ 20 on 68Ga-PSMA PET/CT. The initial 10 participants will receive one cycle of 5GBq Lu-PSMA intravenously and the latter 10 men will receive two cycles of 5GBq Lu-PSMA per cycle six weeks apart. RP with PLND will be performed six weeks later. Participants will be followed up for three years. The primary outcome is to determine the radiation absorbed dose in the prostate and involved lymph nodes. Three-time point quantitative single-photon emission computed tomography (SPECT/CT) will be used to estimate radiation dosimetry using a voxelated technique incorporating partial volume correction. Marrow absorbed dose will also be evaluated using serial blood measures to model pharmacokinetic clearance with a multi-phase exponential model. Translational research samples will include the original biopsy, prostatectomy specimen and plasma/whole blood samples. Secondary objectives include evaluation of the PSMA PET/CT imaging response (defined by SUVmax decline >30%), PSA response, pathological response following Lu-PSMA, adverse effects of Lu-PSMA, surgical safety, and health-related quality of life. Post estimates for time-to-event endpoints will be estimated using the Kaplan-Meier method. The first patient was recruited in July 2020 and recruitment is expected to take up to two years. ClinicalTrials.gov Identifier: NCT04430192. Funding: Movember and Medical Research Future Fund (MRFF), Endocyte Inc., a Novartis Company, E.J. Whitten Foundation. Clinical trial information: NCT04430192.

Navigating systemic therapy for metastatic castration-naïve prostate cancer

INTRODUCTION

The last decade has seen a remarkable shift in the treatment landscape of advanced prostate cancer, none more so than in the management of metastatic castration-naïve disease.

METHODS

This narrative review will examine existing and emerging evidence supporting systemic therapy use for metastatic castration-naïve prostate cancer (mCNPC) and provide guidance on the selection of these agents with respect to optimising patient outcomes.

RESULTS

The addition of either docetaxel (chemohormonal approach) or an AR pathway inhibitor (abiraterone, enzalutamide or apalutamide) is a reasonable standard of care option for men commencing long-term ADT for mCNPC. While the issue of disease volume as a predictive biomarker for docetaxel benefit has previously been debated, recent data support consideration of upfront docetaxel in all patients, regardless of metastatic burden. Decisions regarding systemic treatment for men with mCNPC should be based on comprehensive consideration of disease, patient and logistical factors. Multiple novel therapeutics for mCNPC are currently under active investigation.

CONCLUSION

The introduction of potent systemic therapy earlier in the mCNPC disease course has resulted in dramatic improvements in clinical outcomes for patients. As the management of mCNPC continues to evolve, the future remains promising, with the expectation of ongoing improvements to patient outcomes and quality of life.

Indirect Comparisons of Efficacy between Combination Approaches in Metastatic Hormone-sensitive Prostate Cancer: A Systematic Review and Network Meta-analysis

CONTEXT

There have been substantial changes in the management of men with metastatic hormone-sensitive prostate cancer (mHSPC) over the past 5 yr, with upfront combination therapies replacing androgen-deprivation therapy (ADT) alone. A range of therapies have entered the space with no clear answer regarding their comparative efficacy.

OBJECTIVE

To perform a systematic review and network meta-analysis to characterise the comparative efficacy of combination approaches in men with mHSPC.

EVIDENCE ACQUISITION

We searched multiple databases and abstracts of major meetings up to June 2019 for randomised trials of patients receiving first-line therapy for metastatic disease, a combination of ADT and one (or more) of taxane-based chemotherapy, and androgen receptor-targeted therapies. The primary endpoint was overall survival (OS) and we evaluated progression-free survival as a secondary outcome. We performed subgroup analysis based on the volume of disease.

EVIDENCE SYNTHESIS

We found seven trials that met our eligibility criteria using either docetaxel, abiraterone acetate, enzalutamide, or apalutamide in combination with ADT. All agents in combination with ADT were shown to be superior to ADT alone; enzalutamide + ADT had the lowest absolute hazard ratio compared with ADT only (hazards ratio 0.53, 95% confidence interval 0.37-0.75), and an estimated 76.9% probability that it is the preferred treatment to prolong OS compared with other combination treatments, or with ADT alone. Enzalutamide appeared to have better OS compared with docetaxel in men with low-volume disease, but there was no difference in other comparisons.

CONCLUSIONS

Combination therapy with any of docetaxel, abiraterone acetate, enzalutamide, or apalutamide provides a significant OS benefit when compared with ADT alone. We did not identify significant differences in OS between different combination therapies. Subtle differences between these options provide clinicians considerable flexibility when selecting options for individual patients.

PATIENT SUMMARY

Many men with metastatic, hormone-sensitive prostate cancer should be managed with upfront combination therapy instead of androgen-deprivation therapy alone. Clinicians may consider many factors during the decision-making process, and thus management should be tailored for patients individually.

The Role of Local Therapy for Oligometastatic Prostate Cancer: Should We Expect a Cure?

The role of local treatment in oligometastatic prostate cancer remains contentious. Treatment of the prostate in metastatic disease may confer benefit, but prospective data are lacking. With improvements in treatments, aggressive strategies directed at metastases have increasingly become of clinical interest. Current evidence suggests good local control can be achieved; however, further data are required to determine overall cancer outcomes. This article evaluates the evidence available and consider whether local treatment of oligometastatic disease is a feasible, safe, and a positive strategy in this disease cohort. Cure should not be expected, although prolonged disease and treatment-free survival may be observed.