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.

Clinical impact of Prostate-Specific Membrane Antigen Positron Emission Tomography (PET) on intensification or deintensification of advanced renal cell carcinoma management

PURPOSE

There is an emerging role of the use of Prostate-Specific Membrane Antigen (PSMA) Positron Emission Tomography (PET) in renal cell carcinoma. Herein, we report our experience in use of PSMA PET in recurrent or metastatic renal cell carcinoma (RCC).

METHODS

A retrospective analysis of all patients who underwent PSMA PET for suspected recurrent or de-novo metastatic RCC between 2015 and 2020 at three institutions was performed. The primary outcome was change in management (intensification or de-intensification) following PSMA PET scan. Secondary outcomes included histopathological correlation of PSMA avid sites, comparison of sites of disease on PSMA PET to diagnostic CT and time to systemic treatment.

RESULTS

Evolution: Phase II study of radionuclide 177Lu-PSMA-617 therapy versus 177Lu-PSMA-617 in combination with ipilimumab and nivolumab for men with metastatic castration-resistant prostate cancer (mCRPC; ANZUP 2001)

TPS271

Background: Combination immune checkpoint inhibitors (ICI) with ipilimumab and nivolumab has been shown to induce adaptive immune responses in patients with mCRPC, albeit resulting in modest clinical benefit. There is growing evidence that radiation may enhance the activity of ICI by modulating the tumour immune microenvironment. We hypothesize that the radionuclide 177Lu-PSMA-617 may result in immunogenic cell death and therefore synergise with combination ICI to improve long term clinical outcomes. EVOLUTION aims to determine the activity and safety of ipilimumab and nivolumab in combination with 177Lu-PSMA-617 in patients with mCRPC. Methods: This open label, multicentre, phase 2 study will randomly assign 100 participants with mCRPC in a 2:1 ratio stratified by site and prior exposure to docetaxel to either: the experimental combination of 177Lu-PSMA-617 7.5 GBq every 6 weeks for up to 6 doses plus ipilimumab 3 mg/kg every 6 weeks x 4 doses and nivolumab 1 mg/kg every 3 weeks x 8 doses during induction, followed by nivolumab 480 mg every 4 weeks x 18 doses during maintenance or 177Lu-PSMA-617 alone. Key eligibility criteria include progression on prior androgen receptor pathway inhibitors, no more than one line of prior chemotherapy, significant PSMA avidity on 68GaPSMA-11 PET/CT (SUVmax ≥15 at one disease site and SUVmax ≥10 at measurable sites of disease > 10 mm), no FDG positive/PSMA negative disease and no contraindications to ICI. The primary endpoint is 12-month PSA progression-free survival (PSA-PFS). Secondary endpoints are PSA response rate, adverse events, radiographic-PFS, overall survival, objective response rate, duration of response and health-related quality of life. Correlative studies will evaluate exploratory biomarkers as potential predictive/prognostic factors. Assessments include clinical reviews and blood tests at baseline, then every 3-4 weeks; CT and bone scan at baseline, then every 12 weeks; 68Ga-PSMA-11 and 18F FDG PET/CTs at baseline; 68Ga-PSMA-11 PET/CT at week 24 and 177Lu-PSMA-617 SPECT/CT 24 hours after each 177Lu-PSMA-617 dose. Translational bloods include circulating tumour DNA and peripheral blood mononuclear cells collected at baseline, weeks 13 and 25, and at radiological progression. Optional fresh biopsies will be collected at baseline, weeks 3-5 and at progression. A sample size of 100 provides 90% power at the 10% level of significance to reject the null hypothesis (that 1 year PSA-PFS is 20%) if the alternative hypothesis is true (that 1 year PSA-PFS is 35%). Accrual as of the 11th of October 2022 is 23. Clinical trial information: NCT05150236 .

Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) compared to computed tomography (CT) for advanced renal cell carcinoma (RCC)

4540

Background: There is emerging role of the use of PSMA PET in RCC. Herein, we report our experience in use of PSMA PET in recurrent or metastatic RCC in Brisbane, Australia. Methods: Patients (pts) who underwent PSMA PET and conventional diagnostic CT for metastatic or recurrent RCC between 2015 and 2020 at three institutions were identified. Retrospective chart reviews were conducted using standardized collection template. The outcomes included percentage of patients who had a change in management secondary to PSMA PET findings, comparison of metastasis detection for PSMA PET vs. CT, and biopsy histology of PSMA avid sites. Results: 42 PSMA PET were performed in 40 patients. 10 pts (25%) and 30 pts (75%) had PSMA PET in the metastatic disease and recurrent disease setting, respectively. Table 1 highlights demographics. Overall, 12 pts (30%, n=3 metastatic, n=9 recurrent) had a change in management following PSMA PET. In the metastatic disease group, 2 pts (20%) underwent initial systemic therapy (after histological confirmation) due to higher burden of disease shown with PSMA PET than CT, while systemic therapy was changed for 1 pt (10%). In the recurrent disease group, PSMA improved delineation of suspected recurrence (compared to CT) resulting in resection rather than surveillance (n=4; 13%) or change in surgical approach for resection (n=1; 3%). PSMA PET distribution showed more metastatic sites than CT leading to systemic therapy rather than resection of recurrence (n=2; 7%), while absent PSMA activity for suspected recurrence on CT led to surveillance rather than resection (n=2; 7%). PSMA PET detected more sites of metastases compared with conventional scan in 6 pts (60%) with metastatic disease and in 9 pts (30%) with recurrent disease. 26 pts had biopsy of PSMA avid sites. Majority of pts had confirmed recurrence of clear cell renal carcinoma (n= 22; 85%). Other histology included sarcomatoid renal cell carcinoma (n=2; 8%), carcinoid (n=1; 4%), and urothelial cancer (n=1; 4%). In 2 instances, biopsy/resection was performed of a suspected recurrence on CT that was not PSMA avid, and neither showed malignancy. Conclusions: PSMA PET detected more accurately metastatic and recurrent disease, with high pathological concordance, to result in change in management for 30% of patients. Prospective study is warranted to further investigate the utility of PSMA PET scan in advanced RCC.[Table: see text]

PRINCE: Phase I trial of 177Lu-PSMA-617 in combination with pembrolizumab in patients with metastatic castration-resistant prostate cancer (mCRPC)

5017

Background: The VISION and TheraP trials have established the safety and efficacy of 177Lu-PSMA-617 in mCRPC with a 50% PSA response rate (PSA50-RR) of 46% and 66% and median progression free survival (PFS) of 8.7 and 5.1 months, respectively. More effective treatments are required as disease progression remains universal. Immunotherapy has limited single-agent efficacy in mCRPC. We hypothesise that by potentially inducing immunogenic cell death, 177Lu-PSMA-617 may act synergistically with pembrolizumab, an anti-programmed death 1 inhibitor, to enhance the depth and durability of response. PRINCE is a Phase I trial evaluating the safety and efficacy of this combination. Methods: mCRPC patients with high PSMA expression (SUVmax ≥ 20 in an index lesion, SUVmax > 10 for all lesions ≥ 10mm), and no FDG+ve/PSMA-ve lesions on paired baseline PET/CT screening, received up to 6 cycles of 177Lu-PSMA-617 (starting at 8.5 GBq, reducing by 0.5 GBq with each cycle) every 6 weeks in conjunction with 200mg of pembrolizumab every 3 weeks for up to 2 years. Response evaluation was undertaken as per PCWG3 and RECIST criteria. Co-primary endpoints were safety and PSA50-RR. Secondary endpoints included PSA-PFS, radiographic PFS (rPFS), overall survival (OS), and patient reported outcomes (PROs). This analysis was undertaken after the last patient had 12 months follow-up. Results: 37 patients (median age 72 years; prior docetaxel 73%; prior androgen receptor targeted agent 100%) received a median of 5 cycles (range: 2 to 6) of 177Lu-PSMA-617 and 12 doses (range: 6 to 19) of pembrolizumab. The median follow up was 16 months. PSA50-RR was 76% (28/37 [95% CI 59-88]) and 7/10 (70%) patients with RECIST-measurable disease had a partial response. Median rPFS, PSA-PFS and OS was 11.2 months (95% CI: 5.1-14.1), 8.2 months (95% CI: 5.1-11.2) and 17.8 months (95% CI:13.4-not estimable). 12-month rPFS and OS was 38% (95% CI: 22-54) and 83% (95% CI: 67-92), respectively. Common (≥10%) treatment-related adverse events (TRAE) were mainly Grade (G) 1-2, including xerostomia (78%), fatigue (43%), pruritus (27%), nausea (27%), rash (24%), diarrhoea (14%), anorexia (16%), thrombocytopenia (16%), elevated ALT (11%), arthralgia (11%) and a flare in bone pain (11%). Haematologic TRAEs included G2-3 anaemia (8%), G1-2 thrombocytopenia (16%), and G1 neutropenia (3%). G3 immune-related AEs occurred in 10 (27%) patients with no dominant manifestation. 5 (14%) patients discontinued pembrolizumab due to toxicity. PROs including BPI-SF and FACT-P were stable throughout the study. Conclusions: The combination of 177Lu-PSMA-617 and pembrolizumab had promising activity. Toxicities were generally consistent with those of single-agent 177Lu-PSMA-617 and pembrolizumab and were not clearly augmented by combination use. No new safety concerns were observed. Clinical trial information: NCT03658447.

UpFrontPSMA: a randomized phase 2 study of sequential 177 Lu-PSMA-617 and docetaxel vs docetaxel in metastatic hormone-naïve prostate cancer (clinical trial protocol)

OBJECTIVE

To assess the activity and safety of sequential lutetium-177 (¹⁷⁷ Lu)-PSMA-617 and docetaxel vs docetaxel on a background of androgen deprivation therapy (ADT) in men with de novo metastatic hormone-naïve prostate cancer (mHNPC).

PATIENTS AND METHODS

UpFrontPSMA (NCT04343885) is an open-label, randomized, multicentre, phase 2 trial, recruiting 140 patients at 12 Australian centres. Key eligibility criteria include: prostate cancer with a histological diagnosis within 12 weeks of screening commencement; prostate-specific antigen (PSA) >10 ng/mL at diagnosis; ≤4 weeks on ADT; evidence of metastatic disease on computed tomography (CT) and/or bone scan; high-volume prostate-specific membrane antigen (PSMA)-avid disease with a maximum standardized uptake value >15; and absence of extensive discordant fluorodeoxyglcuose (FDG)-positive, PSMA-negative disease. ⁶⁸ Ga-PSMA-11 and ¹⁸ F-FDG positron-emission tomography (PET)/CT undergo central review to determine eligibility. Patients are randomized 1:1 to experimental treatment, Arm A (¹⁷⁷ Lu-PSMA-617 7.5GBq q6w × 2 cycles followed by docetaxel 75 mg/m² q3w × 6 cycles), or standard-of-care treatment, Arm B (docetaxel 75 mg/m² q3w × 6 cycles). All patients receive continuous ADT. Patients are stratified based on disease volume on conventional imaging and duration of ADT at time of registration. The primary endpoint is the proportion of patients with undetectable PSA (≤0.2 ng/L) at 12 months after study treatment commencement. Secondary endpoints include safety, time to castration resistance, overall survival, PSA and radiographic progression-free survival, objective tumour response rate, early PSMA PET response, health-related quality of life, and frequency and severity of adverse events. Enrolment commenced in April 2020.

RESULTS AND CONCLUSIONS

The results of this trial will generate data on the activity and safety of ¹⁷⁷ Lu-PSMA-617 in men with de novo mHNPC in a randomized phase 2 design.

Role of PSMA PET/CT imaging in the diagnosis, staging and restaging of prostate cancer

Prostate-specific membrane antigen (PSMA) PET/CT is a novel imaging technique for the detection and staging of either primary or recurrent prostate cancer. Early studies demonstrated its improved sensitivity and specificity over and in combination with other currently employed imaging techniques, such as multiparametric MRI, bone scan, PET and CT. However, the lack of strength and confidence in these studies has meant incorporation of PSMA PET/CT into clinical guidelines and practice has been limited to date. In response, a number of high-quality prospective studies have recently emerged and reflect exciting results seen in preceding publications. Here we recount some of the key earlier publications, report results from the latest studies and look to the future discussing some of the eagerly awaited ongoing clinical trials.

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.

UpFrontPSMA: A randomized phase II study of sequential 177Lu-PSMA617 and docetaxel versus docetaxel in metastatic hormone-naïve prostate cancer (mHNPC)

TPS180

Background: 177Lu‐PSMA-617 (Lu-PSMA) is a radiolabeled small-molecule that binds with high affinity to PSMA enabling highly targeted delivery of beta radiation to prostate cancer cells. In metastatic castration-resistant prostate cancer, Lu-PSMA showed superior activity to Cabazitaxel in the TheraP trial. Although androgen deprivation therapy (ADT) + Docetaxel is a standard of care for de novo high-volume mHNPC, outcomes remain sub-optimal for many patients. We hypothesize that Lu-PSMA prior to docetaxel will achieve a higher undetectable PSA rate at 12 months compared to docetaxel alone in men with newly-diagnosed high-volume mHNPC. Methods: UpFrontPSMA is an open label, randomized, stratified, 2-arm, multi-center, phase 2 clinical trial recruiting 140 patients at 11 Australian centers. Key eligibility criteria include histological diagnosis of prostate cancer within 12 weeks, PSA > 10ng/ml at diagnosis, < 4 weeks on ADT, and high-volume (≥ 4 bone metastases with ≥ 1 outside the axial skeleton, and/or visceral metastases), PSMA-avid disease on 68Ga-PSMA-11 PET/CT with no major discordance on 18FDG-PET/CT. Patients will be randomized 1:1 to the experimental arm (Lu-PSMA 7.5 GBq q6w x 2 cycles followed 6 weeks later by docetaxel 75mg/m2 q3w x 6 cycles), or standard-of-care Arm (docetaxel alone). All patients will receive continuous ADT. Assessments will be done every 3 weeks during study treatment, and then every 6-12 weeks until unequivocal disease progression. CT and whole body bone scan will be performed at baseline and every 12 weeks, 68Ga-PSMA-11 PET/CT at baseline and 12 weeks, and 18FDG-PET/CT at baseline and 12 weeks (if applicable). Correlative samples will include optional tumour tissue (baseline and disease progression), and serial plasma/whole blood collection. The primary endpoint is undetectable PSA (≤ 0.2 ng/ml) at 12 months. Secondary endpoints are safety, time to castration resistance, PSA-progression-free-survival (PSA-PFS), radiographic PFS, radiographic response rates, early PSMA-PET response rates, quality of life and overall survival. Exploratory endpoints are prognostic and predictive value of PET-derived parameters and of biomarkers identified in plasma/whole blood/tumour tissue. The study will have 85% power to reject the null hypothesis if the true 12 month undetectable PSA rate in the experimental Arm is 50%. The power calculation assumes no more than 10 patients (7%) of the 140 patients will be unevaluable or lost to follow-up in 1 year, 5% alpha and two-sided test for proportions. As of October 13, 2020, accrual stands at 4. UpFrontPSMA is an investigator-led, academic trial sponsored by Peter MacCallum Cancer Centre in collaboration with ANZUP Cancer Trials Group with study coordination provided by the Centre for Biostatistics and Clinical Trials (BaCT) Clinical trial information: NCT04343885.

Actinium-225 Prostate-specific Membrane Antigen Theranostics: Will α Beat β?

Optimisation of prostate-specific membrane antigen (PSMA) based radioligand therapy (RLT) requires a focus on prospective trials.

A role of PSMA PET/CT in multimodality imaging approach in adenoid cystic carcinoma

Adenoid cystic carcinoma is a rare disease and characterised by slow but unrelenting local progression and risk of haematogenous metastases. We present a case of locally unresectable disease where PSMA PET/CT provided complementary staging and early treatment response assessment.