Influence of metastatic sites and burden on oncological outcomes in patients progressing to metastatic castration resistant prostate cancer.

PURPOSE: Metastatic castration-resistant prostate cancer (mCRPC) patients harbor reduced life expectancy after first-line treatment progression. Currently, no information is available regarding the influence of metastatic sites and osseous burden on progression-free (PFS) and overall survival (OS) of mCRPC patients. METHODS: We relied on the Frankfurt Metastatic Cancer Database of the Prostate (FRAMCAP) database to select patients progressing to mCRPC and stratified them according to lymph node vs. osseous vs. visceral metastatic sites. Moreover, we stratified osseous mCRPC patients regarding the number of metastatic lesions. Endpoints were PFS and OS in uni- and multivariable Cox regression models. RESULTS: Of 363 patients, 9.4% harbored M1a vs. 78% M1b vs. 12% M1c mCRPC with significantly higher PSA in M1b (9 vs. 22 vs. 8ng/ml). Rates of DeNovo (15% vs. 60% vs. 56%) were significantly lower in the M1a mCRPC group, compared to M1b and M1c (p < 0.001). In PFS analyses, a median of 12.7 vs. 10.1 vs. 15.9 months for M1a vs. M1b vs. M1c mCRPC was observed (p > 0.05). In multivariable Cox regression models, M1c mCRPC was independently at higher risk for progression (hazard ratio [HR]: 5.93, p = 0.048), relative to M1a. Regarding OS, significant differences were observed (p = 0.002), with median OS of 58 vs. 42 vs. 25 months for M1a vs. M1b vs. M1c mCRPC and corresponding HRs of 1.54 (p = 0.11) and 2.76 (p < 0.01). In multivariable models M1c mCRPC was associated with higher risk of death (HR: 3.56, p = 0.049), relative to M1a. No differences were observed after stratification according to number of bone lesions (all p ≥ 0.05). CONCLUSION: M1c mCRPC patients are independently at higher risk for progression and death, while M1a patients harbor best cancer-control outcomes.

The Association of Statin Use With Survival Outcomes in Patients With Metastatic Castration-Resistant Prostate Cancer (mCRPC) Treated With Androgen Receptor Targeted Therapies (ART).

BACKGROUND: Statins may provide a compounded effect on ART by decreasing cholesterol levels thus decreasing de novo androgen synthesis and tumor cell viability. We investigated the clinical efficacy of concurrent statin use on outcomes of patients with mCRPC taking ART. METHODS: A single-institution retrospective analysis of patients with mCRPC receiving ART from 2010 to 2021 was performed. Our primary outcome was PSA progression free survival (PFS), and our secondary outcomes were overall survival (OS). Patient characteristics were collected in addition to ART treatment course, statin treatment, and survival outcomes. Cox proportional hazards regression model was used to estimate hazard ratios (HR) for OS and PSA PFS and multivariable logistic regression to determine risk factors. RESULTS: 153 patients with mCRPC treated with ART were included. A total of 67 patients (43.8%) received concurrent statins. Median PSA PFS was 20.4 months for patients that received statins versus 15.3 months for patients who did not receive statins. Median OS was 45.1 months for patients who received concurrent statins versus 29.7 months for patients who did not. On univariate and multivariate survival analyses, there was no statistically significant difference between groups for PSA PFS (HR 0.7; CI 0.44-1.1; P = .123) and OS (HR 0.67; CI 0.42-1.06; P = .089). CONCLUSIONS: Our analysis suggests that statins do not significantly improve clinical outcomes in patients with mCRPC. Ultimately, current understanding remains limited, and prospective studies are needed, but here we provide a cost-effective, timely, and selective preliminary analysis.

PSMA PET/CT for treatment response evaluation at predefined time points is superior to PSA response for predicting survival in metastatic castration-resistant prostate cancer patients.

BACKGROUND: In metastatic castration-resistant prostate cancer (mCRPC), using serum prostate-specific antigen (PSA) levels to evaluate treatment response is not always accurate. This study aimed to assess the efficacy of PSMA PET/CT at specific time points for evaluating treatment response and predicting survival in mCRPC patients, compared to PSA. METHODS: Sixty mCRPC patients underwent [18F]PSMA-1007 PET/CT at baseline and for treatment response evaluation of either androgen receptor-targeted agents (after 3 months) or chemotherapy (after completion), and were retrospectively analysed. Visual assessment categorised overall response and response of the worst responding lesion as partial response, stable disease, or progressive disease, using the EAU/EANM criteria. Additionally, percentage changes in SUVmax, total tumour volume and total lesion uptake (tumour volume * SUVmean) were calculated. PSA response was defined according to the PCWG3 criteria. Cox regression analysis identified predictors of overall survival. RESULTS: PSMA PET/CT and PSA response were discordant in 47 % of patients, and PSMA PET/CT response was worse in 89 % of these cases. Overall response on PSMA PET/CT independently predicted overall survival (progression versus non-progression: HR = 4.05, p < 0.001), outperforming PSA response (progression versus non-progression: HR = 2.53, p = 0.010) and other PSMA PET/CT parameters. Among patients with a PSA decline of > 50 %, 31 % showed progressive disease on PSMA PET/CT, correlating with higher mortality risk (progression versus non-progression: HR = 4.38, p = 0.008). No flare in PSMA uptake was observed in this cohort. CONCLUSIONS: PSMA PET/CT for assessing treatment response at predefined time points was superior to PSA-based response for predicting overall survival in mCRPC patients treated with androgen receptor-targeted agents and chemotherapy. PSMA PET/CT showed the ability to detect disease progression earlier than PSA levels, which can affect treatment decisions and has the potential to improve patient outcomes. We recommend further research to validate these findings in larger patient cohorts, to extend the number of treatments, and to evaluate cost-effectiveness and impact on patient outcomes.

Assessment of Different Castration Resistance Definitions and Staging Modalities in Metastatic Castration-Resistant Prostate Cancer.

Background/Objectives: Progression to metastatic castration-resistant prostate cancer (mCRPC) is defined either biochemically, radiographically or both. Moreover, staging for mCRPC can be performed either conventionally or with molecular imaging such as prostate-specific membrane antigen computer tomography (PSMA-PET/CT). Methods: We relied on the Frankfurt Metastatic Cancer Database of the Prostate (FRAMCAP) database to compare progression-free (PFS) and overall survival (OS) outcomes regarding the cause of castration resistance and the staging modality used. Results: Overall, 35% progressed to mCRPC biochemically vs. 23% radiographically vs. 42% biochemically + radiographically. The PSA nadir in mHSPC (1.4 vs. 0.4 vs. 0.8 ng/mL) and PSA level at mCRPC progression (15 vs. 2 vs. 21 ng/mL, both p ≤ 0.01) were significantly higher for biochemical vs. radiographic vs. both progressed patients. In PFS and OS analyses, no significant differences were observed among all three compared groups. In the comparison of the staging used for progression to mCRPC, 67% received conventional vs. 33% PSMA-PET/CT, with higher metastatic burden in mHSPC and osseous lesions in mCRPC for conventionally staged patients (both p < 0.01). In PFS (15.3 vs. 10.1 months, hazard ratio [HR]: 0.75) and OS analyses (52.6 vs. 34.3 months, HR: 0.61, both p < 0.05), PSMA-PET/CT harbored better prognosis; however, this did not hold after multivariable adjustment. Similar results were observed for further analyses in second- and third-line mCRPC or patients with a PSA level of ≥2 ng/mL. Conclusions: The cause of progression to mCRPC seems not to influence cancer-control outcomes, despite important baseline tumor characteristic differences. The PSMA-PET/CT staging modality might be associated with better PFS and OS outcomes, possibly due to its more sensitive detection of progression or new metastatic lesions.

Analysis of Molecular Imaging Biomarkers Derived from [18F]FDG PET/CT in mCRPC: Whole-Body Total Lesion Glycolysis (TLG) Predicts Overall Survival in Patients Undergoing [225Ac]Ac-PSMA-617-Augmented [177Lu]Lu-PSMA-617 Radioligand Therapy.

Background/Objectives: The augmentation of [177Lu]Lu-PSMA-617 radioligand therapy by alpha emitting [225Ac]Ac-PSMA-617, known as the tandem therapy concept, is a promising escalating treatment option in advanced mCRPC. In this study, we evaluated the value of [18F]FDG PET/CT-derived molecular imaging biomarkers for predicting response and outcome to PSMA tandem RLT in n = 33 patients with insufficient response on [177Lu]Lu-PSMA-617 monotherapy. Methods: Six different molecular imaging parameters at baseline, i.e., before initiation of PSMA tandem RLT with respect to SUVmax, SUVpeak, SUV5, SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were tested for association with response and overall survival (OS). Results: After the initiation of augmentation, 24.2% of patients with a previously insufficient response experienced partial remission, and 39.4% experienced stable disease. The median OS was 7 months (95% CI: 4-11 months). None of the tested parameters were able to predict the response (all p > 0.529). In contrast, the [18F]FDG PET/CT-derived whole-body molecular imaging parameter TLG was significantly (p = 0.029) associated with OS of patients undergoing [225Ac]Ac-PSMA-617 augmented [177Lu]Lu-PSMA-617 RLT after insufficient response to [177Lu]Lu-PSMA-617 monotherapy. Conclusion: Implementing [18F]FDG PET/CT in the management of PSMA-RLT in clinical practice may contribute to outcome prediction and provide a route to more individualized management in mCRPC.

Matched-pair analysis of mCRPC patients receiving 177Lu-labeled PSMA-targeted radioligand therapy in a 4-week versus 6-week treatment interval.

BACKGROUND: The optimal regimen for 177Lu-labeled prostate-specific membrane antigen-targeted radioligand therapy, including treatment intervals, remains under study, with evidence suggesting shorter intervals could benefit patients with high disease volume and rapid progression. This retrospective analysis evaluated treatment toxicity, PSA response, PSA-progression-free survival (PSA-PFS), and overall survival (OS) in matched cohorts of mCRPC patients receiving 177Lu-PSMA-RLT at 4-week versus 6-week intervals. RESULTS: A PSA response (PSA decline ≥ 50%) was achieved in 47.8% and 21.7% of patients in the 4-week and 6-week treatment interval groups, respectively (p = 0.12). There was a trend towards longer PSA-PFS in the 4-week group compared to the 6-week group (median PSA-PFS, 26.0 weeks vs. 18.0 weeks; HR 0.6; p = 0.2). Although not statistically significant, there was a trend towards shorter OS in the 4-week group compared to the 6-week group (median OS, 15.1 months vs. 18.4 months; HR 1.3; p = 0.5). The 4-week group had a significantly greater decrease in leucocyte and platelet counts compared to the 6-week group (38.5% vs. 18.2% and 26.7% vs. 10.7%; p = 0.047 and p = 0.02). Severe adverse events were modest in both groups. CONCLUSIONS: Intensifying treatment intervals from 6 weeks to 4 weeks showed some improvements in PSA response and PSA-PFS for mCRPC patients, but did not significantly affect OS. Additionally, bone marrow reserve was significantly reduced with the intensified regimen. Therefore, the overall benefit remains uncertain, and further prospective studies are needed to compare 4-week and 6-week intervals regarding toxicity, treatment response, and outcome.

Prognostic Role of PSMA-Targeted Imaging in Metastatic Castration-Resistant Prostate Cancer: An Overview.

OBJECTIVES: Prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) has gained a primary role in prostate cancer (PCa) imaging, overcoming conventional imaging and prostate-specific antigen (PSA) serum levels, and has recently emerged as a promising technique for monitoring therapy response in metastatic castration-resistant prostate cancer (mCRPC) patients treated with novel hormonal therapy, taxanes, and radioligand therapy (RLT). In this review, we aim to provide an overview of the most relevant aspects under study and future prospects related to the prognostic role of PSMA PET/CT in mCRPC. METHODS: A systematic literature search was performed in the following databases: MEDLINE, PubMed, and EMBASE databases. The study focused exclusively on English-language studies, excluding papers not pertinent to the topic. RESULTS: PSMA PET imaging offers a higher sensitivity and specificity than conventional imaging and provides accurate staging and efficient diagnosis of distant metastases. The data presented herein highlight the usefulness of PET in risk stratification, with a prognostic potential that can have a significant impact on clinical practice. Several prospective trials are ongoing and will shortly provide more evidence supporting the prognostic potential of PET PSMA data in this clinical scenario. CONCLUSIONS: Current evidence proves the prognostic role of PSMA PET/CT in different settings, with raising relevance also in the context of mCRPC.

Outcomes for Patients with Metastatic Castration-Resistant Prostate Cancer and Liver Metastasis Receiving [177Lu]Lu-PSMA-617.

It is well known that patients with liver metastasis from metastatic castration-resistant prostate cancer have poor or only transient responses to many forms of systemic therapy. Data on outcomes after treatment with [177Lu]Lu-PSMA-617 (LuPSMA) are scarce. The VISION trial reports a hazard ratio for overall survival (OS) in the subgroup of patients with liver metastasis without disclosing the absolute duration of survival. Using real-world clinical data, we examined this important subgroup of patients, describing prostate-specific antigen (PSA) response and OS. Methods: A single-institution database was assembled to include all patients receiving LuPSMA at Mayo Clinic in Rochester, Minnesota, for whom treatment was initiated between March 2022 and March 2023. Baseline clinicopathologic and imaging characteristics were abstracted. Patients were then categorized by presence or absence of liver metastasis on pretreatment prostate-specific membrane antigen (PSMA) PET. PSA response and OS for the 2 groups (liver metastasis vs. no liver metastasis) were compared using χ2 testing and the Kaplan-Meier method, respectively. A multivariate Cox regression analysis was performed, including established prognostic factors. Finally, those with pretreatment circulating tumor DNA as determined in an 83-gene panel were assessed for the presence of pathogenic and likely pathogenic alterations. These findings were summarized using descriptive statistics and compared between the 2 cohorts using the Fisher exact test. Results: The overall cohort consisted of 273 patients, including 43 (15.75%) with liver metastasis on pretreatment PSMA PET/CT. The median number of cycles received was 3 (range, 1-6) for patients with liver metastasis and 5 (range, 1-6) for those without hepatic involvement. The 50% or greater reduction in PSA from baseline response rate was lower for those with liver metastasis than for those without (30.23% [13/43] vs 49.77% [106/213], P = 0.019). At a median follow-up of 10 mo (interquartile range, 9-13 mo), there was a significant difference in median OS (8.35 mo vs. not reached, P < 0.001). On multivariate analysis, the presence of liver metastasis was independently associated with shorter survival (hazard ratio, 4.06; P < 0.001). Conclusion: Our data suggest that the presence of liver metastasis predicts poorer outcomes in patients receiving LuPSMA treatment. Alternative and combination approaches should be explored to maximize the antitumor activity of radiopharmaceutical therapy in the liver.

Multivariable models of outcomes with [177Lu]Lu-PSMA-617: analysis of the phase 3 VISION trial.

Background: [177Lu]Lu-PSMA-617 (177Lu-PSMA-617) prolonged life in patients with metastatic castration-resistant prostate cancer (mCRPC) in VISION (NCT03511664). However, distinguishing between patients likely and unlikely to respond remains a clinical challenge. We present the first multivariable models of outcomes with 177Lu-PSMA-617 built using data from VISION, a large prospective phase 3 clinical trial powered for overall survival. Methods: Adults with progressive post androgen receptor pathway inhibitor and taxane prostate-specific membrane antigen (PSMA)-positive mCRPC received 177Lu-PSMA-617 plus protocol-permitted standard of care (SoC) or SoC alone. In this post hoc analysis, multivariable Cox proportional hazards models of overall survival (OS) and radiographic progression-free survival (rPFS), and a logistic regression model of prostate-specific antigen response (≥50% decline; PSA50) were constructed and evaluated using C-index or receiver operating characteristic (ROC) analyses with bootstrapping validation. Nomograms were constructed for visualisation. Findings: Patients were randomised between June 2018 and October 2019. Data from all 551 patients in the 177Lu-PSMA-617 arm were analysed in multivariable modelling. The OS nomogram (C-index, 0.73; 95% confidence interval [CI], 0.70-0.76) included whole-body maximum standardised uptake value (SUVmax), time since diagnosis, opioid analgesic use, aspartate aminotransferase, haemoglobin, lymphocyte count, presence of PSMA-positive lesions in lymph nodes, lactate dehydrogenase (LDH), alkaline phosphatase (ALP), and neutrophil count. The rPFS nomogram (C-index, 0.68; 0.65-0.72) included SUVmax, time since diagnosis, opioid analgesic use, lymphocyte count, presence of liver metastases by computed tomography, LDH, and ALP. The PSA50 nomogram (area under ROC curve, 0.72; 95% CI, 0.68-0.77) included SUVmax, lymphocyte count and ALP. Performances of the OS and rPFS models were maintained when they were reconstructed excluding SUVmax. Interpretation: These models of outcomes with 177Lu-PSMA-617 are the first built using prospective phase 3 data. They show that a combination of pretreatment laboratory, clinical, and imaging parameters, reflecting both patient and tumour status, influences outcomes. These models are important for aiding treatment selection, patient management, and clinical trial design. Funding: Novartis.

Talazoparib Plus Enzalutamide in Patients With HRR-Deficient mCRPC: Practical Implementation Steps for Oncology Nurses and Advanced Practice Providers.

BACKGROUND: About one-quarter of patients with advanced prostate cancer have alterations in homologous recombination repair (HRR) genes. In a global phase 3 study, talazoparib plus enzalutamide significantly improved progression-free survival in patients with HRR-deficient metastatic castration-resistant prostate cancer (mCRPC). OBJECTIVES: This article reviews the role of oncology nurses and advanced practice providers (APPs) in administering talazoparib plus enzalutamide in patients with mCRPC. METHODS: This review and hypothetical case study illustrate the role of oncology nurses and APPs in the administration of talazoparib plus enzalutamide and the management of adverse events to ensure safe and effective use in clinical practice. FINDINGS: Oncology nurses and APPs play an important role in the dosing and administration of talazoparib plus enzalutamide and can recognize and manage adverse events in patients with HRR-deficient mCRPC.

Safety and clinical activity of BMS-986365 (CC-94676), a dual androgen receptor ligand-directed degrader and antagonist, in heavily pretreated patients with metastatic castration-resistant prostate cancer.

BACKGROUND: Metastatic castration-resistant prostate cancer (mCRPC) that progresses on androgen receptor pathway inhibitors (ARPIs) may continue to be driven by AR signaling. BMS-986365 is an orally administered ligand-directed degrader targeting the AR via a first-in-class dual mechanism of AR degradation and antagonism. CC-94676-PCA-001 (NCT04428788) is a phase I multicenter study of BMS-986365 in patients with progressive mCRPC. PATIENTS AND METHODS: Patients who progressed on androgen deprivation therapy, one or more ARPIs, and taxane chemotherapy (unless declined/ineligible) were enrolled. The study included dose escalation (part A) and expansion (part B) of BMS-986365 up to 900 mg twice daily. Primary objectives were safety and tolerability, and to define maximum tolerated dose and/or recommended phase II dose. Key secondary endpoints included decline in prostate-specific antigen ≥50% (PSA50) and radiographic progression-free survival (rPFS). RESULTS: Parts A and B enrolled 27 and 68 patients, respectively. In part B, the median number of prior therapies was 4 (range 2-11). The most common treatment-related adverse events were asymptomatic prolonged corrected QT interval (47%) and bradycardia (34%). Part A maximum tolerated dose was not reached and recommended phase II dose selection is ongoing. Across part B three highest doses (400-900 mg twice daily, n = 60), PSA50 was 32% (n = 19), including 50% (n = 10/20) at 900 mg; median rPFS (95% confidence interval) was 6.3 months (5.3-12.6 months), including 8.3 months (3.8-16.6 months) at 900 mg; and rPFS was longer in patients without versus with prior chemotherapy: 16.5 months (5.5 months-not evaluable) versus 5.5 months (2.7-8.3 months), respectively. Efficacy was observed in patients with mCRPC with AR ligand binding domain (LBD) WT or with AR LBD mutations. CONCLUSIONS: BMS-986365 was well tolerated, with a manageable safety profile, and demonstrated activity in heavily pretreated patients with mCRPC with potentially higher benefit in chemotherapy-naive patients. These data show the potential of BMS-986365 to overcome resistance to current ARPIs, regardless of AR LBD mutation status.

Efficacy and Toxicity of [177Lu]Lu-PSMA-617 for Metastatic Castration-Resistant Prostate Cancer: Results from the U.S. Expanded-Access Program and Comparisons with Phase 3 VISION Data.

The phase 3 VISION trial demonstrated that [177Lu]Lu-PSMA-617 prolonged progression-free survival and overall survival (OS) in prostate-specific membrane antigen [PSMA]-positive metastatic castration-resistant prostate cancer (mCRPC) patients who progressed on taxane-based chemotherapy and androgen receptor-signaling inhibitors (ARSIs). The U.S. expanded-access program (EAP; NCT04825652) was opened to provide access to [177Lu]Lu-PSMA-617 for eligible patients until regulatory approval was obtained. This study aimed to evaluate the efficacy and safety profile of [177Lu]Lu-PSMA-617 within the EAP and compare the results with those from the VISION trial. Methods: Patients enrolled in the EAP at 4 institutions in the United States with available toxicity and outcome data were included. Outcome measures included OS, a prostate-specific antigen (PSA) response rate (RR) of at least 50%, and incidences of toxicity according to Common Terminology Criteria for Adverse Events version 5.0. Differences in baseline characteristics, outcome data, and toxicity between the EAP and VISION were evaluated using t testing of proportions and survival analyses. Results: In total, 117 patients with mCRPC who received [177Lu]Lu-PSMA-617 within the EAP between May 2021 and March 2022 were eligible and included in this analysis. Patients enrolled in the EAP were more heavily pretreated with ARSI (≥2 ARSI regimens: 70% vs. 46%; P < 0.001) and had worse performance status at baseline (Eastern Cooperative Oncology Group score ≥ 2: 19% vs. 7%; P < 0.001) than VISION patients. EAP and VISION patients had similar levels of grade 3 or higher anemia (18% vs. 13%; P = 0.15), thrombocytopenia (13% vs. 8%; P = 0.13), and neutropenia (3% vs. 3%; P = 0.85) and similar PSA RRs (42% vs. 46%; P = 0.50) and OS (median: 15.1 vs. 15.3 mo; P > 0.05). Conclusion: Patients with PSMA-positive mCRPC who received [177Lu]Lu-PSMA-617 within the EAP were later in their disease trajectory than VISION patients. Patients enrolled in the EAP achieved similar PSA RRs and OS and had a safety profile similar to that of the VISION trial patients.

Personalized dosimetry assessment of [177Lu]Lu-PSMA-617 radioligand therapy in the management of metastatic castration-resistant prostate cancer.

INTRODUCTION: Prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) is revolutionizing the treatment landscape for metastatic castration-resistant prostate cancer (mCRPC) patients. This study aimed to establish patient-specific radiation dosimetry for [177Lu]Lu-PSMA-617 RLT in Iranian patients with mCRPC. METHOD: Twelve biopsy-proven prostate cancer patients (aged 68.73 ± 5.26 yr) underwent 6.62 ± 0.36 GBq [177Lu]Lu-PSMA-617 RLT. Post-therapy whole-body planar scans were acquired approximately at 4, 48, and 72 h post-administration, alongside a single SPECT/CT around 48 h using Siemens Symbia T2 to obtain cumulated activity. An imaging protocol and dosimetry approach were designed to balance between time efficacy and accuracy in post-therapeutic dosimetry. Using accurate activity calibration, S-values were calculated by importing SPECT/CT images as the source/geometry into the Geant4 application for the tomographic emission (GATE) Monte Carlo (MC) toolkit. The Medical Internal Radiation Dose (MIRD) scheme was followed for subsequent absorbed dose (AD) calculations in organs at risk (OAR) and tumoral lesions using the dose actor and accumulated activities for precise dose estimations. RESULTS: Using the MC approach, the mean ADs to the liver, spleen, right and left kidneys, and tumor lesions were 0.11 ± 0.04 Gy/GBq, 0.08 ± 0.03 Gy/GBq, 0.34 ± 0.09 Gy/GBq, 0.34 ± 0.10 Gy/GBq, and 0.83 ± 0.54 Gy/GBq, respectively. Notably, tumoral lesions demonstrated significantly higher ADs, indicating enhanced uptake of radiopharmaceuticals by malignant cells. CONCLUSIONS: This study indicates that the ADs of OARs and tumoral lesions from [177Lu]Lu-PSMA-617 RLT in patients with mCRPC are consistent with existing literature. The dosimetry findings suggest that increasing the administered activity of [177Lu]Lu-PSMA-617 RLT is feasible and does not pose a significant risk of adverse effects on OARs, as supported by our data. However, to validate the safety and efficacy of higher doses, further clinical follow-up studies are recommended.

Phase II trial of multi-kinase inhibitor ESK981 in patients with metastatic castration-resistant prostate cancer.

ESK981 is a potent tyrosine kinase and PIKfyve lipid kinase inhibitor. This phase II trial evaluated the efficacy of ESK981 as a single agent in patients with androgen receptor-positive (AR +) metastatic castration-resistant prostate cancer (mCRPC). Eligible patients had mCRPC with progression on AR-targeted agents and without prior chemotherapy treatment. Each patient received 160 mg ESK981 once daily for 5 days per week for 4 weeks per cycle (except for an adverse event (AE) occurrence). The primary endpoints were a 50% reduction in prostate-specific antigen (PSA50), and safety. Secondary endpoints included the time and the duration of PSA response, PSA progression rates, PSA progression free survival (PFS) and overall survival (OS). Exploratory investigations included whole exome sequencing in patients before treatment, and morphological evaluation of biopsy samples pre- and post-treatment. PSA was evaluated in 13 patients. Only one patient (7.7% two-sided 95% Wilson CI (0.4%, 33.3%)) experienced a reduction in their PSA levels by 50% or more. The most common grade 3 treatment-related AEs were cardiac disorders, diarrhea, hypertension, alanine transaminase and aspartate transaminase elevations. No grade 4-5 events occurred. Median PFS was 1.8 months, and median OS was 12.1 months. Peripheral immune cells showed increased T cell activation and cytokine production in two patients who received 12-weeks of ESK981. Although relatively well tolerated, ESK981 alone showed no anti-tumor activity in patients with AR + mCRPC and its further evaluation as a single agent in AR + mCRPC is not warranted. (Trial registration: ClinicalTrials.gov, NCT03456804. Registration date: March 7, 2018).

Early treatment response assessment with [177Lu]PSMA whole-body-scintigraphy compared to interim PSMA-PET.

BACKGROUND: Prostate-specific membrane antigen positron emission tomography (PSMA-PET) is an essential tool for patient selection before radioligand therapy (RLT). Interim-staging with PSMA-PET during RLT allows for therapy monitoring. However, its added value over post-treatment imaging is poorly elucidated. The aim of this study was to compare early treatment response assessed by post-therapeutic whole-body scans (WBS) with interim-staging by PSMA-PET after 2 cycles in order to prognosticate OS. METHODS: Men with metastasized castration-resistant PC (mCRPC) who had received at least two cycles of RLT, and interim PSMA-PET were evaluated retrospectively. PROMISE V2 framework was used to categorize PSMA expression and assess response to treatment. Response was defined as either disease control rate (DCR) for responders or progression for non-responders. RESULTS: A total of 188 men with mCRPC who underwent RLT between February 2015 and December 2021 were included. The comparison of different imaging modalities revealed a strong and significant correlation with Cramer V test: e.g. response on WBS during second cycle compared to interim PET after two cycles of RLT (cφ = 0.888, P < 0.001, n = 188). The median follow-up time was 14.7 months (range: 3-63 months; 125 deaths occurred). Median overall survival (OS) time was 14.5 months (95% CI: 11.9-15.9). In terms of OS analysis, early progression during therapy revealed a significantly higher likelihood of death: e.g. second cycle WBS (15 vs. 25 months, P < 0.001) with a HR of 2.81 (P < 0.001) or at PET timepoint after 2 cycles of RLT (11 vs. 24 months, P < 0.001) with a HR of 3.5 (P < 0.001). For early biochemical response, a PSA decline of at least 50% after two cycles of RLT indicates a significantly lower likelihood of death (26 vs. 17 months, P < 0.001) with a HR of 0.5 (P < 0.001). CONCLUSION: Response assessment of RLT by WBS and interim PET after two cycles of RLT have high congruence and can identify patients at risk of poor outcome. This indicates that interim PET might be omitted for response assessment, but future trials corroborating these findings are warranted.

Outcomes of First Subsequent Taxane Therapy in Patients with Metastatic Castration-Resistant Prostate Cancer Who Previously Received Docetaxel Intensification for Metastatic Castration-Sensitive Prostate Cancer.

BACKGROUND: The management of advanced prostate cancer continues to evolve rapidly, particularly with the earlier use of survival-prolonging therapies in metastatic castration-sensitive prostate cancer (mCSPC). Though approved prior to the use of intensification therapy in mCSPC, taxane-based chemotherapies remain a relevant option for patients with metastatic castration-resistant prostate cancer (mCRPC). However, there is little evidence determining the outcomes of taxane chemotherapies as the first subsequent taxane (FST) in mCRPC pts who received docetaxel intensification (DI) in mCSPC. The purpose of this study is to compare outcomes between the survival-prolonging taxanes, docetaxel and cabazitaxel as FST after DI. METHODS: New patient consults seen at the Cross Cancer Institute from 1 July 2014 to 31 December 2020 were retrospectively reviewed. Pts were considered eligible if they received DI for mCSPC and then received either docetaxel or cabazitaxel in mCRPC. Variables of interest were collected from electronic medical records. The primary endpoint was ≥50% PSA response at 12 weeks relative to baseline for FST. Secondary endpoints included OS from mCSPC diagnosis, as well as PFS and OS from the FST start date. PSA responses were compared using the chi-squared test, and time-based endpoints were compared using the Kaplan-Meier method. RESULTS: In total, 34 pts were identified: docetaxel = 22 and cabazitaxel = 12 as FST. 91.2% of pts (docetaxel 95.5% vs. cabazitaxel 83.3%) received FST in 2nd line mCRPC. The median age at diagnosis (63.1 vs. 67.1 yrs, p = 0.236) and the median time to CRPC (18.6 vs. 14.2 mos, p = 0.079) were similar for docetaxel and cabazitaxel, respectively. The median time to FST (24.1 vs. 34.6 mos, p = 0.036) and OS from mCSPC diagnosis (30.9 vs. 52.7 mos, p = 0.002) were significantly shorter for pts receiving cabazitaxel vs. docetaxel. PSA responses occurred in 40.9% of pts treated with docetaxel compared to 25.0% treated with cabazitaxel (p = 0.645). There was no significant difference in median PFS (2.7 vs. 3.5 mos, p = 0.727) or median OS (11.4 vs. 8.1 mos, p = 0.132) from the time of FST for pts treated with docetaxel vs. cabazitaxel, respectively. CONCLUSIONS: Both docetaxel and cabazitaxel demonstrated activity as FST after DI in mCSPC. Pts who received cabazitaxel had a shorter time to FST and OS from mCSPC. The reasons for this may reflect clinician preference for cabazitaxel in pts with aggressive or rapidly progressing disease. No difference was found in PSA response, PFS, or OS from FST with docetaxel compared to cabazitaxel. While limited by its retrospective nature and small sample size, this study suggests that docetaxel is active as FST despite treatment with DI in mCSPC.

Durable benefit from poly(ADP-ribose) polymerase inhibitors in metastatic prostate cancer in routine practice: biomarker associations and implications for optimal clinical next-generation sequencing testing.

BACKGROUND: Controlled trials have consistently demonstrated the efficacy of poly(ADP-ribose) polymerase inhibitors (PARPis) in patients with metastatic castration-resistant prostate cancer (mCRPC) and BRCA1 or BRCA2 alterations (BRCAalt). However, the reported efficacy of PARPi for alterations in other homologous recombination repair (HRR) genes is less consistent. We sought to evaluate the routine practice effectiveness of PARPi between and within these groups. DESIGN: Patient-level data from a deidentified nationwide (USA-based) cancer clinico-genomic database between January 2011 and September 2023 were extracted. Patients with mCRPC and comprehensive genomic profiling by liquid biopsy [circulating tumor DNA (ctDNA)] or tissue (tumor) biopsy and who received single-agent PARPi were included and grouped by BRCAalt, ATMalt, other HRR, or no HRR. We further subcategorized BRCAalt into homozygous loss (BRCAloss) and all other deleterious BRCAalt (otherBRCAalt). RESULTS: A total of 445 patients met inclusion criteria: 214 with tumor and 231 with ctDNA. BRCAalt had more favorable outcomes to PARPi compared with ATM, other HRR, and no HRR groups. Within the BRCAalt subgroup, compared with other BRCAalt, BRCAloss had a more favorable time to next treatment (median 9 versus 19.4 months, P = 0.005), time to treatment discontinuation (median 8 versus 14 months, P = 0.006), and routine practice overall survival (median 14.7 versus 19.4 months, P = 0.016). Tumor BRCAloss prevalence (3.1%) was similar to ctDNA prevalence in liquid biopsy specimens with high tumor fraction (>20%). BRCAloss was not detected in orthogonal germline testing. CONCLUSIONS: PARPi routine practice effectiveness between groups mirrors prospective trials. Within the BRCAalt group, BRCAloss had the best outcomes. Unless the ctDNA tumor fraction is very high, somatic tissue testing (archival or metastatic) should be prioritized to identify patients who may benefit most from PARPi. When tissue testing is not clinically feasible, sufficient ctDNA tumor fraction levels for detection are enriched at clinical timepoints associated with tumor progression.

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.

Analysis of Molecular Imaging and Laboratory Baseline Biomarkers in PSMA-RLT: Whole-Body Total Lesion PSMA (TLP) Predicts Overall Survival.

The aim of this retrospective study was to identify pre-therapeutic predictive laboratory and molecular imaging biomarkers for response and overall survival (OS) in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT). Pre-therapeutic laboratory and [68Ga]Ga-PSMA-11 PET/CT data of n = 102 mCRPC patients receiving [177Lu]Lu-PSMA-617 RLT within a prospective registry (REALITY Study, NCT04833517) were analyzed including laboratory parameters such as alkaline phosphatase (ALP), prostate-specific antigen (PSA), gamma glutamyl transferase (GGT), glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), neuron specific enolase (NSE), hemoglobin (Hb), and imaging parameters such as maximum standardized uptake value of the tumor lesions (SUVmax), the mean standardized uptake value of all tumor lesions (SUVmean), the whole-body molecular tumor volume (MTV), and the whole-body total lesion PSMA (TLP). Mann-Whitney U test, univariate and multivariable Cox-regression were performed to test for association of the parameters with response and OS. The SUVmean of all lesions was significantly different between responders and non-responders (SUVmean responders 8.95 ± 2.83 vs. non-responders 7.88 ± 4.46, p = 0.003), whereas all other tested biochemical and imaging parameters did not reveal significant differences. Hb and the molecular imaging parameters MTV and TLP showed a significant association with OS (p = 0.013, p = 0.005; p = 0.009) in univariant Cox regression; however, only TLP remained significant in multivariable analysis (Hazard ratio 1.033, p = 0.009). This study demonstrates a statistically significant association between the quantitative PET/CT imaging parameter SUVmean and PSA response, as well as between the baseline TLP and OS of mCRPC patients undergoing RLT.