Trial Design and Objectives for Castration-Resistant Prostate Cancer: Updated Recommendations From the Prostate Cancer Clinical Trials Working Group 3

Baseline PSMA PET/CT parameters predict overall survival and treatment response in metastatic castration-resistant prostate cancer patients

OBJECTIVE

Metastatic castration-resistant prostate cancer (mCRPC) is a heterogeneous disease with varying survival outcomes. This study investigated whether baseline PSMA PET/CT parameters are associated with survival and treatment response.

METHODS

Sixty mCRPC patients underwent [18F]PSMA-1007 PET/CT before treatment with androgen receptor-targeted agents (ARTAs) or chemotherapy. Intensity-based parameters, volumetric parameters, metastatic sites and DmaxVox (distance between the two outermost voxels) from baseline PSMA PET/CT were collected, as well as age, Gleason score and laboratory parameters. Cox regression analysis evaluated their prognostic value for overall survival (OS). Additionally, a preliminary lesion-level analysis was done (n = 241 lesions) with lesion location and twelve radiomic features selected from previous literature. Logistic regression evaluated their association with PSMA PET/CT-based lesion progression after 3-4 months of treatment.

RESULTS

Total tumour volume (PSMA-TV) (HR = 1.41 per doubling [1.17-1.70]), total lesion uptake (TL-PSMA) (HR = 1.40 per doubling [1.16-1.69]) and DmaxVox (HR = 1.31 per 10 cm increase [1.07-1.62]) were prognostic for OS, each independent of baseline PSA level (HR = 0.82 per doubling [0.68-0.98]), haemoglobin level (HR = 0.68 per mmol/L increase [0.49-0.95]) and line of treatment. On lesion-level, location (prostate vs bone OR = 0.23 [0.06-0.83]) and SUVmean (OR = 1.72 per doubling [1.08-2.75]) were independent prognostic markers for lesion progression, morphological and texture-based radiomic features were not.

CONCLUSION

Baseline PSMA PET/CT scans have prognostic value in mCRPC patients and can potentially aid in treatment decision-making. DmaxVox can serve as a simpler alternative to PSMA-TV when automated segmentation software is not available. When combined with PSMA-TV, lower PSA levels indicated worse OS, which may be a marker of tumour dedifferentiation. Further research is needed to validate these models in larger patient cohorts.

KEY POINTS

Question mCRPC is a highly heterogeneous disease, requiring good prognostic markers. Findings PSMA-TV was the best independent prognostic marker for OS; maximum distance between lesions (DmaxVox) can be used as a simpler alternative. Clinical relevance Baseline PSMA PET/CT parameters representing tumour burden were independently associated with OS in mCRPC patients, providing prognostic insights for clinical decision-making. Although PSMA-TV was the best prognostic marker, DmaxVox can serve as an easier to obtain alternative.

Impact of adding carboplatin to docetaxel chemotherapy on testosterone levels and treatment outcomes in metastatic docetaxel-resistant prostate cancer

Docetaxel resistance, particularly post-androgen-receptor targeted therapy (ART), undermines its clinical utility in metastatic castration-resistant prostate cancer (mCRPC). This study explores the impact of docetaxel plus carboplatin (DC) chemotherapy on serum testosterone levels in metastatic docetaxel-resistant prostate cancer (mDRPC) patients. 123 mDRPC patients were categorized into three groups: (1) no previous ART (n = 65), (2) previous ART with serum free testosterone (FT) > detection limit (DL) at baseline (n = 31), and (3) previous ART with FT < DL at baseline (n = 27). Salvage DC chemotherapy led to significant reductions in FT and total testosterone (TT) levels in groups 1 and 2 (p < 0.05). Group 1 saw FT decrease from 0.85 pg/mL to below the DL (< 0.18 pg/mL) with 54.3% achieving complete reduction (CR); group 2 showed FT decrease from 0.28 pg/mL to below the DL with 67.7% achieving CR; group 3 had baseline FT values already below the DL with 96.3% maintaining this level. TT reductions to below the DL occurred in all groups. Low FT was an independent predictor for better PFS and for improved OS in groups 1 and 2. Our data indicate that adding carboplatin may improve the therapeutic effects of docetaxel in a castration-dependent setting.

O-GalNAc Glycosylation Activates MBL-Mediated Complement and Coagulation Cascades to Drive Organotropic Metastasis

Liver metastasis is prevalent among patients with neuroendocrine prostate cancer (NEPC) and other types of neuroendocrine (NE) cancers, featuring with an aggressive clinical course and a dismal prognosis. However, the cellular and molecular mechanisms underlying liver-specific metastatic tropism in NE cancers remain poorly understood. Intriguingly, it is found that NEPC liver metastatic foci are frequently associated with thrombi. NEPC cells express an aberrantly elevated level of glycosyltransferase Galnt9. Notably, the Galnt9-mediated O-GalNAc glycosylation on the cell membrane of NE cancer cells, particularly on the adhesion molecule Annexin A2, activates the mannose-binding lectin (MBL) complement signaling in the liver. This cascade stimulates platelet activation and thrombus formation, ultimately facilitating hepatic metastasis of NEPC. Inhibition of O-GalNAc glycosylation or knockdown of Galnt9 demonstrates efficacy in restraining the liver metastasis of NEPC, small cell lung cancer (SCLC), and colorectal neuroendocrine cancer. These findings identify Galnt9-mediated O-GalNAc glycosylation as a targetable mechanism driving liver metastasis through activation of MBL complement and coagulation cascades across a broad spectrum of NE cancers.

Value of Whole-body Magnetic Resonance Imaging Using the MET-RADS-P Criteria for Assessing the Response to Intensified Androgen Deprivation Therapy in Metastatic Hormone-naïve and Castration-resistant Prostate Cancer

BACKGROUND AND OBJECTIVES

We assessed the agreement between prostate-specific antigen (PSA) and imaging responses using whole-body magnetic resonance imaging (wbMRI). Our aim was to explore the potential prognostic value of PSA and wbMRI responses in metastatic hormone-naïve prostate cancer (mHNPC) and castration-resistant PC (mCRPC).

METHODS

wbMRI was prospectively performed in 37 patients with mHNPC and 51 with mCRPC before and after 6-12 mo of androgen deprivation therapy and an androgen receptor pathway inhibitor (ARPI). Imaging responses were defined according to the Metastasis Reporting and Data System for PC (MET-RADS-P) criteria. A PSA response was defined as PSA ≤0.2 ng/ml in mHNPC and a ≥50% decrease from the pretreatment level in mCRPC. Agreement between PSA and wbMRI responses was assessed using Cohen's κ. The association between time to subsequent treatment and overall survival (OS) was analyzed using Cox regression analysis.

KEY FINDINGS AND LIMITATIONS

Agreement between PSA and wbMRI responses was fair in mHNPC (κ = 0.30) but none to slight in mCRPC (κ = 0.15). In mHNPC, patients with a PSA or wbMRI response were less likely to receive subsequent treatments; wbMRI progression was associated with a significantly higher risk of death (hazard ratio 8.59; p = 0.002). In mCRPC, two-thirds of patients with a PSA response showed progression on wbMRI; neither PSA nor wbMRI progression changed the likelihood of starting a subsequent treatment or the risk of death.

CONCLUSIONS AND CLINICAL IMPLICATIONS

In mHNPC, wbMRI progression was associated with a higher risk of needing subsequent treatment and shorter OS.

PATIENT SUMMARY

We evaluated the agreement between routine PSA (prostate-specific antigen) test results and whole-body MRI (magnetic resonance imaging) scans for assessing the response of metastatic prostate cancer to treatment. There was disagreement between the PSA and MRI results, mainly for patients with cancer that was resistant to hormone-based treatment. Combining PSA with whole-body MRI might provide a more accurate picture of the response of advanced prostate cancer to treatment.

Learning From Evidence: Changes in Real-World Use of Second Androgen Receptor Targeted Treatments in Metastatic Castration-Resistant Prostate Cancer (mCRPC)

BACKGROUND

Androgen receptor targeted therapies (ART) play a major role in the treatment of metastatic castration-resistant prostate cancer (mCRPC). In recent years consensus has been reached that treatment with a second ART should be avoided due to low response rates. The aim of this study was to investigate if new scientific insights led to changes in clinical daily practice in the Netherlands.

METHODS

Patients included in the Dutch CAPRI-3 prostate cancer registry, currently encompassing 19 hospitals, and treated with at least 1 ART (ie, abiraterone or enzalutamide) were included. Patients were stratified based on start date of first ART (ART1) according to standard of care between 2016-2017, 2018-2019 and 2020-2021. Second ART (ART2) was defined as either direct (ART1>ART2) or at any given time (any ART2).

RESULTS

Between the first and last ART1 group, the prevalence of ART1>ART2 declined from 14.3% to 6.5% (P = .001) and the prevalence of any ART2 from 27.6% to 10.7% (P < .001). The decline was observed before recommendations were included in European guidelines. The use of other life-prolonging drugs (LPDs) after ART1 (ART1>LPD) increased. Patients who were selected for ART1>ART2 instead of ART1>LPD were older, less frequently treated with taxane-based chemotherapy for mHSPC and had a longer time to development of mCRPC.

CONCLUSIONS

New scientific insights were incorporated into clinical daily practice, with a significant decline in in the prevalence of sequential ART treatment, even before recommendations were included in European guidelines.

Prognostic Value of Response Evaluation Using PSMA PET/CT in Patients with Metastatic Prostate Cancer (RECIP 1.0): A Systematic Review and Meta-analysis

RATIONALE AND OBJECTIVES

Recently, the Response Evaluation Using PSMA PET/CT in Patients with Metastatic Castration-Resistant Prostate Cancer (RECIP 1.0) was proposed to better evaluate treatment response in prostate cancer patients using PET/CT with prostate-specific membrane antigen (PSMA) than more traditional approaches like metabolic PET evaluation response criteria in solid tumor (PERCIST 1.0). This system showed promising results in single-center studies. We aim to evaluate the prognostic performance of RECIP 1.0 in assessing treatment outcomes in metastatic prostate cancer patients with a systematic review and meta-analysis.

MATERIALS AND METHODS

Searches were conducted across PubMed/MEDLINE, EMBASE, and Web of Science databases through March 2024. Only studies involving patients with metastatic prostate cancer who underwent PSMA PET/CT to assess therapeutic response and who were evaluated using the RECIP 1.0 criteria were included. Pooled hazard ratios for mortality and concordance indices (c-index) of RECIP were assessed. A secondary analysis compared RECIP 1.0 to PSMA PET Progression Criteria (PPP) in head-to-head studies.

RESULTS

From an initial 553 reports, eight met the eligibility criteria after full-text review (n=516 patients) and six underwent quantitative analysis. RECIP 1.0 significantly differentiated between disease progression and non-progression in terms of mortality risk (HR: 3.48; 95% CI: 2.64-4.59). A sub-analysis of three studies with 174 patients demonstrated a pooled c-index of 0.68 (95% CI: 0.65-0.71). Comparison involving 224 patients from three studies indicated a non-significant trend favoring RECIP 1.0 over PPP.

CONCLUSION

RECIP 1.0 offers robust prognostic value for assessing metastatic prostate cancer treatment outcomes.

Kinetics of PSMA PET signal after radiotherapy in prostate cancer lesions: A single-center retrospective study

PURPOSE

To evaluate the kinetics of prostate-specific membrane antigen (PSMA) PET uptake in irradiated lesions using serial PSMA PET/CT scans.

METHODS

Patients with prostate cancer who underwent 68Ga-PSMA-11 PET/CT before (PET1) and after radiotherapy (PET2) were retrospectively included. Percentage changes in SUVmax (ΔSUVmax) of the irradiated lesion were measured. The presence of residual uptake was visually assessed on PET2. When available, follow-up imaging was used for lesion validation. Morphologic or uptake disappearance on follow-up scans was defined as loco-regional complete response (L-CR). Clinical and PET characteristics were compared between lesions with and without residual uptake. An optimal timing for response assessment was calculated by receiver-operating-curve analysis.

RESULTS

Eighty-nine patients with 217 irradiated lesions (106 lymph nodes, 85 bone, 21 prostate/prostate bed) receiving ablative radiotherapy were included. Lesion uptake was lower at later time points and was lowest at 9-12 months after radiotherapy. Sixty-eight lesions showed residual uptake on PET2. Residual uptake was more common in lesions imaged at an earlier time point after radiotherapy (median: 7.9 vs. 13.0 months, p = 0.001), lesions in the prostate/prostate bed (p < 0.001), and lesions with higher baseline SUVmax (p = 0.001). Thirty-one residual uptake-positive lesions had available follow-up imaging, of which 24 lesions were confirmed to be L-CR. Risk factors for not achieving L-CR were lesions with prolonged uptake (p = 0.002) and those in the prostate/prostate bed (p = 0.003). The optimal time point for predicting L-CR was 8.6 months.

CONCLUSIONS

Timing and tumor site affect the PSMA PET signal after radiotherapy, and should be considered when assessing response on post-radiotherapy PSMA PET.

Biodistribution and dosimetry of [177Lu]Lu-SibuDAB in patients with metastatic castration-resistant prostate cancer

PURPOSE

Several prostate-specific membrane antigen (PSMA) radiopharmaceuticals have been used for the treatment of metastatic, castration-resistant prostate cancer (mCRPC). In an attempt to improve the tumour accumulation, new PSMA ligands were developed with an albumin-binding entity to enhance the blood circulation and, hence, tumour accumulation. In preclinical studies, [177Lu]Lu-SibuDAB, a radiopharmaceutical with moderate albumin-binding properties, outperformed [177Lu]Lu-PSMA-617 and [177Lu]Lu-PSMA-I&T. The aim of this study was to evaluate the dosimetry of [177Lu]Lu-SibuDAB in patients diagnosed mCRPC.

METHODS

Seventeen patients (median age 72 years, range 63‒83) diagnosed with progressive disease of mCRPC were included in this prospective study after exhausting all available treatment options. They were injected with 5.3 ± 0.5 GBq (mean ± standard deviation) [177Lu]Lu-SibuDAB as a first treatment cycle. Sixteen of these patients underwent sequential whole-body SPECT/CT and activity determination in venous blood samples for dosimetry purposes. Absorbed doses to the salivary glands, liver, spleen, kidneys, and red marrow as well as selected tumour lesions were calculated in OLINDA/EXM™ and compared to published values for previously established PSMA radiopharmaceuticals.

RESULTS

Absorbed dose coefficients (ADC) to tumours (9.9 ± 5.4 Gy/GBq) were about 2-fold higher than those reported for clinically approved PSMA radiopharmaceuticals. ADC to salivary glands, liver, spleen, kidneys and red marrow were higher (0.5 ± 0.2, 0.2 ± 0.05, 0.2 ± 0.1, 1.8 ± 0.6, 0.1 ± 0.04 Gy/GBq, respectively) than for [177Lu]Lu-PSMA-617 and [177Lu]Lu-PSMA-I&T, but lower than for [177Lu]Lu-PSMA-ALB-56, a previously investigated long-circulating PSMA radiopharmaceutical. The tumour-to-kidneys, tumour-to-red marrow, tumour-to-salivary glands ADC ratio were 6.6, 102, 33.1. These ratios were comparable to those of [177Lu]Lu-PSMA-617 and [177Lu]Lu-PSMA-I&T for kidneys and red-marrow, but higher for salivary glands.

CONCLUSION

[177Lu]Lu-SibuDAB showed a prolonged blood circulation time and, hence, a significantly increased absorbed tumour dose, while tumour-to-organ ADC ratios were similar to conventional PSMA radiopharmaceuticals. Further clinical investigations to evaluate the efficacy and safety of [177Lu]Lu-SibuDAB are, thus, warranted.

Initial management approach for localized/locally advanced disease is critical to guide metastatic castration-resistant prostate cancer care

BACKGROUND

Currently, several therapies are available for metastatic castration-resistant prostate cancer (mCRPC) but no specific clinical factors to personalize treatment. We first sought the prognostic value of duration on androgen-deprivation therapy (ADT) for hormone-sensitive prostate cancer (HSPC) in patients receiving androgen-receptor-signaling inhibitors (ARSI) for mCRPC.

METHODS

A multicenter cohort of mCRPC patients who started ARSI between July 2011 and October 2021 was identified. Based on their initial disease burden and duration on ADT for HSPC, primary progressive (PP) men were classified into four groups: low/intermediate-risk localized disease (LOC) and high-risk localized/locally advanced disease (LAD) and short-term (ST) < 24 vs. long-term (LT) ADT ≥ 24 months, whereas de novo (DN) mHSPC were subdivided into short-time vs. long-time to CRPC.

RESULTS

We included 919 mCRPC patients with a median age of 77 years [interquartile range (IQR) = 71-82)]. Median ADT duration in HSPC was 24 months (IQR = 14-40). Median follow-up was 91 months (IQR = 62-138), median OS and PFS from ARSI start were 20 (IQR 10-32) and 10 months (IQR = 5-19), respectively. In PP developing metastatic disease (n = 655, 71.3%), LOC and LAD with ST ADT had a greater than almost double-risk of death compared to LT ADT (LOC/ST: hazard ratio [HR] = 2.01; 95% CI 1.54-2.64; LAD/ST: HR = 1.73; 95% CI 1.34-2.24; p < 0.001). In the multivariate analysis including age, prognostic cohort, Gleason, ECOG, radical radiotherapy and prostatectomy, groups with ST ADT were associated with worse OS compared to LT ADT (LOC/ST: HR = 1.84; 95% CI 1.38-2.45; p < 0.001; LAD/ST: HR = 1.59; 95% CI 1.21-2.10; p < 0.001), along with ECOG > 2 (HR = 1.55; 95% CI 1.06-2.26; p = 0.03). There were also similar results of PFS. Moreover, long-time to CRPC in patients with history of DN mHSPC (n = 264, 28.7%) resulted in a better OS/PFS (HR = 0.76, 95% CI 0.56-1.02, p = 0.064 and HR = 0.74, 95% CI 0.55-0.99, p = 0.042, respectively).

CONCLUSIONS

Our study showed that duration on ADT for mHSPC was significantly associated with survival in mCRPC undergoing ARSI. These findings suggest a possible connection between initial management of prostate tumour and a better prognostication in mCRPC. Prospective trials are warranted.

A multidisciplinary approach to address unmet needs in the management of patients with non-metastatic castration-resistant prostate cancer

BACKGROUND

With the availability of second-generation androgen receptor inhibitors (SGARIs), the treatment landscape has changed dramatically for patients with nonmetastatic castration-resistant prostate cancer (nmCRPC). In clinical trials, the SGARIs (apalutamide, enzalutamide, darolutamide) increased metastasis-free survival (MFS), overall survival (OS), and patient quality of life compared to placebo. These drugs were subsequently integrated into nmCRPC clinical practice guidelines. With advances in radiographic imaging, disease assessment, and patient monitoring, nmCRPC strategies are evolving to address limitations related to tracking disease progression using prostate-specific antigen (PSA) kinetics.

METHODS

A panel of 10 multidisciplinary experts in prostate cancer conducted reviews and discussions of unmet needs in the management and monitoring of patients with nmCRPC in order to develop consensus recommendations.

RESULTS

Across the SGARI literature, patient MFS and OS are generally comparable for all treatments, but important distinctions exist regarding short- and long-term drug safety profiles and drug-drug interactions. With respect to disease monitoring, a substantial proportion of patients using SGARIs may experience disease progression without rising PSA levels, suggesting a need for enhanced radiographic imaging in addition to PSA monitoring. Recent data also indicate that novel prostate-specific membrane antigen positron emission tomography radiotracers provide enhanced accuracy for disease detection, as compared to conventional imaging.

CONCLUSIONS

Clinical decision-making in nmCRPC has become more complex, with new opportunities to apply precision medicine to patient care. Multidisciplinary teams can ensure that patients with nmCRPC receive optimal and individualized disease management.

A Phase 1/2 multicenter trial of DKN-01 as monotherapy or in combination with docetaxel for the treatment of metastatic castration-resistant prostate cancer (mCRPC)

BACKGROUND

Dickkopf-related protein 1 (DKK1) is a Wingless-related integrate site (Wnt) signaling modulator that is upregulated in prostate cancers (PCa) with low androgen receptor expression. DKN-01, an IgG4 that neutralizes DKK1, delays PCa growth in pre-clinical DKK1-expressing models. These data provided the rationale for a clinical trial testing DKN-01 in patients with metastatic castration-resistant PCa (mCRPC).

METHODS

This was an investigator-initiated parallel-arm phase 1/2 clinical trial testing DKN-01 alone (monotherapy) or in combination with docetaxel 75 mg/m2 (combination) for men with mCRPC who progressed on ≥1 AR signaling inhibitors. DKK1 status was determined by RNA in-situ expression. The primary endpoint of the phase 1 dose escalation cohorts was the determination of the recommended phase 2 dose (RP2D). The primary endpoint of the phase 2 expansion cohorts was objective response rate by iRECIST criteria in patients treated with the combination.

RESULTS

18 pts were enrolled into the study-10 patients in the monotherapy cohorts and 8 patients in the combination cohorts. No DLTs were observed and DKN-01 600 mg was determined as the RP2D. A best overall response of stable disease occurred in two out of seven (29%) evaluable patients in the monotherapy cohort. In the combination cohort, five out of seven (71%) evaluable patients had a partial response (PR). A median rPFS of 5.7 months was observed in the combination cohort. In the combination cohort, the median tumoral DKK1 expression H-score was 0.75 and the rPFS observed was similar between patients with DKK1 H-score ≥1 versus H-score = 0.

CONCLUSION

DKN-01 600 mg was well tolerated. DKK1 blockade has modest anti-tumor activity as a monotherapy for mCRPC. Anti-tumor activity was observed in the combination cohorts, but the response duration was limited. DKK1 expression in the majority of mCRPC is low and did not clearly correlate with anti-tumor activity of DKN-01 plus docetaxel.

Heterogeneity of the Treatment Effect with PARP Inhibitors in Metastatic Castration-resistant Prostate Cancer: A Living Interactive Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE

Selection of patients harboring mutations in homologous recombination repair (HRR) genes for treatment with a PARP inhibitor (PARPi) is challenging in metastatic castration-resistant prostate cancer (mCRPC). To gain further insight, we quantitatively assessed the differential efficacy of PARPi therapy among patients with mCRPC and different HRR gene mutations.

METHODS

This living meta-analysis (LMA) was conducted using the Living Interactive Evidence synthesis framework. We included clinical trials assessing PARPi as monotherapy in pretreated mCRPC or in combination with an androgen receptor pathway inhibitor (ARPI) in treatment-naïve patients. Random-effects meta-analyses were performed for a priori subgroups stratified by HRR status, BRCA status, and each gene.

KEY FINDINGS AND LIMITATIONS

This first report for our LMA includes 13 trials (4278 patients). Among patients with pretreated mCRPC receiving PARPi monotherapy, the tumor response rate per 100 person-months was numerically higher for patients with BRCA2 (50% prostate-specific antigen response [PSA50%] 3.3; objective response rate [ORR] 3.3), BRCA1 (PSA50% 1.2; ORR 2.0), or PALB2 (PSA50% 3.3; ORR 1.4) alterations than for patients with ATM (PSA50% 0.4; ORR 0.3), CDK12 (PSA50% 0.2; ORR 0.2), or CHEK2 (PSA50% 1.0; ORR 0.7) alterations. Among patients receiving PARPi + ARPI, a significant radiographic progression-free survival benefit was observed in those with BRCA (hazard ratio [HR] 0.28, 95% confidence interval [CI] 0.13-0.62) or CDK12 (HR 0.58, 95% CI 0.35-0.95) alterations, but not in patients with PALB2 (HR 0.53, 95% CI 0.21-1.32), ATM (HR 0.93, 95% CI 0.57-1.53), or CHEK2 (HR 0.92, 95% CI 0.53-1.61) alterations. An overall survival benefit was observed for patients with BRCA alterations (HR 0.47, 95% CI 0.31-0.71) after adjustment for crossover and subsequent therapy, but not for patients with PALB2 (HR 0.33, 95% CI 0.10-1.16), ATM (HR 0.97, 95% CI 0.57-1.67), CDK12 (HR 0.80, 95% CI 0.36-1.78), or CHEK2 (HR 0.81, 95% CI 0.37-1.75) alterations.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Our LMA delivers information on the effect of PARPi therapy in relation to specific gene alterations in mCRPC via an interactive web platform. The evidence suggests the greatest PARPi benefit in patients with BRCA alterations, a strong signal of benefit in patients with PALB2 or CDK12 alterations, and no benefit in patients with ATM or CHEK2 alterations.

Expanding the scope of PSMA-RLT: evaluating treatment in challenging mCRPC patients with poor performance status (ECOG 3)

PURPOSE

Given the increasing inclusion of ECOG 3 patients in oncology practice, data on this subgroup in the context of prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) remain limited. This study evaluates the safety and outcome of PSMA-RLT in metastatic castration-resistant prostate cancer (mCRPC) patients with ECOG performance status 3.

METHODS

In this analysis, a cohort of 18 mCRPC patients with ECOG performance status 3 who received PSMA-RLT was examined. The median number of treatment cycles was 2 (range: 1-10), with a mean cumulative administered activity of 21.5 ± 15.0 GBq (range: 2.7-62.6 GBq) of [177Lu]Lu-PSMA-617. Outcome and adverse events including hematologic and renal toxicities, fatigue, and xerostomia were analyzed.

RESULTS

50% of patients achieved either stable disease or a partial biochemical response. Median progression-free survival and overall survival were 1.3 months and 2.8 months, respectively. Severe adverse events were uncommon, occurring in three patients: one developed grade 3 leukopenia, another experienced grade 3 thrombocytopenia, and one patient had pancytopenia of grade 3/4. No higher RLT-induced grade of renal toxicity and xerostomia were observed, whilst symptoms of fatigue improved in the cohort.

CONCLUSION

This study indicates that PSMA-RLT is a feasible and overall well-tolerated treatment for mCRPC ECOG 3 patients with manageable toxicity profile. Despite limited survival outcomes, ECOG 3 status may be considered not to be a categorical exclusion criterion for RLT. Future prospective studies should further investigate the role of PSMA-RLT in this challenging subgroup.

177Lu-PSMA-617 Consolidation Therapy After Docetaxel in Patients with Synchronous High-Volume Metastatic Hormone-Sensitive Prostate Cancer: A Randomized, Phase 2 Trial

177Lu-prostate-specific membrane antigen-617 (177Lu-PSMA-617) has shown positive survival outcomes in metastatic castration-resistant prostate cancer. However, there are limited data in the hormone-sensitive setting. Here, in the CONSOLIDATE trial (177Lu-PSMA-617 Consolidation Therapy After Docetaxel in Patients with Synchronous High-Volume Metastatic Hormone-Sensitive Prostate Cancer), we intended to evaluate the role of 177Lu-PSMA-617 as consolidation therapy for residual disease after chemohormonal treatment in patients with synchronous high-volume metastatic hormone-sensitive prostate cancer (mHSPC). Methods: This was an investigator-initiated randomized, parallel-group, open-label phase 2 trial. Synchronous high-volume mHSPC patients treated with androgen-deprivation therapy plus docetaxel and having residual nonprogressive disease after docetaxel completion (defined as prostate-specific antigen [PSA] > 0.2 ng/mL with PSMA-positive disease on 68Ga-PSMA-11 PET/CT) were randomized in a 1:1 ratio to the experimental arm (177Lu-PSMA-617, 7.4 GBq/cycle × 2, 6 wk apart with protocol-permitted standard of care) or control arm (protocol-permitted standard of care alone). The primary endpoint was the proportion of patients achieving a PSA level of 0.2 ng/mL or less at 6 mo from randomization. Secondary endpoints included objective radiographic response rate, radiographic progression-free survival (PFS), PSA PFS, and toxicities. Results: The trial was terminated early because of poor accrual after the coronavirus disease pandemic and a change in treatment guidelines for mHSPC. Thirty high-volume mHSPC patients were randomized between January 2021 and June 2024. The primary endpoint was achieved in 9 of 15 (60%; 95% CI, 35%-85%) patients in the experimental arm versus 2 of 15 (13%; 95% CI, 0%-30%) in the control arm (risk ratio, 4.5; 95% CI, 1.2-17.4; P = 0.008). The objective radiographic response rates were 8 of 15 (53%; 95% CI, 28%-78%) and 1 of 15 (7%; 95% CI, 0%-19%) in the experimental and control arms, respectively (P = 0.014). The estimated median radiographic PFS and PSA PFS were 18 mo (95% CI, 9-27 mo) and 15 mo (95% CI, 12-18 mo), respectively, in the experimental arm versus 9 mo (95% CI, 4-14 mo) and 9 mo (95% CI, 1-17 mo), respectively, in the control arm. No grade 3 or 4 toxicity was noted with the addition of 177Lu-PSMA-617 in the experimental arm. Conclusion: In synchronous high-volume mHSPC patients having residual disease after chemohormonal treatment, 177Lu-PSMA-617 consolidation therapy demonstrated promising efficacy and safety outcomes. Larger phase 3 trials are warranted to definitively establish its survival benefit.

Retreatment of Metastatic Castration-Resistant Prostate Cancer Patients with 223Ra Therapy in Daily Practice

223Ra-dichloride (223Ra) is an approved therapeutic option for patients with metastatic castration-resistant prostate cancer (mCRPC) who have symptomatic bone metastases. After an initial course of 6 223Ra injections, treatment may be repeated. The purpose of this study was to evaluate the safety and efficacy of 223Ra retreatment of mCRPC in a real-world population. Methods: This multicenter, retrospective cohort study included patients who had mCRPC and bone metastases who previously received 6 consecutive injections of 223Ra and received at least 1 223Ra retreatment injection between 2014 and 2024. The primary endpoint was safety, measured as hematologic and nonhematologic adverse events (AEs), including skeletal-related events. Secondary endpoints included the number of injections administered, overall survival, and biochemical response rates. Exploratory analyses intended to identify variables associated with alkaline phosphatase response during retreatment, completion of 223Ra retreatment, and overall survival. Results: Sixty-one patients were evaluated. Median age was 75 y, 44% of patients received prior chemotherapy, and 87% of patients previously received at least 1 androgen receptor pathway inhibitor. The median number of prior systemic therapies was 3. In total, 56 patients (95%) experienced at least 1 hematologic AE, including 14% with grade 3 hematologic AEs. Forty-four patients (72%) experienced at least 1 nonhematologic AE during 223Ra retreatment. No grade 4 or 5 AEs occurred. Patients received a median of 6 223Ra retreatment injections. Overall survival was 16.9 mo (95% CI, 11.9-21.9 mo), and 56% of patients had an alkaline phosphatase response of at least 30%. High baseline hemoglobin levels, no prior chemotherapy, and a prostate-specific antigen response of at least 30% during the initial 223Ra course were predictors for completion of 6 223Ra retreatment injections. A prior skeletal-related event, baseline performance status, and baseline hemoglobin level were prognostic for survival in this population. Conclusion: 223Ra retreatment was well tolerated and is therefore deemed safe in selected patients with mCRPC. In addition, the high number of administered injections and the high alkaline phosphatase response rate suggest that retreatment is beneficial to patients with advanced mCRPC. Patients with high hemoglobin levels, good performance status, and prior prostate-specific antigen response to 223Ra therapy may be the best candidates for 223Ra retreatment.

Skin rash induced by apalutamide correlated with age and relative dose intensity adjusted by body surface area in Japanese patients with prostate cancer

OBJECTIVE

Common adverse events associated with apalutamide include skin rashes and occur more frequently in Japanese patients. This study used relative dose intensity (RDI) and body surface area (BSA) to investigate the risk of skin adverse events and the efficacy of apalutamide in patients with prostate cancer.

METHODS

We retrospectively reviewed data from 63 patients with prostate cancer who were treated with an initial dose of 240 mg apalutamide, and RDI (%) was calculated. Patient backgrounds were compared, and factors contributing to rash development were analyzed. Progression-free survival (PFS), defined as the time to castration-resistant prostate cancer, was analyzed using overall RDI/BSA in metastatic castration-sensitive prostate cancer (mCSPC) patients.

RESULTS

The receiver operating characteristic curve analysis showed that RDI/BSA had a slightly stronger association with rash occurrence than RDI/kg. Univariate analysis identified age and RDI/BSA as significant risk factors for rash occurrence, particularly when both an age cutoff of 72 years and a RDI/BSA cutoff of 56 were met. PFS in mCSPC patients showed no significant differences among tRDI/BSA groups (<36, 36-55, >55) or between patients with and without dose reductions. Cutoff points (36 and 55) were based on the maximum tRDI/BSA values assuming continuous administration of 120 mg or 180 mg apalutamide in patients with a minimum BSA of 1.36 m2.

CONCLUSIONS

Age and RDI/BSA were associated with rash occurrence, suggesting a need for dose reduction of apalutamide. A dose reduction to 180 or 120 mg may be appropriate in such cases when considering efficacy.

The Role of SPECT/CT in 177Lu-PSMA-617 Theranostics: Case-based Review of Response and Progression Patterns

Lutetium-177 prostate-specific membrane antigen-617 (Lu-PSMA) has demonstrated efficacy in improving progression-free survival and overall survival in patients with metastatic castration-resistant prostate cancer (mCRPC). Post-treatment single photon emission tomography/computed tomography (SPECT/CT) imaging is an emerging tool for monitoring treatment response, enabling the tracking of functional changes during therapy. While quantitative SPECT analysis can predict patient outcomes, qualitative assessments are more practical and time-efficient in clinical settings. This case-based review examines treatment responses based on post-treatment SPECT/CT imaging, categorizing them into favorable response, progression, and mixed response patterns to improve interpretation and guide therapeutic adjustments, aiming to optimize management of mCRPC with Lu-PSMA therapy.

Phase I, First-in-Human Study of FOR46 (FG-3246), an Immune-Modulating Antibody-Drug Conjugate Targeting CD46, in Patients With Metastatic Castration-Resistant Prostate Cancer

PURPOSE

FOR46, a fully human antibody conjugated to monomethyl auristatin E, targets a tumor-selective epitope of CD46, which is overexpressed in metastatic castration-resistant prostate cancer (mCRPC). FOR46 demonstrates potent nonclinical activity in enzalutamide-resistant CRPC models.

PATIENTS AND METHODS

This was a phase I, first-in-human, dose escalation/expansion study in patients with progressive mCRPC after treatment with ≥one androgen signaling inhibitors (ClinicalTrials.gov identifier: NCT03575819). The starting dose of FOR46 was 0.1 mg/kg given intravenously every 3 weeks. The primary objective was to determine the maximally tolerated dose (MTD). Whole-blood mass cytometry (cytometry by time of flight) was used to characterize peripheral immune response and CD46 expression in CRPC tissue that underwent central pathology review.

RESULTS

Fifty-six patients were enrolled. Dose-limiting toxicities included neutropenia (n = 4), febrile neutropenia (n = 1), and fatigue (n = 1). The MTD was 2.7 mg/kg using adjusted body weight. The most common grade ≥3 adverse events across all dose levels were neutropenia (59%), leukopenia (27%), lymphopenia (7%), anemia (7%), and fatigue (5%). One grade 3 febrile neutropenia event was observed. There were no treatment-related deaths. In the efficacy evaluable subset (patients with adenocarcinoma treated with a starting dose ≥1.2 mg/kg, n = 40), the median radiographic progression-free survival was 8.7 months (range, 0.1-33.9). Fourteen of 39 evaluable patients (36%) achieved a PSA50 response. The confirmed objective response rate was 20% (5 of 25 RECIST-evaluable patients). The median duration of response was 7.5 months. Responders had a significantly higher on-treatment frequency of circulating effector CD8+ T cells.

CONCLUSION

FOR46 demonstrated encouraging preliminary clinical activity with a manageable safety profile. Targeting CD46 elicited an immune priming effect that was associated with clinical outcomes.

Clinical benefits of androgen receptor signaling inhibitors in patients with metastatic hormone-sensitive prostate cancer: real-world data from a multi-center study

BACKGROUND

This study investigated clinical benefits of androgen receptor signaling inhibitor (ARSI) in patients with synchronous metastatic hormone-sensitive prostate cancer (mHSPC) based on real-world data from multiple centers.

METHODS

Clinical records of 1107 mHSPC patients who commenced vintage (bicalutamide) (n = 801) or ARSI (n = 306) treatment in addition to androgen deprivation therapy between 1999 and 2024 were reviewed. Progression-free and overall survival (OS) were examined, and prognostic factors were analyzed using multivariate cox proportional hazard modeling. Propensity score matching (PSM) analysis was performed to balance background characteristics.

RESULTS

Median age and initial prostate-specific antigen level were 73 years and 229 ng/ml, respectively. Kaplan-Meier analysis revealed that upfront ARSI treatment was associated with longer progression-free survival (P < 0.0001, hazard ratio [HR] = 0.37) and OS (P = 0.0088, HR = 0.58) than combined androgen blockade after PSM analysis. In particular, an OS benefit of upfront ARSI was observed in high-volume patients (P = 0.0052, HR = 0.56). ARSI use after castration-resistant prostate cancer (CRPC) development correlated with improved OS as compared to patients without ARSI use (P < 0.0001, HR = 0.52). Multivariate analysis identified ARSI therapy as an independent prognostic factor for OS both when used upfront (P = 0.0141, HR = 0.61) and after CRPC development (P < 0.0001, HR = 0.55). In addition, categorizing all patients into groups receiving no ARSI, ARSI after CRPC, or ARSI as upfront therapy revealed 5-year OS rates of 55.65%, 59.85%, and 65.01%, respectively.

CONCLUSIONS

Early use of ARSI in Japanese patients with mHSPC appears clinically beneficial. Our findings suggest the prognostic importance for optimal treatment intensification.

Emerin Dysregulation Drives the Very-Small-Nuclear Phenotype and Lineage Plasticity That Associate with a Clinically Aggressive Subtype of Prostate Cancer

PURPOSE

Circulating tumor cells (CTC) with a very-small-nuclear phenotype (vsnCTC) in prostate cancer are characterized by nuclei smaller than 8.5 μm. Our previous studies established an association between vsnCTCs and visceral metastasis. Reduction of emerin (EMD), a nuclear envelope protein, contributes to prostate cancer metastasis and nuclear shape instability. In this study, we investigated the correlation between EMD expression and the vsnCTC phenotype and its clinical impact.

EXPERIMENTAL DESIGN

We analyzed CTCs from 93 patients with metastatic castration-resistant prostate cancer and categorized them as either vsnCTC+ or vsnCTC- and compared overall survival and progression-free survival. C4-2B, 22Rv1, and DU145 with EMD knockdown were developed and characterized by nuclear size and gene expression by gene set enrichment analysis. Abiraterone- and enzalutamide-resistant C4-2B cells were also characterized by nuclear size and EMD expression.

RESULTS

Patients who were vsnCTC+ had significantly worse overall survival and progression-free survival compared with patients who were vsnCTC-. EMD expression was markedly reduced in CTCs from patients who were vsnCTC+ compared with patients who were vsnCTC-, with a significant positive correlation between EMD expression and CTC nuclear size. EMD knockdown in prostate cancer cells resulted in smaller nuclei, enhanced invasion, and the upregulation of genes associated with lineage plasticity. Additionally, abiraterone- and enzalutamide-resistant C4-2B cells had smaller nuclei and lower EMD expression. vsnCTC+ cells also showed enhanced platinum sensitivity.

CONCLUSIONS

The presence of vsnCTCs represents a novel hallmark of an aggressive subtype of metastatic castration-resistant prostate cancer closely linked to EMD loss and lineage plasticity. These findings highlight the importance of EMD dysregulation in the vsn phenotype, disease progression, and therapeutic resistance in patients with prostate cancer.

PSMA Radioligand Therapy in Advanced Age: Insights From an 85y+ mCRPC Patient Cohort

PURPOSE

With increasing life expectancy, the number of older patients with metastatic castration-resistant prostate cancer (mCRPC) continues to rise, but this group is currently underrepresented in clinical trials. This study aims to assess the efficacy and safety of prostate-specific membrane antigen (PSMA) targeted radioligand therapy (RLT) in patients over 85 years old with mCRPC.

MATERIALS AND METHODS

A retrospective analysis was conducted on 21 mCRPC patients aged 85 years or older receiving PSMA-RLT (range: 85-96 y). The median number of treatment cycles was 4 (range: 1-13 cycles), with a mean cumulative administered activity of 26.9±17.3 GBq (range: 8.0-87.2  GBq) of [177Lu]Lu-PSMA-617. Adverse events, including anemia, thrombocytopenia, leukopenia, renal impairment, fatigue, and xerostomia were classified according to CTCAE version 5.0.

RESULTS

The mean best PSA response across the cohort was -37.6±73.3%, with 62% (13 of 21 patients) showing partial remission. Median progression-free survival and overall survival were 4.6 and 14.7 months, respectively. Severe adverse events were rare, occurring in 2 patients: 1 case of grade 3 anemia and 1 of grade 3 thrombocytopenia.

CONCLUSIONS

The results demonstrate that PSMA-RLT is an effective and well-tolerated treatment for mCRPC patients over 85 years, with clinical outcomes and safety comparable to those observed in studies involving younger populations. This highlights its potential as a valuable therapeutic option for this aging patient group.

Changing metastatic patterns associate with dynamics of circulating tumor DNA in metastatic castration-resistant prostate cancer

BACKGROUND

Circulating tumor DNA (ctDNA) acts as an early biomarker of the efficacy of androgen receptor signaling inhibitor (ARSI) therapy. In this study, we aimed to reveal if ctDNA can supplement imaging to better predict metastasis burden and radiographic progression disease (PD) in metastatic castration-resistant prostate cancer (mCRPC).

METHODS

Targeted next-generation sequencing was performed to assess ctDNA fraction. Radiographic evidence was documented by conventional imaging according to Prostate Cancer Working Group 3 criteria.

RESULTS

We prospectively collected plasma samples from 112 mCRPC with bone (n = 77), lymph nodal (n = 31), and visceral (n = 4) metastases. Only bone metastatic patterns were significantly associated with median ctDNA at baseline, during treatment and at PD (P <.0001). At first radiographic restaging, 24 (31.2%) men with a progressive worsening of bone disease had early ctDNA rise with a % ctDNA variation of 150.6% (interquartile range [IQR] = 104.9-210.7] compared with 11.1% (IQR = 0-36.6), P <.0001, in men with no change in bone disease. Univariate analysis showed that early ctDNA rise was significantly associated with progression free/overall survival (PFS/OS). In multivariable analysis including ctDNA change from baseline to 3-month treatment, variation of bone metastatic patterns (from oligometastatic to polymetastatic and/or to widespread disease), presence of visceral metastasis, age, PSA, performance status and prior docetaxel therapy, the transition from low- to high-ctDNA within 3 months of starting ARSI therapy was a significant predictor of OS (HR = 2.50, 90% CI, 1.06-5.88, P =.035) and persistent high level of ctDNA was a predictor of PFS (HR = 2.53, 95% CI, 1.10-5.81, P =.028). Metastatic involvement demonstrated that the transition from bone polymetastatic to widespread disease and the presence of visceral metastases were both associated with worse OS (HR = 2.43, 95% CI, 1.10-5.35, P =.028, and HR = 3.40, 95% CI, 1.50-7.66, P =.003, respectively). Prior therapy with docetaxel represented an independent predictor of both PFS and OS (HR = 2.47, 95% CI, 1.40-4.35, P =.002, and HR = 1.78, 95% CI, 1.00-3.15, P =.049, respectively).

CONCLUSIONS

Early ctDNA variation might reflect changes in metastatic burden and, likely, in bone metastatic patterns on ARSI therapy allowing to track pattern of disease progression and to predict outcome.

Addition of zoledronic acid to enzalutamide and androgen deprivation therapy in metastatic hormone-sensitive prostate cancer: the randomized phase II BONENZA trial

BACKGROUND

Zoledronic acid (ZA) in combination with androgen deprivation therapy (ADT) has never proved additional activity in patients with advanced prostate cancer. However, conventional imaging is poorly reliable in monitoring disease response of metastatic bone lesions.

METHODS

BonEnza is a randomized phase II multicenter clinical trial designed to compare activity of ADT plus Enzalutamide (E) plus/minus ZA in term of bone response rate by Whole-Body Diffusion-Weighted Magnetic Resonance Imaging (WB-DW-MRI). From February 2018 to June 2021, 126 patients with metastatic hormone-sensitive prostate cancer (mHSPC) and bone metastasis at bone scan were enrolled. Patients were randomized in a 1:1 to receive E 160 mg OD orally alone (E arm) or in combination with ZA 4 mg intravenously every 4 weeks (EZ arm). Primary endpoint of the study was overall response rate (ORR) in bone metastases, secondary endpoints were ORR with conventional imaging, progression free survival (PFS) and overall survival (OS). A logistic model was used to evaluate the association between treatment arm and ORR.

RESULTS

After a median follow-up of 31.9 months, according to an intent to treat analysis, the ORR was superimposable in both arms: 69.8% (95% Confidence Interval [CI]: 57.5-79.9%), Odds Ratio: 1.00 (95%CI 0.47-2.15; p > 0.9). No advantage in favor of EZ arm over E arm emerged either in terms of PFS (Hazard Ratio [HR] 0.77, 95%CI 0.44-1.37; p = 0.4) or OS (HR 1.09; 95%CI 0.54-2.2; p = 0.8). A main limitation of this study was the inability of WB-DW-MRI to evaluate disease response in 17 patients.

CONCLUSIONS

ZA did not improve bone response rate to E plus ADT in mHSPC patients. WB-DW-MRI is a reliable technique to evaluate the response of prostate cancer bone metastases to systemic therapy.

Current androgen receptor antagonists under investigation for resistant prostate cancer: progress and challenges

INTRODUCTION

Prostate cancer represents a significant oncological challenge, with its natural history predominantly driven by androgen receptor (AR) signaling. The pivotal role of this pathway underscores the rationale for targeting AR activity in therapeutic strategies. However, the development of resistance mechanisms has highlighted the need for advanced therapies to address the complexity of the castration-resistant status.

AREAS COVERED

We analyzed the evolving role of second-generation androgen receptor signaling inhibitors (ARSIs) in the management of non-metastatic and metastatic castration-resistant prostate cancer, we critically examine emerging combination strategies involving ARSIs, novel agents targeting resistance pathways, and the mechanisms underlying treatment resistance. The review also provides insights into future directions for enhancing outcomes. PubMed literature research using keywords related to castration-resistant prostate cancer and its treatments was performed, including the most relevant trials and reviews.

EXPERT OPINION

ARSIs have revolutionized the management of prostate cancer, providing substantial clinical benefits and representing the cornerstone of current treatment paradigms. However, key challenges remain, including determining optimal treatment sequencing, overcoming resistance mechanisms, and tailoring therapies to specific molecular subtypes. Biomarker-driven approaches are critical for refining patient selection and improving therapeutic outcomes. Ongoing trials investigating novel hormonal-axis-directed agents and innovative combination therapies aim to expand the arsenal of effective treatment.

Safety and Tolerability of Relugolix in Combination with Abiraterone or Apalutamide for Treatment of Patients with Advanced Prostate Cancer: Data from a 52-Week Clinical Trial

BACKGROUND

The gonadotropin-releasing hormone (GnRH) receptor antagonist relugolix is the only oral androgen deprivation therapy (ADT) indicated for advanced prostate cancer (aPC). Combining ADT with androgen receptor signaling inhibitors (ARSIs) has shown improved clinical outcomes.

OBJECTIVE

To assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of relugolix in combination with ARSIs in patients with aPC.

METHODS

In this 52-week, open-label study, patients received relugolix (120 mg once daily) with abiraterone (1,000 mg once daily) and corticosteroid (Part 1) or relugolix (240 mg once daily) with apalutamide (240 mg once daily) (Part 2). Metastatic castration-sensitive patients were eligible for both parts, whereas castration-resistant patients were eligible for Part 1 if metastatic and Part 2 if non-metastatic. Adverse events and other safety data were evaluated over 52 weeks, while pharmacodynamic and pharmacokinetic (Part 2 only) data were assessed over 12 weeks. Medication adherence to relugolix was measured by pill count.

RESULTS

Of 48 patients, 21 completed Part 1 and 20 completed Part 2. Most adverse events were grade 1 or 2, with hypertension (Part 1) and rash (Part 2) being most common. Mean testosterone concentrations remained below castrate level. Median prostate-specific antigen concentration was 0.04 ng/mL at week 12 in both parts. Concentrations of relugolix, apalutamide, and N-desmethyl-apalutamide were stable over 12 weeks similar to previous data. Relugolix adherence rates were > 97% in both parts.

CONCLUSIONS

The safety/tolerability profile of both combination therapies was consistent with those of the individual drugs. These findings support using relugolix in combination with abiraterone or apalutamide as treatment of aPC.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT04666129.

Prognostic 18F-flotufolastat PET parameters for outcome assessment of 177Lu-labeled PSMA-targeted radioligand therapy in metastatic castration-resistant prostate cancer

PURPOSE

This retrospective analysis evaluates baseline 18F-flotufolastat positron emission tomography (PET) parameters as prognostic parameters for treatment response and outcome in patients with metastatic castration-resistant prostate cancer (mCRPC) undergoing treatment with [177Lu]Lu-PSMA-I&T.

METHODS

A total of 188 mCRPC patients with baseline 18F-flotufolastat PET scans were included. Tumor lesions were semiautomatically delineated, with imaging parameters including volume-based and standardized uptake value (SUV)-based metrics. Outcome measures included prostate-specific antigen (PSA) response, PSA-progression-free survival (PSA-PFS), and overall survival (OS). Univariate and multivariate regression analyses assessed the impact of baseline imaging and pretherapeutic clinical parameters on outcome. Event time distributions were estimated with the Kaplan-Meier method, and groups were compared with log-rank tests.

RESULTS

Significant prognostic parameters for PSA response and PSA-PFS included log-transformed whole-body SUVmax (odds ratio (OR), 3.26, 95% confidence interval (CI), 2.01-5.55 and hazard ratio (HR), 0.51, 95% CI, 0.4-0.66; both p < 0.001) and prior chemotherapy (OR 0.3, 95% CI, 0.12-0.72 and HR 1.64, 95% CI, 1.07-2.58; p = 0.008 and p = 0.028, respectively). For OS, significant prognosticators were the following log-transformed parameters: number of lesions (HR 1.38, 95% CI, 1.24-1.53; p < 0.001), TTV (HR 1.27, 95% CI, 1.18-1.37; p < 0.001), and ITLV (HR 1.24, 95% CI, 1.16-1.33; p < 0.001), with log-transformed TTV (HR 1.15, 95% CI, 1.04-1.27; p = 0.008) remaining significant in multivariate analysis.

CONCLUSION

At baseline, SUV-based 18F-flotufolastat PET metrics (e.g., whole-body SUVmax) serve as significant positive prognosticators for short-term outcomes (PSA response and PSA-PFS). In contrast, volume-based metrics (e.g., TTV) are significant negative prognosticators for long-term outcome (OS), in mCRPC patients treated with [177Lu]Lu-PSMA-I&T.

The Safety and Efficacy of Targeted Alpha Therapy, Ac-225 Prostate-Specific Membrane Antigen, in Patients With Metastatic Castration-Resistant Prostate Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Metastatic castration resistance prostate cancer (mCRPC) is a challenging disease with a significant burden of mortality and morbidity. Most of the patients attain resistance to the available treatments, necessitating further novel therapies in this clinical setting. Actinium 225 (225Ac) prostate-specific membrane antigen (PSMA) radioligand therapy has emerged as a promising option and has been utilized for the last decade. Although a few meta-analyses were performed on the efficacy and safety of 225Ac-PSMA RLT in mCRPC patients, several current studies have been added to the literature since the latest meta-analysis. We aimed to gather all individual studies to perform up-to-date meta-analyses.

METHODS

We searched the literature using Pubmed-Medline, Web of Science, Elsevier-Sceince Direct, and Cochrane-Central databases. The data for any PSA decline, over 50% PSA decline, overall survival (OS), progression-free survival (PFS), and toxicity profile were captured from the studies eligible for meta-analysis. We utilized the random effect model to generate pooled estimates.

RESULTS

The sixteen eligible studies contained 1102 patients. Sixty-three percent of patients achieved more than 50% PSA decline, while 82% had any PSA decline after the completion of therapy. The pooled mean OS and PFS were 12.72 months (9.52-15.91) and 11.02 months (6.88-15.15), respectively. The most common adverse event was xerostomia, with a pooled proportion of 84%. Grade ≥ 3 anemia, thrombocytopenia, leucopenia, and nephrotoxicity were encountered in 9%, 5%, 4%, and 4% of the patients.

CONCLUSIONS

225Ac-PSMA RLT is an efficacious and safe treatment for mCRPC. Future well-designed randomized controlled studies comparing 225Ac-PSMA RLT with other approved therapeutic options would better comprehend the exact role of this therapy in the treatment sequence of mCRPC.

The Prognostic Value of the Prostate Adenocarcinoma With Ductal Feature in Patients With Advanced Prostate Cancer Treated With Abiraterone Acetate

BACKGROUND

The prognostic value of the prostate adenocarcinoma (PAC) with ductal feature in patients with advanced prostate cancer treated with abiraterone acetate has not been scrutinized. This study aims to explore the predictive value of PAC with ductal feature on the therapeutic efficacy of abiraterone therapy in metastatic prostate cancer (mPCa) patients.

METHODS

We retrospectively analyzed data from 569 patients with mPCa receiving abiraterone at either the metastatic hormone-sensitive (mHSPC, N = 165) or castration-resistant prostate cancer (mCRPC, N = 404) stage. PSM was performed to balance the baseline characteristics between individuals with and without ductal features. Kaplan-Meier curves and Cox regression were used to analyze the predictive significance of ductal feature on abiraterone efficacy, including PSA response, PSA progression-free survival (PSA-PFS), radiographic progression-free survival (rPFS), and overall survival (OS).

RESULTS

Totally, ductal feature was detected in 40/569 (7.0%) men, with 18 and 22 in the mHSPC and mCRPC cohorts, respectively. The PSA response rate was comparable for people with and without ductal features for both cohorts. Notably, in the mHSPC cohort, patients with and without ductal features shared similar median PSA-PFS (not reached vs. 32.6-months, p = 0.593) and rPFS (not reached vs. 35.0-months, p = 0.768). Similar results were observed in the mCRPC cohort (median PSA-PFS: 21.2- vs. 11.6-months, p = 0.100; median rPFS: 34.6- vs. 18.7-months, p = 0.092). COX regression further revealed that ductal feature was not an indicator of unfavorable PSA-PFS or rPFS in the mHSPC and mCRPC cohort.

CONCLUSION

In conclusion, our findings indicated that there is insufficient evidence to differentiate the therapeutic efficacy of AA in mPCa based on the presence or absence of ductal features. However, further validation through larger-scale studies is required to substantiate them.

Development and validation of a machine learning-based risk model for metastatic disease in nmCRPC patients: a tumor marker prognostic study

BACKGROUND

Nonmetastatic castration-resistant prostate cancer (nmCRPC) is a clinical challenge due to the high progression rate to metastasis and mortality. To date, no prognostic model has been developed to predict the metastatic probability for nmCRPC patients. In this study, we developed and externally validated a machine-learning model capable of calculating risk scores and predicting the likelihood of metastasis in nmCRPC patients.

PATIENTS AND METHODS

A total of 2716 nmCRPC patients were included in this study. The training and testing datasets were derived from SPARTAN (NCT01946204) and ARAMIS (NCT02200614), respectively. Regarding metastasis-free survival as the endpoint, we subjected 13 clinical features to 10 machine-learning models and their combinations to predict metastasis. Model performance was assessed through accuracy (AUC), calibration (slope and intercept), and clinical utility (DCA). The risk score calculated by the model and risk factors based on eight identified variates were used for metastatic risk stratification.

RESULTS

The final prognostic model included eight prognostic factors, including novel hormone therapy application, Gleason score, previous treatments received (both surgery and radiotherapy, or neither), Race (White), PSA doubling time (PSADT), hemoglobin (HGB), and lgPSA. The prognostic model resulted in a C-index of 0.724 (95% CI 0.700-0.747) in internal validation and relatively good performance through tAUC (>0.70 at 3-month intervals between 6 and 39 months) in external validation. In the risk score stratifying strategy, compared with the low-risk group, the metastasis HRs for medium- and high-risk groups were 1.72 (95% CI 1.39-2.12) and 4.43 (95% CI 3.66-5.38); as for risk factor count, the HRs are 1.98 (95% CI 1.50-2.61) and 4.17 (95% CI 3.16-5.52), respectively.

CONCLUSIONS

In this study, we developed and validated a machine learning prognostic model to predict the risk of metastasis in nmCRPC patients. This model can assist in the risk stratification of nmCRPC patients, guide follow-up strategies, and aid in selecting personalized treatment intensities.

Real-world effectiveness of rezvilutamide plus androgen deprivation therapy in patients with low-volume, metastatic hormone-sensitive prostate cancer: a retrospective multicenter study

Background

The CHART study established the combination of rezvilutamide and androgen deprivation therapy (ADT) as a standard treatment for patients with high-volume metastatic hormone-sensitive prostate cancer (mHSPC). However, the therapeutic outcomes of this regimen in patients with low-volume mHSPC remain insufficiently defined. This study thus aimed to assess the real-world effectiveness of rezvilutamide combined with ADT in the treatment of low-volume mHSPC.

Methods

This multicenter, noninterventional, observational study was conducted in China and included adult patients diagnosed with low-volume mHSPC who were treated with rezvilutamide in combination with ADT as determined by the investigator. The study assessed prostate-specific antigen (PSA) responses at multiple time points (3, 6, 9, and 12 months), including a PSA decline ≥50% (PSA50), a PSA decline ≥90% (PSA90), and a PSA level <0.2 ng/mL (undetectable PSA). Subgroup analyses of PSA responses were conducted according to baseline characteristics, including age, Eastern Cooperative Oncology Group performance status (ECOG PS), and Gleason score.

Results

Between August 29, 2023 and December 31, 2024, a total of 257 patients were enrolled in the study. The median age was 73 years [interquartile range (IQR), 68-77 years], and the median baseline PSA level was 38 ng/mL (IQR, 7-100 ng/mL). PSA responses were observed as early as 3 months after initiating rezvilutamide treatment, with 88% [176/199; 95% exact confidence interval (CI): 83-93%] achieving PSA50, 75% (149/199; 95% exact CI: 68-81%) achieving PSA90, and 54% (108/199; 95% exact CI: 47-61%) achieving undetectable PSA levels. These responses further improved at subsequent time points (6, 9, and 12 months). By 12 months, 100% (12/12; 95% exact CI: 74-100%) achieved PSA50, 92% (11/12; 95% exact CI: 62-100%) achieved PSA90, and 83% (10/12; 95% exact CI: 52-98%) had undetectable PSA levels.

Conclusions

This study is the first to evaluate the effectiveness of rezvilutamide in patients with low-volume mHSPC. In a real-world clinical setting, the combination of rezvilutamide and ADT demonstrated favorable PSA response in this patient population. These findings provide additional treatment options for patients with low-volume mHSPC and support the need for further large-scale research on rezvilutamide in this subgroup.

Evidence-Based Clinical Protocols to Monitor Efficacy of [177Lu]Lu-PSMA Radiopharmaceutical Therapy in Metastatic Castration-Resistant Prostate Cancer Using Real-World Data

Our objectives were to assess the prognostic value of posttherapy [177Lu]Lu-PSMA (LuPSMA) SPECT/CT by visual evaluation using RECIP 1.0 during LuPSMA therapy and develop an evidence-based clinical protocol to monitor the efficacy of LuPSMA. Methods: Patients with metastatic castration-resistant prostate cancer who received at least 2 LuPSMA cycles between April 2019 and November 2023 were retrospectively included in this study. Pairs of baseline and interim LuPSMA SPECT/CT (SPECT) and PSMA PET/CT (PET) images after 2 therapy cycles were analyzed per visual RECIP 1.0. Changes in prostate-specific antigen (PSA) levels at 12 wk were categorized by Prostate Cancer Working Group Criteria 3 guidelines and combined with RECIP 1.0 reads to determine disease progression using a composite classification method (PSA + RECIP). The primary outcome was the prognostic value of posttherapeutic SPECT by RECIP 1.0 for overall survival (OS). The clinical protocol was developed on the basis of the prognostic accuracy (Harrell concordance index, or C-index) of SPECT versus PET and the combination of SPECT plus PSA (SPECT + PSA) versus the combination of PET plus PSA (PET + PSA). Results: Data from 105 patients were evaluated. Progressive disease determined by SPECT was associated with shorter OS compared with stable disease (hazard ratio, 2.5; 95% CI, 1.2-5.3; P = 0.015) and with partial response (hazard ratio, 6.5; 95% CI, 2.7-15.7; P < 0.001). Of the 73 patients who underwent PET after 2 cycles, 7 (10%), 30 (41%), 22 (30%), and 30 (41%) had tumor progression shown by SPECT, PET, SPECT + PSA, and PET + PSA, respectively. The C-index for SPECT was inferior compared with that for PET (0.54 vs. 0.66; P < 0.001), whereas the C-indices for SPECT + PSA and PET + PSA did not differ significantly (0.62 vs. 0.66, respectively; P = 0.07). Conclusion: Posttherapeutic LuPSMA SPECT/CT per RECIP 1.0 after 2 therapy cycles was prognostic for OS. LuPSMA SPECT/CT identified significantly fewer patients with RECIP-classified progressive disease; however, SPECT + PSA achieved similar prognostic accuracy to PET + PSA for LuPSMA response evaluation.

Prognostic Value of the Circulating Tumor DNA Fraction in Metastatic Castration-resistant Prostate Cancer: Results from the ProBio Platform Trial

BACKGROUND AND OBJECTIVE

The aim of this study was to evaluate the prognostic value of undetectable circulating tumor DNA (ctDNA) and the dose-response relationship between ctDNA levels and survival outcomes in metastatic castration-resistant prostate cancer (mCRPC).

METHODS

We analyzed data for patients enrolled in the ProBio trial up to November 2022 who received an androgen receptor pathway inhibitor or taxane. We compared survival outcomes between patients with undetectable ctDNA and those with detectable ctDNA randomized to physician's choice or investigational arms. Time to no longer clinically benefiting (NLCB) and overall survival (OS) were assessed using Bayesian survival models, with results reported as survival time ratios (STRs). Dose-response relationships were estimated using spike-at-zero models.

KEY FINDINGS AND LIMITATIONS

A total of 220 patients were included, of whom 139 had detectable ctDNA (56 in the physician's choice arm, 83 in investigational arms) and 81 had undetectable ctDNA. In comparison to the undetectable ctDNA group, the physician's choice arm had 60% shorter time to NLCB (STR 0.40, 90% credible interval [CrI] 0.31-0.51) and 51% shorter OS (STR 0.49, 90% CrI 0.38-0.61). Similar results were observed in comparison to the investigational arms. Dose-response analysis revealed that the undetectable ctDNA group had twofold longer time to NLCB (STR 2.05, 90% CrI 1.66-2.57) and 1.6-fold longer OS (STR 1.63, 90% CrI 1.33-2.05) in comparison to the subgroup with a ctDNA fraction of 2.5%. Every 10-point increment in the ctDNA fraction corresponded to a 10% reduction in NLCB and OS times.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Undetectable ctDNA at baseline predicts superior prognosis in mCRPC, suggesting potential for treatment de-escalation and less intensive monitoring for this subgroup of patients. This trial is registered on ClinicalTrials.gov as NCT03903835.

Copenhagen Prospective Personalized Oncology (CoPPO) - Impact of comprehensive genomic profiling in more than 2000 patients in a Phase I setting

PURPOSE

Targeted therapy based on the molecular characterization of tumors has been among the most remarkable advances in cancer medicine. Here, we report the impact of almost 10 years of comprehensive genomic profiling in more than 2000 patients with advanced solid tumors at the Phase 1 unit, Department of Oncology, Rigshospitalet, Copenhagen, Denmark.

MATERIALS AND METHODS

A prospective, single-center, single-arm open-label study (NCT02290522) was conducted, enrolling patients with advanced cancer referred to a Phase I Unit. Fresh tumor tissue was obtained for whole genome or exome sequencing (germline and somatic), RNA sequencing and SNP array. In cases where fresh tumor tissue was unavailable, archived formalin-fixed paraffin-embedded tumor tissue or circulating tumor DNA extracted from plasma were obtained for targeted panels. Genomic reports were reviewed and discussed by a multidisciplinary tumor board and actionable alterations were classified according to the ESMO scale for the clinical actionability of molecular targets (ESCAT). When possible, patients were treated with regimen matched to the genomic profile.

RESULTS

A total of 2147 patients with advanced cancer and exhausted treatment options were enrolled from April 2013 to December 2021. Genomic profiles were obtained in 1866 patients (87%). At least one actionable target was identified in 1062 patients (57%) with a total of 1614 actionable alterations including high RNA CEACAM5 expression (N=559, 35%), homologous recombination deficiency (HRD) alteration (N=314, 20%) and tumor mutational burden-high (N=84, 5%). Overall, 256 patients (24% of the patients with an actionable target) were treated with targeted therapy and among these 14 patients were treated with more than one line of targeted therapy. In total, 274 targeted treatment regimens were initiated, and 259 treatments were evaluable with an overall response (OR) rate of 25% (CI95%: 0.20 - 0.30). ESCAT I/II was associated with improved OR, along with better progression-free survival (PFS) and overall survival (OS).

CONCLUSION

This large-scale study demonstrates that genomic profiling is efficient to identify actionable targets and to match patients to targeted therapies.

Clinical and Translational Results from PORTER, a Multicohort Phase I Platform Trial of Combination Immunotherapy in Metastatic Castration-Resistant Prostate Cancer

PURPOSE

Current immune checkpoint therapies offer limited benefits for metastatic castration-resistant prostate cancer. Novel combinations may enhance immunotherapy efficacy.

PATIENTS AND METHODS

We conducted an open-label, noncomparative platform trial (NCT03835533) in metastatic castration-resistant prostate cancer to assess nivolumab-based combinations. The cohorts were as follows: (A) bempegaldesleukin 0.006 mg/kg and nivolumab 360 mg i.v. every 3 weeks; (B) stereotactic body radiotherapy 30 to 50 Gy, CDX-301 75 μg/kg s.c. for 5 days, poly-ICLC 1 mg intramuscularly weekly twice for 3 weeks, and nivolumab 480 mg every 4 weeks; and (C) CDX-301 75 μg/kg for 10 days, INO-5151 3 mg intramuscularly on lead-in day 8, day 1 of cycles 1 to 3, and then every 12 weeks, and nivolumab 480 mg every 4 weeks. The primary endpoint was safety; secondary endpoints included composite response rate (radiographic, PSA, or circulating tumor cell responses), 6-month disease control rate, progression-free survival, and overall survival. Serial blood and tissue samples were analyzed for pharmacodynamics and association with disease control.

RESULTS

A total of 43 patients were enrolled (n = 14, 15, and 14 in cohorts A, B, and C, respectively). Grade 3 to 4 treatment-related adverse events occurred in 10 (71%), 2 (13%), and 2 (14%) patients, respectively, with one grade 5 treatment-related adverse event in cohort A. Composite response rates were 7% (1/14), 33% (5/15), and 7% (1/14). Across cohorts, 6-month disease control was associated with preexisting memory/regulatory T cells, TNFα, and other inflammatory pathways.

CONCLUSIONS

Cohort B, which combined radiotherapy with CDX-301, poly-ICLC, and nivolumab, demonstrated encouraging clinical activity. Preexisting rather than treatment-induced immune activation was associated with clinical benefit across cohorts, highlighting the importance of baseline immune fitness.

PSMA-targeted radioligand therapy with [177Lu]Lu-LNC1011 for metastatic castration-resistant prostate cancer: a pilot study

BACKGROUND

Preclinical studies have shown that the long-acting PSMA-targeting radiopharmaceutical [177Lu]Lu-LNC1011 based on dansylated amino acid modification had high tumor uptake and prolonged retention. This study aimed to explore its safety and efficacy in patients with metastatic castration-resistant prostate cancer (mCRPC).

METHODS

Eight mCRPC patients who met the inclusion criteria received intravenous treatment with [177Lu]Lu-LNC1011. Treatment was repeated every 6 weeks for up to a maximum of 6 cycles. Molecular imaging and hematology markers were the main evaluation indicators. The primary endpoints were biochemical (PSA) response and molecular imaging response. Toxicity grading was assessed using the Common Terminology Criteria for Adverse Events version 5.0.

RESULTS

Hematological toxicity was the primary side effect. In all patients, adverse events (AEs) after [177Lu]Lu-LNC1011 treatment were primarily characterized by decreased levels of hemoglobin, white blood cells and platelets. Grade 3 anemia was recorded in 1 patient, and grade 2 leukopenia and thrombocytopenia were recorded in 4 patients. The average systemic effective dose was 0.18 mSv/MBq, and the kidney was the organ with the highest absorbed dose (3.11 ± 0.26 mSv/MBq). Long half-life (71.30 ± 8.23 h) and high absorbed dose [5.77, (range 5.5-14 Gy/GBq)] were calculated in the lesions. All patients had a more than 50% decline of PSA during treatment, and one patient dropped to 0 ng/mL. According to assessment criteria adapted from the PERCIST v.1.0 criteria, complete response, partial response, and disease progression were observed in 2 (25%), 4 (50%), and 2 (25%) patients, respectively.

CONCLUSION

[177Lu]Lu-LNC1011 was well tolerated and had acceptable side effects for PSMA-targeted radioligand therapy. Tumor lesions received high radiation doses and had excellent responses to the treatment. Dose escalation studies in a larger number of patients are worth pursuing and necessary to confirm these results. URL OF REGISTRY: https://clinicaltrials.gov/study/NCT06809426?term=NCT06809 .

TRIAL REGISTRATION

NCT06809426, registration date: 2025-01-23.

The real prevalence and clinical courses of non-metastatic castration-resistant prostate cancer: a retrospective single-institutional study

BACKGROUND

Non-metastatic castration-resistant prostate cancer (PCa) has become clinically important in PCa management, with treatments aiming to delay metastasis. However, limited data exist on its prevalence and patient characteristics in real-world settings.

METHODS

We retrospectively investigated the clinical records of 1929 patients who were treated for localized PCa between 2005 and 2018. From this population, we counted patients who progressed to non-metastatic castration-resistant PCa, and summarized the characteristics of the patients.

RESULTS

Among patients who underwent radical prostatectomy (796 patients), radiation therapy (1021 patients), or primary androgen deprivation therapy (ADT) (112 patients), 0.9%, 0.9%, and 5.4%, respectively, were diagnosed with non-metastatic castration-resistant PCa over a median follow-up of 5.5 years. Including referred cases, a total of 45 non-metastatic castration-resistant PCa patients were analyzed. The median age at non-metastatic castration-resistant PCa diagnosis was 76 years, with a median time of 4.8 years from the initiation of ADT to non-metastatic castration-resistant PCa development. From the initial PCa diagnosis, the median time to non-metastatic castration-resistant PCa was 5.9 years. Median metastasis-free survival was 5.2 years, while overall survival was 6.3 years.

CONCLUSION

This study reports the prevalence of non-metastatic castration-resistant PCa at our institution and provides clinical findings of non-metastatic castration-resistant PCa patients by analyzing consecutive localized PCa cases through comprehensive medical chart reviews for every patient.

Radiographic Progression Without Corresponding Prostate-specific Antigen Progression in Patients with Metastatic Castration-sensitive Prostate Cancer Receiving Apalutamide: Secondary Analysis of the TITAN Trial

BACKGROUND AND OBJECTIVE

In prostate cancer treated with androgen deprivation therapy (ADT), the initial sign of treatment resistance is often prostate-specific antigen (PSA) progression, followed by radiographic progression. However, the association between these two forms of progression remains unclear, especially in patients with metastatic castration-sensitive prostate cancer (mCSPC) treated with androgen receptor pathway inhibitors. We sought to evaluate the association between radiographic progression, PSA progression, and outcomes of apalutamide therapy in mCSPC.

METHODS

We analyzed individual participant-level data for patients randomized within the TITAN trial who experienced radiographic progression during follow-up (N = 326). This study investigated radiographic progression without simultaneous or preceding PSA progression, as defined by the Prostate Cancer Working Group 2 (discordant progression), and explored the association of such progression with radiographic progression-free survival.

KEY FINDINGS AND LIMITATIONS

Among the patients who developed radiographic progression, 115 (35.3%) had been treated with apalutamide plus ADT (the apalutamide group) and 211 (64.7%) with placebo plus ADT (the placebo group). Discordant progression occurred in 52.2% of patients (60 of 115) in the apalutamide group and 27.5% (58 of 211) in the placebo group (p < 0.001). A multivariable logistic regression analysis showed that discordant progression was associated with apalutamide treatment. We found evidence of an association between discordant progression and shorter radiographic progression-free survival.

CONCLUSIONS AND CLINICAL IMPLICATIONS

This study found that nearly half of the patients with mCSPC treated with apalutamide who experienced radiographic progression developed it without corresponding PSA progression, suggesting that heavy reliance on PSA monitoring may be inadequate for assessing disease activity in this context.

PATIENT SUMMARY

In patients who have metastatic castration-sensitive prostate cancer (mCSPC) and are being treated with apalutamide, radiographic images may show cancer progression even if prostate-specific antigen tests indicate no change. This highlights the importance of regular imaging when using apalutamide to manage mCSPC.

Clinical Trial Protocol for LuCAB: A Phase I-II Trial Evaluating Cabazitaxel in Combination with [177Lu]Lu-PSMA-617 in Patients with Metastatic Castration-Resistant Prostate Cancer

[177Lu]Lu-prostate-specific membrane antigen (PSMA)-617 is a standard treatment for patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with docetaxel and an androgen receptor pathway inhibitor. However, for many, responses are short and progression is inevitable. Contributing factors to treatment resistance include molecular heterogeneity with variable PSMA expression, micrometastases that may not absorb sufficient radiation from 177Lu to result in cell death, and inherent or acquired radioresistance because of genomic alterations or the tumor microenvironment. Cabazitaxel is a radiosensitizer and may treat PSMA-negative disease that would otherwise evade targeting by [177Lu]Lu-PSMA-617. We hypothesize that the combination of [177Lu]Lu-PSMA-617 and cabazitaxel will be synergistic with an acceptable safety profile. Methods: This investigator-initiated phase I-II trial aims to evaluate the safety, tolerability, and preliminary efficacy of cabazitaxel and [177Lu]Lu-PSMA-617 in combination. Up to 38 patients with mCRPC will receive up to 6 doses of [177Lu]Lu-PSMA-617 administered intravenously every 6 wk at a fixed dose of 7.4 GBq. Cabazitaxel will be administered concurrently (dose range, 12.5-20 mg/m2) on day 2 and day 23 of each 6-wk cycle, with dose escalation determined using a traditional 3 + 3 design to establish the maximum tolerated or administered dose. Key eligibility criteria include a diagnosis of progressive mCRPC with PSMA-positive disease on PSMA PET/CT (SUVmax ≥ 15) and no sites of discordance on [18F]F-FDG PET/CT. Patients must have received prior docetaxel and an androgen receptor pathway inhibitor, have adequate bone marrow and organ function, and have an Eastern Cooperative Oncology Group performance status of 0 or 1. The primary objective is to assess for dose-limiting toxicities and determine the recommended phase II dose of cabazitaxel and [177Lu]Lu-PSMA-617 in combination. Secondary objectives include further safety evaluation through the measurement of the frequency and severity of adverse events, assessment of efficacy, and evaluation of changes in pain and health-related quality of life over the first 12 mo from treatment commencement. Plasma will be collected at baseline, during treatment, and at disease progression for circulating tumor DNA analysis, which will be correlated with clinical outcomes to identify potential biomarkers of treatment response or resistance. Conclusion: Enrollment commenced in August 2022, with anticipated completion in 2025.

Recommendations from the Galician Oncological Society and the Galician Society of Nuclear Medicine for the use of 177Lu-PSMA-617 radioligand-therapy in prostate cancer

Theragnostic is a type of precision medicine that uses molecules linked to radioactive isotopes for the diagnosis and treatment of diseases. In recent years, it has gained significant importance to treat neuroendocrine tumors and is currently being used in prostate cancer. Various radiopharmaceuticals have emerged for diagnosing and detecting lesions showing prostate-specific membrane antigen (PSMA) positivity on the Positron emission tomography/computed tomography scan, being the most widely used labeled with [68Ga] and [18F]. Its use as therapy in prostate cancer (PC) has been assessed in the VISION, TheraP, and PSMAfore clinical trials conducted with the radioligand [177Lu]Lu-PSMA-617, demonstrating significant antitumor activity. The aim of this article is to present practical recommendations, based on current available scientific evidence and on a multidisciplinary consensus, for the diagnosis and treatment with [177Lu]Lu-PSMA-617 in patients with PC.

225 Ac-PSMA-617 Augmentation After Insufficient Response Under 177 Lu-PSMA-617 Radioligand Therapy in mCRPC: Evaluation of Outcome and Safety From a Prospective Registry (REALITY Study)

BACKGROUND

Even though the introduction of 177 Lu-PSMA-617 RLT represents a major milestone in the treatment of mCRPC, there are still patients who do not respond adequately to this therapy and for whom there are only limited options left. Augmenting 177 Lu-PSMA-617 RLT with the alpha-emitter 225 Ac-PSMA-617 may present an escalating treatment option to increase efficacy. In this study, we aim to evaluate outcome and safety of 225 Ac-PSMA-617 augmentation to 177 Lu-PSMA-617 RLT in patients who present insufficient response to monotherapy with 177 Lu-PSMA-617 RLT.

PATIENTS AND METHODS

The study included n = 51 mCRPC patients enrolled in a prospective registry receiving 177 Lu-PSMA-617 monotherapy and showing insufficient response, followed by initiation of 225 Ac-PSMA-617 augmentation, with adjusted activities depending on individual patient characteristics. Biochemical response, progression-free survival, and overall survival were assessed. Adverse events were evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE v.5.0).

RESULTS

After initiation of 225 Ac-PSMA-617 augmentation to 177 Lu-PSMA-617 RLT, 24/51 patients (47.1%) exhibited partial remission, 16/51 (31.4%) stable disease, and 11/51 (21.6%) progressive disease. The median progression-free survival and overall survival rates were 6.3 months and 9.1 months, respectively. The majority of CTCAE gradings remained stable after initiating augmentation. Severe adverse events were rare, and no treatment termination due to side effects was recorded.

CONCLUSIONS

225 Ac-PSMA-617 augmented 177 Lu-PSMA-617 radioligand therapy seems to be an effective escalating treatment option in patients after failure of conventional 177 Lu-PSMA-617 RLT and represents a promising approach balancing antitumor effect and tolerable side effects.

Integrating Prostate Specific Membrane Antigen-PET into Clinical Practice for Prostate Cancer

Prostate surface membrane antigen (PSMA)-PET imaging has significantly shaped the clinical management of prostate cancer, from localized to metastatic disease. It outperforms conventional imaging in both primary staging and detecting recurrence. PSMA-PET incorporation into the clinical workflow can alter treatment decisions, though the impact of observed stage migration on patient outcomes has yet to be well-characterized. There is growing interest in using PSMA-PET to predict treatment response across all stages of prostate cancer, and to select patients for PSMA radioligand therapy. Use of PSMA-PET will continue to expand for clinical applications as its role becomes better defined through prospective studies.

Feasibility and efficacy of therapeutic drug monitoring of abiraterone in metastatic castration resistant prostate cancer patients

BACKGROUND

Previous studies demonstrated better outcomes for mCRPC (metastatic castration resistant prostate cancer) patients with higher abiraterone exposure (minimal plasma concentration (Cmin) > 8.4 ng/mL), but around 40% of patients experience exposure below this target. Pharmacokinetic (PK)-guided interventions following Therapeutic Drug Monitoring (TDM) could optimise exposure and outcomes. We aimed to evaluate the feasibility and effect on treatment outcomes of abiraterone TDM.

METHODS

Patients with low exposure levels (Low-group, Cmin < 8.4 ng/mL) got a PK-guided intervention. We compared exposure, adverse event (AE) incidence, time on treatment (ToT) and Prostate-Specific Antigen response rate (PSArr) between the Low-group and Adequate-group.

RESULTS

We included 167 mCRPC patients, with 56 in the Adequate-group and 111 in the Low-group. Interventions were successful 86% of the time. Exposure between groups became corresponding (Low-group: 7.95 to 20.5 ng/mL, Adequate-group: 20.8 ng/mL, p = 0.72) with comparable AE incidence (17% vs. 23%, p = 0.4). Median ToT and PSArr were similar (351 vs. 379 days, p = 0.35; 61.3% vs. 67.9%, p = 0.51).

CONCLUSIONS

PK-guided interventions improved above target exposure from 33.5% to 81.4% of patients without additional AEs. While historically, low exposure patients had significantly shorter survival, PK-guided interventions eliminated this disparity. As interventions are effective, low-cost and safe, TDM for abiraterone should be considered to enhance treatment outcomes.

The Impact of Doxycycline as an Adjunctive Therapy on Prostate-Specific Antigen, Quality of Life, and Cognitive Function in Metastatic Prostate Cancer Patients: A Phase II Randomized Controlled Trial

Background/Objectives: Metastatic prostate cancer remains a major clinical challenge, with limited therapeutic options. Doxycycline, a tetracycline antibiotic with anti-inflammatory properties, has shown potential as an adjunctive therapy. This study aimed to evaluate its efficacy in reducing prostate-specific antigen (PSA) levels and improving quality of life in patients receiving standard treatment for metastatic prostate cancer. Methods: This phase II, double-blind, randomized controlled trial included 45 participants (aged 57-81 years) assigned to doxycycline (100 mg daily) or a placebo for six months. The primary outcome was the percentage change in PSA levels at 3 and 6 months. Secondary outcomes included quality of life (EQ-5D-5L), cognitive function (Mini-Mental State Examination), and glucose levels. Additionally, a structure-activity relationship (SAR) analysis was performed through an extensive bibliographic review to identify pharmacophores responsible for doxycycline's biological activity, particularly its tetracyclic core. The SAR analysis included tetracyclines and derivatives, androgen-targeting agents, and other pharmacologically relevant molecules used in prostate cancer therapy. Statistical analysis was conducted using multivariate logistic regression. Results: At six months, the doxycycline group showed a median PSA reduction of 60% compared to 10% in the placebo group (p = 0.043). A ≥50% reduction in PSA levels was observed in 71.4% of patients receiving doxycycline versus 20.8% in the placebo group (p = 0.001), with an adjusted relative risk of 10.309 (95% CI: 2.359-45.055, p = 0.002). Quality of life improved, with 7.1% of doxycycline-treated patients reporting poor quality of life compared to 42.9% in the placebo group (p = 0.028). A slight improvement in cognitive function was also noted (p = 0.037). SAR analysis suggested that the tetracyclic ring of doxycycline may play a crucial role in its observed biological effects. Conclusions: Doxycycline demonstrates potential as an adjunctive therapy in metastatic prostate cancer by reducing PSA levels and improving quality of life. The SAR analysis supports the hypothesis that its tetracyclic structure may be responsible for its therapeutic effects. Further large-scale trials are warranted to confirm these findings.

A Case-Control Study of Association Between Serum Levels of 19 Trace Elements with Prostate Cancer in Southwest China

Prostate cancer (PCa) is the most prevalent urological malignancy, exhibiting the highest incidence and the second-highest mortality among all male cancers. The incidence of PCa in men in China is consistently rising. Studies have shown that elemental exposure levels are associated with the occurrence of PCa. However, epidemiological data are limited, and more researches on different regions and races are needed. To clarify the relationship between the occurrence of PCa and serum levels of 19 trace elements. Serum samples from 79 PCa patients and 74 male healthy controls were obtained, and the levels of 19 trace elements were measured using inductively coupled plasma mass spectrometry (ICP-MS). Baseline matching of key demographic characteristics was performed between the two groups. The relationship between serum trace elements levels and PCa, prostate-specific antigen (PSA), and PCa staging were evaluated using the Mann-Whitney U test, logistic regression, and Spearman's correlation analysis. Statistical analysis of the test results revealed that the low levels of Cu, Zn, and Se in serum may be associated with the development of PCa. Moreover, the changes in the interrelationship of trace elements may play a role in the development of PCa.

Cell-free DNA aneuploidy score as a dynamic early response marker in prostate cancer

Cell-free circulating tumor DNA (ctDNA) has emerged as a promising biomarker for response evaluation in metastatic castration-resistant prostate cancer (mCRPC). The current study evaluated the modified fast aneuploidy screening test-sequencing system (mFast-SeqS), a quick, tumor-agnostic and affordable ctDNA assay that requires a small input of DNA, to generate a genome-wide aneuploidy (GWA) score in mCRPC patients, and correlated this to matched metastatic tumor biopsies. In this prospective multicenter study, GWA scores were evaluated from blood samples of 196 mCRPC patients prior to treatment (baseline) with taxanes (docetaxel and cabazitaxel) and androgen receptor signaling inhibitors (ARSI; abiraterone and enzalutamide), and from 74 mCRPC patients at an early timepoint during treatment (early timepoint; median 21 days). Z-scores per chromosome arm were tested for their association with tumor tissue genomic alterations. We found that a high tumor load in blood (GWAhigh) at baseline was associated with poor response to ARSI [HR: 2.63 (95% CI: 1.86-3.72) P < 0.001] but not to taxanes. Interestingly, GWAhigh score at the early timepoint was associated with poor response to both ARSIs [HR: 6.73 (95% CI: 2.60-17.42) P < 0.001] and taxanes [2.79 (95% CI: 1.34-5.78) P = 0.006]. A significant interaction in Cox proportional hazards analyses was seen when combining GWA status and type of treatment (at baseline P = 0.008; early timepoint P = 0.018). In summary, detection of ctDNA in blood by mFast-SeqS is cheap, fast and feasible, and could be used at different timepoints as a potential predictor for outcome to ARSI and taxane treatment in mCRPC.

Comparative efficacy and safety of talazoparib plus enzalutamide and other first-line treatments for metastatic castration-resistant prostate cancer

BACKGROUND

Talazoparib plus enzalutamide (TALA + ENZA) has demonstrated antitumor activity in the phase 3 clinical trial (TALAPRO-2; NCT03395197) as first-line (1L) therapy in men with asymptomatic or mildly symptomatic metastatic castration-resistant prostate cancer (mCRPC). Although many active interventions are available, randomized controlled trials (RCTs) involving talazoparib have only been conducted to assess its efficacy and safety compared to enzalutamide. To estimate comparisons between all relevant interventions, indirect comparisons are needed.

OBJECTIVE

To estimate the comparative efficacy and safety of TALA + ENZA in 1L patients with mCRPC by conducting a systematic literature review and network meta-analyses (NMAs).

METHODS

Databases were searched using Ovid, along with several gray literature sources to identify RCTs evaluating treatments in 1L mCRPC (PROSPERO registration: CRD42021283512). Feasibility assessment evaluated trial suitability for NMA inclusion and Bayesian or frequentist NMAs were conducted for evaluable efficacy and safety outcomes, respectively.

RESULTS

Thirty-three RCTs met the eligibility criteria and were feasible for NMAs. Across multiple efficacy outcomes assessed, except for overall survival (OS), TALA + ENZA was ranked the most efficacious treatment. For OS, TALA + ENZA showed the second-highest probability of being the most effective treatment; second to docetaxel 50 mg plus prednisolone 10 mg. With respect to safety outcomes, TALA + ENZA, in general, showed increased rates of hematological adverse events.

CONCLUSIONS

TALA + ENZA showed favorable results across multiple efficacy endpoints, but not across hematological toxicities compared with other 1L treatments in asymptomatic or mildly symptomatic mCRPC in the all-comers patient population.

Stereotactic Body Radiation Therapy for Oligoprogressive Disease in Androgen-Suppressed Prostate Cancer: Primary Endpoint Analysis of the TRAP Trial

PURPOSE

Optimal management of oligoprogressive prostate cancer while on androgen receptor pathway inhibitors (ARPIs) is not known. The TRAP trial tests the role of stereotactic body radiation therapy (SBRT) in this setting. The objective of this phase 2 prospective, nonrandomized, single-arm trial was to determine if local control of oligoprogressive disease with SBRT can delay further progression by >4 months, postponing time to next therapy.

METHODS AND MATERIALS

Men with castration-resistant prostate cancer with ≤2 oligoprogressive sites developing on treatment with an ARPI, after initial response to therapy, were recruited. All patients were treated to a dose of 30 Gy in 5 fractions (alternate days) or 36 Gy in 6 fractions weekly (prostate only).

RESULTS

Eighty-six men were recruited between October 2018 and February 2023. SBRT was delivered to 81 men. Mean age was 74 years. Most patients (67%) had 1 oligoprogressive disease lesion. Sites irradiated were bone (59%), lung (1%), lymph node (32%), and prostate (7%). Median follow-up was 22.9 months at the time of analysis. Fifty-five (68%) patients had progressed, 33 (41%) of patients progressed within 6 months of radiation therapy. Median progression-free survival (PFS) was 6.4 months (95% CI, 5.9-11.4). An estimated 39% (95% CI, 29-49) of patients have a prolonged PFS of > 12 months. Thirty-three (41%) of patients had started new treatment or died. Median time to either next treatment or death was 27.0 months (95% CI, 14.9-29.6). Median overall survival was 27.2 months (95% CI, 24.7-36.6). Four deaths occurred within 6 months of SBRT; none were related to radiation therapy treatment.

CONCLUSIONS

The TRAP trial has demonstrated a median PFS of 6.4 months after SBRT for oligoprogression of prostate cancer, meeting the primary endpoint. Further analysis of biomarker panel including circulating DNA and whole-body magnetic resonance imaging will promote better patient selection.

RECIP 1.0 + PSA for response assessment in mCRPC patients treated with 225Ac / 177Lu PSMA combination therapy

BACKGROUND

Targeted alpha therapy (TAT) with 225Ac has shown promising results in metastatic castration-resistant prostate cancer (mCRPC) patients pre-treated with [177Lu]Lu-PSMA radioligand therapy (RLT). A combination treatment regimen adding 177Lu to decreased 225Ac activities may improve toxicity profile while maintaining sufficient anti-tumor effect. We therefore evaluated clinical and image-based response parameters in patients treated with 225Ac-/177Lu-PSMA combination therapies (ALCT).

RESULTS

Complete response (RECIP-CR), partial response (RECIP-PR), stable disease (RECIP-SD), progressive disease (RECIP-PD) according to RECIP 1.0 was observed in 0/25 (0%), 12/25 (48%), 9/25 (36%) and 4/25 (16%) patients, respectively. Response by RECIP + PSA was observed in 14/25 (56%) patients and progression by RECIP + PSA in 8/25 (32%) patients. Interrater reliability for visual RECIP was substantial (κ = 0.757, p < 0.001), while agreement between visual and quantitative RECIP was almost fully congruent (κ = 0.879, p < 0.001). OS did not significantly vary among the four different therapy regimens (p > 0.05). When grouping patients with declining / stable PSA as responders, these patients showed no significant difference in overall survival compared to patients with progressive PSA after ALCT (p = 0.312). Similarly, there was no significant difference in median overall survival between patients without RECIP-progression (RECIP-PR + RECIP-SD) and patients with RECIP-progression (RECIP-PD) (p > 0.05), but when applying the composite classification, RECIP + PSA responders survived significantly longer compared to patients with RECIP + PSA progression (p = 0.049).

CONCLUSIONS

ALCT is a promising therapeutic regimen that may prolong survival in patients who progress during [177Lu]Lu-PSMA RLT. Our results motivate to further investigate the use of RECIP + PSA as tool for response assessment and for overall survival prediction in mCRPC under ALCT.