Treatment Of Metastatic Prostate Cancer Research Articles

Prediction of PSA Response after Dexamethasone Switch during Abiraterone Acetate + Prednisolone Treatment of Metastatic Castration-Resistant Prostate Cancer Patients

Background: The aim was to elaborate a predictive model to find responders for the corticosteroid switch (from prednisolone to dexamethasone) at the first prostate-specific antigen (PSA) progression (≥25% increase) during abiraterone acetate (AA) treatment of metastatic castration-resistant prostate cancer (mCRPC) patients. Methods: If PSA has decreased (≥25%) after switch, patients were considered responders. Logistic regression of 19 dichotomized parameters from routine laboratory and patients’ history was used to find the best model in a cohort of 67 patients. The model was validated in another cohort of 42 patients. Results: The model provided 92.5% and 90.5% accuracy in the testing and the validation cohorts, respectively. Overall the accuracy was 91.7%. The AUC of ROC curve was 0.92 (95% CI 0.85–0.96). After a median follow-up of 27.9 (26.3–84) months, the median AA+dexamethasone treatment duration (TD) in non-responders and responders was 4.7 (3.1–6.5) and 11.1 (8.5–12.9) months and the median overall survival (OS) was 23.2 (15.6–25.8) and 33.5 (26.1–38) months, respectively. Multivariate Cox regression revealed that responsiveness was an independent marker of TD and OS. Conclusions: A high accuracy model was developed for mCRPC patients in predicting cases which might benefit from the switch. For non-responders, induction of the next systemic treatment is indicated.

Prostate-Specific Membrane Antigen PET/CT-Guided, Metastasis-Directed Radiotherapy for Oligometastatic Castration-Resistant Prostate Cancer.

Systemic treatments for metastatic castration-resistant prostate cancer (mCRPC) include androgen deprivation therapy, androgen receptor pathway inhibitors, chemotherapy, and radiopharmaceuticals, all of which have associated toxicity. Prostate-specific membrane antigen (PSMA) PET/CT allows for higher sensitivity in detecting metastatic disease than is possible with conventional imaging. We hypothesized that PSMA PET/CT-guided, metastasis-directed radiotherapy may offer durable disease control with low toxicity rates in patients with mCRPC who have a limited number of metastases. Methods: We retrospectively screened 5 prospective PSMA PET/CT studies for patients with mCRPC who had up to 5 sites of oligorecurrent or oligoprogressive disease on PSMA PET/CT and subsequently received definitive-intent, metastasis-directed radiotherapy to all new or progressing sites with concurrent androgen deprivation therapy. Progression-free survival, freedom from new lines of systemic therapy, and overall survival (OS) were calculated from the start of metastasis-directed radiotherapy using Kaplan-Meier analysis. Biochemical response was defined as at least a 50% decrease in prostate-specific antigen 6 mo after the start of treatment. Toxicity was graded using the Common Terminology Criteria for Adverse Events, version 5. Results: Twenty-four patients met the inclusion criteria with a median follow-up of 33.8 mo (interquartile range, 27.6-45.1 mo). Between October 2017 and April 2023, 11 patients (45.8%) had 1 treated site, 10 patients (41.7%) had 2, and 3 patients (12.5%) had 3. Five sites were prostate or prostate bed, 15 were nodal, 19 were osseous, and 1 was visceral. Seventeen patients (70.8%) continued their preexisting systemic therapy, whereas 7 (29.2%) started a new systemic therapy. Median progression-free survival was 16.4 mo (95% CI, 9.8-23.0 mo). The biochemical response rate was 66.7%. Median freedom from a new line of systemic therapy was 29.0 mo (95% CI, 7.6-50.4 mo). Median OS was not reached. The 2- and 4-y OS rates were 91.1% (95% CI, 79.3%-100%) and 68.8% (95% CI, 45.1%-92.5%), respectively. Grade 2 and grade 3 or higher toxicity rates were 4.2% and 0%, respectively. Conclusion: PSMA PET/CT-guided, metastasis-directed radiotherapy appears to offer durable disease control with low toxicity rates for oligometastatic castration-resistant prostate cancer. Further prospective studies are needed to compare metastasis-directed radiotherapy with systemic therapy versus systemic therapy alone and PSMA PET/CT-guided versus conventional imaging-guided radiotherapy.

Combination of PARP Inhibitors and Androgen Receptor Pathway Inhibitors in Metastatic Castration-Resistant Prostate Cancer.

Despite recent advances in the treatment of metastatic prostate cancer, progression to a castration-resistant state remains inevitable for most and prognosis is limited. Genetic testing for homologous recombination repair pathway alterations is recommended for all patients with advanced prostate cancer given that a mutation is present in up to 25% of cases. Poly(ADP-ribose) polymerase (PARPis) are now approved for use in patients with metastatic castration-resistant prostate cancer who have progressed on an androgen receptor pathway inhibitor (ARPI) and harbour a germline or somatic homologous recombination repair mutation. Preclinical data support a synergistic effect with an ARPI and PARPi, and various ARPI-PARPi combinations have therefore been explored in phase III clinical trials. Despite heterogeneous findings, a clear hierarchy of benefit is evident, with patients harbouring a BRCA mutation deriving the greatest magnitude of benefit, followed by any homologous recombination repair mutation. The benefit in homologous recombination repair-proficient cohort is less clear, and questions remain about whether ARPI-PARPi combination therapy should be offered to patients without a homologous recombination repair mutation. With ARPIs now considered standard-of-care for metastatic hormone-sensitive prostate cancer, ARPI-PARPi combination therapy is currently being explored earlier in the treatment paradigm. The purpose of this review is to discuss the rationale behind ARPI-PARPi combination therapy, summarise the results of key clinical trials, and discuss clinical considerations and future perspectives.

Severe neutropenia probably caused by enzalutamide and abiraterone in a prostate cancer patient.

Abiraterone and enzalutamide are two androgen receptor pathway inhibitors approved, among others, for the treatment of metastatic castration-resistant prostate cancer in adult men whose disease has progressed on or after a docetaxel-based regimen. Although hematological effects, especially neutropenia, are one of the main complications of other oral antineoplastic drugs, these adverse effects are infrequent in the case of androgen receptor pathway inhibitors. We report the case of a patient diagnosed with metastatic castration-resistant prostate cancer who discontinued an androgen receptor pathway inhibitor due to drug-related grade 4 neutropenia. His control blood counts before enzalutamide starting were normal. After one month of treatment, he developed a grade 4 neutropenia, with complete neutrophil count recovery four weeks later. He underwent a bone marrow aspiration, which revealed normocelullar results, and enzalutamide was restarted. Three weeks later, the treatment was eventually discontinued due to neutropenia reappearance. Neutrophil count recovery was achieved one month later. Then, he started treatment with abiraterone, but two weeks later neutropenia reappeared. Abiraterone was withdrawn, and the patient recovered from neutropenia 2 weeks later. This case exposes not only the occurrence of rare toxicity of two individual drugs but also the description of a probable drug-class adverse event not reported before. The patient recovered from neutropenia after the androgen receptor pathway inhibitor was withdrawn, thereby supporting the diagnosis of probable drug-induced neutropenia. There is scarce evidence in the literature concerning androgen receptor pathway inhibitor-related neutropenia. However, its life-threatening potential cannot be ignored, so healthcare professionals should be warned of the possibility of the occurrence of such adverse reactions.

A Review of Abiraterone Acetate for the Treatment of Metastatic Castration-Resistant Prostate Cancer

A Review of Abiraterone Acetate for the Treatment of Metastatic Castration-Resistant Prostate Cancer

Real-life Data on First- and Second-Line Treatment of Metastatic Castration-Resistant Prostate Cancer With Abiraterone, Enzalutamide and Cabazitaxel – A multicentric Study From Portugal

Introduction and objectivesNew drugs for metastatic castrate resistant prostate cancer (mCRPC) were approved, first in the pos-docetaxel and then in the pre-docetaxel setting. We aim to assess the real daily practice benefit of abiraterone (Abi), enzalutamide (Enz) and cabazitaxel (Cab) in patients with mCRPC, compare it with RCT results and compare Abi vs Enz. Materials and methodsWe retrospectively collected the data of all consecutive mCRPC patients treated with Abi, Enz or Cab in the six major oncological hospitals in the north of Portugal until December 2020. ResultsA total of 470 treatments pre-docetaxel (163 Abi and 307 Enz) and 373 pos-docetaxel (160 Abi, 148 Enz and 59 Cab) were included, with median follow-up time of 35 months. Mean age was 73.1, 84.4% had ECOG status < 2, ISUP grade was ≥ 4 in 59% and 28.0% had oligometastatic disease. In first line, for Abi and for Enz respectively, the proportion of patients with PSA reduction > 50% was 64.4% and 80.4% (P < .001), the mean duration of treatment (DT) was 10 and 14 months (P = .037) and the median overall survival (OS) was 25 months and 30 months (P = .17). In second line the results for Abi, Enz and Cab were respectively: proportion of patients with PSA reduction > 50% was 40.4%, 57.4% and 24.6% (p for Abi vs Enz=0.004); DT was 7, 8, and 3 months (p for Abi vs Enz = 0.27); OS was 17, 22 and 10 months (p for Abi vs. Enz = 0,07). ConclusionThese drugs have good efficacy in real-world evidence, similar to those reported in randomized clinical trials, with the expected exception of lower OS due to the inclusion of a broader sample of patients. Our results add to the evidence that Enz might have better efficacy in this setting compared with Abi.

Organ and tumor dosimetry including method simplification for [177Lu]Lu-PSMA-I&T for treatment of metastatic castration resistant prostate cancer

BackgroundInternal dosimetry in individual patients is essential for safe and effective radioligand therapy. Multiple time point imaging for accurate dosimetry is time consuming and hence can be demanding for nuclear medicine departments as well as patients. The objectives of this study were (1) to assess absorbed doses to organs at risk and tumor lesions for [177Lu]Lu-PSMA-I&T using whole body SPECT imaging and (2) to investigate possible simplified dosimetry protocols.MethodsThis study included 16 patients each treated with 4 cycles of [177Lu]Lu-PSMA-I&T. They underwent quantitative whole body SPECT/CT imaging (3 bed positions) at four time points (TP) comprising 2 h, 24 h, 48 h and 72–168 h post-injection (p.i.). Full 3D dosimetry (reference method) was performed for all patients and dose cycles for organs at risk (kidneys, parotid glands and submandibular glands) and up to ten tumor lesions per patient (resulting in 90 lesions overall). The simplified dosimetry methods (SM) included (1) generating time activity curves for subsequent cycles using a single TP of imaging applying the kinetics of dose cycle 1, and for organs at risk also (2) simple extrapolation from dose cycle 1 and (3) from both, dose cycle 1 and 2.ResultsNormalized absorbed doses were 0.71 ± 0.32 mGy/MBq, 0.28 ± 0.12 mGy/MBq and 0.22 ± 0.08 mGy/MBq for kidneys, parotid glands and submandibular glands, respectively. Tumor doses decreased from 3.86 ± 3.38 mGy/MBq in dose cycle 1 to 2.01 ± 2.65 mGy/MBq in dose cycle 4. Compared to the full dosimetry approach the SM 1 using single TP imaging at 48 h p.i. resulted in the most accurate and precise results for the organs at risk in terms of absorbed doses per cycle and total cumulated dose. For tumor lesions better results were achieved using the fourth TP (≥ 72 h p.i.).ConclusionSimplification of safety dosimetry protocols is possible for [177Lu]Lu-PSMA-I&T therapy. If tumor dosimetry is of interest a later imaging TP (≥ 72 h p.i.) should be used/added to account for the slower kinetics of tumors compared to organs at risk.

Cost-effectiveness analysis of rezvilutamide versus bicalutamide in the treatment of metastatic hormone-sensitive prostate cancer

ObjectivesThe economic implications of combining rezvilutamide with androgen deprivation therapy (ADT) remain uncertain, despite the observed survival advantages compared with bicalutamide plus ADT. Therefore, this study evaluates the cost-effectiveness of...

Budget Impact Analysis of Olaparib for the Management of Patients with Homologous Recombination Repair (HRR)-Mutated Castration-Resistant Metastatic Prostate Cancer in Argentina.

The aim of this study was to perform a budget impact analysis (BIA) of introducing olaparib treatment for adult patients with metastatic castration-resistant prostate cancer in Argentina. A BIA model was used to estimate the cost difference between the current scenario (without olaparib) and the new scenario (incorporation of olaparib) for a third-party payer over a 5-year time horizon. The budgetary impact is estimated at the national health system level and by healthcare sectors in Argentina. Input parameters were obtained from the literature and validated by local expert opinion. Direct medical costs were obtained from both the Institute for Clinical Effectiveness and Health Policy (IECS) unit cost database and public data in Argentina. The microcosting estimation was used for key variables of the analysis. All costs are reported in US dollars (US$) as for October 2022 (1 US$ = 152.59 Argentine pesos). One-way sensitivity analyses and scenario analyses were conducted to evaluate the model robustness. The incorporation of olaparib, with a wholesale price per pack of US$3176, was associated with a weighted average of the budget impact per member per month (PMPM) of US$0.0191 for the national health system, being slightly higher than the estimated budgeted high impact threshold (US$0.0153). The PMPM budget impact for a 5-year average ranged between US$0.007 (public sector) and US$0.033 (private sector). The duration of treatment with olaparib was the most influential parameter in the budget impact results. The introduction of olaparib for the treatment of metastatic castration-resistant prostate cancer has a high budget impact for Argentina's health system. These findings are informative to support policy decisions aimed to expand the current treatment landscape for prostate cancer.

Fucoidan Inhibits Prostate Cancer Growth Through Modulation of Different Cell Deaths.

Docetaxel (DOC) is the main chemotherapeutic agent for the treatment of advanced metastatic prostate cancer. Docetaxel shows anticancer effects by preventing the depolymerization of microtubules in the cell, therefore preventing cell division. However, the low survival effect of docetaxel has prompted researchers to search for novel therapeutic agents. Fucoidan (FUC) is a sulfated polysaccharide derived from brown algae. It has many bioactivities which makes fucoidan a promising anticancer agent. In this study, the potential anti-tumorigenic and preventive effects of fucoidan with or without docetaxel in prostate cancer were investigated by analyzing different cell death modalities. The in-vivo six groups (n = 8) were conducted; preventive (Pt), docetaxel treated after preventive (Pt-D), control, fucoidan (FUC), docetaxel (DOC), and FUC and DOC (FUC+DOC) combination. Apoptotic, necroptotic, and autophagic cell death-related protein expressions were assessed in tumor tissues by using immunohistochemical staining. Oxidative stress-related lipid peroxidation, glutathione peroxidase, and glutathione levels were also determined in tumor tissues. Although apoptotic, necroptotic, and autophagic cell deaths were significantly induced in agent-treated groups compared to the control. Apoptotic cell death was more significantly induced in FUC and FUC+DOC-treated groups. Necroptotic cell death was increased considerably by inducing MLKL protein expression in all treatment groups. In the FUC, Pt, and DOC groups, LC3A/B expressions were significantly increased. DOC, FUC+DOC, and Pt-D treatments caused a significant increase in Beclin-1 expression. Oxidative stress-related MDA, GPX, and GSH levels significantly decreased with FUC treatment. The anti-tumorigenic effects of FUC and DOC were also demonstrated through tumor size reduction. According to the findings of this study, FUC inhibited tumor growth temporally and dimensionally, especially in preventive applications. FUC and FUC+DOC combinations in both treatment groups showed anti-tumorigenic effects. The results of this study suggest that fucoidan is a promising anticancer agent against prostate cancer. FUC can be considered as a preventive or treatment agent in prostate cancer therapy with DOC. Further studies are needed to fully elucidate the mechanism of action of fucoidan in metastatic prostate cancer.

Androgen deprivation therapy in advanced prostate cancer: insights from a real-world patient survey on health-related quality of life and information and communication sources.

Androgen deprivation therapy (ADT) is a cornerstone treatment for advanced and metastatic prostate cancer. Real-world and patient-reported insights into ADT's impact on health-related quality of life (HRQoL) and communication experiences in healthcare settings remain underexplored. This patient organisation-initiated online survey aimed to assess these aspects. Between December 2022 and August 2023, the patient organisation Think Blue Vlaanderen and the AZ Sint-Jan Hospital (Bruges, Belgium) invited ADT-treated patients to participate in a prospective, online, cross-sectional, patient-reported outcome survey. Demographic, clinical, HRQoL (FACT and EPIC-26), communication sources and information modality data were collected. Descriptive statistics and comparative analyses were applied. A total of 276/312 (88.5%) participating patients were on ADT at time of survey administration and completion, with the majority receiving a 3-monthly regimen. Sexual HRQoL was low and narrowly distributed (median (IQR): 16.7 (16.7-16.7)), with 84% of patients having erectile dysfunction (ED). Patients finding their ED problematic were more likely to seek pharmaceutical treatment. Hormonal HRQoL was widely distributed (median (IQR): 65 (45-85)), which improved with prolonged ADT duration. Physically active patients reported less lack of energy, but increased hot flashes. Within consistent FACT-G summary scores (median (IQR): 64.50 (54.75-77.00)), improved emotional wellbeing with prolonged ADT was noted. Multidisciplinary communication and multimodal information provision improved patient satisfaction. Patient organisation-initiated surveys offer real-world and patient-reported insights. Patient-tailored HRQoL assessments and longitudinal follow-up, physical activity, and multidisciplinary and multimodal communication approaches are warranted to improve patient-centred care in patients receiving ADT.

Impact of the integration of remote clinical oncology pharmacists into routine precision medicine workflows on biomarker testing rates within The US Oncology Network community-based practices.

e13813 Background: The US Oncology Network implemented a centralized, remote clinical oncology pharmacist review program (ClinReview) into select community-based practices. Initially, pharmacists were integrated into a precision medicine workflow process to increase biomarker testing rates among patients receiving adjuvant treatment for non-small cell lung cancer, with recommendations achieving a 100% acceptance rate. Following this success, metastatic prostate cancer patients were incorporated into the established workflow, following updated guideline recommendations for both germline and somatic testing and the 2023 approvals of PARP inhibitors in the first-line treatment setting. With previously reported testing rates only reaching 60%, we sought to evaluate the impact of the pharmacist integration into the precision medicine workflow on biomarker testing in metastatic prostate patients. Methods: Over a 4-month period, ClinReview remotely identified patients with metastatic prostate cancer during normal order review. The EMR was reviewed to assess germline and somatic testing status. If testing was not ordered, the pharmacist sent a recommendation to the treating provider. Initial testing rates for germline and somatic testing, BRCA+ status and provider acceptance rates for testing recommendations were collected. Additional data was collected utilizing a de-identified database. While additional data collection is ongoing, descriptive statistics were utilized to analyze data and the impact of the pharmacists’ interventions. Results: Across 9 practices, 142 patients were initiated on treatment for metastatic prostate cancer. At the time of initial assessment, germline and somatic testing was not ordered in 50% and 37% of patients, respectively. Pharmacists recommended additional testing in 61 patients (43%) with a 73% provider acceptance rate. Findings showed equitable testing rates across racial demographics. Pharmacist workflow integration enhanced combined germline and somatic testing rates, demonstrating an improvement from a baseline of 57% up to 77% currently. Conclusions: Community oncology practices seek to provide high-value care, including offering the most current evidence-based precision medicine testing. These findings highlight the continued need for improved somatic and germline testing in metastatic prostate cancer. However, the implemented precision medicine pharmacist workflow demonstrates the positive impact a clinical pharmacist can have on both testing rates and the potential to improve therapeutic offerings within this growing treatment space. [Table: see text]

Association of baseline characteristics with adverse events (AEs) in the PROpel trial of olaparib (ola) plus abiraterone (abi) as first-line (1L) treatment for metastatic castration-resistant prostate cancer (mCRPC).

e17030 Background: The PROpel trial (NCT03732820) met its primary endpoint and showed a statistically significant radiographic progression-free survival benefit (hazard ratio [HR] 0.66, 95% confidence interval [CI] 0.54–0.81; P&lt;0.0001) with ola + abi vs placebo + abi in 1L mCRPC; whilst not statistically significant, overall survival (OS) was numerically prolonged (median 42.1 vs 34.7 months; HR 0.81, 95% CI 0.67–1.00; P=0.0544). To further inform clinical decision making, we provide exploratory post hoc analysis investigating the relationship between selected patient baseline characteristics and AEs for ola + abi. Methods: Anemia and venous thromboembolism events (VTEs) were identified as the only grade (Gr) ≥3 AEs or AEs of special interest reported in &gt;20 (&gt;5.0%) patients (pts) in the ola + abi arm (data cutoff 12 Oct 2022). Baseline characteristics were correlated with AEs using Cox regression by backwards elimination and analysis with AEs as dependent variables. Baseline characteristics assessed included: age (&lt;70 or ≥70 y), time since diagnosis (&lt;median or ≥median) , ECOG status (0 or 1), metastatic sites (visceral [yes or no], bone only [yes or no]), number of bone metastases (0, 1–4, 5‒9, 10‒20 or &gt;20), Gleason score (&lt;9 or 9–10), homologous recombination repair mutation status (HRRm, non-HRRm or unknown), race (white or non-white), prior docetaxel at metastatic hormone-sensitive prostate cancer (yes or no), pain (symptomatic or asymptomatic/mildly symptomatic), type of progression (prostate-specific antigen [PSA], radiographic or both), prior radiotherapy (yes or no) and albumin, creatinine, lactate dehydrogenase, alkaline phosphatase (ALP), hemoglobin (10&lt;12 or ≥12) and log PSA levels. Results: 398 pts received ola + abi. 64 (16.1%) had Gr ≥3 anemia and 34 (8.5%) a VTE. Baseline characteristics correlated significantly with increased risk of these AEs as shown (Table); characteristics not shown were not associated with AEs. Conclusions: These results provide insight into which baseline characteristics correlate with the risk of Gr ≥3 anemia. Pts with abnormal ALP, pre-existing anemia, ECOG PS 1 or age ≥70 years could be at higher risk and the development of Gr ≥3 anemia during treatment with ola + abi should be monitored. Clinical trial information: NCT03732820 . [Table: see text]

Prostate-specific membrane antigen PET/CT-guided, metastasis-directed radiotherapy for oligometastatic castration-resistant prostate cancer.

e17057 Background: Systemic treatments for metastatic castration-resistant prostate cancer (mCRPC) include androgen deprivation therapy (ADT), androgen receptor pathway inhibitors (ARPIs), chemotherapy, and radiopharmaceutical therapy, all of which have associated toxicity. We hypothesized that prostate-specific membrane antigen (PSMA) PET/CT-guided, metastasis-directed radiotherapy may offer durable disease control with low toxicity rates in patients with mCRPC who have a limited number of metastatic sites. Methods: We retrospectively screened 7 prospective databases of PSMA PET/CT scans conducted between 1/2016-2/2023 for patients with mCRPC who had ≤5 sites of oligorecurrent or oligoprogressive disease and received metastasis-directed radiotherapy to all sites of disease. Castration resistance was defined as either radiographic progression or biochemical progression (two consecutive prostate-specific antigen [PSA] increases ≥3 weeks apart) while on ADT with serum testosterone &lt;50 ng/dL. Progression-free survival (PFS), freedom from new lines of systemic therapy, and overall survival (OS) were calculated from the start of metastasis-directed radiotherapy using Kaplan-Meier analysis. Progression was defined as the first instance of biochemical progression (PSA increase of 25% and 2 ng/mL above nadir, confirmed by repeat measurement ≥3 weeks later), radiographic progression, biopsy-proven recurrence, new systemic or local therapy, or death. Toxicity was graded according to Common Terminology Criteria for Adverse Events (CTCAE), Version 5. Results: Twenty-six patients met inclusion criteria with a median follow-up of 34.6 months (interquartile range, 28.1-47.2 months). All patients previously received ADT, 20 (77%) received ARPIs, and 3 (12%) had prior chemotherapy. Median PSA was 1.2 ng/mL, median time from initial diagnosis was 6.2 years, and median time from castration resistance was 1.8 years. Between 10/2017-4/2023, 12 patients (46.2%) had one treated metastatic site, 11 patients (42.3%) had two, and 3 patients (11.5%) had three. Twenty-four patients (92.3%) received concurrent systemic therapy. Median PFS was 16.4 months (95% confidence interval [CI], 11.4-21.4 months). Four-year PFS was 26.7% (95% CI, 8.9-44.5%). Median time to initiation of a new line of systemic therapy was 18.0 months (95% CI, 0-36.2 months). Four-year freedom from new lines of systemic therapy was 36.1% (95% CI, 15.5-56.7%). Median OS was not reached. Four-year OS was 72.5% (95% CI, 51.1-93.9%). Grade 2 and ≥3 toxicity rates were 3.8% and 0%, respectively. Conclusions: For patients with oligometastatic CRPC, PSMA PET/CT-guided metastasis-directed radiotherapy appears to offer durable disease control with low toxicity. Further prospective studies are needed to compare PSMA PET/CT-guided versus conventional imaging-guided radiotherapy.

Utilization of genetic and genomic data and correlation to outcomes of treatment with PARP inhibitors in advanced or metastatic castrate-resistant prostate cancer.

e17034 Background: Prostate cancer is the second-leading cause of cancer death in men in the United States, with aggressive forms associated with mutations in homologous recombination repair (HRRm) genes. PARP inhibitors (PARPi) (olaparib, rucaparib, niraparib, and talazoparib) are FDA approved for treatment of HRRm metastatic castration-resistant prostate cancer (mCRPC). Previous data have shown PARPi has the greatest benefit in patients with HRRm, but the responses in HRR genes other than BRCA1/2 and ATM are less robust based on available data. Methods: This retrospective study utilized the electronic health record to identify adult patients diagnosed with prostate cancer and treated at Avera Cancer Institute from 1/1/2018 to 12/31/2022 who received somatic (tumor and/or ctDNA) and/or germline genetic testing. Testing results were reviewed for pathogenic HRRm (BRCA1, BRCA2, ATM, ATR, CDK12, CHEK2, FANCA, MLH1, MRE11A, NBN, PALB2, or RAD51C) and treatment histories were reviewed to identify PARPi use. Data about PARPi received, duration, and biochemical response (decline in PSA during therapy) were collected. Results: 191 patients were included in the final analysis. Of these, 88 (46%) patients had germline only testing, 31 (16%) had somatic only testing, and 72 (38%) had both germline and somatic testing completed. 45 patients had HRRm of which 22 were somatic and 33 were germline. The average patient age at time of testing was 70 years. Thirteen of the patients in this cohort received treatment with a PARPi . Twelve of these patients received treatment with olaparib monotherapy, and one patient received olaparib in combination with abiraterone. Average progression free survival was 26 months (range 5-92 months) and the median PFS was 11 months. Four patients were biochemical non-responders, with an average PFS of 8 months, compared to 33 months for the 9 biochemical responders (p=0.04). Gene alterations present in non-responders included germline BRCA1 (n=1), germline CHEK2 (n=2), and somatic ATM (n=1). Germline alterations present in responders included BRCA2 (n=7) and PALB2 (n=2). In patients who received PARPi therapy, the average age of testing was 73 years. Conclusions: The patients found to have HRRm that were treated with a PARPi showed similar responses to previously described data in that the BRCA2 mutated group showed best response, followed by PALB2 mutated tumors. The overall proportion of patients with HRRm that were ultimately treated with PARPi was smaller than expected warranting further investigation. New FDA approvals of PARPi combined with next generation hormonal agents in the first line mCRPC setting are expected to increase utilization of PARPi. Additional outcomes data for individual HRR genes are needed to improve patient selection, outcomes, and reduce unnecessary toxicity due to PARPi therapy.

Docetaxel plus cis-platinum chemotherapy for the posterior line treatment of metastatic castrate-resistant prostate cancer with elevated neuron specific enolase.

e17042 Background: This Study is to figure out the efficacy of docetaxel plus cis-platinum (DC) chemotherapy as the posterior line treatment for metastatic castrate-resistant prostate cancer (mCRPC) with elevated neuron specific enolase (NSE). Methods: We performed a retrospective study of men suffered mCRPC with elevated NSE from December 2019 to August 2022. All men were treated with DC after resistance to previous therapy. Biochemical progression-free survival (BPFS) were depicted using Kaplan-Meier curves. Results: 10 mCRPC patients aged 65.8 ± 7.0 (Median: 66.5, Range: 52-77) received DC for 1 to 10 cycles (Median: 7). Of the 10 patients, 2, 1 and 7 patients underwent DC as the 2nd, 3rd and 4th line therapy, respectively. 3 patients received previous chemotherapy and 9 patients underwent new endocrine therapy. All patients suffered bone metastases, 6 patients suffered distal lymph node metastases and 3 patients suffered visceral metastases. 6.1 ± 2.8 cycles (Median: 7, Range: 1-10) of DC were finished. Median follow-up time was 6.5 (Range: 2-11) months. After DC, Prostate specific antigen (PSA) response rate (&gt;50%) was 90% and NSE response rate (&gt;50%) was 60%. Median BPFS was 10 (Range: 4-18) months. Pain score declined from 6.6 ± 3.1 to 3.9 ± 2.4 evidently (P &lt; 0.05) and Karnofsky (KPS) score increased from 80 ± 14.9 to 91 ± 16.0 significantly (P &lt; 0.05). Of the 6 patients assessed by radiological examinations, 5 patients experienced partial response and 1patient achieved stable disease. Conclusions: Our pilot study showed docetaxel plus cis-platinum chemotherapy was effective for the mCRPC patients with elevated NSE resistant to multi-line therapies, indicating the potential value of DC for mCRPC with neuroendocrine differentiation.

Phase 1 clinical trial of AMG 340, a prostate-specific membrane antigen (PSMA)-targeted T-cell engager with a novel low-affinity CD3 binding domain designed to mitigate toxicity for the treatment of metastatic castration-resistant prostate cancer (mCRPC).

e14587 Background: PSMA, a transmembrane protein highly expressed on the surface of prostate cancer cells, is a validated target in prostate cancer; however, achieving a favorable therapeutic index has been challenging for PSMA-directed T-cell engagers (TCE’s). AMG 340, a PSMA-targeted TCE with a novel low-affinity CD3 binding domain specifically engineered to mitigate cytokine release syndrome (CRS) toxicity and maintain efficacy was investigated in a phase 1, open-label, dose-escalation study (NCT04740034). Methods: Patients (pts) with mCRPC who had received ≥2 prior lines of therapy were treated with AMG 340 monotherapy (1.5–800 mg intravenously every 3 weeks [Q3W]) during dose escalation. The primary outcome measures were dose-limiting toxicities, treatment-emergent adverse events (TEAEs), and pharmacokinetic profile. Secondary outcomes included prostate antigen specific (PSA) response and objective response per response evaluation criteria in solid tumors (RECIST). Results: As of September 6, 2023, a total of 42 pts (mean ± SD age, 68.5±7.8 years) received AMG 340 step up dosing across 11 cohorts. At doses up to 800 mg Q3W, AMG 340 had a manageable side effect profile. Any grade TEAEs reported in ≥30% of pts included CRS (52%), nausea (52%), vomiting (52%), fatigue (48%), diarrhea (38%), increased aspartate aminotransferase (36%), increased alanine aminotransferase (33%), and hypocalcemia (31%). Treatment-related toxicities included CRS (52%; Grade 1, 26%; Grade 2, 24%; Grade ≥3, 2%) and thrombocytopenia (24%; Grade 2, 10%; Grade ≥3, 14%). Step dosing was implemented at doses &gt;40 mg and successfully mitigated CRS incidence and severity after the first dose. The maximal tolerated dose was not reached, as increasing the dose beyond 800 mg was predicted to minimally increase the potential AMG 340 activity. Exposure increased in an approximately dose-proportional manner with no evidence of clinically significant anti-drug antibodies. AMG 340 demonstrated evidence for pharmacodynamic engagement as shown by cytokine induction. Of the 41 PSA evaluable pts, PSA responses were seen across dose levels (PSA50, n=4), but were not dose dependent. Eight of 42 pts remained on treatment after 6 months. Among 27 RECIST evaluable pts, no RECIST responses were observed (n=14 stable disease, n=0 partial or complete response). Conclusions: Despite reaching high doses, no dose response was observed, and AMG 340 did not generate sufficient clinical activity to warrant further exploration. However, AMG 340 demonstrated manageable CRS toxicity showing that decreased CD3-binding strength mitigates CRS, the main toxicity of TCEs. Clinical studies are ongoing evaluating the PSMA protein as a molecular target for prostate cancer. Clinical trial information: NCT04740034 .

Plasma microRNA Signature as Companion Diagnostic for Abiraterone Acetate Treatment in Metastatic Castration-Resistant Prostate Cancer: A Pilot Study.

Abiraterone acetate (AA) serves as a medication for managing persistent testosterone production in patients with metastatic castration-resistant prostate cancer (mCRPC). However, its efficacy varies among individuals; thus, the identification of biomarkers to predict and follow treatment response is required. In this pilot study, we explored the potential of circulating microRNAs (c-miRNAs) to stratify patients based on their responsiveness to AA. We conducted an analysis of plasma samples obtained from a cohort of 33 mCRPC patients before and after three, six, and nine months of AA treatment. Using miRNA RT-qPCR panels for candidate discovery and TaqMan RT-qPCR for validation, we identified promising miRNA signatures. Our investigation indicated that a signature based on miR-103a-3p and miR-378a-5p effectively discriminates between non-responder and responder patients, while also following the drug's efficacy over time. Additionally, through in silico analysis, we identified target genes and transcription factors of the two miRNAs, including PTEN and HOXB13, which are known to play roles in AA resistance in mCRPC. In summary, our study highlights two c-miRNAs as potential companion diagnostics of AA in mCRPC patients, offering novel insights for informed decision-making in the treatment of mCRPC.

Treatment of metastatic hormone-sensitive prostate cancer: from doublet therapy to triplet therapy.

For metastatic prostate cancer, androgen deprivation therapy (ADT) is the key strategy to control the disease. However, after 18-24months of treatment, most patients will progress from metastatic hormone-sensitive prostate cancer (mHSPC) to metastatic castration-resistant prostate cancer (mCRPC) even with ADT. Once patients enter into mCRPC, they face with significant declines in quality of life and a dramatically reduced survival period. Thus, doublet therapy, which combines ADT with new hormone therapy (NHT) or ADT with docetaxel chemotherapy, substitutes ADT alone and has become the "gold standard" for the treatment of mHSPC. In recent years, triplet therapy, which combines ADT with NHT and docetaxel chemotherapy, has also achieved impressive effects in mHSPC. This article provides a comprehensive review of the recent applications of the triplet therapy in the field of mHSPC.

Comparative effectiveness of first-line systemic treatments for metastatic castration-resistant prostate cancer: a systematic review and network meta-analysis.

No head-to-head trials had been performed to estimate the relative effectiveness of poly ADP-ribose polymerase inhibitor (PARPi) and androgen receptor signaling inhibitor (ARSi) in the first-line treatment for metastatic castration-resistant prostate cancer (mCRPC). We aimed to perform a systematic review and network meta-analysis to evaluate the comparative effectiveness of various systemic treatment agents for patients with mCRPC. A comprehensive literature search was conducted for abstracts and full-text articles from the database's inception through April 27, 2023. The study concentrated on assessing radiographic progression-free survival (rPFS) for both overall and homologous recombination repair mutation (HRRm) population, with overall survival (OS) as the secondary measure. Under the Bayesian framework, the overall effect was pooled using the fixed-effects model in base case analysis. Scenario analysis using restricted mean survival time (RMST) methods was performed to test the robustness of the results. Nine studies with 6,830 patients and 8 unique treatment options were included. Network meta-analysis demonstrated that talazoparib in combination with enzalutamide (TALA + ENZA; overall population, hazard ratio [HR], 0.20; 95% credible interval [CrI]: 0.16-0.26; RMST, 3.51; 95% confidence interval [CI] 2.46-4.60; HRRm population, HR, 0.15; 95% CrI: 0.09-0.23; RMST, 4.14; 95% CI 2.84-5.39) was superior to other treatments in the first-line setting in terms of rPFS. The results of Bayesian framework and RMST models showed consistent efficacy ranks. When extrapolated to overall survival benefit, within the Bayesian framework, olaparib plus abiraterone acetate and prednisone (OLAP + AAP) achieved the highest OS benefit for the overall population, which was not statistically significant when compared to TALA + ENZA. However, TALA + ENZA achieved the highest OS benefit at 3years by applying RMST. We suggest that talazoparib in combination with enzalutamide is probably a preferred treatment agent for the overall population and HRRm patients with mCRPC. Given the limitations of network framework and the modeling assumptions undertaken to finalize the analyses, results should be cautiously interpreted.