Androgen Receptor-targeted Therapies Research Articles

Risk Factors for Early Treatment Discontinuation Due to Toxicity Among Patients With Metastatic Castration-resistant Prostate Cancer Receiving Androgen Receptor-targeted Therapy.

Androgen receptor-targeted therapies (ARTs) improve survival outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC); however, a significant portion of patients discontinue treatment for various reasons including treatment-related toxicity. We aim to describe reasons for ART treatment discontinuation and identify predictors associated with increased risk of treatment discontinuation due to toxicity. We performed a single-institution retrospective review of patients with mCRPC receiving ART between 2010 and 2021. Our primary aim was to identify risk factors for treatment discontinuation due to toxicity. Our secondary aim was to describe ART discontinuation patterns among patients with mCRPC. One hundred thirty-three patients with mCRPC started and discontinued ARTs. Fourteen patients (10.5%) discontinued treatment due to toxicity. Common reasons for treatment discontinuation include Prostate Specific Antigen test progression, radiographic progression, toxicity, and death. Significant predictors of treatment discontinuation due to toxicity on bivariate analysis and multivariate analysis included patient-reported falls (odds ratio [OR]: 7.67, CI: [1.31-40.42]; P =0.016), rash (OR: 13.4, CI: [1.35-134.81]; P =0.026), and weakness (OR: 4.16, CI: [1.15-15.0]; P =0.019). Our work presents the first description of ART treatment discontinuation and its causes in the real-world setting, as well as patient-reported side effects. Most patients with mCRPC discontinued treatment due to the progression of disease and a minority of patients discontinued secondary to treatment toxicity. Initial multivariable analysis suggests that patient-reported weakness, falls, and rash were associated with a higher likelihood of treatment discontinuation due to toxicity. Early monitoring of this population can prolong the duration of treatment and prevent unnecessary treatment burden.

Development and Validation of a New BAG-1L–Specific Antibody to Quantify BAG-1L Protein Expression in Advanced Prostate Cancer

BCL-2–associated athanogene-1L (BAG-1L) is a critical co-regulator that binds to and enhances the transactivation function of the androgen receptor, leading to prostate cancer development and progression. Studies investigating the clinical importance of BAG-1L protein expression in advanced prostate cancer have been limited by the paucity of antibodies that specifically recognize the long isoform. In this study, we developed and validated a new BAG-1L–specific antibody using multiple orthogonal methods across several cell lines with and without genomic manipulation of BAG-1L and all BAG-1 isoforms. Following this, we performed exploratory immunohistochemistry to determine BAG-1L protein expression in normal human, matched castration-sensitive prostate cancer (CSPC) and castration-resistant prostate cancer (CRPC), unmatched primary and metastatic CRPC, and early breast cancer tissues. We demonstrated higher BAG-1L protein expression in CRPC metastases than in unmatched, untreated, castration-sensitive prostatectomies from men who remained recurrence-free for 5 years. In contrast, BAG-1L protein expression did not change between matched, same patient, CSPC and CRPC biopsies, suggesting that BAG-1L protein expression may be associated with more aggressive biology and the development of castration resistance. Finally, in a cohort of patients who universally developed CRPC, there was no association between BAG-1L protein expression at diagnosis and time to CRPC or overall survival, and no association between BAG-1L protein expression at CRPC biopsy and clinical outcome from androgen receptor targeting therapies or docetaxel chemotherapy. The limitations of this study include the requirement to validate the reproducibility of the assay developed, the potential influence of pre-analytical factors, timing of CRPC biopsies, relatively small patient numbers, and heterogenous therapies on BAG-1L protein expression, and the clinical outcome analyses performed. We describe a new BAG-1L–specific antibody that the research community can further develop to elucidate the biological and clinical significance of BAG-1L protein expression in malignant and nonmalignant diseases.

Approaches to Prevent and Manage Cardiovascular Disease in Patients Receiving Therapy for Prostate Cancer.

Prostate cancer (PCa) is amongst the most common cancers in men worldwide. Cardiovascular (CV) risk factors and CV disease (CVD) are common comorbidities in this patient population, posing a challenge for PCa-directed therapies which can cause or worsen CVRFs and CVDs. Herein, we summarize the approaches to prevent and manage CVD in patients with PCa receiving therapy. While patients with locally advanced and metastatic PCa benefit from hormonal therapy, these treatments can potentially cause CV toxicity. Androgen receptor targeting therapies, such as androgen deprivation therapy (ADT), can induce metabolic changes and directly impact cardiovascular function, thereby reducing cardiorespiratory fitness and increasing CV mortality. Moreover,more than half of the PCa patients have poorly controlled CV risk factors at baseline. Hence, there is an urgent need to address gaps in preventing and managing CVD in PCa patients. Screening and optimizing CV risk factors and CVD in patients undergoing ADT are essential to reduce CV mortality, the leading non-cancer cause of death in PCa survivors. The risk of CV morbidity and mortality can be further mitigated by considering the patient's cardiovascular risk profile when deciding the choice and duration of ADT. A multidisciplinary team-based approach is crucial to achieve the best outcomes for PCa patients undergoing therapy.

Mitochondrial Alterations in Prostate Cancer: Roles in Pathobiology and Racial Disparities.

Prostate cancer (PCa) affects millions of men worldwide and is a major cause of cancer-related mortality. Race-associated PCa health disparities are also common and are of both social and clinical concern. Most PCa is diagnosed early due to PSA-based screening, but it fails to discern between indolent and aggressive PCa. Androgen or androgen receptor-targeted therapies are standard care of treatment for locally advanced and metastatic disease, but therapy resistance is common. Mitochondria, the powerhouse of cells, are unique subcellular organelles that have their own genome. A large majority of mitochondrial proteins are, however, nuclear-encoded and imported after cytoplasmic translation. Mitochondrial alterations are common in cancer, including PCa, leading to their altered functions. Aberrant mitochondrial function affects nuclear gene expression in retrograde signaling and promotes tumor-supportive stromal remodeling. In this article, we discuss mitochondrial alterations that have been reported in PCa and review the literature related to their roles in PCa pathobiology, therapy resistance, and racial disparities. We also discuss the translational potential of mitochondrial alterations as prognostic biomarkers and as effective targets for PCa therapy.

The effect of statin use on survival outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with androgen receptor targeted therapies (ART).

194 Background: Statins may reinforce and provide a compounded effect on ART by decreasing cholesterol levels thus decreasing de novo androgen synthesis. We aim to investigate the clinical effect of concurrent statin and ART use on outcomes of mCRPC patients. Methods: We conducted a retrospective analysis on mCRPC patients receiving ART from a single institution. Relevant demographic and clinical data was collected in addition to ART treatment course, statin treatment, and survival outcomes. Our primary outcome was PSA progression free survival (PFS) and our secondary outcomes were overall survival (OS) and associated prognostic factors for both PSA PFS and OS. Chi-squared test and Wilcoxon signed ranked test were used to compare baseline characteristics, and a Cox proportional hazards regression model was used to estimate hazard ratios (HR) with 95% confidence interval (CI) for overall survival (OS) and PSA PFS. Results: 153 patients were included in the analysis between 2010 and 2021. 67 patients (mean age 73.8 years) received concurrent statins and 86 patients (mean age 67.6 years) did not. Median PSA PFS was 37.4 months for patients that received concurrent statins and 17.4 months for patients that did not receive statins. On univariate and multivariate analyses, there was no statistically significance difference between groups for PSA PFS (HR 0.7; CI 0.44-1.1; p=0.122). Median OS was 35.6 months for patients that received concurrent statins and 24.0 months for patients who did not. There was no statistical significance between groups for OS on univariate or multivariate analyses (HR 0.67; CI 0.42-1.06; p=0.087). Conclusions: Although results were not statistically significant, our study illustrates that concurrent statin use exhibits improved time to PSA progression and OS in mCRPC patients. Larger multi-center and further prospective studies are warranted to elucidate the relationship between statin use and overall outcomes in this population.

Selected Articles from This Issue

Glioblastoma (GBM) is one of the most aggressive cancers and it is usually refractory to immunotherapies. EGFR variant III (EGFRvIII) is an EGFR mutation commonly present in GBM that generates a unique cell surface neoantigen in tumor cells. Here, Iurlaro and colleagues have designed and developed a novel T cell bispecific antibody (TCB) with specificity for EGFRvIII and CD3. The EGFRvIII-TCB promoted T cell activation and tumor cell killing in EGFRvIII-expressing patient-derived models, and induced tumor regression in GBM patient-derived xenografts (PDX). These results led to the clinical testing of the EGFRvIII-TCB for the treatment of EGFRvIII-expressing GBMs.Comparative oncology clinical trials, carried out in pet dogs with spontaneously occurring cancers, are increasingly recognized a valuable component of the anti-cancer drug discovery and development pathway. In this report, LeBlanc and colleagues conducted a clinical study of a novel orally bioavailable inhibitor of valosin-containing protein (VCP), CB-5339, in pet dogs with a variety of malignancies. This canine trial generated key pharmacokinetic and pharmacodynamic data, defined a tolerable dose and schedule, and discovered an efficacy signal in multiple myeloma. The data generated herein provided a foundation for future studies of this drug in humans with multiple myeloma as well as other tumor types.Glutamine metabolism has been considered an important mechanism for control of tumor growth and survival. Here, Yokoyama and colleagues describe the preclinical pharmacology and mechanism of action of the novel clinical stage glutamine antagonist, DRP-104 (sirpiglenastat). Broadly targeting all 10 glutamine metabolizing enzymes, DRP-104 leads to profound anti-tumor activity related to both direct effects on tumor metabolism as well as immune mediated activity via remodeling of the tumor microenvironment and induction of both innate and adaptive anti-tumor immunity. This unique activity shows promise for the treatment of various tumors including those resistant to immune checkpoint inhibitors.Prostate cancer is the second leading cause of cancer related deaths and most commonly diagnosed cancer in US males. Although androgen receptor-targeted therapies such as enzalutamide are initially effective for the treatment of advanced prostate cancer, resistance occurs frequently. Here, Ning and colleagues have demonstrated that Wnt5A/FZD2 signaling plays vital roles in conferring resistance to enzalutamide and the levels of their expression correlates with aggressive prostate cancer with shortened disease-free survival. Furthermore, a novel bioengineered BERA-Wnt5A siRNA construct significantly suppressed tumor growth and enhanced enzalutamide treatment, suggesting targeting Wnt5A could be developed as a potential therapy for advanced prostate cancer.

Retrospective practice-related care research study on therapy of mCPRC with radium-223 dichloride

During phase III study ERA-223, patients under combination therapy with radium-223 and abiraterone showed an increased risk of bone fractures and a possible higher risk of death. This observation led to a change in the German therapeutic guidelines in 2018. Radium-223 is now only allowed as a third-line monotherapy (besides ADT) in patients with metastatic castration resistant prostate cancer (mCRPC) with symptomatic bone lesions without known visceral metastases or for patients with mCRPC, for whom no other available systematic therapy is suitable. Since almost no data on practice-related care research on the use of radium-223 exist, we consulted members of d-uo (German Uro-Oncologists) over their therapy algorithms. This study analysed data of patients treated with radium-223 between 2014 and 2019. It could be shown that 50% of mCRPC-patients had received radium-223 in the past as third-line therapy. Half of these were treated in combination with new androgen receptor targeted therapies (ARTA) and no increase in bone fractures was observed. This was most likely due to the additional use of bone protecting agents. Despite the late cancer stage, treatment response was seen in almost half of the patients.

Glucocorticoid receptor and androgen receptor-targeting therapy in patients with castration-resistant prostate cancer.

ObjectiveThe glucocorticoid receptor (GR) promotes resistance to androgen receptor (AR)-targeting therapies in castration-resistant prostate cancer (CRPC) by bypassing AR blockade. However, the clinical relevance of evaluating GR expression in patients with CRPC has not been determined. The present study investigated the association of relative GR expression in CRPC tissue samples with treatment response to AR-targeting therapy.MethodsLevels of GR, AR-FL, and AR-V7 mRNAs were measured in prostate cancer tissue from prospectively enrolled CRPC patients who were starting treatment. Patients were divided into groups with high and low AR-V7/AR-FL ratios and with high and low GR/AR-FL ratios. The primary endpoint was prostate-specific antigen (PSA) response rate to treatment.ResultsEvaluation of 38 patients treated with AR-targeting therapies showed that the PSA response rate was significantly higher in patients with low than high AR-V7/AR-FL ratios (77.8% vs. 25.0%, p=0.003) and in patients with low than high GR/AR-FL ratios (81.3% vs. 27.3%, p=0.003). Patients with low GR/AR-FL ratios had higher rates of PSA progression-free survival (46.0% vs. 22.4%, p=0.006), radiologic progression-free survival (28.9% vs. 10.0%, p=0.02), and overall survival (75.2% vs. 48.0%, p=0.037) than patients with high GR/AR-FL ratios. The association of GR/AR-FL ratio with PSA response to AR-targeting therapy remained significant in multivariable models. Evaluation of the 14 patients who received taxane chemotherapy showed that PSA response rates did not differ significantly in those with low and high AR-V7/AR-FL and GR/AR-FL ratios, although no definitive conclusions can be drawn due to the small number of patients.ConclusionRelative GR expression is associated with sensitivity to AR-targeting therapy and survival in patients with CRPC. Large-scale prospective validation and liquid biopsy-based studies are warranted.

Role of Olaparib in the Management of Metastatic Castration-Resistant Prostate Cancer: A Japanese Clinician's Perspective.

Several studies have identified various targetable genomic alterations in prostate cancer, which accumulate during carcinogenesis and cancer progression. Genomic alterations in genes involved in DNA damage repair by homologous recombination repair may predict increased sensitivity to poly-ADP ribose polymerase (PARP) inhibitors. The Phase 3 PROfound trial has shown that treatment with the PARP inhibitor olaparib was associated with an improved radiographic progression-free survival and overall survival among patients with homologous recombination repair-deficient metastatic castration-resistant prostate cancer (mCRPC) after the treatment with androgen receptor targeting therapy, especially in men with BRCA1 or BRCA2 mutation. In Japan, olaparib was approved in December 2020 for the treatment of mCRPC with BRCA1 or BRCA2 mutation. In addition, genetic tests to detect BRCA1 or BRCA2 mutation to select patients who are likely to benefit from olaparib were also approved. This review summarizes the status of olaparib treatment for mCRPC, focusing on the situation in Japan.

Phase 1 study of JNJ-69086420, an actinium-225-labeled antibody targeting human kallikrein-2, for advanced prostate cancer.

TPS5104 Background: Radioligand therapy for metastatic castration resistant prostate cancer (mCRPC) has been shown to prolong survival, delay disease progression, and improve quality of life, raising hopes that these gains will be amplified with even more cancer-specific targets and more powerful radioligands. Human kallikrein-related peptidase 2 (hK2) is a tumor-associated member of the kallikrein family that shares significant homology to prostate-specific antigen and is minimally expressed in normal non-prostate tissues. JNJ-69086420 (JNJ-420; 225Ac-DOTA-h11B6 [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]), is a first-in-class radioimmunotherapy targeted to hK2 antigen. In a phase 0 study of [111In]-DOTA-h11B6, patients with mCRPC (progressed on standard therapies), treatment with a single dose of [111In]-DOTA-h11B6 (2 mg) with/without 8 mg h11B6, demonstrated safety, good tumor localization, nominal normal-organ uptake, and no difference in pharmacokinetics (PK) between 2 and 10 mg antibody mass (Morris et al. J Clin Oncol. 2021 39:6 suppl, 122). We have initiated the first-in-human study to assess the safety, PK, pharmacodynamic (PD), and clinical activity of Ac-225 radiolabeled JNJ-420, to determine its recommended phase 2 dose (RP2D) in adults with advanced PC. Methods: This open-label, multicenter, phase 1 study will recruit approximately 50 men (aged ≥18 years) with advanced PC across dose escalation (Part 1) and expansion (Part 2) parts. Key eligibility criteria: mCRPC with histologic confirmation of adenocarcinoma, Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, adequate organ function based on hematology and serum chemistry, and 1 or more prior novel androgen receptor-targeted therapies (prior chemotherapy acceptable). Key exclusion criteria: prior treatment with radium/strontium/samarium/radioconjugate therapy, superscan findings as protocol defined, active central nervous system metastases. In Part 1, men will receive intravenous (IV) injection of 50 μCi/ 2 mg JNJ-420 (once every 8 weeks) with one or multiple doses; escalation of dose levels to be based on dose limiting toxicities (DLTs) evaluation, until RP2D identification. In Part 2, JNJ-420 is to be given at one of the RP2D(s) determined in Part 1. Primary endpoint is safety (incidence and severity [grading per NCI-CTCAE V5.0] of AEs including DLTs). Secondary endpoints include prostate specific antigen response rate, overall response rate (PCWG3 modified RECIST 1.1 criteria), PK, PD, immunogenicity, and biomarker analyses. Enrollment began in Dec 2020; as of 10 Feb 2022, 4 sites have been initiated and 23 patients enrolled; currently, dose escalation is ongoing. Clinical trial information: NCT04644770.

CREB5 reprograms FOXA1 nuclear interactions to promote resistance to androgen receptor-targeting therapies.

Metastatic castration-resistant prostate cancers (mCRPCs) are treated with therapies that antagonize the androgen receptor (AR). Nearly all patients develop resistance to AR-targeted therapies (ARTs). Our previous work identified CREB5 as an upregulated target gene in human mCRPC that promoted resistance to all clinically approved ART. The mechanisms by which CREB5 promotes progression of mCRPC or other cancers remains elusive. Integrating ChIP-seq and rapid immunoprecipitation and mass spectroscopy of endogenous proteins, we report that cells overexpressing CREB5 demonstrate extensive reprogramming of nuclear protein-protein interactions in response to the ART agent enzalutamide. Specifically, CREB5 physically interacts with AR, the pioneering actor FOXA1, and other known co-factors of AR and FOXA1 at transcription regulatory elements recently found to be active in mCRPC patients. We identified a subset of CREB5/FOXA1 co-interacting nuclear factors that have critical functions for AR transcription (GRHL2, HOXB13) while others (TBX3, NFIC) regulated cell viability and ART resistance and were amplified or overexpressed in mCRPC. Upon examining the nuclear protein interactions and the impact of CREB5 expression on the mCRPC patient transcriptome, we found that CREB5 was associated with Wnt signaling and epithelial to mesenchymal transitions, implicating these pathways in CREB5/FOXA1-mediated ART resistance. Overall, these observations define the molecular interactions among CREB5, FOXA1, and pathways that promote ART resistance.

Phase 1 study of JNJ-69086420, an actinium-225-labeled antibody targeting human kallikrein-2, for advanced prostate cancer.

TPS206 Background: Radioligand therapy for metastatic castration resistant prostate cancer (mCRPC) has been shown to prolong survival, delay disease progression, and improve quality of life, raising hopes that these gains will be amplified with even more cancer-specific targets and more powerful radioligands. Human kallikrein-related peptidase 2 (hK2) is a tumor-associated member of the kallikrein family that shares significant homology to prostate-specific antigen and is minimally expressed in normal non-prostate tissues. JNJ-69086420 (JNJ-420; 225Ac-DOTA-h11B6 [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]), is a first-in-class radioimmunotherapy targeted to hK2 antigen. In a phase 0 study of [111In]-DOTA-h11B6, patients (pts) with mCRPC (progressed on standard therapies), treatment with a single dose of [111In]-DOTA-h11B6 (2 mg) with/without 8 mg h11B6, demonstrated safety, good tumor localization, nominal normal-organ uptake, and no difference in PK between 2 and 10 mg antibody mass (Morris et al. J Clin Oncol. 2021 39:6 suppl, 122). We have initiated the first-in-human study to assess the safety, pharmacokinetics (PK), pharmacodynamic (PD), and clinical activity of Ac-225 radiolabeled JNJ-420, to determine its recommended phase 2 dose (RP2D) in adults with advanced PC. Methods: This open-label, multicenter, phase 1 study will recruit approximately 50 men (aged ≥18 years) with advanced PC across dose escalation (Part 1) and expansion (Part 2) parts. Key eligibility criteria: mCRPC with histologic confirmation of adenocarcinoma, Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, adequate organ function based on hematology and serum chemistry, and 1 or more prior novel androgen receptor-targeted therapies (prior chemotherapy acceptable). Key exclusion criteria: prior treatment with radium/strontium/samarium/radioconjugate therapy, superscan findings as protocol defined, active central nervous system metastases. In Part 1, men will receive intravenous (IV) injection of 50 μCi/ 2 mg JNJ-420 (once every 8 weeks) with one or multiple doses; escalation of dose levels to be based on dose limiting toxicities (DLTs) evaluation, until RP2D identification. In Part 2, JNJ-420 is to be given at one of the RP2D(s) determined in Part 1. Primary endpoint is safety (incidence and severity [grading per NCI-CTCAE V5.0] of AEs including DLTs). Secondary endpoints include prostate specific antigen response rate, overall response rate (PCWG3 modified RECIST 1.1 criteria), PK, PD, immunogenicity, and biomarker analyses. Enrollment began in Dec 2020; as of Sep 2021, 4 sites have been initiated and 14 pts enrolled; currently, dose escalation is ongoing. Clinical trial information: NCT04644770.

Risk of Cognitive Effects in Comorbid Patients With Prostate Cancer Treated With Androgen Receptor Inhibitors.

Prostate cancer (PC) is primarily a disease of older men. As the risk of neurocognitive decline increases as people age, cognitive dysfunction is a potential complication in men with PC, imposing detrimental effects on functional independence and quality of life. Importantly, risk of cognitive decline may increase with exposure to androgen deprivation therapy and other hormonal therapies. Particular consideration should be given to patients with castration-resistant PC (CRPC), many of whom require continuous, long-term androgen deprivation therapy combined with a second-generation androgen receptor inhibitor. Non-comparative evidence from interventional trials of androgen receptor inhibitors in men with non-metastatic CRPC suggests differential effects on cognitive function and central nervous system-related adverse events within this drug class. Drug-drug interactions with concomitant medications for chronic, non-malignant comorbidities differ among ARIs and thus may contribute further to cognitive impairment. Hence, establishing baseline cognitive function is a prerequisite to identifying subsequent clinical decline associated with androgen receptor-targeted therapies. Although brief, sensitive screening tools for cancer-related cognitive dysfunction are lacking, mental status can be ascertained from the initial medical history and neurocognitive examination, progressing to more in-depth evaluation when impairment is suspected. On-treatment neurocognitive monitoring should be integrated into regular clinical follow-up to preserve cognitive function and quality of life throughout disease management. This review summarizes the multiple factors that may contribute to cognitive decline in men with CRPC, awareness of which will assist clinicians to optimize individual treatment. Practical, clinic-based strategies for managing the risks for and symptoms of cognitive dysfunction are also discussed.

Preclinical Models in Prostate Cancer: Resistance to AR Targeting Therapies in Prostate Cancer.

Prostate cancer is an androgen-driven tumor. Different prostate cancer therapies consequently focus on blocking the androgen receptor pathway. Clinical studies reported tumor resistance mechanisms by reactivating and bypassing the androgen pathway. Preclinical models allowed the identification, confirmation, and thorough study of these pathways. This review looks into the current and future role of preclinical models to understand resistance to androgen receptor-targeted therapies. Increasing knowledge on this resistance will greatly improve insights into tumor pathophysiology and future treatment strategies in prostate cancer.

Prevalence of oligoprogression in metastatic hormone-resistant prostate cancer patients on androgen targeted therapies: Could targeted radiotherapy improve patient outcomes?

110 Background: Androgen receptor-targeted therapies (ART) such as Abiraterone and Enzalutamide have shifted the management paradigm of metastatic castrate-resistant prostate cancer (mCRPC). These treatments are well-tolerated with less toxicities compared to chemotherapy, therefore methods to delay chemotherapy are beneficial to patients. Patients eventually become resistant to ARTs, and some patients will progress in a limited number of sites. This study investigated the prevalence of oligoprogressive disease (OPD) amenable to Stereotactic-body radiotherapy (SBRT). OPD is defined as ≤3 metastatic lesions which are progressing or new whilst all other sites of disease are well-controlled by ART. Methods: Retrospective analysis of electronic patient records and imaging studies of 95 patients treated with ART for mCRPC between April 2015 – 2017 from a single centre was undertaken. Data was analysed at the time of first tumour progression on ART. Results: The median (IQR) age of patients was 78.8 (74.4-83.6) years. OPD was found in 27 (28%) patients, 18 (19%) had lesions suitable for SBRT (Table). Seventeen (63%) patients were treated with abiraterone, 10 (27%) patients with enzalutamide. Median (IQR) time from starting ART to OPD was 16.4 (8.6-19.9) months. Five (19%) patients had 3 sites of OPD, 8 (29%) patients had 2 sites of OPD and 14 (52%) patients had 1 site of OPD. Nineteen patients continued ART beyond OPD for ≥3months. OPD was diagnosed using CT scan (56%), whole body diffusion-weighted MRI (22%), choline PET/CT (19%) and bone scan (3%). Six (22%) patients were treated with radiotherapy for OPD, 3 as participants of the TRAP trial (NCT03644303). Median time to subsequent progression after OPD for the 3 patients treated off trial with radiotherapy was 20.5 months. The OPD lesions treated with radiotherapy included the prostate (2 patients, 30 Gy in 5 and 24 Gy in 4 fractions) and para-aortic lymph node (1 patient, 30 Gy in 5 fractions). Median time to subsequent progression after OPD for those who did not receive radiotherapy was 6.4 months. There was no significant difference between median overall survival between patients with OPD and those who progressed with > 3 lesions (7 vs 9.2 years, P= 0.54). Ten (66%) patients who progressed after initial OPD on continuation of ART progressed with further OPD (≤3 lesions including original OPD lesion). Conclusions: OPD is prevalent in patients on ART for mCRPC. The most frequent site of OPD was in bone and majority of patients had only 1 site of OPD at presentation. These results identify a cohort of patients who may benefit from SBRT to maximise ART treatment. Fourteen (14%) patients met entry criteria for TRAP trial which is currently testing the role of SBRT to sites of OPD in mCRPC. [Table: see text]

Overall survival of patients with metastatic castrate-resistant prostate cancer (mCRPC) who have PTEN tumor suppressor gene loss of function.

58 Background: It is estimated that more than 40% of patients with mCRPC have functional loss of phosphatase and tensin homolog (PTEN) tumor suppressor gene, which is associated with unfavorable prognosis and reduced response to androgen receptor-targeting therapy. We describe patient characteristics and survival outcomes by PTEN LOF status among patients with mCRPC in real-world clinical practice. Methods: We conducted a retrospective cohort study using data from the nationwide Flatiron Health-Foundation Medicine mCRPC Clinico-Genomic database (FH-FMI CGDB), a de-identified database linking data derived from electronic health records with genomic data derived from FMI comprehensive genomic profiling (CGP) tests. The study included patients ≥18 years old, with a primary diagnosis of mCRPC between 1/1/2013 and 6/30/2019 who underwent FMI CGP testing and who had a valid PTEN LOF status. Patients were included if their PTEN report date and mCRPC diagnosis date occurred before death or censoring. PTEN LOF status was identified via FMI’s CGP testing. Kaplan-Meier (KM) methods assessed overall survival (OS) by PTEN LOF status from the date of mCRPC diagnosis (later of metastasis and castration resistance) until death or end of study follow-up. A stratified Cox regression model was used to estimate the hazard of death. The Cox model was adjusted for age, race and sequence of metastasis/CRPC diagnoses, and was stratified by the year of mCRPC diagnosis. Adjustments to account for left-truncation and survivorship bias were made in the KM analysis and the Cox regression model. Results: Among the 458 patients who met the eligibility criteria, 174 (38%) had PTEN LOF. The majority of the study sample (76%) was diagnosed with castration-resistance after metastasis. The PTEN LOF group had a higher percentage of white patients (80% vs. 68%; p= 0.01) compared to the PTEN non-LOF group. The mean age of the study sample was 68 years, and there was no difference in mean age at diagnosis by PTEN LOF status ( p= 0.17). Based on the KM estimates adjusted for left-truncation, the median OS was 14.3 months (95% confidence interval [CI]: 11.1-19.7) in the PTEN LOF group compared to 18.3 months (95%CI: 15.5-21.5) in the PTEN non-LOF group (log-rank p= 0.049). In the multivariable Cox model, the PTEN LOF group had numerically 30% higher risk of death compared to the PTEN non-LOF group (hazard ratio = 1.30; 95% CI: 0.99-1.71; p= 0.057). Conclusions: Among real-world patients with mCRPC in the CGDB, PTEN LOF could be associated with poorer survival outcomes, potentially highlighting the unmet need among these patients. Additional studies with larger cohorts are needed to better evaluate the survival outcomes of patients with PTEN LOF. Therapeutic agents acting on the PTEN/PI3K/AKT/mTOR pathway are being tested in clinical trials, and could potentially improve outcomes in this subgroup of patients with mCRPC.

PSMA-targeted radiopharmaceutical therapy in patients with metastatic castration-resistant prostate cancer

The treatment of patients with metastatic castration-resistant prostate cancer has mostly involved androgen receptor-targeted therapies (ARTTs) and cytotoxic chemotherapy for over a decade. Prostate-specific membrane antigen (PSMA)-targeted radiopharmaceutical therapy with lutetium-177 [177Lu]Lu-PSMA-617 delivers β radiation to cells expressing PSMA. The retrospective data from Germany investigating PSMA-targeted radiopharmaceutical therapy in men with metastatic castration-resistant prostate cancer were promising,1 but the first prospective results from Australia, the LuPSMA study,2 provided credible safety and efficacy data.

Treatment-emergent neuroendocrine prostate cancer with a germline BRCA2 mutation: identification of a candidate reversion mutation associated with platinum/PARP-inhibitor resistance.

Neuroendocrine prostate cancer (NEPC) is a highly aggressive histologic subtype of prostate cancer associated with a poor prognosis. Its incidence is expected to increase as castration-resistant disease emerges from the widespread use of potent androgen receptor-targeting therapies, such as abiraterone and enzalutamide. Defects in homologous recombination repair genes, such as BRCA1/2, are also being increasingly detected in individuals with advanced prostate cancer. We present the case of a 65-yr-old man with a germline BRCA2 mutation who developed explosive treatment-emergent, small-cell neuroendocrine prostate cancer. He achieved a complete response to platinum-containing chemotherapy, but a limited remission duration with the use of olaparib, a poly(ADP-ribose) polymerase (PARP) inhibitor, as maintenance therapy. Upon relapse, tumor genomic profiling revealed a novel 228-bp deletion in exon 11 of the BRCA2 gene. The addition of the anti-PD1 drug pembrolizumab to olaparib was ineffective. This case highlights the ongoing challenges in treating neuroendocrine prostate cancer, even in the setting of homologous recombination repair deficiency.

Development of an immunofluorescent AR-V7 circulating tumor cell assay - A blood-based test for men with metastatic prostate cancer.

Here we describe the development of a protein immunofluorescent assay for the detection of nuclear-localized androgen receptor variant 7 (AR-V7) protein within circulating tumor cells (CTCs) identified in patient blood samples. Used in the clinic, the test result serves as a validated biomarker of futility for patients with progressing metastatic castration-resistant prostate cancer (mCRPC) who are treated with androgen receptor targeted therapies (AATT) in whom nuclear-localized AR-V7 CTCs are identified and have received level 2A evidence in the 2019 National Cancer Center Network (NCCN) guidelines (v1.0). Assay development was completed on the Epic Sciences rare cell detection platform using control cell lines of known AR-V7 status and clinical testing of mCRPC patient samples obtained at the decision point in management. Using these samples, all assay parameters, scoring criteria, and clinical cutoffs for positivity were prospectively selected and locked. After assay lock, blinded clinical validation testing was initiated on multiple, independent, clinical cohorts as reported by Scher et al (JAMA Oncol. 2016;2:1441-1449; JAMA Oncol. 2018;4:1179-1186) and Armstrong et al (J Clin Oncol. 2019;37:1120-1129).

Advanced Prostate Cancer: AUA/ASTRO/SUO Guideline PART II.

The summary presented herein represents Part II of the two-part series dedicated to Advanced Prostate Cancer: AUA/ASTRO/SUO Guideline discussing prognostic and treatment recommendations for patients with castration-resistant disease. Please refer to Part I for discussion of the management of patients with biochemical recurrence without metastatic disease after exhaustion of local treatment options as well as those with metastatic hormone-sensitive prostate cancer. The Advanced Prostate Cancer Panel created evidence- and consensus-based guideline statements to aid clinicians in the management of patients with advanced prostate cancer. Such statements are summarized in figure 1[Figure: see text] and detailed herein. The systematic review utilized to inform this guideline was conducted by an independent methodological consultant. A research librarian conducted searches in Ovid MEDLINE (1998 to January Week 5 2019), Cochrane Central Register of Controlled Trials (through December 2018), and Cochrane Database of Systematic Reviews (2005 through February 6, 2019). An updated search was conducted prior to publication through January 20, 2020. The methodology team supplemented searches of electronic databases with the studies included in the prior AUA review and by reviewing reference lists of relevant articles. This guideline attempts to improve a clinician's ability to treat patients diagnosed with advanced prostate cancer. Continued research and publication of high-quality evidence from future trials will be essential to improve the level of care for these patients.