Rucaparib or Physician's Choice in Metastatic Prostate Cancer.

BACKGROUND: In a phase 2 study, rucaparib, an inhibitor of poly(ADP-ribose) polymerase (PARP), showed a high level of activity in patients who had metastatic, castration-resistant prostate cancer associated with a deleterious BRCA alteration. Data are needed to confirm and expand on the findings of the phase 2 study. METHODS: In this randomized, controlled, phase 3 trial, we enrolled patients who had metastatic, castration-resistant prostate cancer with a BRCA1, BRCA2, or ATM alteration and who had disease progression after treatment with a second-generation androgen-receptor pathway inhibitor (ARPI). We randomly assigned the patients in a 2:1 ratio to receive oral rucaparib (600 mg twice daily) or a physician's choice control (docetaxel or a second-generation ARPI [abiraterone acetate or enzalutamide]). The primary outcome was the median duration of imaging-based progression-free survival according to independent review. RESULTS: Of the 4855 patients who had undergone prescreening or screening, 270 were assigned to receive rucaparib and 135 to receive a control medication (intention-to-treat population); in the two groups, 201 patients and 101 patients, respectively, had a BRCA alteration. At 62 months, the duration of imaging-based progression-free survival was significantly longer in the rucaparib group than in the control group, both in the BRCA subgroup (median, 11.2 months and 6.4 months, respectively; hazard ratio, 0.50; 95% confidence interval [CI], 0.36 to 0.69) and in the intention-to-treat group (median, 10.2 months and 6.4 months, respectively; hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001 for both comparisons). In an exploratory analysis in the ATM subgroup, the median duration of imaging-based progression-free survival was 8.1 months in the rucaparib group and 6.8 months in the control group (hazard ratio, 0.95; 95% CI, 0.59 to 1.52). The most frequent adverse events with rucaparib were fatigue and nausea. CONCLUSIONS: The duration of imaging-based progression-free survival was significantly longer with rucaparib than with a control medication among patients who had metastatic, castration-resistant prostate cancer with a BRCA alteration. (Funded by Clovis Oncology; TRITON3 ClinicalTrials.gov number, NCT02975934.).

Extended Safety and Tolerability of Darolutamide for Nonmetastatic Castration-Resistant Prostate Cancer and Adverse Event Time Course in ARAMIS.

BACKGROUND: Patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) are usually asymptomatic and seek treatments that improve survival but have a low risk of adverse events. Darolutamide, a structurally distinct androgen receptor inhibitor (ARi), significantly reduced the risk of metastasis and death versus placebo in ARAMIS. We assessed the extended safety and tolerability of darolutamide and the time-course profile of treatment-emergent adverse events (TEAEs) related to ARis and androgen-suppressive treatment. PATIENTS AND METHODS: Patients with nmCRPC were randomized 2:1 to darolutamide (n = 955) or placebo (n = 554). After trial unblinding, patients could receive open-label darolutamide. Tolerability and TEAEs were assessed every 16 weeks. Time interval-specific new and cumulative event rates were determined during the first 24 months of the double-blind period. RESULTS: Darolutamide remained well tolerated during the double-blind and open-label periods, with 98.8% of patients receiving the full planned dose. The incidence of TEAEs of interest in the darolutamide group was low and ≤2% different from that in the placebo group, except for fatigue. When incidences were adjusted for exposure time, there were minimal differences between the darolutamide double-blind and double-blind plus open-label periods. The rate of initial onset and cumulative incidence of grade 3/4 TEAEs and serious TEAEs were similar for darolutamide and placebo groups over 24 months. CONCLUSION: Extended treatment with darolutamide was well tolerated and no new safety signals were observed. Most ARi-associated and androgen-suppressive treatment-related TEAEs occurred at low incidences with darolutamide, were similar to placebo, and showed minimal increase over time with continued treatment. TRIAL NUMBER: ClinicalTrials.gov identifier NCT02200614.

Examining the ability of the Cancer and Aging Research Group tool to predict toxicity in older men receiving chemotherapy or androgen-receptor-targeted therapy for metastatic castration-resistant prostate cancer.

BACKGROUND: Because multiple treatments are available for metastatic castrate-resistant prostate cancer (mCRPC) and most patients are elderly, the prediction of toxicity risk is important. The Cancer and Aging Research Group (CARG) tool predicts chemotherapy toxicity in older adults with mixed solid tumors, but has not been validated in mCRPC. In this study, its ability to predict toxicity risk with docetaxel chemotherapy (CHEMO) was validated, and its utility was examined in predicting toxicity risk with abiraterone or enzalutamide (A/E) among older adults with mCRPC. METHODS: Men aged 65+ years were enrolled in a prospective observational study at 4 Canadian academic cancer centers. All clinically relevant grade 2 to 5 toxicities over the course of treatment were documented via structured interviews and chart review. Logistic regression was used to identify predictors of toxicity. RESULTS: Seventy-one men starting CHEMO (mean age, 73 years) and 104 men starting A/E (mean age, 76 years) were included. Clinically relevant grade 3+ toxicities occurred in 56% and 37% of CHEMO and A/E patients, respectively. The CARG tool was predictive of grade 3+ toxicities with CHEMO, which occurred in 36%, 67%, and 91% of low, moderate, and high-risk groups (P = .003). Similarly, grade 3+ toxicities occurred among A/E users in 23%, 48%, and 86% with low, moderate, and high CARG risk (P < .001). However, it was not predictive of grade 2 toxicities with either treatment. CONCLUSIONS: There is external validation of the CARG tool in predicting grade 3+ toxicity in older men with mCRPC undergoing CHEMO and demonstrated utility during A/E therapy. This may aid with treatment decision-making.

Management of anticoagulation in patients with metastatic castration-resistant prostate cancer receiving abiraterone + prednisone.

PURPOSE: Abiraterone has been proven to be an effective agent used in the management of metastatic castration-resistant prostate cancer, significantly improving overall and progression-free survival. Due to the pharmacodynamic and pharmacokinetic properties of abiraterone, concurrent use with anticoagulation may pose a challenge for clinicians. Thrombosis within the cancer setting continues to increase patient mortality; therefore, appropriate anticoagulation through the use of a management algorithm can reduce adverse events and increase quality of life. METHODS: A review of the literature was preformed by a medical oncologist, haematologist and pharmacists to identify relevant randomized controlled trials, meta-analyses and retrospective studies. Major society guidelines were reviewed to further aid in developing the anticoagulation protocol for non-valvular atrial fibrillation and venous thromboembolism within this patient population. After reviewing the literature, a clinical framework was designed to aid clinicians in the management of those patients receiving abiraterone concurrently with an anticoagulant. RESULTS: In this review, we describe the potential interactions between abiraterone and various anticoagulants and provide management strategies based on the most recent literature for atrial fibrillation, venous thromboembolism and mechanical heart valves to avoid potential drug-drug interactions. CONCLUSION: Abiraterone therapy has become a mainstay of the management of advanced prostate cancer and is often used over prolonged years. In this review, we have summarized a framework of how to use abiraterone in men with prostate cancer on anticoagulants. Evidence available to date suggests that patients with an indication for anticoagulation such as atrial fibrillation, venous thromboembolism and mechanical heart valves can be treated safely with abiraterone in the appropriate setting, with appropriate monitoring.

Bone Health and Bone-Targeted Therapies for Nonmetastatic Prostate Cancer: A Systematic Review and Meta-analysis.

BACKGROUND: Bone health is a significant concern in men with prostate cancer. PURPOSE: To evaluate the effectiveness of drug, supplement, and lifestyle interventions aimed at preventing fracture, improving bone mineral density (BMD), or preventing or delaying osteoporosis in men with nonmetastatic prostate cancer. DATA SOURCES: Ovid MEDLINE (1946 to 19 January 2017), EMBASE (1980 to 18 January 2017), and the Cochrane Database of Systematic Reviews (19 January 2017). STUDY SELECTION: Randomized trials and systematic reviews of trials that were published in English; involved men with nonmetastatic prostate cancer; and compared bone-targeted therapies with placebo, usual care, or other active treatments. DATA EXTRACTION: Two reviewers independently extracted study characteristics and assessed study risk of bias for each outcome. DATA SYNTHESIS: Two systematic reviews and 28 reports of 27 trials met inclusion criteria. All trials focused on men with nonmetastatic prostate cancer who were initiating or continuing androgen deprivation therapy (ADT). Bisphosphonates were effective in increasing BMD, but no trial was sufficiently powered to detect reduction in fractures. Denosumab improved BMD and reduced the incidence of new radiographic vertebral fractures in 1 high-quality trial. No trials compared calcium or vitamin D versus placebo. Three lifestyle intervention trials did not show a statistically significant difference in change in BMD between exercise and usual care. LIMITATIONS: Most trials were of moderate quality. Only 2 randomized controlled trials were designed to examine fracture outcomes. Potential harms of treatments were not evaluated. CONCLUSION: Both bisphosphonates and denosumab improve BMD in men with nonmetastatic prostate cancer who are receiving ADT. Denosumab also reduces risk for radiographic vertebral fractures, based on 1 trial. More trials studying fracture outcomes are needed in this population. PRIMARY FUNDING SOURCE: Program in Evidence-Based Care.

Impact of CTLA-4 blockade in conjunction with metronomic chemotherapy on preclinical breast cancer growth.

BACKGROUND: Although there are reports that metronomic cyclophosphamide (CTX) can be immune stimulating, the impact of its combination with anti-CTLA-4 immunotherapy for the treatment of cancer remains to be evaluated. METHODS: Murine EMT-6/P breast cancer, or its cisplatin or CTX-resistant variants, or CT-26 colon, were implanted into Balb/c mice. Established tumours were monitored for relative growth following treatment with anti-CTLA-4 antibody alone or in combination with; (a) metronomic CTX (ldCTX; 20 mg kg-1 day-1), b) bolus (150 mg kg-1) plus ldCTX, or (c) sequential treatment with gemcitabine (160 mg kg-1 every 3 days). RESULTS: EMT-6/P tumours responded to anti-CTLA-4 therapy, but this response was less effective when combined with bolus plus ldCTX. Anti-CTLA-4 could be effectively combined with either ldCTX (without a bolus), or with regimens of either sequential or concomitant gemcitabine, including in orthotopic EMT-6 tumours, and independently of the schedule of drug administration. Tumour responses were confirmed with CT-26 tumours but were less pronounced in drug-resistant EMT-6/CTX or EMT-6/DDP tumour models than in the parent tumour. A number of tumour bearing mice developed spontaneous metastases under continuous therapy. The majority of cured mice rejected tumour re-challenges. CONCLUSIONS: Metronomic CTX can be combined with anti-CTLA-4 therapy, but this therapy is impaired by concomitant bolus CTX. Sequential therapy of anti-CTLA-4 followed by gemcitabine is effective in chemotherapy-naive tumours, although tumour relapses can occur, in some cases accompanied by the development of spontaneous metastases.

High prevalence of potential drug-drug interactions in patients with castration-resistant prostate cancer treated with abiraterone acetate.

PURPOSE: Abiraterone acetate (AA), used to treat metastatic castration-resistant prostate cancer (mCRPC), inhibits androgen biosynthesis by blocking cytochrome P450 (CYP) 17A1. It also inhibits other cytochromes involved in the metabolism of various widely used medications. As such, there is presumably a high potential for drug-drug interactions (DDIs) that can diminish the efficacy of AA or concurrent medications, or increase the risk of DDI-related adverse events (AEs). However, the scale of AA-associated DDIs is currently unknown. METHODS: We conducted a retrospective review of pharmacy records and electronic patient charts to retrieve individual drug histories and on-treatment AEs of mCRPC patients beginning AA therapy in a tertiary care setting. Potential DDIs were analyzed using two commercial databases, Lexicomp and Micromedex. RESULTS: Eighty-four informative patients were identified. Sixty-five patients (77 %) and 44 patients (52 %) were flagged for one or more potential DDIs by the Lexicomp and Micromedex databases, respectively. One hundred eighty-four potential DDIs were identified overall, with a median of 1 DDI per patient in both databases. Possibly due to rigorous DDI screening before AA treatment initiation, we did not identify a definite instance of DDI-related AEs. CONCLUSIONS: The use of commercial DDI databases suggests a substantial risk of potentially consequential DDIs in mCRPC patients undergoing AA therapy. However, prospective investigations with larger patient populations are required to better establish the clinical relevance of these DDIs.

Safety of enzalutamide in patients with metastatic castration-resistant prostate cancer previously treated with docetaxel: expanded access in North America.

BACKGROUND: The open-label, single-arm enzalutamide expanded access program (EAP) in the United States and Canada evaluated the safety of enzalutamide in patients with metastatic castration-resistant prostate cancer (mCRPC) who had previously received docetaxel. METHODS: Patients (n = 507) received enzalutamide 160 mg/day until disease progression, intolerable adverse events (AEs), or commercial availability occurred. AEs and other safety variables were assessed on day 1, weeks 4 and 12, and every 12 weeks thereafter. Data following transition to commercial drug were not collected. RESULTS: Median age was 71 years (range 43-97); 426 patients (83.9%) had a baseline ECOG score of ≤1. In addition to docetaxel, the majority of patients had received prior prostate cancer treatments such as abiraterone (76.1%) or cabazitaxel (28.6%). Median study treatment duration was 2.6 months (range 0.03-9.07). The most frequently reported reasons for discontinuation were commercial availability of enzalutamide (46.7%) and progressive disease (33.7%). A total of 88.2% of patients experienced AEs; 45.4% experienced AEs with a maximum grade of 1 or 2. Fatigue (39.1%), nausea (22.7%), and anorexia (14.8%) were the most commonly reported AEs. Seizure was reported in four patients (0.8%). The most commonly reported event leading to death was progression of metastatic prostate cancer (7.7%). CONCLUSION: In this heavily pretreated EAP population with progressive mCRPC, enzalutamide was well tolerated and the safety profile was consistent with that of the AFFIRM trial.

Temsirolimus Maintenance Therapy After Docetaxel Induction in Castration-Resistant Prostate Cancer.

LESSONS LEARNED: Temsirolimus maintenance therapy after docetaxel induction chemotherapyis safe in patients with castration-resistant prostate cancer, although biochemical or tumor responses are rare;does not diminish quality of life; anddelays radiological and/or symptomatic progression by approximately 6 months. BACKGROUND: No standard therapy is available for men with castration-resistant prostate cancer (CRPC) who have responded to docetaxel and do not yet have disease progression. Hence, we designed a single-arm phase II trial to explore whether the mTOR inhibitor temsirolimus can maintain the response to docetaxel without compromising quality of life. METHODS: After successful docetaxel induction (75 mg/m(2) every 3 weeks; 6-10 cycles), 21 CRPC patients underwent temsirolimus maintenance treatment (25 mg weekly; 4 weeks per cycle). The primary endpoint was the time to treatment failure (TTTF) (i.e., radiological and/or symptomatic progression). The secondary endpoints included the tumor response rate (RECIST 1.0), safety (National Cancer Institute Common Terminology Criteria for Adverse Events, version 3.0), quality of life (Functional Assessment of Cancer Therapy-Prostate [FACT-P]), pain (Present Pain Intensity [PPI] scale), prostate-specific antigen (PSA) parameters, including time to PSA progression (TTPP) according to Prostate Cancer Clinical Trials Working Group criteria, and serial enumeration of circulating endothelial cells (CECs) and endothelial progenitor cells (CEPs). RESULTS: Patients received a median of 7 cycles of temsirolimus (range, 1-28), resulting in a median TTTF of 24.3 weeks (95% confidence interval [CI], 16.1-33.0), 1 partial tumor response (4.8%), 1 PSA response (4.8%), and a median TTPP of 12.2 weeks (95% CI, 7.8-23.9). Grade 3-4 adverse events were infrequent, and FACT-P and PPI scores remained stable during treatment. CECs did not predict clinical benefit, and CEPs were not consistently detectable. CONCLUSION: Temsirolimus maintenance therapy after successful docetaxel induction is feasible, does not adversely affect quality of life, and, in this exploratory single-arm phase II study, resulted in a median TTTF of 24.3 weeks.

In vivo passage of human prostate cancer cells in mice results in stable gene expression changes affecting numerous cancer-associated biological processes.

BACKGROUND: While therapeutic resistance is difficult to model in vitro in its entirety, in vivo passage and re-derivation of treatment resistant prostate cancer cell variants is a strategy to study therapeutic resistance more comprehensively. However, the process of in vivo passage itself may result in gene expression changes that could confound the analysis of such resistant cell variants compared to their parental cell lines. METHODS: We compared the expression profiles of parental PC-3 human prostate cancer cells and PC-3 cells re-derived after in vivo passage in athymic nude mice. Whole transcriptome information was obtained using the SOLiD 4 system (Applied Biosystems). Differentially expressed genes were mapped to genes in the Database for Annotation, Visualization and Integrated Discovery for gene enrichment and functional annotation analysis. The expression of a panel of these genes was validated using quantitative RT-PCR. RESULTS: Altogether, 21,032 distinct transcripts were found in PC-3 and/or NS1.1. Of these, 906 were differentially regulated (≥2-fold) in NS1.1 versus PC-3. 337 transcripts were upregulated, and 569 were downregulated, including genes previously associated with various aspects of prostate carcinogenesis such as TLR4 and IGFBP5, respectively. Gene ontology analysis of the differentially expressed transcripts revealed enrichment for biological processes such as cell adhesion, migration, and angiogenesis. CONCLUSIONS: When using in vivo as opposed to in vitro derived prostate cancer cell variants for comparative genetic studies of complex traits such as therapeutic resistance, one may be better served to use similarly in vivo passaged control cell variants instead of parental cell lines.

Preclinical analysis of resistance and cross-resistance to low-dose metronomic chemotherapy.

Low-dose metronomic chemotherapy is an emerging form of chemotherapy with distinct mechanisms of action from conventional chemotherapy (e.g., antiangiogenesis). Although developed to overcome resistance to conventional chemotherapy, metronomic chemotherapy is subject to resistance on its own. However, there is a paucity of information on mechanisms of resistance, on cross-resistance between metronomic regimens using different cytotoxic drugs, and on cross-resistance between metronomic versus conventional chemotherapy, or versus targeted antiangiogenic therapy. Herein we show that PC-3 human prostate cancer xenografts were sensitive to both metronomic cyclophosphamide and metronomic docetaxel, but resistant to metronomic topotecan. Conventional docetaxel was only moderately active in parental PC-3 and in metronomic cyclophosphamide resistant PC-3 tumors. However, in metronomic cyclophosphamide resistant PC-3 tumors combining conventional docetaxel or bolus cyclophosphamide therapy with continued metronomic cyclophosphamide was superior to each treatment alone. Furthermore, bevacizumab had single-agent activity against metronomic cyclophosphamide resistant PC-3 tumors. Microarray analyses identified altered regulation of protein translation as a potential mechanism of resistance to metronomic cyclophosphamide. Our results suggest that sensitivity to metronomic chemotherapy regimens using different cytotoxic drugs not only depends on shared mechanisms of action such as antiangiogenesis, but also on as yet unknown additional antitumor effects that appear to be drug-specific. As clinically observed with targeted antiangiogenic agents, the continued use of metronomic chemotherapy beyond progression may amplify the effects of added second-line therapies or vice versa. However, metronomic chemotherapy is no different from other systemic therapies in that predictive biomarkers will be essential to fully exploit this novel use of conventional chemotherapeutics.

The effects of denosumab on calcium profiles in advanced cancer patients with bone metastases.

OBJECTIVE: To retrospectively examine the incidence and management of hypocalcemia for patients with bone metastases treated with denosumab. METHODS: Patients who had a record of filling a prescription of denosumab for treatment of bone metastases at the outpatient pharmacy at the Odette Cancer Centre from May 2011 to February 2013 were included in the analysis. Demographic information, previous bisphosphonate usage, calcium and albumin values, and adverse events were obtained using the Sunnybrook Electronic Patient Record system (EPR) and the Oncology Symptom Control and Information Resource (OSCIR). Hypocalcemia was defined as a calcium value below 2.0 mmol/L within a 28-day±7-day window after the last injection of denosumab based on the Common Terminology Criteria for Adverse Events (CTCAE) grade 2 hypocalcemia. RESULTS: A total of 55 patients had record of a prescription for denosumab filled with an average age of 62 years (range 40 to 93 years), 18 (32.7%) were males and 37 (67.3%) were females. Twenty-nine (52.7%) patients had primary breast cancer, 12 (21.8%) prostate, 10 (18.2%) lung, and 4 (7.3%) with other types. Using CTCAE grading of hypocalcemia, 17 (32.7%) patients experienced grade 1, 4 (7.7%) patients grade 2, 4 (7.7%) patients grade 3, and 1 (1.9%) patient grade 4. The number of injections before the incident of hypocalcemia was a median of one injection (range 1 to 14). Time from the first hypocalcemia lab value to normocalcemia was a median of 33 days. CONCLUSIONS: This study found that 9 of 52 (17.3%) patients had at least one incidence of hypocalcemia of grade 2 or higher after receiving denosumab. Cautionary measures should be taken to avoid hypocalcemia in patients receiving denosumab.

Prostate Cancer Liver Metastasis: An Ominous Metastatic Site in Need of Distinct Management Strategies.

Prostate cancer liver metastasis (PCLM), seen in upwards of 25% of metastatic castration-resistant PC (mCRPC) patients, is the most lethal site of mCRPC with a median overall survival of 10-14 months. Despite its ominous prognosis and anticipated rise in incidence due to longer survival with contemporary therapy, PCLM is understudied. This review aims to summarize the existing literature regarding the risk factors associated with the development of PCLM, and to identify areas warranting further research. A literature search was conducted through Ovid MEDLINE from 2000 to March 2023. Relevant subject headings and text words were used to capture the following concepts: "Prostatic Neoplasms", "Liver Neoplasms", and "Neoplasm Metastasis". Citation searching identified additional manuscripts. Forty-one studies were retained for detailed analysis. The clinical risk factors for visceral/liver metastasis included <70 years, ≥T3 tumor, N1 nodal stage, de novo metastasis, PSA >20 ng/mL, and a Gleason score >8. Additional risk factors comprised elevated serum AST, LDH or ALP, decreased Hb, genetic markers like RB1 and PTEN loss, PIK3CB and MYC amplification, as well as numerous PC treatments either acting directly or indirectly through inducing liver injury. Further research regarding predictive factors, early detection strategies, and targeted therapies for PCLM are critical for improving patient outcomes.

Correlates and predictors of sarcopenia among men with metastatic castrate-resistant prostate cancer.

INTRODUCTION: Sarcopenia is a predictor of clinical outcomes in men with metastatic castrate-resistant prostate cancer (mCRPC); however, correlates and predictors of sarcopenia are poorly understood in this population. The aim of this study was to examine correlates and predictors of sarcopenia in men with mCRPC prior to treatment. METHODS: A secondary analysis of an observational study was performed. Participants were receiving care for mCRPC at the Princess Margaret Cancer Centre. Sarcopenia was assessed prior to treatment and was defined as the combination of low grip strength (<35.5 kg), low gait speed (<0.8 m/s), and computed tomography-derived low muscle mass or density. Participants' sociodemographic and clinical characteristics, comorbidity information, and clinically relevant blood markers were collected prior to treatment and were used to identify correlates and predictors of sarcopenia through Spearman correlations and multivariable logistic regression, respectively. RESULTS: In total, 110 men had complete data on sarcopenia measures and were included in the analysis. Sarcopenia was identified in 30 (27.3%) participants. Pre-treatment sarcopenia was moderately correlated with dependence in one or more instrumental activities of daily living (IADLs) (r=0.412), Vulnerable Elders Survey-13 (r=0.404), and a lower hemoglobin (r=0.407 per 10 g/L decrease). In adjusted logistic regression, dependence in one or more IADLs (odds ratio [OR] 4.37, 95% confidence interval [CI] 1.37-13.86, p=0.012), and a 10 g/L decrease in hemoglobin (OR 1.70, 95% CI 1.13-2.57, p=0.012) were significantly associated with sarcopenia. CONCLUSIONS: In settings where assessment of sarcopenia is not feasible, evaluation of IADLs and hemoglobin may be used to identify high-risk patients that can benefit from supportive care strategies aiming to improve muscle mass and function.

Mainstream Model of Genetic Testing for Prostate Cancer at a Large Tertiary Cancer Centre.

BACKGROUND: An estimated 20% to 30% of men with advanced prostate cancer carry a mutation in DNA damage repair genes, of which half are estimated to be germline. Eligibility criteria for germline genetic testing expanded significantly for Ontario patients in May 2021 and many centers adopted a "mainstream" model, defined as oncologist-initiated genetic testing. METHODS: We conducted a retrospective chart review to report on the first-year mainstream experience of a large tertiary oncologic center, the Sunnybrook Odette Cancer Centre. All patients who underwent mainstream at the discretion of their treating physician were included. A subset underwent somatic profiling as part of clinical trial screening. Descriptive statistics were used to report baseline clinicopathologic characteristics and treatments received. RESULTS: Between May 1, 2021, and May 30, 2022, 174 patients with prostate cancer underwent mainstream germline genetic testing with a 19-gene panel. Median age was 75 (IQR 68-80), and 82% of patients were diagnosed with either de novo metastatic or high-risk localized prostate adenocarcinoma. Fourteen patients (8%; 95% CI 4%-12%) were found to have a deleterious germline mutation, including pathogenic or likely pathogenic variants in BRCA1/2, ATM, CHEK2, PMS2, RAD51C, HOXB13, and BRIP1. Forty-nine patients (28%; 95% CI 21%-35%) were found to have a variant of uncertain significance. Thirty-four patients also had next-generation sequencing (NGS) of their somatic tissue. Among this subset, 8 of 34 (23%) had an alteration in homologous recombination repair (HRR) genes. Of the 14 patients with a germline mutation, none had a prior personal history of malignancy and 6 (43%) did not have any first- or second-degree relatives with history of prostate, pancreatic, breast, or ovarian cancer. CONCLUSION: We report on the real-world characteristics of prostate cancer patients who underwent mainstream germline genetic testing. Personal history and family history of cancer cannot reliably stratify patients for the presence of pathogenic germline variants.

177Lu-PSMA-617 in Metastatic Castration-Resistant Prostate Cancer: A Review of the Evidence and Implications for Canadian Clinical Practice.

Prostate-specific membrane antigen (PSMA) is highly expressed in prostate cancer and a therapeutic target. Lutetium-177 (177Lu)-PSMA-617 is the first radioligand therapy to be approved in Canada for use in patients with metastatic castration-resistant prostate cancer (mCRPC). As this treatment represents a new therapeutic class, guidance regarding how to integrate it into clinical practice is needed. This article aims to review the evidence from prospective phase 2 and 3 clinical trials and meta-analyses of observational studies on the use of 177Lu-PSMA-617 in prostate cancer and discuss how Canadian clinicians might best apply these data in practice. The selection of appropriate patients, the practicalities of treatment administration, including necessary facilities for treatment procedures, the assessment of treatment response, and the management of adverse events are considered. Survival benefits were observed in clinical trials of 177Lu-PSMA-617 in patients with progressive, PSMA-positive mCRPC who were pretreated with androgen receptor pathway inhibitors and taxanes, as well as in taxane-naïve patients. However, the results of ongoing trials are awaited to clarify questions regarding the optimal sequencing of 177Lu-PSMA-617 with other therapies, as well as the implications of predictive biomarkers, personalized dosimetry, and combinations with other therapies.

Understanding the incidence, duration, and severity of symptoms through daily symptom monitoring among frail and non-frail older patients receiving metastatic prostate cancer treatments.

INTRODUCTION: Older adults with metastatic prostate cancer (mPC) experience high symptom burden associated with treatment. Frailty may exacerbate treatment toxicity. The aim of this study was to explore short-term treatment toxicity in patients with metastatic prostate cancer. MATERIALS AND METHODS: Older adults with metastatic prostate cancer starting chemotherapy, androgen-receptor-axis targeted therapies, or radium-223 participated in a prospective, multicentre, observational study. Participants self-reported symptoms daily using the Edmonton Symptom Assessment System for one treatment cycle via internet or telephone. The most common moderate-to-severe symptoms (score≥4), their duration, and the proportion of participants who experienced improvements in symptom severity (score<4) after reporting moderate-to-severe symptoms at baseline were determined using descriptive statistics. Once-weekly symptom questionnaires were administered and analyzed using linear mixed effect models. Symptom incidence, duration, and frailty associations were assessed using t-tests and chi-square tests. RESULTS: Ninety participants completed the study (mean age=77 years [standard deviation=6.1], 42% frail [Vulnerable Elders Survey≥3]). The most common moderate-to-severe symptoms across cohorts were fatigue (46.8%), insomnia (42.9%), poor wellbeing (41.2%), pain (37.5%), and decreased appetite (37.1%). Poor wellbeing had a higher incidence in frail participants (62.5% in frail vs. 31.4% in non-frail, p=0.039). Symptom duration varied across cohorts and between frail and non-frail participants. Among participants who reported moderate-to-severe symptoms at baseline, no more than 15% improved in any symptom. There were statistically significant improvements in weekly symptoms for fatigue, decreased appetite, and insomnia in the chemotherapy cohort only. DISCUSSION: Limitations include a short follow-up duration, lack of a control group, and few radium-223 participants. Regular symptom monitoring can help clinicians understand temporal patterns and durations of symptoms and inform supportive care approaches.

TOward a comPrehensive supportive Care intervention for Older men with metastatic Prostate cancer (TOPCOP3): A pilot randomized controlled trial and process evaluation.

INTRODUCTION: Current management of metastatic prostate cancer (mPC) includes androgen receptor axis-targeted therapy (ARATs), which is associated with substantial toxicity in older adults. Geriatric assessment and management and remote symptom monitoring have been shown to reduce toxicity and improve quality of life in patients undergoing chemotherapy, but their efficacy in patients being treated with ARATs has not been explored. The purpose of this study is to examine whether these interventions, alone or in combination, can improve treatment tolerability and quality of life (QOL) for older adults with metastatic prostate cancer on ARATs. MATERIALS AND METHODS: TOPCOP3 is a multi-centre, factorial pilot clinical trial coupled with an embedded process evaluation. The study includes four treatment arms: geriatric assessment and management (GA + M); remote symptom monitoring (RSM); geriatric assessment and management plus remote symptom monitoring; and usual care and will be followed for six months. The aim is to recruit 168 patients between two cancer centres in Toronto, Canada. Eligible participants will be randomized equally via REDCap. Participants in all arms will complete a comprehensive baseline assessment upon enrollment following the Geriatric Core dataset, as well as follow-up assessments at 1.5, 3, 4.5, and 6 months. The co-primary outcomes will be grade 3-5 toxicity and QOL. Toxicities will be graded using the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0. QOL will be measured by patient self-reporting using the EuroQol 5 dimensions of health questionnaire. Secondary outcomes include fatigue, insomnia, and depression. Finally, four process evaluation outcomes will also be observed, namely feasibility, fidelity, and acceptability, along with implementation barriers and facilitators. DISCUSSION: Data will be collected to observe the effects of GA + M and RSM on QOL and toxicities experienced by older adults receiving ARATs for metastatic prostate cancer. Data will also be collected to help the design and conduct of a definitive multicentre phase III randomized controlled trial. This study will extend supportive care interventions for older adults with cancer into new areas and inform the design of larger trials. TRIAL REGISTRATION: The trial is registered at clinicaltrials.gov (registration number: NCT05582772).