[177Lu]Lu-PSMA-617 plus enzalutamide in patients with metastatic castration-resistant prostate cancer (ENZA-p): an open-label, multicentre, randomised, phase 2 trial.

BACKGROUND: Enzalutamide and lutetium-177 [177Lu]Lu-prostate-specific membrane antigen (PSMA)-617 both improve overall survival in patients with metastatic castration-resistant prostate cancer. Androgen and PSMA receptors have a close intracellular relationship, with data suggesting complementary benefit if targeted concurrently. In this study, we assessed the activity and safety of enzalutamide plus adaptive-dosed [177Lu]Lu-PSMA-617 versus enzalutamide alone as first-line treatment for metastatic castration-resistant prostate cancer. METHODS: ENZA-p was an open-label, randomised, controlled phase 2 trial done at 15 hospitals in Australia. Participants were men aged 18 years or older with metastatic castration-resistant prostate cancer not previously treated with docetaxel or androgen receptor pathway inhibitors for metastatic castration-resistant prostate cancer, gallium-68 [68Ga]Ga-PSMA-PET-CT (PSMA-PET-CT) positive disease, Eastern Cooperative Oncology Group performance status of 0-2, and at least two risk factors for early progression on enzalutamide. Participants were randomly assigned (1:1) by a centralised, web-based system using minimisation with a random component to stratify for study site, disease burden, use of early docetaxel, and previous treatment with abiraterone acetate. Patients were either given oral enzalutamide 160 mg daily alone or with adaptive-dosed (two or four doses) intravenous 7·5 GBq [177Lu]Lu-PSMA-617 every 6-8 weeks dependent on an interim PSMA-PET-CT (week 12). The primary endpoint was prostate-specific antigen (PSA) progression-free survival, defined as the interval from the date of randomisation to the date of first evidence of PSA progression, commencement of non-protocol anticancer therapy, or death. The analysis was done in the intention-to-treat population, using stratified Cox proportional hazards regression. This trial is registered with ClinicalTrials.gov, NCT04419402, and participant follow-up is ongoing. FINDINGS: 162 participants were randomly assigned between Aug 17, 2020, and July 26, 2022. 83 men were assigned to the enzalutamide plus [177Lu]Lu-PSMA-617 group, and 79 were assigned to the enzalutamide group. Median follow-up in this interim analysis was 20 months (IQR 18-21), with 32 (39%) of 83 patients in the enzalutamide plus [177Lu]Lu-PSMA-617 group and 16 (20%) of 79 patients in the enzalutamide group remaining on treatment at the data cutoff date. Median age was 71 years (IQR 64-76). Median PSA progression-free survival was 13·0 months (95% CI 11·0-17·0) in the enzalutamide plus [177Lu]Lu-PSMA-617 group and 7·8 months (95% CI 4·3-11·0) in the enzalutamide group (hazard ratio 0·43, 95% CI 0·29-0·63, p<0·0001). The most common adverse events (all grades) were fatigue (61 [75%] of 81 patients), nausea (38 [47%]), and dry mouth (32 [40%]) in the enzalutamide plus [177Lu]Lu-PSMA-617 group and fatigue (55 [70%] of 79), nausea (21 [27%]), and constipation (18 [23%]) in the enzalutamide group. Grade 3-5 adverse events occurred in 32 (40%) of 81 patients in the enzalutamide plus [177Lu]Lu-PSMA-617 group and 32 (41%) of 79 patients in the enzalutamide group. Grade 3 events that occurred only in the enzalutamide plus [177Lu]Lu-PSMA-617 group included anaemia (three [4%] of 81 participants) and decreased platelet count (one [1%] participant). No grade 4 or 5 events were attributed to treatment on central review in either group. INTERPRETATION: The addition of [177Lu]Lu-PSMA-617 to enzalutamide improved PSA progression-free survival providing evidence of enhanced anticancer activity in patients with metastatic castration-resistant prostate cancer with risk factors for early progression on enzalutamide and warrants further evaluation of the combination more broadly in metastatic prostate cancer. FUNDING: Prostate Cancer Research Alliance (Movember and Australian Federal Government), St Vincent's Clinic Foundation, GenesisCare, Roy Morgan Research, and Endocyte (a Novartis company).

Drug-drug interaction potential among patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) treated with novel androgen receptor inhibitors.

BACKGROUND: Nonmetastatic castration-resistant prostate cancer (nmCRPC) patients are often older and use concurrent medications that increase the potential for drug-drug interactions (pDDIs). This study assessed pDDI prevalence in real-world nmCRPC patients treated with apalutamide, darolutamide, or enzalutamide. RESEARCH DESIGN AND METHODS: Castrated prostate cancer patients without metastases prior to androgen receptor inhibitor initiation were identified retrospectively via Optum Clinformatics Data Mart claims data (8/2019-3/2021). The top 100 concomitant medications were assessed for pDDIs. RESULTS: Among 1,515 patients (mean age: 77 ± 8 years; mean Charlson Comorbidity Index: 3 ± 3), 340 initiated apalutamide, 112 darolutamide, and 1,063 enzalutamide. Common concomitant medication classes were cardiovascular (80%) and central nervous system (52%). Two-thirds of the patients received ≥5 concomitant medications; 30 (30/100 medications) pDDIs were identified for apalutamide and enzalutamide each and 2 (2/100 medications) for darolutamide. Most pDDIs had risk ratings of C or D, but four for apalutamide were rated X. Approximately 58% of the patients on apalutamide, 5% on darolutamide, and 54% on enzalutamide had ≥1 identified pDDI. CONCLUSIONS: Results showed a higher frequency of pDDIs in patients receiving apalutamide and enzalutamide vs darolutamide. The impact of these could not be determined retrospectively. DDI risk should be carefully evaluated when discussing optimal therapy for patients with nmCRPC.

Determination of enzalutamide long-term safety and efficacy for castration-resistant prostate cancer patients after combined anti-androgen blockade followed by alternative anti-androgen therapy: a multicenter prospective DELC study.

BACKGROUND: Alternative anti-androgen therapy has been widely used as a first-line treatment for castration-resistant prostate cancer, and it may affect treatment outcome of subsequent agents targeting the androgen receptor axis. We conducted the prospective observational DELC (Determination of Enzalutamide Long-term safety and efficacy for Castration-resistant prostate cancer patients after combined anti-androgen blockade followed by alternative anti-androgen therapy) study to evaluate the efficacy of enzalutamide in patients with castration-resistant prostate cancer who underwent prior combined androgen blockade with bicalutamide and then alternative anti-androgen therapy with flutamide. METHODS: The DELC study enrolled 163 Japanese patients with castration-resistant prostate cancer who underwent alternative anti-androgen therapy with flutamide following failure of initial combined androgen blockade with bicalutamide in multiple institutions between January 2016 and March 2019. Primary endpoint was overall survival. Administration of enzalutamide was started at 160 mg orally once daily in all patients. RESULTS: The rate of decline of prostate-specific antigen by 50% or more was 72.2%, and median overall survival was 42.05 months. Multivariate analysis revealed that higher pretreatment serum levels of prostate-specific antigen (≥11.3 ng/mL; P = 0.004), neuron-specific enolase (P = 0.014) and interleukin-6 (≥2.15 pg/mL; P = 0.004) were independent risk factors for overall survival. Fatigue (30.0%), constipation (19.6%) and appetite loss (17.8%) were the most common clinically relevant adverse events. The enzalutamide dose was not reduced in any patient under the age of 70, but adherence was decreased in those over 70. CONCLUSIONS: In the DELC study, the safety of enzalutamide was comparable to that in previous reports. Serum levels of neuron-specific enolase and interleukin-6 were suggested as prognostic factors for castration-resistant prostate cancer with potential clinical utility.

Which traits affect how long patients with advanced prostate cancer live when treated with enzalutamide?

WHAT IS THIS SUMMARY ABOUT?: This is a summary of a research article originally published in European Journal of Cancer. The PROSPER study involved men who had a type of advanced prostate cancer called nonmetastatic castration-resistant prostate cancer (nmCRPC). In men with nmCRPC, their cancer has progressed on traditional hormone therapy but scans show that it has not spread to other parts of the body. The main results of the PROSPER study showed that patients treated with enzalutamide lived longer than patients treated with placebo. For this analysis, researchers looked at whether this was different depending on patients' traits. WHAT WERE THE RESULTS?: Researchers found that age and location did not affect how long patients lived when treated with enzalutamide. They found three patient traits that did make a difference. Being able to carry out daily activities, low prostate-specific antigen level (PSA level), and receiving no other prostate cancer treatments after the study meant that patients were more likely to live longer. WHAT DO THE RESULTS OF THE STUDY MEAN?: Patients with nmCRPC treated with enzalutamide lived longer than patients treated with placebo. Age and location did not affect how long these patients lived, but other traits did. Clinical Trial Registration: NCT02003924 (ClinicalTrials.gov).

Lycopene enhances the sensitivity of castration-resistant prostate cancer to enzalutamide through the AKT/EZH2/ androgen receptor signaling pathway.

Enzalutamide is an effective drug for the treatment of castration-resistant prostate cancer (CRPC), but acquired enzalutamide resistance is usually unavoidable within the short term in many patients. Lycopene, a safe and effective phytochemical, has been documented to have anticancer activity in a variety of tumors, especially for prostate cancer (PCa). The aim of this study was to provide data support for the combination of lycopene and enzalutamide in the treatment of CRPC. To this end, tissues from patients with primary prostate cancer (PPC) and CRPC were examined by immunohistochemical analysis and found that p-AKT and p-EZH2 were overexpressed in CRPC. Furthermore, Kaplan-Meier survival analysis showed that the high expression of p-AKT and p-EZH2 may be related to the poor prognosis of patients. In addition, the expression of p-AKT, p-EZH2 and androgen receptor (AR) were significantly down-regulated in 22RV1 and C4-2B cells and the proliferation and invasion of CRPC cells were inhibited after treatment with lycopene, while SC79 (an AKT agonist) markedly rescue this effect. Of note, a combination of lycopene and enzalutamide significantly inhibited the proliferation and invasion of CRPC cells in vitro, as well as tumor growth and bone metastasis in vivo. These results suggest that the enhanced antitumor effects of enzalutamide by lycopene may be related to the reduction of AR protein levels through lycopene-mediated inhibition of AKT/EZH2 pathway, which may provide a new approach to improve the efficacy of enzalutamide in CRPC.

Atezolizumab with enzalutamide versus enzalutamide alone in metastatic castration-resistant prostate cancer: a randomized phase 3 trial.

Early clinical data indicate that some patients with castration-resistant prostate cancer may benefit from program death ligand-1 (PD-L1) inhibition, especially with enzalutamide. The IMbassador250 trial (no. NCT03016312) enrolled 759 men with metastatic castration-resistant prostate cancer whose disease progressed on abiraterone. The addition of atezolizumab to enzalutamide in an open-label randomized trial did not meet the primary endpoint of improved overall survival in unselected patients (stratified hazard ratio 1.12, 95% confidence interval (0.91, 1.37), P = 0.28), despite an acceptable safety profile. In archival tumor samples, prostate tumors showed comparatively low expression of key immune biomarkers. DNA damage-response alterations, phosphatase and tensin homolog status and PD-L1 expression levels were similar between hormone-sensitive and castration-resistant prostate cancers. In planned biomarker analysis, longer progression-free survival was seen with atezolizumab in patients with high PD-L1 IC2/3, CD8 expression and established immune gene signatures. Exploratory analysis linked progression-free survival in the atezolizumab arm with immune genes such as CXCL9 and TAP1, together with other potentially relevant biomarkers including phosphatase and tensin homolog alterations. Together these data indicate that the expected biology associated with response to immune checkpoint inhibitors is present in prostate cancer, albeit in fewer patients. Careful patient selection may be required for immune checkpoint inhibitors to identify subgroups of patients who may benefit from this treatment approach.

Medication adherence among patients with advanced prostate cancer using oral therapies.

Aims: In light of the extended overall survival and improved quality of life provided by advanced prostate cancer (PC) oral therapies, this study aimed to describe treatment adherence to advanced PC oral therapies and evaluate associated patient characteristics and subsequent healthcare resource utilization (HRU). Patients & methods: Patients with advanced PC initiating apalutamide, enzalutamide or abiraterone acetate were identified from administrative data (October 1, 2014-September 30, 2019). Adherence and persistence at six months postinitiation were used to evaluate patient factors and HRU. Results: Aged ≥75 years, Black race, chemotherapy use and higher pharmacy paid amounts were associated with poor adherence/persistence, which translated to higher HRU. Conclusions: Strategies to increase adherence and persistence may improve patient outcomes and associated HRU.

Lay abstract This study included 27,262 patients with advanced prostate cancer who started taking one of three oral cancer medications (apalutamide, enzalutamide or abiraterone acetate) between October 2014 and September 2019. Patients who were black, aged 75 years or older, who had chemotherapy or who had higher prescription costs had the most difficulty following dosing guidelines or staying on treatment. Patients who did not follow dosing guidelines required more healthcare services. In light of the extended survival and improved quality of life that oral cancer medication for advanced prostate cancer provides, helping patients to take the correct medication dose, at the right time, and for the recommended length of time may improve their outcomes and reduce medical costs.

Real-world outcomes of second novel hormonal therapy or radium-223 following first novel hormonal therapy for mCRPC.

Aim: To evaluate real-world clinical outcomes of radium-223 or alternative novel hormonal therapy (NHT) following first-line NHT for metastatic castration-resistant prostate cancer (mCRPC). Patients & methods: Retrospective analysis of the US Flatiron database (ClinicalTrials.gov identifier: NCT03896984). Results: In the radium-223 cohort (n = 120) versus the alternative NHT cohort (n = 226), proportionally more patients had prior symptomatic skeletal events and bone-only metastases, and first-line NHT duration was shorter. Following second-line therapy, 49 versus 39% of patients received subsequent life-prolonging therapy; of these, 47 versus 76% received taxane. Median overall survival was 10.8 versus 11.2 months. Conclusion: Real-world patients with mCRPC had similar median overall survival following second-line radium-223 or alternative NHT after first-line NHT. Many patients received subsequent therapy, with less taxane use after radium-223.

Lay abstract Patients with metastatic castration-resistant prostate cancer are often first treated with novel hormonal therapy (NHT) using abiraterone or enzalutamide. To aid decisions about what treatment to use next, we reviewed information about patients who were treated with an alternative NHT (226 patients) or the nuclear medicine radium-223 (120 patients) after the first NHT. Most patients given radium-223 had cancer that had spread to their bones only, whereas many patients given an alternative NHT had cancer in their bones and other parts of their body. Around one in four patients given radium-223 and one in five given an alternative NHT had symptoms related to their bone metastases after starting treatment. Five in every ten patients given radium-223 received further therapy, including chemotherapy in 50% of these patients, while four in every ten patients given an alternative NHT received further therapy, including chemotherapy in 75%. On average, patients lived for almost a year after starting radium-223 or an alternative NHT.

Phase II study of enzalutamide in androgen receptor positive, recurrent, high- and low-grade serous ovarian cancer.

OBJECTIVES: We sought to determine the safety and efficacy of the oral androgen receptor antagonist enzalutamide in patients with previously treated, recurrent, AR-positive (AR+) ovarian cancer. METHODS: This was a single-institution phase II study of patients with AR+ ovarian cancer with measurable disease with 1-3 prior lines of chemotherapy; patients were screened for enrollment from 11/2013-7/2018. Following consent, archival tissue was evaluated for AR+. Enrolled patients received daily enzalutamide 160 mg until progression of disease or treatment discontinuation. Adverse events were graded by CTCAE v4.0. Co-primary endpoints were 6-month progression-free survival (PFS6) and overall response rate (ORR) by RECIST 1.1 criteria. RESULTS: During the study period, 160 patients were screened and 59 (45 high-grade serous [HGS] and 14 low-grade serous [LGS]) consented to treatment on study. There was 1 confirmed and 1 unconfirmed partial response. The ORR was 1.7% (90% CI: 0.2-100%). The overall PFS6 rate (as binary) was 22% (90% CI: 15.1-100%). The 6-month PFS rate (as time to event) was 19.8% for HGS patients (90% CI: 12.7-100%) and 38.5% (90% CI: 21.7%-100%) for LGS patients. Grade 3 toxicities occurred in 6 patients (one toxicity (Grade 3 rash) was considered a dose-limiting toxicity). One patient died of cardiac arrest after 42 days on treatment of a cardiac arrest not attributed to study drug. CONCLUSIONS: The study met its primary endpoint, with a PFS6 rate of 22% (n = 13); however, the overall response rate was low. Enzalutamide was well tolerated and may be a potential treatment option in select patients.

Phase I clinical trial of HC-1119 soft capsule in Chinese healthy adult male subjects: Pharmacokinetics and safety of single-dose proportionality and effects of food.

BACKGROUND: Preclinical studies showed that HC-1119, a deuterated version of enzalutamide, could competitively inhibit androgen binding to androgen receptor by blocking the transmission of androgen receptor signaling pathway as enzalutamide, inducing apoptosis of prostate cancer cells and reducing the proliferation of prostate cancer cells. Animal pharmacokinetic studies also show that deuterization of enzalutamide as HC-1119 could retain the basic properties of mother drug, increases the stability of compounds to metabolic enzymes and the drug exposure in vivo, prolong the half-life and reduce the production of metabolites, which may lead to a better efficacy and safety of HC-1119 compared with enzalutamide. METHODS: To evaluate the pharmacokinetics and safety of HC-1119 and the effects of food on pharmacokinetics in healthy adult Chinese men after single-dose administration of HC-1119. A total of 47 Chinese healthy adult male subjects received HC-1119 soft capsule at a single oral dose of 40, 80, or 160 mg followed on fasting or 160 mg after high-fat meal respectively. HC-1119 prototype and its metabolites M1 and M2 in plasma were collected individually in a total 23 time points. Pharmacokinetics were determined by sensitive LC/MS/MS for dose-proportionality study. RESULTS: In subjects taking HC-1119 soft capsules on fasting, Cmax of HC-1119 prototype increased dose-dependently. Either Cmax and AUC0-∞ of M1 or Cmax of M2 showed statistically significant difference. Dose-proportionality evaluation showed linear pharmacokinetic characteristics in Cmax of HC-1119 prototype, Cmax and AUC0-∞ of M2 in dose range of 40-160 mg. Cmax of HC-1119 was significantly different between the two groups as 160 mg HC-1119 on fasting or after a high-fat diet respectively, while the other parameter were not. HC-1119 and its metabolites M1 and M2 showed a linear dynamic trend. CONCLUSIONS: HC-1119 is expected to have lower clinical dose than the similar drug enzalutamide. The absorption of HC-1119 and the main pharmacokinetic parameters of HC-1119 and its metabolites M1 and M2 were not affected by high-fat diet. The clinical application of HC-1119 soft capsule in the later stage can be recommended for both fasting and postprandial. The safety and tolerance were good in this population.

Abiraterone acetate and prednisolone with or without enzalutamide for high-risk non-metastatic prostate cancer: a meta-analysis of primary results from two randomised controlled phase 3 trials of the STAMPEDE platform protocol.

BACKGROUND: Men with high-risk non-metastatic prostate cancer are treated with androgen-deprivation therapy (ADT) for 3 years, often combined with radiotherapy. We analysed new data from two randomised controlled phase 3 trials done in a multiarm, multistage platform protocol to assess the efficacy of adding abiraterone and prednisolone alone or with enzalutamide to ADT in this patient population. METHODS: These open-label, phase 3 trials were done at 113 sites in the UK and Switzerland. Eligible patients (no age restrictions) had high-risk (defined as node positive or, if node negative, having at least two of the following: tumour stage T3 or T4, Gleason sum score of 8-10, and prostate-specific antigen [PSA] concentration ≥40 ng/mL) or relapsing with high-risk features (≤12 months of total ADT with an interval of ≥12 months without treatment and PSA concentration ≥4 ng/mL with a doubling time of <6 months, or a PSA concentration ≥20 ng/mL, or nodal relapse) non-metastatic prostate cancer, and a WHO performance status of 0-2. Local radiotherapy (as per local guidelines, 74 Gy in 37 fractions to the prostate and seminal vesicles or the equivalent using hypofractionated schedules) was mandated for node negative and encouraged for node positive disease. In both trials, patients were randomly assigned (1:1), by use of a computerised algorithm, to ADT alone (control group), which could include surgery and luteinising-hormone-releasing hormone agonists and antagonists, or with oral abiraterone acetate (1000 mg daily) and oral prednisolone (5 mg daily; combination-therapy group). In the second trial with no overlapping controls, the combination-therapy group also received enzalutamide (160 mg daily orally). ADT was given for 3 years and combination therapy for 2 years, except if local radiotherapy was omitted when treatment could be delivered until progression. In this primary analysis, we used meta-analysis methods to pool events from both trials. The primary endpoint of this meta-analysis was metastasis-free survival. Secondary endpoints were overall survival, prostate cancer-specific survival, biochemical failure-free survival, progression-free survival, and toxicity and adverse events. For 90% power and a one-sided type 1 error rate set to 1·25% to detect a target hazard ratio for improvement in metastasis-free survival of 0·75, approximately 315 metastasis-free survival events in the control groups was required. Efficacy was assessed in the intention-to-treat population and safety according to the treatment started within randomised allocation. STAMPEDE is registered with ClinicalTrials.gov, NCT00268476, and with the ISRCTN registry, ISRCTN78818544. FINDINGS: Between Nov 15, 2011, and March 31, 2016, 1974 patients were randomly assigned to treatment. The first trial allocated 455 to the control group and 459 to combination therapy, and the second trial, which included enzalutamide, allocated 533 to the control group and 527 to combination therapy. Median age across all groups was 68 years (IQR 63-73) and median PSA 34 ng/ml (14·7-47); 774 (39%) of 1974 patients were node positive, and 1684 (85%) were planned to receive radiotherapy. With median follow-up of 72 months (60-84), there were 180 metastasis-free survival events in the combination-therapy groups and 306 in the control groups. Metastasis-free survival was significantly longer in the combination-therapy groups (median not reached, IQR not evaluable [NE]-NE) than in the control groups (not reached, 97-NE; hazard ratio [HR] 0·53, 95% CI 0·44-0·64, p<0·0001). 6-year metastasis-free survival was 82% (95% CI 79-85) in the combination-therapy group and 69% (66-72) in the control group. There was no evidence of a difference in metatasis-free survival when enzalutamide and abiraterone acetate were administered concurrently compared with abiraterone acetate alone (interaction HR 1·02, 0·70-1·50, p=0·91) and no evidence of between-trial heterogeneity (I2 p=0·90). Overall survival (median not reached [IQR NE-NE] in the combination-therapy groups vs not reached [103-NE] in the control groups; HR 0·60, 95% CI 0·48-0·73, p<0·0001), prostate cancer-specific survival (not reached [NE-NE] vs not reached [NE-NE]; 0·49, 0·37-0·65, p<0·0001), biochemical failure-free-survival (not reached [NE-NE] vs 86 months [83-NE]; 0·39, 0·33-0·47, p<0·0001), and progression-free-survival (not reached [NE-NE] vs not reached [103-NE]; 0·44, 0·36-0·54, p<0·0001) were also significantly longer in the combination-therapy groups than in the control groups. Adverse events grade 3 or higher during the first 24 months were, respectively, reported in 169 (37%) of 451 patients and 130 (29%) of 455 patients in the combination-therapy and control groups of the abiraterone trial, respectively, and 298 (58%) of 513 patients and 172 (32%) of 533 patients of the combination-therapy and control groups of the abiraterone and enzalutamide trial, respectively. The two most common events more frequent in the combination-therapy groups were hypertension (abiraterone trial: 23 (5%) in the combination-therapy group and six (1%) in control group; abiraterone and enzalutamide trial: 73 (14%) and eight (2%), respectively) and alanine transaminitis (abiraterone trial: 25 (6%) in the combination-therapy group and one (<1%) in control group; abiraterone and enzalutamide trial: 69 (13%) and four (1%), respectively). Seven grade 5 adverse events were reported: none in the control groups, three in the abiraterone acetate and prednisolone group (one event each of rectal adenocarcinoma, pulmonary haemorrhage, and a respiratory disorder), and four in the abiraterone acetate and prednisolone with enzalutamide group (two events each of septic shock and sudden death). INTERPRETATION: Among men with high-risk non-metastatic prostate cancer, combination therapy is associated with significantly higher rates of metastasis-free survival compared with ADT alone. Abiraterone acetate with prednisolone should be considered a new standard treatment for this population. FUNDING: Cancer Research UK, UK Medical Research Council, Swiss Group for Clinical Cancer Research, Janssen, and Astellas.

Consistent survival benefit of enzalutamide plus androgen deprivation therapy in men with nonmetastatic castration-resistant prostate cancer: PROSPER subgroup analysis by age and region.

BACKGROUND: Enzalutamide combined with androgen deprivation therapy (ADT) significantly prolonged metastasis-free survival and overall survival (OS) versus ADT alone in patients with non-metastatic castration-resistant prostate cancer (nmCRPC) with rapidly rising prostate-specific antigen (PSA). The objective of this post hoc analysis of the PROSPER trial is to evaluate OS benefit and safety of enzalutamide in patients across age and regional subgroups. PATIENTS AND METHODS: Eligible men with nmCRPC, PSA doubling time ≤10 months and PSA ≥2 ng/mL with continued ADT use were randomised 2:1 to enzalutamide 160 mg or placebo. OS and safety were examined by age (<70 vs ≥70 years) and region (North America, Europe, Asia or the rest of the world). The impact of prior and subsequent therapy was also examined. RESULTS: In total, 1401 men were enrolled (median age, 74 years). Enzalutamide plus ADT reduced the risk of death, independent of age or region. Multivariate analyses identified Eastern Cooperative Oncology Group (ECOG) status (P < 0.0001), log (PSA; P = 0.0002) and subsequent therapy (P < 0.0001) as statistically significant factors impacting OS. Safety was consistent across age and regional subgroups. Any grade treatment-emergent adverse events were similar across age groups, were more common in the placebo group and had regional variation. CONCLUSIONS: In men with nmCRPC and rapidly rising PSA, the benefit and safety of enzalutamide were consistent across age and regional subgroups. Variables impacting OS included ECOG status, log (PSA) and subsequent therapy. CLINICALTRIALS. GOV IDENTIFIER: NCT02003924.

Initial dose reduction of enzalutamide does not decrease the incidence of adverse events in castration-resistant prostate cancer.

BACKGROUND: There was no clear evidence whether the initial dose of enzalutamide affects the incidence of adverse events (AEs), and oncological outcome in patients with castration-resistant prostate cancer (CRPC). METHODS: The clinical charts of 233 patients with CRPC treated with enzalutamide were reviewed retrospectively. After 1:3 propensity score matching (PSM), 124 patients were divided into a reduced dose group and a standard dose group, and the prostate specific antigen (PSA) response and the incidence of AEs were compared. RESULTS: 190 patients with CRPC initiated with standard dose enzalutamide were younger and better performance status compared with 43 patients beginning with reduced dose. After PSM, the baseline characteristics were not different between the standard and the reduced dose group. In the PSM cohort, the PSA response rate was significantly lower in the reduced dose group than in the standard dose group (-66.3% and -87.4%, p = 0.02). The incidence rates of AEs were not statistically different between the groups (22.6% and 34.4%, respectively, p = 0.24). CONCLUSION: Initiating treatment with a reduced dose of enzalutamide did not significantly decrease the incidence rate of AEs, and it showed poorer PSA response rate. There is no clear rationale for treating with a reduced initial dose of enzalutamide to reduce the incidence of AEs.

Comparison of real-life data of abiraterone acetate and enzalutamide in metastatic castration-resistant prostate cancer.

To compare enzalutamide (E) and abiraterone acetate (AA) in terms of efficacy, survival and to characterize prognostic factors affecting survival in metastatic castration-resistant prostate cancer (mCRPC) patients. A total of 250 patients treated with E or AA in 5 centers were included. The number of patients with no prostate specific antigen (PSA) decline was higher in the AA group than that in the E group, and the proportion of patients with a PSA decline of ≥ 50% was higher in the E group (p = 0.020). Radiological progression free survival (rPFS) and overall survival (OS) were significantly longer in the E group when compared to that in the AA group (p < 0.001 and p = 0.027, respectively). In the E group, rPFS was significantly longer than that in the AA group in both pre- and post-docetaxel settings (p = 0.010 and p = 0.003, respectively). OS was similar in the pre-docetaxel setting; but in the post-docetaxel setting, E group had a significantly longer OS than the AA group (p = 0.021). In the multivariate analysis performed in the whole patient group, we found that good prognostic factors for rPFS were E treatment, being ≥ 75 years and a PSA decline of ≥ 50% while there was no factor affecting OS. With longer OS and PFS, E seems to be more suitable for mCRPC patients in the post-docetaxel setting than AA.

Association of Chemotherapy, Enzalutamide, Abiraterone, and Radium 223 With Cognitive Function in Older Men With Metastatic Castration-Resistant Prostate Cancer.

Importance: Older adults are at greater risk of cognitive decline with various oncologic therapies. Some commonly used therapies for advanced prostate cancer, such as enzalutamide, have been linked to cognitive impairment, but published data are scarce, come from single-group studies, or focus on self-reported cognition. Objective: To longitudinally examine the association between cognitive function and docetaxel (chemotherapy), abiraterone, enzalutamide, and radium Ra 223 dichloride (radium 223) in older men with metastatic castration-resistant prostate cancer. Design, Setting, and Participants: A multicenter, prospective, observational cohort study was conducted across 4 academic cancer centers in Ontario, Canada. A consecutive sample of 155 men age 65 years or older with metastatic castration-resistant prostate cancer starting any treatment with docetaxel, abiraterone acetate, enzalutamide, or radium Ra 223 dichloride (radium 223) were enrolled between July 1, 2015, and December 31, 2019. Exposures: First-line chemotherapy (docetaxel), abiraterone, enzalutamide, or radium 223. Main Outcomes and Measures: Cognitive function was measured at baseline and end of treatment using the Montreal Cognitive Assessment, the Trail Making Test part A, and the Trail Making Test part B to assess global cognition, attention, and executive function, respectively. Absolute changes in scores over time were analyzed using univariate and multivariable linear regression, and the percentages of individuals with a decline of 1.5 SDs in each domain were calculated. Results: A total of 155 men starting treatment with docetaxel (n = 51) (mean [SD] age, 73.5 [6.2] years; 34 [66.7%] with some postsecondary education), abiraterone (n = 29) (mean [SD] age, 76.2 [7.2] years; 18 [62.1%] with some postsecondary education), enzalutamide (n = 54) (mean [SD] age, 75.7 [7.4] years; 33 [61.1%] with some postsecondary education), and radium 223 (n = 21) (mean [SD] age, 76.4 [7.2] years; 17 [81.0%] with some postsecondary education) were included. Most patients had stable cognition or slight improvements during treatment. A cognitive decline of 1.5 SDs or more was observed in 0% to 6.5% of patients on each measure of cognitive function (eg, 3 of 46 patients [6.5%; 95% CI, 2.2%-17.5%] in the group receiving chemotherapy [docetaxel] had a decline of 1.5 SDs for Trails A and Trails B). Although patients taking enzalutamide had numerically larger declines than those taking abiraterone, differences were small and clinically unimportant. Conclusions and Relevance: These findings suggest that most older men do not experience significant cognitive decline in attention, executive function, and global cognition while undergoing treatment for advanced prostate cancer regardless of the treatment used.

A real-world evaluation of radium-223 in combination with abiraterone or enzalutamide for the treatment of metastatic castration-resistant prostate cancer.

INTRODUCTION: Radium-223, abiraterone, and enzalutamide have each been shown to significantly improve survival as monotherapy in patients with metastatic castration-resistant prostate cancer. However, effects of combination radium-223 plus abiraterone or enzalutamide on survival and safety remain unclear. PATIENTS AND METHODS: This single-center retrospective cohort study used electronic health record data of patients with metastatic castration-resistant prostate cancer and bone metastases who were treated with radium-223 between April 1, 2014 and February 19, 2019. Patients who received radium-223 monotherapy were compared to patients who received a combination of radium-223 plus either abiraterone or enzalutamide. The primary endpoint was overall survival. Secondary endpoints included progression-free survival, time to symptomatic skeletal event, symptomatic skeletal event-free survival, and incidence of drug-related adverse events. Time-to-event analyses were estimated by log rank tests using Kaplan-Meier curves. Hazard ratios and 95% confidence intervals were derived from Cox proportional hazards models. Chi-square tests evaluated difference in serious adverse events between the two arms. RESULTS: A total of 60 patients met inclusion criteria (n = 41 in the monotherapy arm, n = 19 in the combination arm). Differences in median overall survival were not observed (12.7 vs. 12.8 months; HR 1.15, 95% CI 0.59-2.23; P = 0.68), but median progression-free survival was significantly longer in the combination arm (7.6 vs. 4.9 months; HR 1.94, 95% CI 1.11-3.40; P = 0.02). Significant differences were not observed in time to first SSE (P = 0.97), SSE-free survival (P = 0.16), or in the overall incidence of serious adverse events (P = 0.45). CONCLUSION: Combination radium-223 plus abiraterone or enzalutamide did not improve overall survival, but prolonged progression-free survival without increasing the incidence of serious adverse events in metastatic castration-resistant prostate cancer patients with bone metastases. However, these results are limited by small numbers and patient selection inherent in retrospective analysis.

Effectiveness of first-line abiraterone versus enzalutamide among patients ≥80 years of age with metastatic castration-resistant prostate cancer: A retrospective propensity score-weighted comparative cohort study.

BACKGROUND: Metastatic castration-resistant prostate cancer (mCRPC) disproportionately affects the elderly. There is limited data assessing the efficacy and tolerability of abiraterone acetate (AA) versus enzalutamide in this population. OBJECTIVE: To compare the clinical efficacy and tolerability of AA versus enzalutamide in patients ≥ 80 years with mCRPC. DESIGN, SETTING AND PARTICIPANTS: A retrospective propensity-weighted comparative cohort study of first-line AA versus enzalutamide among patients with mCRPC aged ≥80 years. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Inverse probability treatment weights based on propensity scores were generated to assess the treatment effect of AA versus enzalutamide on time to PSA progression (TTPP), time to progression (TTP) (first of PSA/radiographic/clinical progression) and overall survival using a weighted Cox proportional hazards model. PSA response rate (PSA RR) was compared between groups using Χ2. RESULTS AND LIMITATIONS: One hundred fifty-three patients received AA, and 125 received enzalutamide. Enzalutamide was associated with higher PSA RR (61.6% vs 43.8%, P < 0.004), and TTP (hazard ratio [HR] 0.66, 95% confidence interval [CI] 0.50-0.88, P = 0.01) but not TTPP (HR 0.73, 95% CI 0.53-1.01, P = 0.06). There were significantly more dose reductions with enzalutamide (22.9% vs 44.8%, P > 0.001) but there was no interaction between median proportion of full dose received and TTPP or TTP for either drug. Rates of treatment discontinuation (for reasons other than progression) were also significantly different between AA and enzalutamide (28.8% vs 40.8%, respectively, P = 0.04). The most common reason for dose reductions and discontinuation of enzalutamide was fatigue (30.4% and 5.6%, respectively). CONCLUSIONS: Despite more dose reductions and a higher treatment discontinuation rate, enzalutamide was associated with a higher PSA RR and longer time to progression, than AA. Given that clinical outcomes were not adversely impacted by decreased treatment exposure, dose modification may be a useful treatment strategy to balance toxicity and tolerance.

A drug safety evaluation of enzalutamide to treat advanced prostate cancer.

INTRODUCTION: Prostate cancer (PC) is the most common cancer in North American men. Advanced PC is incurable. The androgen receptor antagonist enzalutamide is used to manage advanced PC, often over a period of months or years; it is therefore important to evaluate the safety profile of enzalutamide. AREAS COVERED: This literature review presents safety data from pivotal trials and real-world data studies of enzalutamide in patients with advanced PC, including metastatic hormone-sensitive prostate cancer (mHSPC), nonmetastatic castration-resistant prostate cancer (nmCRPC), and metastatic castration-resistant prostate cancer (mCRPC). A large body of evidence supports the maintenance or improvement in the health-related quality of life (HRQoL) afforded by enzalutamide treatment in patients with mHSPC, nmCRPC, or chemotherapy-naïve mCRPC, as well as improvement in the HRQoL in patients with later-stage symptomatic mCRPC. Efficacy data from clinical trials are also briefly discussed. EXPERT OPINION: We aim to provide clinicians with a better understanding of how to properly interpret enzalutamide clinical trial safety data. This knowledge may help clinicians guide their patients with PC to achieve optimal clinical benefit from enzalutamide therapy, and to properly manage their patients to mitigate any potential risk.

KEYNOTE-641: a Phase III study of pembrolizumab plus enzalutamide for metastatic castration-resistant prostate cancer.

Current treatment options for men with metastatic castration-resistant prostate cancer (mCRPC) are noncurative, and median survival upon development of mCRPC is approximately 3 years. The novel hormonal agent enzalutamide has an established role in the mCRPC treatment paradigm, and emerging evidence suggests potential synergism with enzalutamide and the PD-1 inhibitor pembrolizumab in men with mCRPC. Here, we describe the design and rationale for the multicenter, randomized, double-blind, Phase III KEYNOTE-641 study, which will be conducted to compare the efficacy and safety of pembrolizumab plus enzalutamide with that of enzalutamide plus placebo in mCRPC. Clinical trial registration: NCT03834493 (ClinicalTrials.gov).