A net-work meta-analysis of the cardiac safety for next-generation hormonal agents in treating castration-resistant prostate cancer: How to choose drugs appropriately?

BACKGROUND

Researchers have shown that using next-generation hormonal agents (NHA) for castration-resistant prostate cancer (CRPC) would lead to increased risk of cardiac adverse effects, making clinician choices more complex.

METHODS

We systematically searched Pubmed, Cochrane Library, and Embase databases for research published before October 2022. Agents were ranked according to their effectiveness based on cardiac adverse effects using the surface under the cumulative ranking curve.

RESULTS

A total of 21 Randomized Controlled Trials (RCT) with 19, 083 patients were included in present study. Our results showed that abiraterone and enzalutamide could lead to a significantly higher hypertension rate compared with placebo; whereas no significant difference was detected between four NHAs and placebo in ischemic heart disease incidence. All four NHAs could significantly increase the risk of cardiotoxicity.

CONCLUSIONS

NHAs are generally acceptable in terms of cardiovascular disease compared to placebo in patients with CRPC.

Oncological Outcomes in Men with Metastatic Castration-Resistant Prostate Cancer Treated with Enzalutamide with versus without Confirmatory Bone Scan

PURPOSE

In men with metastatic castration-resistant prostate cancer (mCRPC), new bone lesions are sometimes not properly categorized through a confirmatory bone scan, and clinical significance of the test itself remains unclear. This study aimed to demonstrate the performance rate of confirmatory bone scans in a real-world setting and their prognostic impact in enzalutamide-treated mCRPC.

MATERIALS AND METHODS

Patients who received oral enzalutamide for mCRPC during 2014-2017 at 14 tertiary centers in Korea were included. Patients lacking imaging assessment data or insufficient drug exposure were excluded. The primary outcome was overall survival (OS). Secondary outcomes included performance rate of confirmatory bone scans in a real-world setting. Kaplan-Meier analysis and multivariate Cox regression analysis were performed.

RESULTS

Overall, 520 patients with mCRPC were enrolled (240 [26.2%] chemotherapy-naïve and 280 [53.2%] after chemotherapy). Among 352 responders, 92 patients (26.1%) showed new bone lesions in their early bone scan. Confirmatory bone scan was performed in 41 patients (44.6%), and it was associated with prolonged OS in the entire population (median, 30.9 vs. 19.7 months; p < 0.001), as well as in the chemotherapy-naïve (median, 47.2 vs. 20.5 months; p=0.011) and post-chemotherapy sub-groups (median, 25.5 vs. 18.0 months; p=0.006). Multivariate Cox regression showed that confirmatory bone scan performance was an independent prognostic factor for OS (hazard ratio 0.35, 95% confidence interval, 0.18 to 0.69; p=0.002).

CONCLUSION

Confirmatory bone scan performance was associated with prolonged OS. Thus, the premature discontinuation of enzalutamide without confirmatory bone scans should be discouraged.

Enzalutamide and Quality of Life in Biochemically Recurrent Prostate Cancer

Enzalutamide and Quality of Life in Prostate CancerFreedland et al. present the health-related quality of life outcomes for patients with biochemically recurrent prostate cancer who were randomly assigned to enzalutamide plus leuprolide, enzalutamide monotherapy, or leuprolide alone (EMBARK trial). The key objectives were to determine differences in time to first and confirmed clinically meaningful deterioration in pain and time to first and confirmed clinically meaningful deterioration in functional status. There were no differences among the key outcomes among all three groups.

Phase II Study of Enzalutamide for Patients With Androgen Receptor-Positive Salivary Gland Cancers (Alliance A091404)

PURPOSE

The androgen receptor (AR) is expressed (+) in a subset of salivary gland cancers (SGCs). This phase II trial evaluated the efficacy of the antiandrogen enzalutamide in AR+ SGC.

METHODS

Patients with locally advanced/unresectable or metastatic AR+ SGCs were enrolled. Enzalutamide (160 mg) was given orally once daily. The primary end point was the best overall response rate per RECIST v1.1 within eight cycles. Confirmed responses in ≥ 5 of 41 patients would be considered promising. Secondary end points were progression-free survival, overall survival, and safety.

RESULTS

Forty-six patients were enrolled; 30 (65.2%) received prior systemic therapy, including 13 (28.3%) with AR-targeted drugs. Of seven (15.2%) partial responses (PRs), only two (4.3%) were confirmed per protocol and counted toward the primary end point. Twenty-four patients (52.2%) had stable disease; 15 (32.6%) had progression of disease as best response. Twenty-six patients (56.5%) experienced tumor regression in target lesions; 18 (39.1%) had partial response/stable disease ≥ 6 months. Tumor regressions were observed in female patients (5 of 6 [83.3%]) and those who received prior AR- (6 of 13 [46.2%]) or human epidermal growth factor receptor 2-targeted therapies (5 of 8 [62.5%]). Three patients remained on treatment at data cutoff (duration, 32.2-49.8 months). The median progression-free survival was 5.6 months (95% CI, 3.7 to 7.5); the median overall survival was 17.0 months (95% CI, 11.8 to 30.0). The most common adverse events were fatigue, hypertension, hot flashes, and weight loss. Total and free testosterone levels increased by a mean of 61.2% and 48.8%, respectively, after enzalutamide.

CONCLUSION

Enzalutamide demonstrated limited activity in AR+ SGC, failing to meet protocol-defined success in part because of a lack of response durability. Strategies to enhance the efficacy of antiandrogen therapy are needed.

Adjuvant enzalutamide for the treatment of early-stage androgen-receptor positive, triple-negative breast cancer: a feasibility study

PURPOSE

Chemotherapy with or without immunotherapy remains the mainstay of treatment for triple-negative breast cancer (TNBC). A subset of TNBCs express the androgen receptor (AR), representing a potential new therapeutic target. This study assessed the feasibility of adjuvant enzalutamide, an AR antagonist, in early-stage, AR-positive (AR +) TNBC.

METHODS

This study was a single-arm, open-label, multicenter trial in which patients with stage I-III, AR ≥ 1% TNBC who had completed standard-of-care therapy were treated with enzalutamide 160 mg/day orally for 1 year. The primary objective of this study was to evaluate the feasibility of 1 year of adjuvant enzalutamide, defined as the treatment discontinuation rate of enzalutamide due to toxicity, withdrawal of consent, or other events related to tolerability. Secondary endpoints included disease-free survival (DFS), overall survival (OS), safety, and genomic features of recurrent tumors.

RESULTS

Fifty patients were enrolled in this study. Thirty-five patients completed 1 year of therapy, thereby meeting the prespecified trial endpoint for feasibility. Thirty-two patients elected to continue with an optional second year of treatment. Grade ≥ 3 treatment-related adverse events were uncommon. The 1-year, 2-year, and 3-year DFS were 94%, 92% , and 80%, respectively. Median OS has not been reached.

CONCLUSION

This clinical trial demonstrates that adjuvant enzalutamide is a feasible and well-tolerated regimen in patients with an early-stage AR + TNBC. Randomized trials in the metastatic setting may inform patient selection through biomarker development; longer follow-up is needed to determine the effect of anti-androgens on DFS and OS in this patient population.

Phase Ib/II Study of Enzalutamide with Samotolisib (LY3023414) or Placebo in Patients with Metastatic Castration-Resistant Prostate Cancer

PURPOSE

To report efficacy and safety of samotolisib (LY3023414; PI3K/mTOR dual kinase and DNA-dependent protein kinase inhibitor) plus enzalutamide in patients with metastatic castration-resistant prostate cancer (mCRPC) following cancer progression on abiraterone.

PATIENTS AND METHODS

In this double-blind, placebo-controlled phase Ib/II study (NCT02407054), following a lead-in segment for evaluating safety and pharmacokinetics of samotolisib and enzalutamide combination, patients with advanced castration-resistant prostate cancer with progression on prior abiraterone were randomized to receive enzalutamide (160 mg daily)/samotolisib (200 mg twice daily) or placebo. Primary endpoint was progression-free survival (PFS) assessed by Prostate Cancer Clinical Trials Working Group criteria (PCWG2). Secondary and exploratory endpoints included radiographic PFS (rPFS) and biomarkers, respectively. Log-rank tests assessed treatment group differences.

RESULTS

Overall, 13 and 129 patients were enrolled in phase Ib and II, respectively. Dose-limiting toxicity was not reported in patients during phase Ib and mean samotolisib exposures remained in the targeted range despite a 35% decrease when administered with enzalutamide. In phase II, median PCWG2-PFS and rPFS was significantly longer in the samotolisib/enzalutamide versus placebo/enzalutamide arm (3.8 vs. 2.8 months; P = 0.003 and 10.2 vs. 5.5 months; P = 0.03), respectively. Patients without androgen receptor splice variant 7 showed a significant and clinically meaningful rPFS benefit in the samotolisib/enzalutamide versus placebo/enzalutamide arm (13.2 months vs. 5.3 months; P = 0.03).

CONCLUSIONS

Samotolisib/enzalutamide has tolerable side effects and significantly improved PFS in patients with mCRPC with cancer progression on abiraterone, and this may be enriched in patients with PTEN intact and no androgen receptor splice variant 7.

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, C_max of HC-1119 prototype increased dose-dependently. Either C_max and AUC_0-∞ of M1 or C_max of M2 showed statistically significant difference. Dose-proportionality evaluation showed linear pharmacokinetic characteristics in C_max of HC-1119 prototype, C_max and AUC_0-∞ of M2 in dose range of 40-160 mg. C_max 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.

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 effectiveness and safety outcomes of abiraterone versus enzalutamide in patients with metastatic castration-resistant prostate cancer: a systematic review and meta-analysis

PURPOSE

To compare the effectiveness and safety between abiraterone and enzalutamide in the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC).

METHODS

We systematically searched for relevant articles from PubMed, Cochrane, Embase from their inception through November 4, 2019. Available articles from conferences were searched. The endpoints were prostate-specific antigen (PSA) response, overall survival (OS), progression-free survival (PFS), number of patients with any adverse event (AE).

RESULTS

15 cohort studies involving 3546 participants were included in this meta-analysis. Pooled result showed that PSA response rate in the enzalutamide group was significantly greater than that in the abiraterone group (867 patients, risk ratio (RR) 0.69, 95% confidence interval (CI) 0.61-0.79, p＜0.00001, I2=29%). There was no significant difference in the total incidence of AEs between two groups (730 patients, RR 0.42, 95% CI 0.14-1.31, p = 0.14, I2=84%). The common adverse events observed in the published articles were fatigue and perceived cognitive impairments. Patients who received enzalutamide had the higher risk to have the feeling of fatigue compared with abiraterone group (2555 patients, RR 0.45, 95% CI 0.24-0.85, p=0.01, I2=92%). And there was no statistical difference between two groups respect to the side effect of perceived cognitive impairments (1856 patients, RR 0.94, 95% CI 0.47-1.88, p=0.85, I2=15%).

CONCLUSIONS

Our results demonstrated that enzalutamide was associated with higher PSA response rate compared to abiraterone in patients with mCRPC, and no significant difference was found between two groups in the overall AE. But enzalutamide use induced higher risk of the AE of fatigue.

Enzalutamide With Radiation Therapy for Intermediate-Risk Prostate Cancer: A Phase 2 Study

PURPOSE

Androgen deprivation therapy (ADT) is often used as adjuvant treatment with radiation therapy (RT) for intermediate-risk prostate cancer. ADT is associated with multiple side effects, including weight gain, loss of libido, and hot flashes. In contrast, antiandrogen monotherapy has been generally better tolerated. This study aimed to assess the effectiveness of enzalutamide (an antiandrogen) monotherapy with RT for the treatment of intermediate-risk prostate cancer.

METHODS AND MATERIALS

This trial was an open-label, phase 2 study of 6 months of enzalutamide monotherapy with external beam RT for intermediate-risk prostate cancer. Enzalutamide was initiated 2 months before external beam RT. The primary endpoint was prostate-specific antigen (PSA) response measured at the end of enzalutamide administration at the 6-month timepoint. Secondary endpoints included assessment of toxicity and changes in anthropomorphic body measurement, sexual function, and metabolism. The sample size was 64 patients. The hypothesis was that if ≥60% of the patients did not achieve a PSA nadir of ≤0.2 ng/mL, the study results would be deemed negative.

RESULTS

The results met the prespecified endpoint for efficacy in that PSA values ≤0.2 ng/mL were observed in 49 of 64 patients (77%), and 60 of 64 patients (94%) had PSA values ≤0.5ng/mL. The most frequent adverse events were hypertension and gynecomastia. There were no changes in anthropomorphic body measurements and only modest erectile dysfunction.

CONCLUSIONS

Using PSA response as an endpoint, enzalutamide monotherapy may be as effective as ADT in combination with external beam RT for patients with intermediate-risk prostate cancer, and it is associated with fewer side effects. Randomized trials comparing enzalutamide with ADT are justified.

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.

Clinical and immunologic impact of short-course enzalutamide alone and with immunotherapy in non-metastatic castration sensitive prostate cancer

BACKGROUND

The standard treatment for non-metastatic castration sensitive prostate cancer (nmCSPC) is androgen deprivation therapy (ADT) or surveillance. This study evaluated the potential synergy of immunotherapy and enzalutamide (without ADT) in nmCSPC. In addition, the immunologic impact of enzalutamide was also evaluated in men with normal testosterone.

METHODS

Patients with rising prostate-specific antigen (PSA) after definitive therapy, normal testosterone and no radiographic metastasis were randomized to enzalutamide for 3 months with/without PROSTVAC for 6 months. Thereafter, patients could be retreated with another 3 month course of enzalutamide when PSA returned to baseline. Immune profiles were evaluated in these patients.

RESULTS

Thirty-eight patients were randomized with a median PSA=4.38 ng/dL and PSA doubling time=4.1 months. No difference was observed between the two groups for PSA growth kinetics, but PSA responses to enzalutamide were noteworthy regardless of PROSTVAC. The median PSA decline after short-course enzalutamide without ADT/testosterone lowering therapy was 99% in both courses. The median time to PSA recovery to baseline after each 84-day course of enzalutamide was also noteworthy because of the duration of response after enzalutamide was discontinued. After the first and second 3 month cycle of enzalutamide, PSA recovery to baseline took a median 224 (range 84-1246) and 189 days (78-400), respectively. The most common adverse events related to the enzalutamide were grade 1 fatigue (71%) and grade 1 breast pain/nipple tenderness (81%). The only grade 3 toxicity was aspartate aminotransferase (AST)/alanine aminotransferase (ALT) elevation in two patients. Enzalutamide was independently associated with immune changes, increasing natural killer cells, naïve-T cells, and decreasing myeloid-derived suppressor cells.

CONCLUSIONS

Three months of enzalutamide without ADT induced substantial PSA control beyond the treatment period and was repeatable, perhaps representing an alternative to intermittent ADT in nmCSPC. In addition, enzalutamide was associated with immune changes that could be relevant as future immune combinations are developed. TRAIL REGISTRATION NUMBER: clinicaltrials.gov (NCT01875250).

Risk of major adverse cardiovascular events among second-line hormonal therapy for metastatic castration-resistant prostate cancer: A real-world evidence study

BACKGROUND

To evaluate the possible major adverse cardiovascular events (MACE) associated with second-line hormonal therapy in patients with metastatic castration-resistant prostate cancer (mCRPC).

METHODS

We performed a population-based real-world cohort study of 4962 prostate cancer patients between 2014 and 2017 utilizing the Chang Gung Research Database of Taiwan. The second-line hormonal therapies included enzalutamide and abiraterone acetate. The outcomes of interest were MACE, including acute coronary syndrome (ACS), ischemic stroke (IS), and heart failure (HF) events that resulted in hospitalization. Cox proportional-hazards models with inverse probability of treatment weighting (IPTW) with propensity scores were used.

RESULTS

After IPTW, 288 patients were prescribed second-line hormonal therapy and 1575 received first-line androgen-deprivation therapy (ADT). Of all patients diagnosed with MACE, the event rates were 2.92% in the second-line hormonal group and 2.22% in the first-line ADT group. The mean follow-up period was 9.52 months for the second-line hormonal group. Patients who received second-line hormonal therapy exhibited a significantly increased risk for MACE (hazard ratio [HR]: 3.15; 95% confidence interval [CI]: 2.03-4.89), ACS (HR: 4.94; 95% CI: 2.36-10.33), and HF (HR: 2.83; 95% CI: 1.53-5.25), compared with the first-line ADT group, but a similar risk for IS was observed in both groups (HR: 1.70; 95% CI: 0.95-3.04).

CONCLUSIONS

The real-world evidence study revealed increased risks for MACE in mCRPC patients receiving second-line hormonal therapy.

A Phase Ib/IIa Study of the Pan-BET Inhibitor ZEN-3694 in Combination with Enzalutamide in Patients with Metastatic Castration-resistant Prostate Cancer

PURPOSE

ZEN-3694 is a bromodomain extraterminal inhibitor (BETi) with activity in androgen-signaling inhibitor (ASI)-resistant models. The safety and efficacy of ZEN-3694 plus enzalutamide was evaluated in a phase Ib/IIa study in metastatic castration-resistant prostate cancer (mCRPC).

PATIENTS AND METHODS

Patients had progressive mCRPC with prior resistance to abiraterone and/or enzalutamide. 3+3 dose escalation was followed by dose expansion in parallel cohorts (ZEN-3694 at 48 and 96 mg orally once daily, respectively).

RESULTS

Seventy-five patients were enrolled (N = 26 and 14 in dose expansion at low- and high-dose ZEN-3694, respectively). Thirty (40.0%) patients were resistant to abiraterone, 34 (45.3%) to enzalutamide, and 11 (14.7%) to both. ZEN-3694 dosing ranged from 36 to 144 mg daily without reaching an MTD. Fourteen patients (18.7%) experienced grade ≥3 toxicities, including three patients with grade 3 thrombocytopenia (4%). An exposure-dependent decrease in whole-blood RNA expression of BETi targets was observed (up to fourfold mean difference at 4 hours post-ZEN-3694 dose; P ≤ 0.0001). The median radiographic progression-free survival (rPFS) was 9.0 months [95% confidence interval (CI), 4.6-12.9] and composite median radiographic or clinical progression-free survival (PFS) was 5.5 months (95% CI, 4.0-7.8). Median duration of treatment was 3.5 months (range, 0-34.7+). Lower androgen receptor (AR) transcriptional activity in baseline tumor biopsies was associated with longer rPFS (median rPFS 10.4 vs. 4.3 months).

CONCLUSIONS

ZEN-3694 plus enzalutamide demonstrated acceptable tolerability and potential efficacy in patients with ASI-resistant mCRPC. Further prospective study is warranted including in mCRPC harboring low AR transcriptional activity.

Enzalutamide and Survival in Nonmetastatic, Castration-Resistant Prostate Cancer

BACKGROUND

Preliminary trial results showed that enzalutamide significantly improved metastasis-free survival among men who had nonmetastatic, castration-resistant prostate cancer and rapidly increasing prostate-specific antigen (PSA) levels while taking androgen-deprivation therapy. Results from the final analysis of overall survival have not yet been reported.

METHODS

In this double-blind, phase 3 trial, men with nonmetastatic, castration-resistant prostate cancer (defined on the basis of conventional imaging and a PSA doubling time of ≤10 months) who were continuing to receive androgen-deprivation therapy were randomly assigned (in a 2:1 ratio) to receive enzalutamide at a dose of 160 mg or placebo once daily. Overall survival was assessed with a group sequential testing procedure and an O'Brien-Fleming-type alpha-spending function.

RESULTS

As of October 15, 2019, a total of 288 of 933 patients (31%) in the enzalutamide group and 178 of 468 (38%) in the placebo group had died. Median overall survival was 67.0 months (95% confidence interval [CI], 64.0 to not reached) in the enzalutamide group and 56.3 months (95% CI, 54.4 to 63.0) in the placebo group (hazard ratio for death, 0.73; 95% CI, 0.61 to 0.89; P = 0.001). The exposure-adjusted rate of adverse events of grade 3 or higher was 17 per 100 patient-years in the enzalutamide group and 20 per 100 patient-years in the placebo group. Adverse events in the enzalutamide group were consistent with those previously reported for enzalutamide; the most frequently reported events were fatigue and musculoskeletal events.

CONCLUSIONS

Enzalutamide plus androgen-deprivation therapy resulted in longer median overall survival than placebo plus androgen-deprivation therapy among men with nonmetastatic, castration-resistant prostate cancer and a rapidly rising PSA level. The risk of death associated with enzalutamide was 27% lower than with placebo. Adverse events were consistent with the established safety profile of enzalutamide. (Funded by Pfizer and Astellas Pharma; PROSPER ClinicalTrials.gov number, NCT02003924.).

Olaparib for Metastatic Castration-Resistant Prostate Cancer

BACKGROUND

Multiple loss-of-function alterations in genes that are involved in DNA repair, including homologous recombination repair, are associated with response to poly(adenosine diphosphate-ribose) polymerase (PARP) inhibition in patients with prostate and other cancers.

METHODS

We conducted a randomized, open-label, phase 3 trial evaluating the PARP inhibitor olaparib in men with metastatic castration-resistant prostate cancer who had disease progression while receiving a new hormonal agent (e.g., enzalutamide or abiraterone). All the men had a qualifying alteration in prespecified genes with a direct or indirect role in homologous recombination repair. Cohort A (245 patients) had at least one alteration in BRCA1, BRCA2, or ATM; cohort B (142 patients) had alterations in any of 12 other prespecified genes, prospectively and centrally determined from tumor tissue. Patients were randomly assigned (in a 2:1 ratio) to receive olaparib or the physician's choice of enzalutamide or abiraterone (control). The primary end point was imaging-based progression-free survival in cohort A according to blinded independent central review.

RESULTS

In cohort A, imaging-based progression-free survival was significantly longer in the olaparib group than in the control group (median, 7.4 months vs. 3.6 months; hazard ratio for progression or death, 0.34; 95% confidence interval, 0.25 to 0.47; P<0.001); a significant benefit was also observed with respect to the confirmed objective response rate and the time to pain progression. The median overall survival in cohort A was 18.5 months in the olaparib group and 15.1 months in the control group; 81% of the patients in the control group who had progression crossed over to receive olaparib. A significant benefit for olaparib was also seen for imaging-based progression-free survival in the overall population (cohorts A and B). Anemia and nausea were the main toxic effects in patients who received olaparib.

CONCLUSIONS

In men with metastatic castration-resistant prostate cancer who had disease progression while receiving enzalutamide or abiraterone and who had alterations in genes with a role in homologous recombination repair, olaparib was associated with longer progression-free survival and better measures of response and patient-reported end points than either enzalutamide or abiraterone. (Funded by AstraZeneca and Merck Sharp & Dohme; PROfound ClinicalTrials.gov number, NCT02987543.).

TBCRC 032 IB/II Multicenter Study: Molecular Insights to AR Antagonist and PI3K Inhibitor Efficacy in Patients with AR+ Metastatic Triple-Negative Breast Cancer

PURPOSE

Preclinical data demonstrating androgen receptor (AR)-positive (AR+) triple-negative breast cancer (TNBC) cells are sensitive to AR antagonists, and PI3K inhibition catalyzed an investigator-initiated, multi-institutional phase Ib/II study TBCRC032. The trial investigated the safety and efficacy of the AR-antagonist enzalutamide alone or in combination with the PI3K inhibitor taselisib in patients with metastatic AR+ (≥10%) breast cancer.

PATIENTS AND METHODS

Phase Ib patients [estrogen receptor positive (ER+) or TNBC] with AR+ breast cancer received 160 mg enzalutamide in combination with taselisib to determine dose-limiting toxicities and the maximum tolerated dose (MTD). Phase II TNBC patients were randomized to receive either enzalutamide alone or in combination with 4 mg taselisib until disease progression. Primary endpoint was clinical benefit rate (CBR) at 16 weeks.

RESULTS

The combination was tolerated, and the MTD was not reached. The adverse events were hyperglycemia and skin rash. Overall, CBR for evaluable patients receiving the combination was 35.7%, and median progression-free survival (PFS) was 3.4 months. Luminal AR (LAR) TNBC subtype patients trended toward better response compared with non-LAR (75.0% vs. 12.5%, P = 0.06), and increased PFS (4.6 vs. 2.0 months, P = 0.082). Genomic analyses revealed subtype-specific treatment response, and novel FGFR2 fusions and AR splice variants.

CONCLUSIONS

The combination of enzalutamide and taselisib increased CBR in TNBC patients with AR+ tumors. Correlative analyses suggest AR protein expression alone is insufficient for identifying patients with AR-dependent tumors and knowledge of tumor LAR subtype and AR splice variants may identify patients more or less likely to benefit from AR antagonists.

Cabazitaxel versus Abiraterone or Enzalutamide in Metastatic Prostate Cancer

BACKGROUND

The efficacy and safety of cabazitaxel, as compared with an androgen-signaling-targeted inhibitor (abiraterone or enzalutamide), in patients with metastatic castration-resistant prostate cancer who were previously treated with docetaxel and had progression within 12 months while receiving the alternative inhibitor (abiraterone or enzalutamide) are unclear.

METHODS

We randomly assigned, in a 1:1 ratio, patients who had previously received docetaxel and an androgen-signaling-targeted inhibitor (abiraterone or enzalutamide) to receive cabazitaxel (at a dose of 25 mg per square meter of body-surface area intravenously every 3 weeks, plus prednisone daily and granulocyte colony-stimulating factor) or the other androgen-signaling-targeted inhibitor (either 1000 mg of abiraterone plus prednisone daily or 160 mg of enzalutamide daily). The primary end point was imaging-based progression-free survival. Secondary end points of survival, response, and safety were assessed.

RESULTS

A total of 255 patients underwent randomization. After a median follow-up of 9.2 months, imaging-based progression or death was reported in 95 of 129 patients (73.6%) in the cabazitaxel group, as compared with 101 of 126 patients (80.2%) in the group that received an androgen-signaling-targeted inhibitor (hazard ratio, 0.54; 95% confidence interval [CI], 0.40 to 0.73; P<0.001). The median imaging-based progression-free survival was 8.0 months with cabazitaxel and 3.7 months with the androgen-signaling-targeted inhibitor. The median overall survival was 13.6 months with cabazitaxel and 11.0 months with the androgen-signaling-targeted inhibitor (hazard ratio for death, 0.64; 95% CI, 0.46 to 0.89; P = 0.008). The median progression-free survival was 4.4 months with cabazitaxel and 2.7 months with an androgen-signaling-targeted inhibitor (hazard ratio for progression or death, 0.52; 95% CI, 0.40 to 0.68; P<0.001), a prostate-specific antigen response occurred in 35.7% and 13.5% of the patients, respectively (P<0.001), and tumor response was noted in 36.5% and 11.5% (P = 0.004). Adverse events of grade 3 or higher occurred in 56.3% of patients receiving cabazitaxel and in 52.4% of those receiving an androgen-signaling-targeted inhibitor. No new safety signals were observed.

CONCLUSIONS

Cabazitaxel significantly improved a number of clinical outcomes, as compared with the androgen-signaling-targeted inhibitor (abiraterone or enzalutamide), in patients with metastatic castration-resistant prostate cancer who had been previously treated with docetaxel and the alternative androgen-signaling-targeted agent (abiraterone or enzalutamide). (Funded by Sanofi; CARD ClinicalTrials.gov number, NCT02485691.).

Orally Bioavailable Androgen Receptor Degrader, Potential Next-Generation Therapeutic for Enzalutamide-Resistant Prostate Cancer

PURPOSE

Androgen receptor (AR)-targeting prostate cancer drugs, which are predominantly competitive ligand-binding domain (LBD)-binding antagonists, are inactivated by common resistance mechanisms. It is important to develop next-generation mechanistically distinct drugs to treat castration- and drug-resistant prostate cancers.

EXPERIMENTAL DESIGN

Second-generation AR pan antagonist UT-34 was selected from a library of compounds and tested in competitive AR binding and transactivation assays. UT-34 was tested using biophysical methods for binding to the AR activation function-1 (AF-1) domain. Western blot, gene expression, and proliferation assays were performed in various AR-positive enzalutamide-sensitive and -resistant prostate cancer cell lines. Pharmacokinetic and xenograft studies were performed in immunocompromised rats and mice.

RESULTS

UT-34 inhibits the wild-type and LBD-mutant ARs comparably and inhibits the in vitro proliferation and in vivo growth of enzalutamide-sensitive and -resistant prostate cancer xenografts. In preclinical models, UT-34 induced the regression of enzalutamide-resistant tumors at doses when the AR is degraded; but, at lower doses, when the AR is just antagonized, it inhibits, without shrinking, the tumors. This indicates that degradation might be a prerequisite for tumor regression. Mechanistically, UT-34 promotes a conformation that is distinct from the LBD-binding competitive antagonist enzalutamide and degrades the AR through the ubiquitin proteasome mechanism. UT-34 has a broad safety margin and exhibits no cross-reactivity with G-protein-coupled receptor kinase and nuclear receptor family members.

CONCLUSIONS

Collectively, UT-34 exhibits the properties necessary for a next-generation prostate cancer drug.

Fatigue, quality of life and metabolic changes in men treated with first-line enzalutamide versus abiraterone plus prednisolone for metastatic castration-resistant prostate cancer (HEAT): a randomised trial protocol

INTRODUCTION

Enzalutamide and abiraterone acetate plus prednisolone (AAP) are used in combination with androgen-deprivation therapy to further suppress the androgen stimulation of metastatic castration-resistant prostate cancer (mCRPC). First-line mCRPC treatment with enzalutamide and AAP yields similar overall survival and radiographic progression-free survival in phase III trials. Thus, treatment selection relies on patient choice, cost and side effects. The aim of this randomised trial is to investigate differences in fatigue, health-related quality of life (HRQoL) and metabolic side effects in men with mCRPC treated with first-line enzalutamide versus AAP.

METHODS AND ANALYSIS

In this ongoing open-label randomised (1:1) clinical trial, enzalutamide is compared with AAP as first-line treatment for men with mCRPC. The primary endpoint is fatigue assessed with the questionnaire Functional Assessment of Chronic Illness Therapy-Fatigue version 4. Secondary endpoints are changes in body composition (ie, fat mass, visceral adipose tissue, subcutaneous adipose tissue and lean body mass assessed with dual energy X-ray absorptiometry), glucose metabolism assessed with a 2-hour oral glucose tolerance test, serum lipids, blood pressure and HRQoL assessed with the questionnaire Functional Assessment of Cancer Therapy-Prostate (FACT-P). All study endpoints are assessed at baseline and 12-week postintervention. Blood and urine samples are collected at baseline and at time of progression on allocated treatment for future investigation of predictive and prognostic biomarkers in prostate cancer treatment. The planned sample size is 170 participants. All participants are recruited from Herlev and Gentofte Hospital, Denmark. Estimated last patient's last visit is February 2020.

ETHICS AND DISSEMINATION

The study received project approval from the National Committee on Health Research Ethics and Danish Data Protection Agency and Danish Medicines Agency (EudraCT no.: 2017-000027-99). The results of the study will be published in peer-reviewed international journals and will be presented at national and international conferences and symposiums.

TRIAL REGISTRATION NUMBER

Clinicaltrialsregister.eu (2017-000099-27).

Enzalutamide with Standard First-Line Therapy in Metastatic Prostate Cancer

BACKGROUND

Enzalutamide, an androgen-receptor inhibitor, has been associated with improved overall survival in men with castration-resistant prostate cancer. It is not known whether adding enzalutamide to testosterone suppression, with or without early docetaxel, will improve survival in men with metastatic, hormone-sensitive prostate cancer.

METHODS

In this open-label, randomized, phase 3 trial, we assigned patients to receive testosterone suppression plus either open-label enzalutamide or a standard nonsteroidal antiandrogen therapy (standard-care group). The primary end point was overall survival. Secondary end points included progression-free survival as determined by the prostate-specific antigen (PSA) level, clinical progression-free survival, and adverse events.

RESULTS

A total of 1125 men underwent randomization; the median follow-up was 34 months. There were 102 deaths in the enzalutamide group and 143 deaths in the standard-care group (hazard ratio, 0.67; 95% confidence interval [CI], 0.52 to 0.86; P = 0.002). Kaplan-Meier estimates of overall survival at 3 years were 80% (based on 94 events) in the enzalutamide group and 72% (based on 130 events) in the standard-care group. Better results with enzalutamide were also seen in PSA progression-free survival (174 and 333 events, respectively; hazard ratio, 0.39; P<0.001) and in clinical progression-free survival (167 and 320 events, respectively; hazard ratio, 0.40; P<0.001). Treatment discontinuation due to adverse events was more frequent in the enzalutamide group than in the standard-care group (33 events and 14 events, respectively). Fatigue was more common in the enzalutamide group; seizures occurred in 7 patients in the enzalutamide group (1%) and in no patients in the standard-care group.

CONCLUSIONS

Enzalutamide was associated with significantly longer progression-free and overall survival than standard care in men with metastatic, hormone-sensitive prostate cancer receiving testosterone suppression. The enzalutamide group had a higher incidence of seizures and other toxic effects, especially among those treated with early docetaxel. (Funded by Astellas Scientific and Medical Affairs and others; ENZAMET (ANZUP 1304) ANZCTR number, ACTRN12614000110684; ClinicalTrials.gov number, NCT02446405; and EU Clinical Trials Register number, 2014-003190-42.).

LncRNA-p21 alters the antiandrogen enzalutamide-induced prostate cancer neuroendocrine differentiation via modulating the EZH2/STAT3 signaling

While the antiandrogen enzalutamide (Enz) extends the castration resistant prostate cancer (CRPC) patients' survival an extra 4.8 months, it might also result in some adverse effects via inducing the neuroendocrine differentiation (NED). Here we found that lncRNA-p21 is highly expressed in the NEPC patients derived xenograft tissues (NEPC-PDX). Results from cell lines and human clinical sample surveys also revealed that lncRNA-p21 expression is up-regulated in NEPC and Enz treatment could increase the lncRNA-p21 to induce the NED. Mechanism dissection revealed that Enz could promote the lncRNA-p21 transcription via altering the androgen receptor (AR) binding to different androgen-response-elements, which switch the EZH2 function from histone-methyltransferase to non-histone methyltransferase, consequently methylating the STAT3 to promote the NED. Preclinical studies using the PDX mouse model proved that EZH2 inhibitor could block the Enz-induced NED. Together, these results suggest targeting the Enz/AR/lncRNA-p21/EZH2/STAT3 signaling may help urologists to develop a treatment for better suppression of the human CRPC progression.

Plasma Androgen Receptor and Docetaxel for Metastatic Castration-resistant Prostate Cancer

Plasma androgen receptor (AR) gain identifies metastatic castration-resistant prostate cancer (mCRPC) patients with worse outcome on abiraterone/enzalutamide, but its relevance in the context of taxane chemotherapy is unknown. We aimed to evaluate whether docetaxel is active regardless of plasma AR and to perform an exploratory analysis to compare docetaxel with abiraterone/enzalutamide. This multi-institutional study was a pooled analysis of AR status, determined by droplet digital polymerase chain reaction, on pretreatment plasma samples. We evaluated associations between plasma AR and overall/progression-free survival (OS/PFS) and prostate-specific antigen (PSA) response rate in 163 docetaxel-treated patients. OS was significantly shorter in case of AR gain (hazard ratio [HR]=1.61, 95% confidence interval [CI]=1.08-2.39, p=0.018), but not PFS (HR=1.04, 95% CI 0.74-1.46, p=0.8) or PSA response (odds ratio=1.14, 95% CI=0.65-1.99, p=0.7). We investigated the interaction between plasma AR and treatment type after incorporating updated data from our prior study of 73 chemotherapy-naïve, abiraterone/enzalutamide-treated patients, with data from 115 first-line docetaxel patients. In an exploratory analysis of mCRPC patients receiving first-line therapies, a significant interaction was observed between plasma AR and docetaxel versus abiraterone/enzalutamide for OS (HR=0.16, 95% CI=0.06-0.46, p<0.001) and PFS (HR=0.31, 95% CI=0.12-0.80, p=0.02). Specifically, we reported a significant difference for OS favoring abiraterone/enzalutamide for AR-normal patients (HR=1.93, 95% CI=1.19-3.12, p=0.008) and a suggestion favoring docetaxel for AR-gained patients (HR=0.53, 95% CI=0.24-1.16, p=0.11). These data suggest that AR-normal patients should receive abiraterone/enzalutamide and AR-gained could benefit from docetaxel. This treatment selection merits prospective evaluation in a randomized trial. PATIENT SUMMARY: We investigated whether plasma androgen receptor (AR) predicted outcome in metastatic castration-resistant prostate cancer (mCRPC) patients treated with docetaxel, and we performed an exploratory analysis in patients treated with docetaxel or AR-directed drugs as first-line mCRPC therapy. We showed that plasma AR normal favored hormonal treatment, whilst plasma AR-gained patients may have had a longer response to docetaxel, suggesting that plasma AR status could be a useful treatment selection biomarker.

Impact of timing of administration of bone supportive therapy on pain palliation from radium-223

BACKGROUND

Skeletal-related events cause significant morbidity in patients with metastatic castration-resistant prostate cancer. In the ALSYMPCA study, radium-223 (Ra223) was found to provide pain palliation in addition to prolonged survival and reduced skeletal-related events (SREs). Given previous evidence that bisphosphonates impacted pain relief from the radiopharmaceutical samarium-153, we evaluated whether the timing of bone supportive therapy (BST) such as zoledronic acid or denosumab affected pain palliation from Ra223.

METHODS

We identified patients who received Ra223 at University of Southern California or Mayo Clinic Arizona. Patients were evaluable for pain response if they had baseline pain score > 0 and at least 1 pain score documented after Ra223 with pain medication use data. Patients were evaluable for pain flare if they had known baseline pain score and at least 2 pain scores documented after Ra223. Pain response was defined as > 2 point decrease in pain on a 10-point scale; flare was defined as > 2 point increase followed by return to baseline or lower.

RESULTS

Of 65 patients, 22 (34%) received BST. Median number of doses Ra223 was 5 (range 2-6). Fourteen patients were evaluable for pain response and 34 for pain flare. Eighteen patients received concurrent abiraterone (abi) or enzalutamide (enza), and 16 did not. Pain response occurred in 6/6 (100%) patients who received BST within 1 month prior to first Ra223 dose and 4/8 (50%) patients who did not receive BST. Pain flare occurred in 6/21 patients (29%) without BST and 2/13 (15%) with BST (p = 0.44). 6/10 (60%) patients with pain response had a decline in alkaline phosphatase (ALP) level, but there was no consistent pattern of ALP changes in patients with flare. 8/8 patients with pain response had no PSA decline. 6/8 (75%) and 2/18 (11%) patients on abi/enza had pain response and flare respectively, and 4/6 (67%) and 6/16 (38%) patients without concurrent abi/enza had response/flare.

CONCLUSIONS

BST within 1 month prior to first Ra223 dose was associated with increased likelihood of pain palliation and might prevent pain flare. Concurrent use of abi/enza was not associated with increased likelihood of pain response but was associated with decreased likelihood of pain flare.

Treatment Duration, Healthcare Resource Utilization, and Costs Among Chemotherapy-Naïve Patients with Metastatic Castration-Resistant Prostate Cancer Treated with Enzalutamide or Abiraterone Acetate: A Retrospective Claims Analysis

Introduction

Enzalutamide and abiraterone acetate (plus prednisone) are new hormonal treatments for metastatic castration-resistant prostate cancer (mCRPC). This study compared treatment duration, healthcare resource utilization (HRU), and treatment costs for chemotherapy-naïve mCRPC patients treated with enzalutamide or abiraterone acetate in the USA.

Methods

Chemotherapy-naïve mCRPC patients initiating treatment with enzalutamide or abiraterone acetate were identified from administrative claims. Continuous enrollment ≥ 6 months before and ≥ 3 months after the index date (initiation date of enzalutamide or abiraterone acetate) was required. Treatment duration, all-cause and prostate cancer-related HRU, and costs were estimated during the post-index period. Multivariable analyses compared HRU and costs between cohorts, adjusting for baseline characteristics.

Results

Overall, 920 chemotherapy-naïve patients initiated enzalutamide and 2310 initiated abiraterone acetate (median follow-up, 10.7 and 13.5 months, respectively). More enzalutamide-treated patients had corticosteroid-sensitive comorbidities at baseline. Treatment duration was longer with enzalutamide versus abiraterone acetate (median, 10.7 vs. 8.8 months; P = 0.008). Enzalutamide was associated with fewer all-cause inpatient admissions [adjusted incidence rate ratio (95% confidence interval) 0.87 (0.76, 0.99)], days of hospitalization [0.84 (0.70, 1.02)], and outpatient visits [0.94 (0.90, 0.98)], and fewer prostate cancer-related outpatient visits [0.92 (0.87, 0.96)] compared with abiraterone acetate. Enzalutamide was also associated with lower prostate cancer-related inpatient and emergency department costs [adjusted differences, $122 (P = 0.024) and $28 (P = 0.009), respectively].

Conclusion

Chemotherapy-naïve mCRPC patients treated with enzalutamide versus abiraterone acetate had longer treatment duration and incurred lower HRU and prostate cancer-related inpatient and emergency department costs.

Funding

Astellas Pharma Inc.

Electronic supplementary material

The online version of this article (10.1007/s12325-018-0774-1) contains supplementary material, which is available to authorized users.

Abiraterone Alone or in Combination With Enzalutamide in Metastatic Castration-Resistant Prostate Cancer With Rising Prostate-Specific Antigen During Enzalutamide Treatment

Purpose Enzalutamide resistance could result from raised androgens and be overcome by combination with abiraterone acetate. PLATO ( ClinicalTrials.gov identifier: NCT01995513) interrogated this hypothesis using a randomized, double-blind, placebo-controlled design. Patients and Methods In period one, men with chemotherapy-naïve metastatic castration-resistant prostate cancer received open-label enzalutamide 160 mg daily. Men with no prostate-specific antigen (PSA) increase at weeks 13 and 21 were treated until PSA progression (≥ 25% increase and ≥ 2 ng/mL above nadir), then randomly assigned at a one-to-one ratio in period two to abiraterone acetate 1,000 mg daily and prednisone 5 mg twice daily with either enzalutamide or placebo (combination or control group, respectively) until disease progression as defined by the primary end point: progression-free survival (radiographic or unequivocal clinical progression or death during study). Secondary end points included time to PSA progression and PSA response in period two. Results Of 509 patients enrolled in period one, 251 were randomly assigned in period two. Median progression-free survival was 5.7 months in the combination group and 5.6 months in the control group (hazard ratio, 0.83; 95% CI, 0.61 to 1.12; P = .22). There was no difference in the secondary end points. Grade 3 hypertension (10% v 2%) and increased ALT (6% v 2%) or AST (2% v 0%) were more frequent in the combination than the control group. Conclusion Combining enzalutamide with abiraterone acetate and prednisone is not indicated after PSA progression during treatment with enzalutamide alone; hypertension and elevated liver enzymes are more frequent with combination therapy.

[Enzalutamide in castration resistant prostate cancer.]

Androgen deprivation therapy is part of the initial treatment of patients with metastatic prostate cancer. Nevertheless, after an initial response and despite maintaining an effective testosterone suppression, the tumor is able to continue growing.Enzalutamide is an oral second generation pure antiandrogen that acts at various levels in the signal activation cascade of the androgen receptor and has demonstrated being effective in this phase of the disease. In the clinical trials completed, it has demonstrated benefits in overall patient survival in patients with the diagnosis of metastatic castration resistant prostate cancer. Recent studies have also demonstrated benefits in progression free survival in patients with non-metastatic castration resistant prostate cancer. Enzalutamide has an excellent toxicity profile, but we have to avoid it in patients with history of seizure episodes, mainly if they are under anti-epileptic drug therapy. Enzalutamide is rapidly metabolized by the liver, mainly through the CYP2C8 and to a lesser extent by CYP3A4/5 so that its metabolism may be altered when cytochrome isoenzyme inductor or inhibitor drugs are given concomitantly. Moreover, enzalutamide may require dose adjustment for other drugs since it is a potent inductor of CYP3A4 and a moderate inductor of CYP2C9 y el CYP2C19. Even though treatment with enzalutamide has significantly altered the natural history of the disease, in most cases it will progress by development of resistance mechanisms, among which we may emphasize androgen receptor mutations, overexpression, amplification and variants, as well as the intracrine production of androgens. Enzalutamide must be considered as first line therapy in patients with castration resistant prostate cancer.

Enzalutamide in Men with Nonmetastatic, Castration-Resistant Prostate Cancer

BACKGROUND

Men with nonmetastatic, castration-resistant prostate cancer and a rapidly rising prostate-specific antigen (PSA) level are at high risk for metastasis. We hypothesized that enzalutamide, which prolongs overall survival among patients with metastatic, castration-resistant prostate cancer, would delay metastasis in men with nonmetastatic, castration-resistant prostate cancer and a rapidly rising PSA level.

METHODS

In this double-blind, phase 3 trial, we randomly assigned, in a 2:1 ratio, men with nonmetastatic, castration-resistant prostate cancer and a PSA doubling time of 10 months or less who were continuing androgen-deprivation therapy to receive enzalutamide (at a dose of 160 mg) or placebo once daily. The primary end point was metastasis-free survival (defined as the time from randomization to radiographic progression or as the time to death without radiographic progression).

RESULTS

A total of 1401 patients (median PSA doubling time, 3.7 months) underwent randomization. As of June 28, 2017, a total of 219 of 933 patients (23%) in the enzalutamide group had metastasis or had died, as compared with 228 of 468 (49%) in the placebo group. The median metastasis-free survival was 36.6 months in the enzalutamide group versus 14.7 months in the placebo group (hazard ratio for metastasis or death, 0.29; 95% confidence interval, 0.24 to 0.35; P<0.001). The time to the first use of a subsequent antineoplastic therapy was longer with enzalutamide treatment than with placebo (39.6 vs. 17.7 months; hazard ratio, 0.21; P<0.001; such therapy was used in 15% vs. 48% of patients) as was the time to PSA progression (37.2 vs. 3.9 months; hazard ratio, 0.07; P<0.001; progression occurred in 22% vs. 69% of patients). At the first interim analysis of overall survival, 103 patients (11%) receiving enzalutamide and 62 (13%) receiving placebo had died. Adverse events of grade 3 or higher occurred in 31% of the patients receiving enzalutamide, as compared with 23% of those receiving placebo.

CONCLUSIONS

Among men with nonmetastatic, castration-resistant prostate cancer with a rapidly rising PSA level, enzalutamide treatment led to a clinically meaningful and significant 71% lower risk of metastasis or death than placebo. Adverse events were consistent with the established safety profile of enzalutamide. (Funded by Pfizer and Astellas Pharma; PROSPER ClinicalTrials.gov number, NCT02003924 .).

A phase I study of niclosamide in combination with enzalutamide in men with castration-resistant prostate cancer

BACKGROUND

Niclosamide, an FDA-approved anti-helminthic drug, has activity in preclinical models of castration-resistant prostate cancer (CRPC). Potential mechanisms of action include degrading constitutively active androgen receptor splice variants (AR-Vs) or inhibiting other drug-resistance pathways (e.g., Wnt-signaling). Published pharmacokinetics data suggests that niclosamide has poor oral bioavailability, potentially limiting its use as a cancer drug. Therefore, we launched a Phase I study testing oral niclosamide in combination with enzalutamide, for longer and at higher doses than those used to treat helminthic infections.

METHODS

We conducted a Phase I dose-escalation study testing oral niclosamide plus standard-dose enzalutamide in men with metastatic CRPC previously treated with abiraterone. Niclosamide was given three-times-daily (TID) at the following dose-levels: 500, 1000 or 1500mg. The primary objective was to assess safety. Secondary objectives, included measuring AR-V expression from circulating tumor cells (CTCs) using the AdnaTest assay, evaluating PSA changes and determining niclosamide's pharmacokinetic profile.

RESULTS

20 patients screened and 5 enrolled after passing all screening procedures. 13(65%) patients had detectable CTCs, but only one was AR-V+. There were no dose-limiting toxicities (DLTs) in 3 patients on the 500mg TID cohort; however, both (N = 2) subjects on the 1000mg TID cohort experienced DLTs (prolonged grade 3 nausea, vomiting, diarrhea; and colitis). The maximum plasma concentration ranged from 35.7 to 182 ng/mL and was not consistently above the minimum effective concentration in preclinical studies. There were no PSA declines in any enrolled subject. Because plasma concentrations at the maximum tolerated dose (500mg TID) were not consistently above the expected therapeutic threshold, the Data Safety Monitoring Board closed the study for futility.

CONCLUSIONS

Oral niclosamide could not be escalated above 500mg TID, and plasma concentrations were not consistently above the threshold shown to inhibit growth in CRPC models. Oral niclosamide is not a viable compound for repurposing as a CRPC treatment.

CLINICAL TRIAL REGISTRY

Clinicaltrials.gov: NCT02532114.

Enzalutamide for the Treatment of Androgen Receptor-Expressing Triple-Negative Breast Cancer

Purpose Studies suggest that a subset of patients with triple-negative breast cancer (TNBC) have tumors that express the androgen receptor (AR) and may benefit from an AR inhibitor. This phase II study evaluated the antitumor activity and safety of enzalutamide in patients with locally advanced or metastatic AR-positive TNBC. Patients and Methods Tumors were tested for AR with an immunohistochemistry assay optimized for breast cancer; nuclear AR staining > 0% was considered positive. Patients received enzalutamide 160 mg once per day until disease progression. The primary end point was clinical benefit rate (CBR) at 16 weeks. Secondary end points included CBR at 24 weeks, progression-free survival, and safety. End points were analyzed in all enrolled patients (the intent-to-treat [ITT] population) and in patients with one or more postbaseline assessment whose tumor expressed ≥ 10% nuclear AR (the evaluable subgroup). Results Of 118 patients enrolled, 78 were evaluable. CBR at 16 weeks was 25% (95% CI, 17% to 33%) in the ITT population and 33% (95% CI, 23% to 45%) in the evaluable subgroup. Median progression-free survival was 2.9 months (95% CI, 1.9 to 3.7 months) in the ITT population and 3.3 months (95% CI, 1.9 to 4.1 months) in the evaluable subgroup. Median overall survival was 12.7 months (95% CI, 8.5 months to not yet reached) in the ITT population and 17.6 months (95% CI, 11.6 months to not yet reached) in the evaluable subgroup. Fatigue was the only treatment-related grade 3 or higher adverse event with an incidence of > 2%. Conclusion Enzalutamide demonstrated clinical activity and was well tolerated in patients with advanced AR-positive TNBC. Adverse events related to enzalutamide were consistent with its known safety profile. This study supports additional development of enzalutamide in advanced TNBC.

Bipolar androgen therapy in men with metastatic castration-resistant prostate cancer after progression on enzalutamide: an open-label, phase 2, multicohort study

BACKGROUND

Prostate cancer that progresses after enzalutamide treatment is poorly responsive to further antiandrogen therapy, and paradoxically, rapid cycling between high and low serum testosterone concentrations (bipolar androgen therapy [BAT]) in this setting might induce tumour responses. We aimed to evaluate BAT in patients with metastatic castration-resistant prostate cancer that progressed after enzalutamide.

METHODS

We did this single-centre, open-label, phase 2, multicohort study in the USA. We included patients aged 18 years or older who had histologically confirmed and radiographically documented metastatic castration-resistant prostate cancer, with no more than two previous second-line hormonal therapies, and a castrate concentration of testosterone. Patients were asymptomatic, with Eastern Cooperative Oncology Group performance status of 0-2, and did not have high-risk lesions for tumour flare (eg, >5 sites of visceral disease or bone lesions with impending fracture). For the cohort reported here, we required patients to have had progression on enzalutamide with a continued prostate-specific antigen (PSA) rise after enzalutamide treatment discontinuation. Patients received BAT, which consisted of intramuscular testosterone cipionate 400 mg every 28 days until progression and continued luteinising hormone-releasing hormone agonist therapy. Upon progression after BAT, men were rechallenged with oral enzalutamide 160 mg daily. The co-primary endpoints were investigator-assessed 50% decline in PSA concentration from baseline (PSA50) for BAT (for all patients who received at least one dose) and for enzalutamide rechallenge (based on intention-to-treat analysis). These data represent the final analysis for the post-enzalutamide cohort, while two additional cohorts (post-abiraterone and newly castration-resistant prostate cancer) are ongoing. The trial is registered with ClinicalTrials.gov, number NCT02090114.

FINDINGS

Between Aug 28, 2014, and May 18, 2016, we accrued 30 eligible patients and treated them with BAT. Nine (30%; 95% CI 15-49; p<0·0001) of 30 patients achieved a PSA50 to BAT. 29 patients completed BAT and 21 proceeded to enzalutamide rechallenge, of whom 15 (52%; 95% CI 33-71; p<0·0001) achieved a PSA50 response. During BAT, the only grade 3-4 adverse event occurring in more than one patient was hypertension (three [10%] patients). Other grade 3 or worse adverse events occurring during BAT in one [3%] patient each were pulmonary embolism, myocardial infarction, urinary obstruction, gallstone, and sepsis. During enzalutamide retreatment, no grade 3-4 toxicities occurred in more than one patient. No treatment-related deaths were reported during either BAT or enzalutamide retreatment.

INTERPRETATION

BAT is a safe therapy that resulted in responses in asymptomatic men with metastatic castration-resistant prostate cancer and also resensitisation to enzalutamide in most patients undergoing rechallenge. Further studies with BAT are needed to define the potential clinical role for BAT in the management of metastatic castration-resistant prostate cancer and the optimal strategy for sequencing between androgen and antiandrogen therapies in metastatic castration-resistant prostate cancer to maximise therapeutic benefit to patients.

FUNDING

National Institutes of Health and National Cancer Institute.

[A Case of Castration-Resistant Prostate Cancer with Fatal Convulsive Seizure after Administration of Enzalutamide]

Enzalutamide, an androgen receptor antagonist, is a standard drug for the treatment of castrationresistant prostate cancer. A 77-year-old man developed a seizure after administration of enzalutamide. The patient presented with general fatigue and high fever approximately 5 weeks after oral administration of enzalutamide. Several days later, a seizure attack occurred at home, resulting in cardiopulmonary arrest. The patient was taken to the hospital emergency room but could not be resuscitated. We described a 63-year-old man who was diagnosed with clinical T1c prostate cancer, with a Gleason score of 6 (3＋3), and a preoperative prostate-specific antigen (PSA) level of 5. 27 ng/ml. Radical prostatectomy(RP) was performed and final pathologyshowed Gleason score 3＋4, pT2c with negative surgical margin. In spite of suggested surgical radicality, PSA was 3.32, 4.78, 5.93 ng/ml, at 1, 2, and 3 months after RP, respectively. However, radiological investigation revealed no metastasis. Because of this clinical discrepancy, we checked the PSA-α1-antichemotrypsin level and found it to be ≦0.1 ng/ml. From these results, false PSA elevation caused byinterference of positive heterophilic antibodies was suggested and demonstrated byseveral immunoassays.

Post hoc analyses of East Asian patients from the randomized placebo-controlled PREVAIL trial of enzalutamide in patients with chemotherapy-naïve, metastatic castration-resistant prostate cancer

BACKGROUND

Enzalutamide is an androgen receptor (AR) inhibitor that acts on different steps in the AR signaling pathway. In PREVAIL, an international, phase III, double-blind, placebo-controlled trial, enzalutamide significantly reduced the risk of radiographic progression by 81% (hazard ratio [HR], 0.19; P < .0001) and reduced the risk of death by 29% (HR, 0.71; P < .0001) compared with placebo in chemotherapy-naïve men with metastatic castration-resistant prostate cancer.

METHODS

To evaluate treatment effects, safety, and pharmacokinetics of enzalutamide in East Asian patients from the PREVAIL trial, we performed a post hoc analysis of the Japanese, Korean, and Singaporean patients. PREVAIL enrolled patients with asymptomatic or mildly symptomatic chemotherapy-naïve metastatic castration-resistant prostate cancer who had progressed on androgen deprivation therapy. During the study, patients received enzalutamide (160 mg/d) or placebo (1:1) until death or discontinuation because of radiographic progression or skeletal-related event and initiation of subsequent therapy. Centrally assessed radiographic progression-free survival (rPFS) and overall survival (OS) were coprimary endpoints. The secondary endpoints of the PREVAIL trial were investigator-assessed rPFS, time to initiation of chemotherapy, time to prostate-specific antigen (PSA) progression, and PSA response (≥50% decline).

RESULTS

Of 1717 patients, 148 patients were enrolled at sites in East Asia (enzalutamide 73, placebo 75). Treatment effect of enzalutamide versus placebo was consistent with that for the overall population as indicated by the HRs (95% confidence interval) of 0.38 (0.10-1.44) for centrally assessed rPFS, 0.59 (0.29-1.23) for OS, 0.33 (0.19-0.60) for time to chemotherapy, and 0.32 (0.20-0.50) for time to PSA progression. In East Asian patients, PSA responses were observed in 68.5% and 14.7% of enzalutamide- and placebo-treated patients, respectively. The enzalutamide plasma concentration ratio (East Asian:non-Asian patients) was 1.12 (90% confidence interval, 1.05-1.20) at 13 weeks. Treatment-related adverse events grade ≥ 3 occurred in 1.4% and 2.7% of enzalutamide- and placebo-treated East Asian patients, respectively.

CONCLUSIONS

Treatment effects and safety of enzalutamide in East Asian patients were generally consistent with those observed in the overall study population from PREVAIL. CLINICALTRIALS.

GOV NUMBER

NCT01212991.

Androgen receptor gene status in plasma DNA associates with worse outcome on enzalutamide or abiraterone for castration-resistant prostate cancer: a multi-institution correlative biomarker study

BACKGROUND

There is an urgent need to identify biomarkers to guide personalized therapy in castration-resistant prostate cancer (CRPC). We aimed to clinically qualify androgen receptor (AR) gene status measurement in plasma DNA using multiplex droplet digital PCR (ddPCR) in pre- and post-chemotherapy CRPC.

METHODS

We optimized ddPCR assays for AR copy number and mutations and retrospectively analyzed plasma DNA from patients recruited to one of the three biomarker protocols with prospectively collected clinical data. We evaluated associations between plasma AR and overall survival (OS) and progression-free survival (PFS) in 73 chemotherapy-naïve and 98 post-docetaxel CRPC patients treated with enzalutamide or abiraterone (Primary cohort) and 94 chemotherapy-naïve patients treated with enzalutamide (Secondary cohort; PREMIERE trial).

RESULTS

In the primary cohort, AR gain was observed in 10 (14%) chemotherapy-naïve and 33 (34%) post-docetaxel patients and associated with worse OS [hazard ratio (HR), 3.98; 95% CI 1.74-9.10; P < 0.001 and HR 3.81; 95% CI 2.28-6.37; P < 0.001, respectively], PFS (HR 2.18; 95% CI 1.08-4.39; P = 0.03, and HR 1.95; 95% CI 1.23-3.11; P = 0.01, respectively) and rate of PSA decline ≥50% [odds ratio (OR), 4.7; 95% CI 1.17-19.17; P = 0.035 and OR, 5.0; 95% CI 1.70-14.91; P = 0.003, respectively]. AR mutations [2105T>A (p.L702H) and 2632A>G (p.T878A)] were observed in eight (11%) post-docetaxel but no chemotherapy-naïve abiraterone-treated patients and were also associated with worse OS (HR 3.26; 95% CI 1.47-not reached; P = 0.004). There was no interaction between AR and docetaxel status (P = 0.83 for OS, P = 0.99 for PFS). In the PREMIERE trial, 11 patients (12%) with AR gain had worse PSA-PFS (sPFS) (HR 4.33; 95% CI 1.94-9.68; P < 0.001), radiographic-PFS (rPFS) (HR 8.06; 95% CI 3.26-19.93; P < 0.001) and OS (HR 11.08; 95% CI 2.16-56.95; P = 0.004). Plasma AR was an independent predictor of outcome on multivariable analyses in both cohorts.

CONCLUSION

Plasma AR status assessment using ddPCR identifies CRPC with worse outcome to enzalutamide or abiraterone. Prospective evaluation of treatment decisions based on plasma AR is now required.

CLINICAL TRIAL NUMBER

NCT02288936 (PREMIERE trial).

Lactate dehydrogenase predicts combined progression-free survival after sequential therapy with abiraterone and enzalutamide for patients with castration-resistant prostate cancer

BACKGROUND

An array of clinical issues remains to be resolved for castration-resistant prostate cancer (CRPC), including the sequence of drug use and drug cross-resistance. At present, no clear guidelines are available for the optimal sequence of use of novel agents like androgen-receptor axis-targeted (ARAT) agents, particularly enzalutamide, and abiraterone.

METHODS

This study retrospectively analyzed a total of 69 patients with CRPC treated with sequential therapy using enzalutamide followed by abiraterone or vice versa. The primary outcome measure was the comparative combined progression-free survival (PFS) comprising symptomatic and/or radiographic PFS. Patients were also compared for total prostate-specific antigen (PSA)-PFS, overall survival (OS), and PSA response. The predictors of combined PFS and OS were analyzed with a backward-stepwise multivariate Cox model.

RESULTS

Of the 69 patients, 46 received enzalutamide first, followed by abiraterone (E-A group), and 23 received abiraterone, followed by enzalutamide (A-E group). The two groups were not significantly different with regard to basic data, except for hemoglobin values. In a comparison with the E-A group, the A-E group was shown to be associated with better combined PFS in Kaplan-Meier analysis (P = 0.043). Similar results were obtained for total PSA-PFS (P = 0.049), while OS did not differ between groups (P = 0.62). Multivariate analysis demonstrated that pretreatment lactate dehydrogenase (LDH) values and age were significant predictors of longer combined PFS (P < 0.05). Likewise, multivariate analysis demonstrated that pretreatment hemoglobin values and performance status were significant predictors of longer OS (P < 0.05).

CONCLUSIONS

The results of this study suggested the A-E sequence had longer combined PSA and total PSA-PFS compared to the E-A sequence in patients with CRPC. LDH values in sequential therapy may serve as a predictor of longer combined PFS.

IAP Antagonists Enhance Apoptotic Response to Enzalutamide in Castration-Resistant Prostate Cancer Cells via Autocrine TNF-α Signaling

BACKGROUND

Castration-resistant prostate cancer (CRPC) remains incurable and identifying effective treatments continues to present a clinical challenge. Although treatment with enzalutamide, a second generation androgen receptor (AR) antagonist, prolongs survival in prostate cancer patients, responses can be limited by intrinsic resistance or acquired resistance. A potential mechanism of resistance to androgen axis inhibition is evasion of apoptosis. Inhibitor of apoptosis proteins (IAPs) are found to be overexpressed in prostate cancer and function to block apoptosis and promote survival signaling. Novel, small-molecule IAP antagonists, such as AEG40995, are emerging as a strategy to induce apoptosis and increase therapeutic response in cancer.

METHODS

Human prostate cancer cell lines LNCaP and C4-2 were treated with enzalutamide with or without addition of IAP antagonist AEG40995 and proliferation and survival were determined by MTS and clonogenic assay. Western blot was used to evaluate IAP protein expression changes and PARP-1 cleavage was assessed as indication of apoptosis. Flow cytometry was performed to analyze apoptosis in treated cells. Caspase activity was determined by luminescence assay. Quantitative real-time PCR and immunometric ELISA was used to assess TNF-α (transcript and protein levels, respectively) in response to treatment.

RESULTS

In this study, we demonstrate that IAP antagonist AEG40995 exhibits minimal effects on prostate cancer cell proliferation or survival, but rapidly degrades cIAP1 protein. Combination treatment with enzalutamide demonstrates that AEG40995 increases apoptosis and reduces proliferation and clonogenic survival in cell line models of prostate cancer. Mechanistically, we demonstrate that apoptosis in response to enzalutamide and IAP antagonist requires activation of caspase-8, suggesting extrinsic/death receptor apoptosis signaling. Assessment of TNF-α in response to combination treatment with enzalutamide and AEG40995 reveals increased mRNA expression and autocrine protein secretion. Blocking TNF-α signaling abrogates the apoptotic response demonstrating that TNF-α plays a critical role in executing cell death in response to this drug combination.

CONCLUSIONS

These findings suggest that IAP antagonists can increase sensitivity and amplify the caspase-mediated apoptotic response to enzalutamide through TNF-α signaling mechanisms. Combination with an IAP antagonist increases enzalutamide sensitivity, lowers the apoptotic threshold and may combat drug resistance in patients with prostate cancer. Prostate 77:866-877, 2017. © 2017 Wiley Periodicals, Inc.

The primary care physician's role in the monitoring and management of the potential sequelae of the medical treatment of prostate cancer: early and late

Significant progress has been made in the management of aggressive prostate cancer. The established old and new treatments have resulted in the significant delay in progression of disease, improvement of the quality of life, as well as the increase in the overall survival of men with advanced prostate cancer. However, these therapies carry with them possible adverse effects that primary care physicians are experienced in managing. Thus, there is an increasing need for the urologist to involve and partner closely with the primary care practitioner to prevent, identify and manage the potential side effects of these life-changing therapies.

Prognostic parameters for response to enzalutamide after docetaxel and abiraterone treatment in metastatic castration-resistant prostate cancer patients; a possible time relation

BACKGROUND

Abiraterone Acetate (AA) and Enzalutamide (Enz) are effective hormonal treatments in mCRPC patients. Retrospective studies suggested clinical cross-resistance between Enz and AA. However, 12.8-39.1% of patients previously treated with docetaxel (Doc) and AA do respond to Enz. These responders have not been characterized.

METHODS

102 Enz treated mCRPC patients after AA and Doc treatment were included in this study. Differences in patient characteristics and previous treatment outcomes between PSA responders and non-responders on Enz were evaluated.

RESULTS

Median Progression-Free Survival was 12.2 weeks (95%CI 11.7-14.3) and Overall Survival 43.5 weeks (95%CI 37.4-61.2). There were 26 (25%) Enz-responders and 76 (75%) non-responders. Significant higher percentages of Gleason scores ≥ 8 and PSA doubling times (PSA-DT) <3 months were found in Enz responders than in non-responders. The interval between end of AA and start of Enz treatment (IAE) for responders was 24.6 weeks (IQR 4.0-48.1) and 8.9 weeks for non-responders (IQR 3.7-25.9) (P = 0.08). In an IAE <40 days subgroup (34 patients), Enz responses were related to AA non-responsiveness, while univariate and logistic regression analysis of baseline criteria of a subgroup of patients with an IAE ≥ 40 (68 patients) revealed significant differences in baseline PSA levels, PSA-DT <3 months, Gleason scores ≥ 8 and IAE's between Enz responders and non-responders.

CONCLUSIONS

PSA response to Enz after previous AA and Doc treatment was associated with a longer IAE, a higher Gleason score and a PSA-DT <3 months. Identification of these patients might be of value for sequencing of treatment options.

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.

[Clinical efficacy and safety of enzalutamide in metastatic castration-resistant prostate cancer: systematic review and meta-analysis]

Enzalutamide, abiraterone-acetate, and cabazitaxel are licensed post-docetaxel treatments of metastatic castration-resistant prostate cancer (mCRPC) in Hungary. The objectives of the study were to assess the efficacy and safety of post-docetaxel enzalutamide treatment and to compare it with abiraterone and with cabazitaxel, using Medline-based systematic literature search, and meta-analysis of randomised controlled trials (RCT). Overall 3 RCTs were included, one for each substance. Compared to placebo, enzalutamide proved significant efficacy in each primary and secondary endpoint. Enzalutamide extended median overall survival by 4.8 months. Due to lack of a common comparator in the cabazitaxel trial, only enzalutamide and abiraterone were involved in an indirect comparison. No significant difference was identified either in the primary endpoint (overall survival) (HR: 0.97, 95% CI: 0.75-1.25) or in frequencies of adverse events between these two treatments. However, enzalutamide was significantly more efficacious than abiraterone in 3 secondary endpoints: time to prostate-specific antigen (PSA) progression (HR: 0.43, 95% CI: 0.31-0.59), radiographic progression-free survival (HR: 0.6, 95% CI: 0.5-0.72), and PSA response rate (RR: 7.48, 95% CI: 2.83-19.72). Enzalutamide therapy proved clinical efficacy and safety in patients with post-docetaxel mCRPC. In the indirect comparison, efficacy and safety of abiraterone and enzalutamide were found to be similar.

Enzalutamide in metastatic prostate cancer before chemotherapy

BACKGROUND

Enzalutamide is an oral androgen-receptor inhibitor that prolongs survival in men with metastatic castration-resistant prostate cancer in whom the disease has progressed after chemotherapy. New treatment options are needed for patients with metastatic prostate cancer who have not received chemotherapy, in whom the disease has progressed despite androgen-deprivation therapy.

METHODS

In this double-blind, phase 3 study, we randomly assigned 1717 patients to receive either enzalutamide (at a dose of 160 mg) or placebo once daily. The coprimary end points were radiographic progression-free survival and overall survival.

RESULTS

The study was stopped after a planned interim analysis, conducted when 540 deaths had been reported, showed a benefit of the active treatment. The rate of radiographic progression-free survival at 12 months was 65% among patients treated with enzalutamide, as compared with 14% among patients receiving placebo (81% risk reduction; hazard ratio in the enzalutamide group, 0.19; 95% confidence interval [CI], 0.15 to 0.23; P<0.001). A total of 626 patients (72%) in the enzalutamide group, as compared with 532 patients (63%) in the placebo group, were alive at the data-cutoff date (29% reduction in the risk of death; hazard ratio, 0.71; 95% CI, 0.60 to 0.84; P<0.001). The benefit of enzalutamide was shown with respect to all secondary end points, including the time until the initiation of cytotoxic chemotherapy (hazard ratio, 0.35), the time until the first skeletal-related event (hazard ratio, 0.72), a complete or partial soft-tissue response (59% vs. 5%), the time until prostate-specific antigen (PSA) progression (hazard ratio, 0.17), and a rate of decline of at least 50% in PSA (78% vs. 3%) (P<0.001 for all comparisons). Fatigue and hypertension were the most common clinically relevant adverse events associated with enzalutamide treatment.

CONCLUSIONS

Enzalutamide significantly decreased the risk of radiographic progression and death and delayed the initiation of chemotherapy in men with metastatic prostate cancer. (Funded by Medivation and Astellas Pharma; PREVAIL ClinicalTrials.gov number, NCT01212991.).

[Enzalutamide-a novel androgen receptor inhibitor that provides treatment options for patients with castration-resistant prostate cancer]

The recent emergence of new hormonal or chemotherapeutic drugs has resulted in a paradigm shift in the treatment of castration-resistant prostate cancer(CRPC). Enzalutamide is a rationally designed, orally administered androgen receptor(AR)inhibitor. It inhibits multiple points in the androgen receptor signalling pathway, which is considered an important driver of CRPC, including the inhibition of androgen binding to the AR, nuclear translocation of the AR complex, and binding of the AR complex to deoxyribonucleic acid(DNA). Unlike other anti-androgens(such as bicalutamide), enzalutamide does not act as a partial AR agonist. The first in human phase I/II trial was conducted in the United States in both chemotherapy-naïve patients and postchemotherapy patients with progressive metastatic CRPC(mCRPC). The results showed encouraging antitumor activity of enzalutamide by considering all outcomes assessed in the trial. The first reported phase III trial was a randomized, double-blind, placebo-controlled, multinational study involving 1,199 patients with mCRPC that progressed even after docetaxel therapy(AFFIRM trial). Enzalutamide was associated with significant benefits over the placebo considering time-to-event outcomes(i.e. prolonged overall survival[OS], delayed time to prostatic specific antigen[PSA]progression[TTPP], prolonged radiographic progression free survival[rPFS], time to the first skeletal related event[SRE])as well as objective response outcomes(i.e. PSA, soft tissue, and quality of life[QOL]). On the basis of the AFFIRM results, Astellas and Medivation filed a new drug application with the United States Food and Drug Administration and the European Medicines Agency in 2012, and obtained their approval. Another phaseI/II enzalutamide trial was conducted in both chemotherapy-naïve patients and post-chemotherapy pa- tients with progressive mCRPC. Enzalutamide at a dose of 160mg/day was well tolerated, and it showed pharmacokinetic characteristics, adverse events, and anti-tumor activity profiles similar to that of the non-Japanese population. On the basis of the results of the studies summarized above, a new drug application was submitted to the Ministry of Health, Labour, and Welfare of Japan in May 2013 and obtained the approval in Mar 2014. The second phase III trial was a randomized, double-blind, placebo-controlled, multinational study of 1,717 chemotherapy- naïve patients with CRPC(PREVAIL trial). An interim analysis recently demonstrated the significant benefits of enzalutamide over the placebo considering both OS and rPFS. In light of these results, the Independent Data Monitoring Committee (IDMC)advised terminating the study early, and suggested treating the patients in the placebo group with enzalutamide. This paper reviews the developmental history of enzalutamide, its pharmacokinetic and pharmacodynamic characteristics, as well as available efficacy and tolerability data yielded in clinical trials of patients with CRPC.