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

Novel hormonal therapies in the management of advanced prostate cancer: extrapolating Asian findings to Southeast Asia

There is a paucity of information on the use of novel hormonal agents in Southeast Asian patients. We reviewed the clinical roles of novel hormonal therapy (NHT), namely abiraterone acetate (AA), enzalutamide, apalutamide and darolutamide, in the management of advanced prostate cancer, and data on its use in Asian patients, in order to extrapolate these findings to the Southeast Asian patient population. There are some differences in the molecular features between the NHTs, which influenced their respective permeabilities through the blood-brain barrier. The Asian sub-analyses of the landmark studies of each NHT were limited. The primary endpoints of the Asian sub-analyses generally reflect the efficacy outcomes of the respective landmark study. Hypertension, fatigue, musculoskeletal disorders, rash, and hot flushes were among the common toxicities observed in Asian patients. Real-world data on AA in the Asian setting is favourable, but data is limited for enzalutamide, apalutamide and darolutamide. Based on the sub-analyses and real-world data, the efficacy and safety of NHTs in the Asian patients showed a similar trend to the respective landmark studies. The lack of clinical trials in the Southeast Asian region hampers the ability to make a robust conclusion on any specific efficacy or safety differences that may be present; clinicians must assume that the broader Asian sub-analyses and real-world data reflects Southeast Asian patients' outcomes.

Efficacy and safety of therapies for advanced prostate cancer in Asia: Evidence from a systematic literature review

OBJECTIVES

Several therapies are available for the treatment of advanced/metastatic prostate cancer (PC). However, the systematic assessment of evidence pertaining to the use of these therapies in Asian patients is lacking.

METHODS

A systematic literature review (SLR) was conducted using PubMed/Medline search in May 2021 to identify the randomized/nonrandomized controlled trials (RCTs/non-RCTs) and real-world observational studies (prospective/retrospective). Only studies published as full manuscripts in English were included if reporting the efficacy, effectiveness, and/or safety of treatments in Asian patients with advanced/metastatic PC.

RESULTS

Of the 1,898 retrieved publications, 24 studies were included. These studies had patients with nonmetastatic castration-resistant PC (n = 2), metastatic castration-sensitive PC (n = 4), and metastatic castration-resistant PC (n = 18). Study designs included RCTs (n = 7), non-RCTs (n = 2), and real-world studies (n = 15). Treatments used in included studies were abiraterone acetate plus prednisone (AAP; n = 6), enzalutamide, lutetium-177 prostate-specific membrane antigen (177Lu-PSMA; n = 4 each), docetaxel (n = 3), apalutamide, radium-223 (n = 2 each), darolutamide, cabazitaxel, and pembrolizumab (n = 1 each). The evidence from RCTs (i.e., ARAMIS, SPARTAN, ARCHES, TITAN, LATITUDE, PREVAIL) demonstrated the clinical benefits of apalutamide, darolutamide, enzalutamide, and AAP in terms of overall, disease-free, and metastasis-free survival in Asian patients. These treatments were reported to be well tolerated, with no new safety signals identified in Asian population. The efficacy and safety profiles in Asian patients were consistent with the overall trial population. Data from real-world studies supported the effectiveness and tolerability of AAP, enzalutamide, radium-223, docetaxel, cabazitaxel, 177Lu-PSMA, and pembrolizumab in patients with advanced/metastatic PC.

CONCLUSIONS

This SLR of the Asian data on therapies for advanced PC from the pivotal and real-world studies confirms similar efficacy and safety outcomes, consistent with the results from the pivotal clinical trials. These findings will help clinicians make better treatment decisions in clinical practice for patients with advanced/metastatic PC.

Enzalutamide in Chemotherapy-Naïve Metastatic Castration-Resistant Prostate Cancer: An Asian Multiregional, Randomized Study

INTRODUCTION

Enzalutamide significantly improved clinical outcomes compared with placebo in patients with chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC) with disease progression despite androgen deprivation therapy (ADT) in the PREVAIL study. However, few patients from Asia were enrolled. Our study (NCT02294461) aimed to evaluate the safety and efficacy of enzalutamide in this disease setting in patients in mainland China, Korea, Taiwan, and Hong Kong.

METHODS

In this double-blind, phase III study, patients with asymptomatic/mildly symptomatic metastatic prostate cancer and disease progression despite ADT were randomized to enzalutamide (160 mg/day) or placebo. The primary endpoint was time to prostate-specific antigen (PSA) progression. Secondary endpoints included overall survival, radiographic progression-free survival, time to first skeletal-related event (SRE), time to initiation of cytotoxic chemotherapy, PSA response ≥ 50%, best overall soft-tissue response, and safety. Pre-planned interim analysis was scheduled following approximately 175 PSA-progression events (67% of targeted total of 261 events). An additional 5-year landmark analysis of overall survival, time to antineoplastic therapy, and safety was performed.

RESULTS

The double-blind study period was stopped after interim analysis owing to the benefit of enzalutamide over placebo. Overall, 388 patients were randomized (enzalutamide, n = 198; placebo, n = 190). Baseline characteristics were balanced between treatment groups. Enzalutamide significantly reduced risk of PSA progression vs placebo (hazard ratio 0.38; 95% CI 0.27-0.52; P < 0.0001). Median time to PSA progression was 8.31 months with enzalutamide and 2.86 months with placebo. Secondary endpoints, including 5-year overall survival, were significantly improved with enzalutamide, except time to first SRE. Adverse-event incidence was similar between enzalutamide and placebo. Fatigue was the most common drug-related adverse event in both treatment groups.

CONCLUSION

Enzalutamide significantly reduced risk of PSA progression, improved secondary efficacy endpoints, and was well tolerated in chemotherapy-naïve Asian patients with mCRPC with disease progression despite ADT.

TRIAL REGISTRATION

www.

CLINICALTRIALS

gov NCT02294461.

Ethnic Pharmacogenomic Differences in the Management of Asian Patients with Metastatic Prostate Cancer

Progression to metastatic disease occurs in about half of all men who develop prostate cancer (PC), one of the most common cancers in men worldwide. Androgen deprivation therapy has been the mainstay therapy for patients with metastatic PC (mPC) since the 1940s. In the last decade, there has been unprecedented advancement in systemic therapies, e.g., taxane, androgen-signalling pathway inhibitors, and biomarker-driven targeted therapies for various stages of disease, resulting in overall survival improvement. Adding to ongoing controversies over how best to treat these patients is the recognition that ethnicity may influence prognosis and outcomes. This review discusses recent evidence for the impacts of Asian ethnicity specifically, which includes environmental, sociocultural, and genetic factors, on the approach to pharmacological management of mPC. Clear inter-ethnic differences in drug tolerability, serious adverse events (AEs), and genetic heterogeneity must all be considered when dosing and scheduling for treatment, as well as designing future precision studies in PC.

High Tumor Burden Predicts Poor Response to Enzalutamide in Metastatic Castration-Resistant Prostate Cancer Patients

Simple Summary

Several available medications are involved in the treatment of metastatic castration-resistant prostate cancer (mCRPC). In this Taiwanese mCRPC cohort receiving enzalutamide patients with high tumor burden (HTB) were defined as those with either appendicular bony metastasis or visceral metastasis. A high tumor burden reduced the PSA response rate, radiological response rate, and progression-free survival duration. In addition, patients’ comorbidities and laboratory data—such as ALP, LDH, ALT, and hemoglobin—were correlated with the treatment efficacy of enzalutamide. Our study revealed a tumor burden before the use of enzalutamide was associated with treatment outcomes. The physician can use this information to estimate the response rate of enzalutamide and help formulate a personalized treatment plan for mCRPC patients.

Abstract

To assess the predictive value of tumor burden on the biochemical response, and radiological response in Taiwanese metastatic castration-resistant prostate cancer (mCRPC) patients receiving enzalutamide. The mCRPC patients treated with enzalutamide were recruited from three hospitals. High tumor burden (HTB) was classified as metastases at either appendicular bone or visceral organ. Good prostate-specific antigen (PSA) response was defined as PSA reduction of 80%. In this cohort, there were 104 (54.2%) HTB patients and 88 (45.8%) with low tumor burden (LTB). Compared to LTB patients, fewer HTB patients had good PSA response (odds ratio: 0.43, range: 0.22–0.87, p = 0.019) and fewer radiological response (complete and partial remission) (odds ratio: 0.78, range: 0.36–1.68, p = 0.52) to enzalutamide. The disease control rate which also contained stable disease, was still lower in HTB (76.0%) than LTB group (92.9%, OR: 0.24, range: 0.07–0.77, p = 0.016) in the multivariable model. In addition, HTB patients had significantly shorter progression–free survival duration than did LTB patients (median: 8.3 vs. 21.6 months, log-rank test p = 0.003) in the univariable analysis. The tumor burden before the use of enzalutamide was associated with treatment outcomes. HTB reduced PSA response rate, radiological response rate and progression-free survival duration.

Efficacy and safety of darolutamide in Japanese patients with nonmetastatic castration-resistant prostate cancer: a sub-group analysis of the phase III ARAMIS trial

Background

Darolutamide, an oral androgen receptor inhibitor, has been approved for treating nonmetastatic castration-resistant prostate cancer (nmCRPC), based on significant improvements in metastasis-free survival (MFS) in the ARAMIS clinical trial. Efficacy and safety of darolutamide in Japanese patients are reported here.

Methods

In this randomized, double-blind, placebo-controlled phase III trial, 1509 patients with nmCRPC and prostate-specific antigen (PSA) doubling time ≤ 10 months were randomized 2:1 to darolutamide 600 mg twice daily or matched placebo while continuing androgen deprivation therapy. The primary endpoint was MFS.

Results

In Japan, 95 patients were enrolled and randomized to darolutamide (n = 62) or placebo (n = 33). At the primary analysis (cut-off date: September 3, 2018), after 20 primary end-point events had occurred, median MFS was not reached with darolutamide vs. 18.2 months with placebo (HR 0.28, 95% CI 0.11–0.70). Median OS was not reached due to limited numbers of events in both groups but favored darolutamide in the Japanese subgroup. Time to pain progression, time to PSA progression, and PSA response also favored darolutamide. Among Japanese patients randomized to darolutamide vs. placebo, incidences of treatment-emergent adverse events (TEAEs) were 85.5 vs. 63.6%, and incidences of treatment discontinuation due to TEAEs were 8.1 vs. 6.1%.

Conclusions

Efficacy outcomes favored darolutamide in Japanese patients with nmCRPC, supporting the clinical benefit of darolutamide in this patient population. Darolutamide was well tolerated; however, due to the small sample size, it is impossible to conclude with certainty whether differences in the safety profile exist between Japanese and overall ARAMIS populations.

Electronic supplementary material

The online version of this article (10.1007/s10147-020-01824-5) contains supplementary material, which is available to authorized users.

Efficacy and Safety of Non-Steroidal Anti-Androgens in Patients with Metastatic Prostate Cancer: Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Prostate cancer (PCa) is the sixth primary cause of cancer death. However, conflicts are present about the efficacy and safety of Non-steroidal anti-androgens (NSAA) for its treatment. The aim of this study was to assess the efficacy and safety of NSAAs versus any comparator for the treatment of advanced or metastatic PCa (mPCa).

METHODS

MEDLINE and the Cochrane Library were searched. References of included studies and clinicaltrials.gov were also searched for relevant studies. Only English language studies after 1990 were considered for review. Randomized controlled trials (RCTs) examining the efficacy and safety of NSAAs as compared with any other comparator including surgery or chemotherapy in mPCa patients were included. The outcomes include efficacy, safety and the tolerability of the treatment. The Cochrane Risk of Bias Assessment Tool was used for quality assessment. Two authors were independently involved in the selection, extraction and quality assessment of included studies and disagreements were resolved by discussion or by consulting a third reviewer.

RESULTS

Fifty-eight out of 1307 non-duplicate RCTs with 29154 patients were considered for the review. NSAA showed significantly better progression-free survival [PFS] (Hazard ratio [HR], 0.60; 95% confidence interval [CI], 0.46-0.78; P=0.0001), time to distant metastasis or death [TTD] (HR, 0.80; 95% CI 0.73-0.91; P<0.0001), objective response (Odds ratio [OR], 1.64; 95% CI 1.06-2.54; P=0.03) and clinical benefits (OR, 1.33; 95% CI 1.08-1.63; P=0.006) as compared to the control group. There was no significant difference observed between the groups in terms of overall survival (HR, 0.95; 95%CI, 0.87-1.03; P=0.18) and time to progression (HR, 0.93; 95% CI 0.77-1.11; P=0.43). Treatment-related adverse events were more with the NSAA group, but the discontinuation due to lack of efficacy reason was 43% significantly lesser than the control group in patients with mPCa. Rest of the outcomes were appeared to be non-significant.

CONCLUSION

Treatment with NSAA was appeared to be better efficacious with respect to PFS, TTD, and response rate with considerable adverse events when compared to the control group in patients with metastatic PCa.

An exploratory retrospective multicenter study of prognostic factors in mCRPC patients undergoing enzalutamide treatment: Focus on early PSA decline and kinetics at time of progression

BACKGROUND

Recent studies have shown that an early prostate-specific antigen (PSA) response to androgen receptor-targeting agents in metastatic castration-resistant prostate cancer (mCRPC) is associated with a better prognosis. We analyzed the early PSA response to enzalutamide (ENZ) by measuring the PSA doubling time (PSADT) and PSA velocity (PSAV) while monitoring oncologic outcomes and survival in Japanese patients.

METHODS

We analyzed a total of 241 patients with mCRPC who were treated with ENZ. The patients' median age was 75 ± 7.9 years (range, 53-93 years). There were 171 (71%) predocetaxel cases, and 70 (29%) post docetaxel cases. PSA-progression-free survival (PFS) and overall survival (OS) were assessed according to Prostate Cancer Working Group 2 criteria. This study was approved by the Institutional Review Board of Gunma University Hospital (No. 1595).

RESULTS

We observed 77 good response (GR; case in which PSA remained low after treatment) cases (31.9%), 125 acquired resistance (AR; decline in PSA after treatment followed by progression) cases (51.9%), and 39 primary resistance (PR; lack of decline in PSA) cases (16.2%). Predocetaxel, PSA-PFS, and OS were significantly higher compared with post docetaxel (PSA-PFS: 47.0 vs 13.4 weeks, P < .001; OS: not yet reached vs 80.7 weeks, P < .001). Multivariate analysis of prognostic factors, including PSA response at 4 weeks, was performed using Cox regression analysis. ECOG PS (0 vs 1-2), hemoglobin (Hb; ≥ 12.2 vs < 12.2 g/dL), time to CRPC ( ≥ 12 vs < 12 m), docetaxel treatment history (no vs yes), and a PSA reduction of 50% at 4 weeks were significant predictors of OS (all, P < .05). In cases of AR (n = 125), multivariate analysis showed that PSA kinetic factors, such as PSADT and PSAV (ng/mL/m), Hb, time to CRPC, PSADT ( ≥ 2 vs < 2 m), and PSAV ( < 20 vs ≥ 20 ng/mL/m), were all predictive of OS following PSA-progression (P < .05).

CONCLUSIONS

Our study has demonstrated that PSA dynamics after ENZ administration may be a useful prognostic factor for mCRPC patients.

Enzalutamide: A Review in Castration-Resistant Prostate Cancer

Oral enzalutamide (Xtandi^®), a second generation androgen receptor inhibitor, is indicated for the treatment of castration-resistant prostate cancer (CRPC) in numerous countries worldwide, with specific indications in this patient population varying between individual countries. Based on extensive experience in the clinical trial and/or real-world settings, oral enzalutamide 160 mg once daily is an effective and generally well tolerated treatment in a broad spectrum of patients with CRPC, including in nonmetastatic and metastatic disease and in chemotherapy-naive and -experienced metastatic CRPC. Enzalutamide is an emerging option for the treatment of men with nonmetastatic CRPC who are at high-risk for developing metastatic disease, and remains an important first-line option in chemotherapy-naive or -experienced patients with metastatic CRPC.

Prognostic factors of oncologic outcomes in metastatic chemotherapy-naïve castration-resistant prostate cancer treated with enzalutamide in actual clinical practice in East Asia

OBJECTIVES

We aimed to evaluate the prognostic factors for chemotherapy-naïve castration-resistant prostate cancer (CRPC) treated with enzalutamide in actual clinical practice using easily accessible clinical variables.

METHODS AND MATERIALS

We retrospectively reviewed the following data from 113 patients with chemotherapy-naïve CRPC treated with enzalutamide: serum levels of prostate-specific antigen (PSA), testosterone, hemoglobin, total protein, albumin, and alkaline phosphatase (ALP); platelet, neutrophil, and lymphocyte counts; neutrophil-to-lymphocyte ratios (NLRs); and liver profiles. PSA progression-free survival (PFS), radiological PFS, and overall survival were estimated by Cox regression analysis.

RESULTS

Compared with baseline levels, laboratory values at 2 months showed significantly lower PSA (160.2 ± 351.5 ng/ml vs. 47.4 ± 117.1 ng/ml) and ALP levels (201.86 ± 223.77 IU/l vs. 148.25 ± 146.81 IU/l) and a significantly higher percentage of lymphocytes (28.1% ± 10.6% vs. 31.2% ± 9.7%); those at 1 month showed a significantly lower percentage of neutrophils (61.0% ± 11.0% vs. 57.1% ± 12.5%). In the multivariate analysis, poor prognostic factors for PSA PFS were Gleason score ≥ 9 (hazard ratio [HR] 2.022; P = 0.0250); visceral metastasis (HR 3.143; P = 0.0002); high NLR (HR 1.205; P = 0.0126); and high ALP (HR 1.002; P = 0.0015). For radiological PFS, high NLR (HR 1.249; P = 0.0002) and high ALP (HR 1.002; P = 0.0001) were associated with poor outcomes. The predictors of poor overall survival were visceral metastasis (HR 3.155; P < 0.0001); high NLR (HR 1.341; P < 0.0001); and high ALP (HR 1.001; P = 0.0017).

CONCLUSION

Enzalutamide is less effective in patients with metastatic chemotherapy-naïve CRPC with Gleason scores ≥ 9, visceral metastasis, high NLR, and high ALP.

Management of patients with advanced prostate cancer in the Asia Pacific region: 'real-world' consideration of results from the Advanced Prostate Cancer Consensus Conference (APCCC) 2017

OBJECTIVE

The Asia Pacific Advanced Prostate Cancer Consensus Conference (APAC APCCC 2018) brought together 20 experts from 15 APAC countries to discuss the real-world application of consensus statements from the second APCCC held in St Gallen in 2017 (APCCC 2017).

FINDINGS

Differences in genetics, environment, lifestyle, diet and culture are all likely to influence the management of advanced prostate cancer in the APAC region when compared with the rest of the world. When considering the strong APCCC 2017 recommendation for the use of upfront docetaxel in metastatic castration-naïve prostate cancer, the panel noted possible increased toxicity in Asian men receiving docetaxel, which would affect this recommendation in the APAC region. Although androgen receptor-targeting agents appear to be well tolerated in Asian men with metastatic castration-resistant prostate cancer, access to these drugs is very limited for financial reasons across the region. The meeting highlighted that cost and access to contemporary treatments and technologies are key factors influencing therapeutic decision-making in the APAC region. Whilst lower cost/older treatments and technologies may be an option, issues of culture and patient or physician preference mean, these may not always be acceptable. Although generic products can reduce cost in some countries, costs may still be prohibitive for lower-income patients or communities. The panellists noted the opportunity for a coordinated approach across the APAC region to address issues of access and cost. Developments in technologies and treatments are presenting new opportunities for the diagnosis and treatment of advanced prostate cancer. Differences in genetics and epidemiology affect the side-effect profiles of some drugs and influence prescribing.

CONCLUSIONS

As the field continues to evolve, collaboration across the APAC region will be important to facilitate relevant research and collection and appraisal of data relevant to APAC populations. In the meantime, the APAC APCCC 2018 meeting highlighted the critical importance of a multidisciplinary team-based approach to treatment planning and care, delivery of best-practice care by clinicians with appropriate expertise, and the importance of patient information and support for informed patient choice.

Survival Outcomes, Prostate-specific Antigen Response, and Tolerance in First and Later Lines of Enzalutamide Treatment for Metastatic Castration-resistant Prostate Cancer: A Real-World Experience in Hong Kong

BACKGROUND

The present study retrospectively evaluated the efficacy and safety of enzalutamide in different lines of metastatic castration-resistant prostate cancer (mCRPC) treatment in a real-world setting.

PATIENTS AND METHODS

The clinical records of patients with mCRPC treated with enzalutamide between August 2015 and October 2017 were retrieved from all 7 public oncology centers in Hong Kong and reviewed. The primary endpoint was progression-free survival (PFS) in first (1L), second (2L), and third or fourth lines (3L or 4L) of CRPC treatment. Secondary endpoints included overall survival (OS), prostate-specific antigen (PSA) response, and tolerance.

RESULTS

Among a total of 117 patients (median age of 73 years [range, 52-90 years]), 34 (29.1%), 57 (48.7%), and 26 (19.3%) patients had enzalutamide as their 1L (chemo-naive), 2L (post-docetaxel or -abiraterone), and 3L or above treatment options. The overall PSA response rates were 43.6%, and were 73.5%, 35.1%, and 19.2% for 1L, 2L, and 3L or 4L treatment, respectively. PFS and OS were significantly associated with the line of treatment in the univariate survival analysis (1L/2L/3L and 4L; PFS, 7.1/3.9/2.2 months; OS, not reached/15.8/7.4 months; both P = .0002) but not in the multivariate analysis. The observed incidence of any fatigue (grade 1 or 2, 54.7%; grade 3 or 4, 9.4%) was much higher than reported in the AFFIRM (A Study Evaluating the Efficacy and Safety of the Investigational Drug MDV3100 [ClinicalTrials.gov Identifier: NCT00974311]) (any grade, 34%) and PREVAIL (A Multinational Phase 3, Randomized, Double-blind, Placebo-controlled Efficacy And Safety Study Of Oral Mdv3100 In Chemotherapy-naïve Patients With Progressive Metastatic Prostate Cancer Who Have Failed Androgen Deprivation Therapy [ClinicalTrials.gov Identifier: NCT00974311]) (any grade, 36%) trials; as well, grade ≥ 2 fatigue was significantly associated with 3L or 4L treatment (P = .01 in both univariate and multivariate analyses).

CONCLUSION

In the real-life setting, there was a higher incidence of enzalutamide-related fatigue than reported in the trials. Earlier lines of enzalutamide treatment were associated with longer PFS and OS, more frequent PSA response, and less fatigue.