Abiraterone Followed by Enzalutamide Versus Enzalutamide Followed by Abiraterone in Chemotherapy-naive Patients With Metastatic Castration-resistant Prostate Cancer

French AFU Cancer Committee Guidelines - Update 2024-2026: Prostate cancer - Management of metastatic disease and castration resistance

PURPOSE OF THIS DOCUMENT

The Oncology Committee of the French Urology Association is proposing updated recommendations for the management of recurrent and/or metastatic prostate cancer (PCa).

METHODS

A systematic review of the literature from 2022 to 2024 was conducted by the CCAFU on the therapeutic management of recurrent PCa following local or metastatic treatment, assessing the references based on their level of evidence.

RESULTS

Molecular imaging is the standard approach for assessing recurrence after local treatment and should not delay early salvage treatment. Androgen deprivation therapy (ADT) is the primary treatment option for metastatic PCa. Intensification of ADT, now cononsidered standard care for metastatic PCa, involves incorporating at least one new-generation hormone therapy (ARPI). For patients with high-volume metastatic disease at diagnosis, adding docetaxel to ADT+ARPI may be considered for eligible patients. In castration-resistant PCa (CRPC) patients, poly(ADP) ribose polymerase (PARP) inhibitors and PSMA radioligand therapy are new treatment options. The combination and sequencing of treatmentsare influenced by several factors, including patient and disease characteristics, prior therapies, genomic status, and molecular imaging findings.

CONCLUSION

This update of French recommendations should help to improve the management recurrent or metastatic PCa patients.

Hormonal Agents in Localized and Advanced Prostate Cancer: Current Use and Future Perspectives

Prostate cancer (PC) is generally a hormone-dependent tumor. Androgen deprivation therapy ( has been the standard of care in metastatic disease for more than 80 years. Subsequent studies have highlighted the efficacy of ADT even in earlier disease settings such as in localized disease or in the case of biochemical recurrence (BCR). Improved knowledge of PC biology and ADT resistance mechanisms have led to the development of novel generation androgen receptor pathway inhibitors (ARPI). Initially used only in patients who became resistant to ADT, ARPI have subsequently shown to be effective when used in patients with metastatic hormone-naive disease and in recent years their effectiveness has also been evaluated in localized disease and in case of BCR. The objective of this review is to describe the current role of agents interfering with the androgen receptor in different stages of PC and to point out future perspectives.

Second-line treatment options in metastatic castration-resistant prostate cancer after progression on first-line androgen-receptor targeting therapies: A systematic review and Bayesian network analysis

OBJECTIVE

To summarize and indirectly compare the efficacy and safety of different second-line systematic therapies after first-line androgen-receptor targeting therapies (ARTs) for biomarker-unselected metastatic castration-resistant prostate cancer (mCRPC) patients.

METHODS

Studies published in English up to May 2023 were identified in PubMed, Web of Science and ASCO-GU 2023. Studies accessing the efficacy and safety of second-line systematic therapies after first-line ARTs for biomarker-unselected mCRPC patients were eligible for current systematic review and network meta-analysis (NMA).

RESULTS

Thirty-two studies with 5388 patients and 10 unique treatment modalities met our inclusion criteria. Current evidence suggested that docetaxel (DOC) combined with the same ART as first-line (ART1) (ART1 + DOC) were associated with significantly improved PSA response, PSA progression-free survival (PFS) and clinical or radiographic PFS (rPFS) compared with other reported second-line systematic therapies, including DOC. An increase in toxicity was observed with ART1 + DOC. Our NMA indicated that DOC monotherapy was only inferior to ART1 + DOC in improvement disease outcomes. The incidence of toxicity between patients received second-line DOC and an alternative ART (ART2) was similar.

CONCLUSION

The available evidence reviewed in our work suggested a clinical benefit of DOC nomotherapy and DOC plus ART1 as the second-line systematic therapy for biomarker-unselected mCRPC patients progressed on a first-line ART. More studies and RCTs are needed to evaluate the optimal second-line treatments for mCRPC patients with one prior first-line ART.

Stereotactic body radiation therapy to postpone systemic therapy escalation for castration-resistant prostate cancer: A multicenter retrospective analysis

Purpose

To evaluate the oncological outcome after stereotactic body radiation therapy (SBRT) for oligoprogressive metastatic castration-resistant prostate cancer (omCRPC) patients.

Materials-Methods

In this retrospective, observational, multi-institutional study, omCRPC patients (≤5 metastases) underwent SBRT. Primary endpoint was systemic therapy escalation-free survival (STE-FS) after SBRT. Local relapse (LR), distant (DP) and isolated biochemical (iBP) progressions were reported with progression-free survival (PFS) and overall survival (OS). Prognostic factors for STE-FS were investigated. Toxicity was reported.

Results

From 01/07 to 09/19, 50 pts with omCRPC underwent SBRT. With a MFU of 23 months [3---100], median STE-FS was 13.1 months (95 %CI 10.8 - 36.4). Median OS was not reached and PFS was 13 months (CI95% 10.1 - 20.8). Post-SBRT PSA remained stable or decreased in 19 pts (38 %). Progression events (LR, DP, iBP) were observed in 34 pts (68 %), among whom 6 relapsed in the irradiated area (local control rate: 88 %). DP and iBP were observed in 28 pts (56 %) and 4 pts (8 %) respectively. In multivariate analysis, post-SBRT biochemical response was an independent prognostic factor for STE-FS. Grade ≥ 3 toxicity occurred in 2 pts.

Conclusion

With excellent local control and tolerance, SBRT for omCRPC patients represents an acceptable approach to defer systemic therapeutic escalation and prevent its side effects. Accurate patient selection for SBRT requires more data with longer follow-up and higher numbers of patients pending the results of upcoming randomized trials.

The prognostic value of Eastern Cooperative Oncology Group performance status on overall survival among patients with metastatic prostate cancer: a systematic review and meta-analysis

Background

There is heterogeneity in the literature regarding the strength of association between Eastern Cooperative Oncology Group performance status (ECOG PS) and mortality. We conducted a systematic review and meta-analysis of studies reporting the prognostic value of ECOG PS on overall survival (OS) in metastatic prostate cancer (mPC).

Methods

PubMed was searched from inception to March 21, 2022. A meta-analysis pooling the effect of ECOG PS categories (≥2 vs. <2, 2 vs. <2, and ≥1 vs. <1) on OS was performed separately for studies including patients with metastatic castration-resistant prostate cancer (mCRPC) and metastatic castration-sensitive prostate cancer (mCSPC) using a random-effects model. Analyses were stratified by prior chemotherapy and study type.

Results

Overall, 75 studies, comprising 32,298 patients, were included. Most studies (72/75) included patients with mCRPC. Higher ECOG PS was associated with a significant increase in mortality risk, with the highest estimate observed among patients with mCRPC with an ECOG PS of ≥2 versus <2 (hazard ratio [HR]: 2.10, 95% confidence interval [CI]: 1.87-2.37). When stratifying by study type, there was a higher risk estimate of mortality among patients with mCRPC with an ECOG PS of ≥1 versus <1 in real-world data studies (HR: 1.98, 95% CI: 1.72-2.26) compared with clinical trials (HR: 1.32, 95% CI: 1.13-1.54; p < 0.001). There were no significant differences in the HR of OS stratified by previous chemotherapy.

Conclusion

ECOG PS was a significant predictor of OS regardless of category, previous chemotherapy, and mPC population. Additional studies are needed to better characterize the effect of ECOG PS on OS in mCSPC.

Real-world outcomes for first line next-generation hormonal agents in metastatic prostate cancer: a systematic review

Aim: This review aims to summarize published evidence on the real-world (RW) outcomes of abiraterone or enzalutamide in first-line metastatic castration-resistant prostate cancer. Materials & methods: Studies reporting on RW effectiveness, safety, economic and/or health-related quality of life outcomes were identified by systematic literature review (2011-2021, incl. Embase®, MEDLINE®) and presented in a qualitative synthesis. Risk of bias was assessed using ROBINS-I or the Molinier checklist. Results: 88 studies (n = 83,427 patients) were included. Median progression-free (40 studies) and overall survival (38 studies) ranged from 3.7 to 20.9 months and 9.8 to 45 months, respectively. Survival, safety and economic outcomes were similar across individual treatments, while limited health-related quality of life evidence suggested improvements with abiraterone. Risk of bias was moderate to high. Conclusion: RW outcomes in first-line metastatic castration-resistant prostate cancer remain poor despite treatment, highlighting an unmet need for new regimens. This review was supported by AstraZeneca and Merck Sharp & Dohme.

Taxanes Versus Androgen Receptor Therapy as Second-Line Treatment for Castrate-Resistant Metastatic Prostate Cancer After First-Line Androgen Receptor Therapy

BACKGROUND

The optimal therapeutic sequence for metastatic castrate-resistance prostate cancer (mCRPC) is still debated. This study aimed to compare activity of taxanes (TAX) versus that of androgen-receptor therapy (ART) in men with mCRPC treated with first-line ART.

PATIENTS AND METHODS

This retrospective study included all consecutive chemo-naive mCRPC patients who have received first-line ART treatment. Progression-free survival (PFS) and overall survival (OS) were compared between patients treated with second-line ART or TAX.

RESULTS

Overall, 175 patients treated with first-line enzalutamide (ENZA, n = 75) or abiraterone (ABI, n = 100) were evaluated. Among them, 69 (39%) and 30 (17%) patients received second-line TAX and ART, respectively, while 76 (43%) patients did not receive further treatment. From the start of first-line therapy, the median PFS and OS were 13 months (95% CI: 11-15) and 34 months (95% CI: 29-39), respectively, without any significant difference between ENZA and ABI. From the start of second-line therapy, the median PFS and OS were 6 months (95% CI: 5-7) and 18 months (95% CI: 14-21), respectively. Compared with ART, docetaxel was associated with significantly higher prostate-specific antigen (PSA, ≥ 50%) (29% vs. 0%, P < .001) and radiological responses (21% vs. 0%, P < .001). PFS was longer in TAX than in ART (6.7 months vs. 4 months, HR: 0.63, 95% CI: 0.41-0.96, P = .034), but there was no significant difference in OS (19 months vs. 12 months, P = .1). After propensity score adjustment, PFS (P = .2) and OS (P = .1) were similar between second-line TAX and ART.

CONCLUSION

In the second-line setting, TAX provides higher PSA and radiological responses than does ART for mCRPC patients who received first-line ART, but the PFS and OS are similar. This study provides new elements to help deciding the best treatment sequence.

Treatment Patterns Among Patients With Advanced Prostate Cancer in Brazil: An Analysis of a Private Healthcare System Database

Background

With the ongoing expansion of life-prolonging therapies approved to treat advanced prostate cancer, there is currently an unmet need to better understand real-world treatment patterns and identify optimal treatment sequencing for men with metastatic castration-resistant prostate cancer (mCRPC).

Methods

In this retrospective, observational cohort analysis, patients with confirmed mCRPC were identified in the Auditron claims database and used to describe mCRPC treatment patterns and trends in the Brazilian private healthcare system from 2014 to 2019. Demographics and clinical characteristics, prostate cancer stage at diagnosis, and type and number of treatment lines were evaluated. The primary endpoint was identification of the drugs used in first-line therapies in mCRPC, and the secondary endpoint included a description of sequential lines of therapy (second and third lines) in mCRPC.

Results

A total of 168 electronic patient records were reviewed. Docetaxel was the most frequently used first-line treatment (35.7%), followed by abiraterone (33.3%) and enzalutamide (13.1%). Docetaxel, abiraterone, and enzalutamide also accounted for 34.6%, 28.0%, and 15.0%, respectively, of second-line therapies. In third-line therapies, cabazitaxel (26.1%), enzalutamide (23.9%), docetaxel (15.2%), and abiraterone (15.2%) were most commonly prescribed. Irrespective of stage at diagnosis, treatment patterns were similar once the disease progressed to the metastatic castration-resistance stage.

Conclusions

Docetaxel was the most frequently utilized therapy for mCRPC treatment, followed by abiraterone and enzalutamide. Although the current analyses provide real-world insights into treatment patterns for patients with mCRPC in Brazil, additional real-world data are needed to further validate and expand on these findings.

TRANSFORMER: A Randomized Phase II Study Comparing Bipolar Androgen Therapy Versus Enzalutamide in Asymptomatic Men With Castration-Resistant Metastatic Prostate Cancer

PURPOSE

Prostate cancer (PCa) becomes resistant to androgen ablation through adaptive upregulation of the androgen receptor in response to the low-testosterone microenvironment. Bipolar androgen therapy (BAT), defined as rapid cycling between high and low serum testosterone, disrupts this adaptive regulation in castration-resistant PCa (CRPC).

METHODS

The TRANSFORMER (Testosterone Revival Abolishes Negative Symptoms, Fosters Objective Response and Modulates Enzalutamide Resistance) study is a randomized study comparing monthly BAT (n = 94) with enzalutamide (n = 101). The primary end point was clinical or radiographic progression-free survival (PFS); crossover was permitted at progression. Secondary end points included overall survival (OS), prostate-specific antigen (PSA) and objective response rates, PFS from randomization through crossover (PFS2), safety, and quality of life (QoL).

RESULTS

The PFS was 5.7 months for both arms (hazard ratio [HR], 1.14; 95% CI, 0.83 to 1.55; P = .42). For BAT, 50% decline in PSA (PSA50) was 28.2% of patients versus 25.3% for enzalutamide. At crossover, PSA50 response occurred in 77.8% of patients crossing to enzalutamide and 23.4% to BAT. The PSA-PFS for enzalutamide increased from 3.8 months after abiraterone to 10.9 months after BAT. The PFS2 for BAT→enzalutamide was 28.2 versus 19.6 months for enzalutamide→BAT (HR, 0.44; 95% CI, 0.22 to 0.88; P = .02). OS was 32.9 months for BAT versus 29.0 months for enzalutamide (HR, 0.95; 95% CI, 0.66 to 1.39; P = .80). OS was 37.1 months for patients crossing from BAT to enzalutamide versus 30.2 months for the opposite sequence (HR, 0.68; 95% CI, 0.36 to 1.28; P = .225). BAT adverse events were primarily grade 1-2. Patient-reported QoL consistently favored BAT.

CONCLUSION

This randomized trial establishes meaningful clinical activity and safety of BAT and supports additional study to determine its optimal clinical integration. BAT can sensitize CRPC to subsequent antiandrogen therapy. Further study is required to confirm whether sequential therapy with BAT and enzalutamide can improve survival in men with CRPC.

Cross-resistance and drug sequence in prostate cancer

The treatment landscape of advanced prostate cancer has widely expanded over the past years with androgen receptor signaling inhibitors (ARSIs) and taxane chemotherapy moving to earlier disease stages in the treatment of prostate cancer. With the increasing use of ARSIs in earlier disease stages, cross-resistance between treatments has emerged, which is a dominant impediment in current clinical practice. To overcome cross-resistance in the treatment of prostate cancer, it is of paramount importance to decipher the mechanisms of cross-resistance between ARSIs and between ARSIs and chemotherapy. Here, molecular mechanisms of resistance to the available therapies including androgen receptor (AR) splice variants, AR overexpression, AR mutations and glucocorticoid receptor upregulation are described. Based on these underlying mechanisms, clinical data of cross-resistance between ARSIs and chemotherapy have been reported. Only recently these data have been confirmed in prospective randomized trials. From these studies, it has become clear that sequential ARSI treatment has no place in the treatment of advanced prostate cancer due to emerging drug resistance. In addition, based on prospective evidence, we argue that it is worth considering an early switch to cabazitaxel treatment in case of lack of benefit on docetaxel regimen after an ARSI treatment. Based on these new insights from randomized trials, several recommendations for treatment sequence are proposed.

Optimizing outcomes for patients with metastatic prostate cancer: insights from South East Asia Expert Panel

AIMS

Clinical decision making is challenging in men with metastatic prostate cancer (mPC), as heterogeneity in treatment options and patient characteristics have resulted in multiple scenarios with little or no evidence. The South East Asia Expert Panel 2019 addressed some of these challenges.

METHODS

Based on evidence in the literature and expert interviews, 19 statements were formulated for key challenges in the treatment of men with castration-sensitive and -resistant prostate cancer in clinical practice. A modified Delphi process was used to reach consensus among experts in the panel and develop clinical practice recommendations.

RESULTS

The majority of the panel preferred a risk-based stratification and recommended abiraterone or enzalutamide as first-line therapy for symptomatic chemotherapy naïve patients. Abiraterone is preferred over enzalutamide as a first-line treatment in these patients. However, the panel did not support the use of abiraterone in high risk lymph-node positive only (N+M0) or in non-metastatic (N0M0) patients. In select patients, low dose abiraterone with food may be used to optimize clinical outcomes. Androgen receptor gene splice variant status may be a useful guide to therapy. In addition, generic versions of approved therapies may improve access to treatment to a broader patient population. The choice of treatment, as well as sequencing are guided by both patient and disease characteristics, preferences, drug access, cost, and compliance.

CONCLUSION

Expert recommendations are key to guidance for the optimal management of mPC. Appropriate choice, timing, and sequence of treatment options can help to tailor therapy to maximize outcomes in men with mPC.

Androgen Deprivation Induces Transcriptional Reprogramming in Prostate Cancer Cells to Develop Stem Cell-Like Characteristics

Enzalutamide, an antiandrogen, is approved for therapy of castration resistant prostate cancer. Clinical applications have shown that approximately 30% of patients acquire resistance after a short period of treatment. However, the molecular mechanisms underlying this resistance is not completely understood. To identify transcriptomic signatures associated with acquisition of drug resistance we profiled gene expression of paired enzalutamide sensitive and resistant human prostate cancer LNCaP (lymph node carcinoma of the prostate) and C4-2B cells. Overlapping genes differentially regulated in the enzalutamide resistant cells were ranked by Ingenuity Pathway Analysis and their functional validation was performed using ingenuity knowledge database followed by confirmation to correlate transcript with protein expression. Analysis revealed that genes associated with cancer stem cells, such as POU5F1 (OCT4), SOX2, NANOG, BMI1, BMP2, CD44, SOX9, and ALDH1 were markedly upregulated in enzalutamide resistant cells. Amongst the pathways enriched in the enzalutamide-resistant cells were those associated with RUNX2, hedgehog, integrin signaling, and molecules associated with elastic fibers. Further examination of a patient cohort undergoing ADT and its comparison with no-ADT group demonstrated high expression of POU5F1 (OCT4), ALDH1, and SOX2 in ADT specimens, suggesting that they may be clinically relevant therapeutic targets. Altogether, our approach exhibits the potential of integrative transcriptomic analyses to identify critical genes and pathways of antiandrogen resistance as a promising approach for designing novel therapeutic strategies to circumvent drug resistance.

The clinical benefit of sequential therapy with androgen receptor axis-targeted agents alone in patients with castration-resistant prostate cancer: A propensity score-matched comparison study

BACKGROUND

The optimal sequential therapy for castration-resistant prostate cancer (CRPC) remains unknown. In recent years, some doubts have emerged regarding the clinical benefit of sequential therapy with androgen receptor axis-targeted agents (ART) such as abiraterone (ABI) or enzalutamide (ENZ) for patients with CRPC. We compared the effect of ART-to-ART (AA) sequential therapy after castration resistance with that of docetaxel (DTX)-combined sequential therapy (ART to DTX or DTX to ART) in patients with CRPC.

METHODS

We retrospectively identified and analyzed the data of 315 patients with CRPC treated in our seven affiliated institutions between 2009 and 2019. All patients received either DTX or ART (ABI or ENZ) as the first- or second-line therapy after castration resistance. We compared the overall survival (OS) and the second progression-free survival (PFS2), calculated from the initiation of first-line therapy after castration resistance, between the AA sequence group and the DTX-combined sequence group. PFS2 was defined as the period from the start of first-line treatment after castration resistance to progression on second-line treatment. To minimize selection bias from possible confounders, we performed propensity score matching using one-to-one nearest neighbor matching without replacement.

RESULTS

Overall, 106 and 209 patients were administered the AA sequential therapy and DTX-combined sequential therapy, respectively. The clinicopathological variables of patients were well balanced after propensity score matching, and there were no significant differences between the two groups. In the propensity score-matched cohort, OS was not significantly different between the two groups (median, 37.9 vs. 45.4 months; hazard ratio [HR], 1.10; 95% confidence interval [CI], 0.68-1.79; p = .701), while PFS2 was significantly shorter in the AA group than in the DTX-combined group (median, 12.9 vs. 21.6 months; HR, 1.70; 95% CI, 1.16-2.48; p = .007).

CONCLUSIONS

Certain patients with CRPC can benefit from ART-to-ART sequential therapy in a daily clinical setting.

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.).

Sequential therapy of abiraterone and enzalutamide in castration-resistant prostate cancer: a systematic review and meta-analysis

BACKGROUND

This systematic review and meta-analysis aimed to assess the prognostic value of sequential of abiraterone (ABI) and enzalutamide (ENZ) therapy in patients with castration-resistant prostate cancer (CRPC).

METHODS

PUBMED, Web of Science, Cochrane Library, and Scopus databases were searched for articles published prior to December 2019 according to the Preferred Reporting Items for Systematic Review and Meta-analysis statement. Studies were deemed eligible if they compared overall survival (OS), combined progression-free survival (PFS), combined prostate specific antigen (PSA)-PFS, and PSA response rates in CRPC patients receiving sequential ABI/ENZ or vice versa. PSA response to both the first and second agents was defined as a >50% decrease in PSA achieved with each of these agents. Formal meta-analyses were performed for these outcomes.

RESULTS

Ten studies with 1096 patients were eligible for the systematic review and eight studies with 643 patients for the meta-analysis. The ABI-to-ENZ sequence was significantly associated with better PFS (pooled hazard ratio (HR): 0.62, 95% confidential interval (CI): 0.49-0.78, P < 0.001), and PSA-PFS (pooled HR: 0.48, 95% CI: 0.38-0.61, P < 0.001) than the ENZ-to-ABI sequence. PSA response rates of both agents were significantly better with the ABI-to-ENZ sequence (risk ratio: 0.21, 95% CI: 0.09-0.47, P < 0.001). In contrast, treatment sequence was not significantly associated with OS (pooled HR: 0.77, 95% CI: 0.59-1.01, P = 0.055).

CONCLUSIONS

ABI-to-ENZ sequential therapy in patients with CRPC was associated with better PFS, PSA-PFS, and PSA response rates. Regardless of sequencing, response to drug therapy was transient for both ABI and ENZ when either agent was used as a secondary therapy. Despite this, treatment sequencing is important to achieve the maximum possible benefit from available drugs in CRPC.

Comparison of Oncologic Outcomes Between Two Alternative Sequences with Abiraterone Acetate and Enzalutamide in Patients with Metastatic Castration-Resistant Prostate Cancer: A Systematic Review and Meta-Analysis

Sequential treatment of androgen receptor axis targeted agents (ARAT), abiraterone acetate (ABI) and enzalutamide (ENZA), in metastatic castration-resistant prostate cancer (mCRPC) demonstrated some positive effects, but cross-resistances between ABI and ENZA that reduce activity have been suggested. Therefore, we conducted a meta-analysis to compare oncologic outcomes between the treatment sequences of ABI-ENZA and ENZA-ABI in patients with mCRPC. The primary endpoint was a combined progression-free survival (PFS), and the secondary endpoint was overall survival (OS). A total of five trials on 553 patients were included in this study. Each of the included studies was retrospective. In two studies including both chemo-naïve and post-chemotherapy mCRPC patients, for ABI-ENZA compared with ENZA-ABI, pooled hazard ratios (HRs) for PFS and OS were 0.37 (p < 0.0001; 95% confidence intervals (CIs), 0.23–0.60) and 0.64 (p = 0.10; 95% CIs, 0.37–1.10), respectively. In three studies with chemo-naïve mCRPC patients only, for ABI-ENZA compared with ENZA-ABI, pooled HRs for PFS and OS were 0.57 (p = 0.02; 95% CIs, 0.35–0.92) and 0.86 (p = 0.39; 95% CIs, 0.61–1.21), respectively. The current meta-analysis revealed that ABI-ENZA had a significantly more favorable oncological outcome, but the level of evidence was low. Therefore, large-scale randomized trials may be needed.

Real-world outcome with abiraterone acetate plus prednisone in Asian men with metastatic castrate-resistant prostate cancer: The Singapore experience

INTRODUCTION

Several small studies have reviewed the efficacy of abiraterone acetate plus prednisolone (AAP) in clinical practice outside a trial setting. We report the largest cohort study of clinical outcomes in metastatic castrate-resistant prostate cancer (mCRPC) patients treated with AAP in a multicenter multiracial clinical setting.

METHODS

A retrospective analysis on mCRPC patients treated at four tertiary hospitals in Singapore from 2012 to 2017 was conducted. Disease characteristics, treatment outcomes, and adverse events were retrieved from electronic medical records. Primary clinical end-point was overall survival (OS). A subset analysis of patients with various variables and OS curves were generated using the Kaplan-Meier method and compared using the log-rank test.

RESULTS

Out of 200 patients with mCRPC treated with AAP, 163 (81.5%) patients were chemo-naïve (CN) and 37 (18.5%) patients were postchemotherapy (PC), with the median age of 68 (34-87) and 65 (52-80) years, respectively. Median OS was 20.0 (95% CI, 18.3-22.9) and 10.5 months (95% CI, 1.1-40.5) for CN and PC cohorts, respectively. A subset analysis of 108 patients showed a significantly longer OS in patients who had prior ADT for more than 12 months in CN patients (P < 0.001). Incidences of G3/G4 events were around 6.6%; most common side effect being hypertension with an incidence of 2.4%.

CONCLUSIONS

Treatment of CN and PC patients with AAP was associated with a comparable OS and progression-free survival to the reported series. Patients who were responsive to prior ADT of 12 months or more were associated with an improved OS.

Managing lines of therapy in castration-resistant prostate cancer: real-life snapshot from a multicenter cohort

PURPOSE

To provide a snapshot of toxicities and oncologic outcomes of Abiraterone (AA) and Enzalutamide (EZ) in a chemo-naïve metastatic castration-resistant prostate cancer (mCPRC) population from a longitudinal real-life multicenter cohort.

METHODS

We prospectively collected data on chemo-naïve mCRPC patients treated with AA or EZ. Primary outcomes were PSA response, oncologic outcomes and toxicity profile. The Kaplan-Meier method was used to compare differences in terms of progression-free survival (PFS) between AA vs EZ and high- vs low-volume disease cohorts. Univariable and multivariable Cox regression analyses were performed to identify predictors of PFS. Toxicity, PSA response rates and oncologic outcomes on second line were compared with those observed on first line.

RESULTS

Out of 137 patients, 88 received AA, and 49 EZ. On first line, patients receiving EZ had significantly higher PSA response compared with AA (95.9% vs 67%, p < 0.001), comparable toxicity rate (10.2% vs 16.3%, p = 0.437) and PFS probabilities (p = 0.145). Baseline PSA and high-volume disease were predictors of lower PFS probabilities at univariable analysis (p = 0.027 and p = 0.007, respectively). Overall, 28 patients shifted to a second-line therapy (EZ or radiometabolic therapy). Toxicity and PSA response rates on second line were comparable to those observed on first line (11.1% vs 12.4%, p = 0.77; 73.1% vs 77.4%, p = 0.62, respectively); 2-year PFS, cancer-specific and overall survival probabilities were comparable to those displayed in first-line cohort (12.1% vs 16.2%, p = 0.07; 85.7% vs 86.4%, p = 0.98; 71% vs 80.3%, p = 0.66, respectively).

CONCLUSIONS

Toxicity profile, PSA response rate and oncological outcomes were comparable between first-line and second-line courses in patients treated with either AA or EZ for mCRPC. Our findings showed the tolerability and oncological effectiveness, when feasible, of two lines of therapy other than chemotherapy.

Real-world Outcomes of Sequential Androgen-receptor Targeting Therapies with or Without Interposed Life-prolonging Drugs in Metastatic Castration-resistant Prostate Cancer: Results from the Dutch Castration-resistant Prostate Cancer Registry

BACKGROUND

Cross resistance between androgen-receptor targeting therapies (ARTs) (abiraterone acetate plus prednisone [ABI+P] or enzalutamide [ENZ]) for treatment of metastatic castration-resistant prostate cancer (mCRPC) may affect responses to second ART (ART2).

OBJECTIVE

To establish treatment duration and prostate-specific antigen (PSA) response of ART2 in real-world mCRPC patients treated with or without other life-prolonging drugs (LPDs; ie, docetaxel, cabazitaxel, or radium-223) between ART1 and ART2.

DESIGN, SETTING, AND PARTICIPANTS

Castration-resistant prostate cancer patients, diagnosed between 2010 and 2016 were retrospectively registered in Castration-resistant Prostate Cancer Registry (CAPRI). Patients treated with both ARTs were clustered into two subgroups: ART1>ART2 or ART1>LPD>ART2.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Outcomes were ≥50% PSA response and treatment duration of ART2. Descriptive statistics and binary logistic regression after multiple imputations were performed.

RESULTS AND LIMITATIONS

A total of 273 patients were included with a median follow-up of 8.4 mo from ART2. Patients with ART1>ART2 were older and had favourable prognostic characteristics at ART2 baseline compared with patients with ART1>LPD>ART2. No differences between ART1>ART2 and ART1>LPD>ART2 were found in PSA response and treatment duration. Multivariate analysis suggested that PSA response of ART2 was less likely in patients with visceral metastases (odds ratio [OR] 0.143, p=0.04) and more likely in patients with a relatively longer duration of androgen-deprivation treatment (OR 1.028, p=0.01) and with ABI + P before ENZ (OR 3.192, p=0.02). A major limitation of this study was missing data, a common problem in retrospective observational research.

CONCLUSIONS

The effect of ART2 seems to be low, with a low PSA response rate and a short treatment duration irrespective of interposed chemotherapy or radium-223, especially in patients with short time on castration, visceral disease, and ENZ before ABI+P.

PATIENT SUMMARY

We observed no differences in outcomes of patients treated with sequential abiraterone acetate plus prednisone (ABI+P) and enzalutamide (ENZ) with or without interposed chemotherapy or radium-223. In general, outcomes were lower than those in randomised trials, questioning the additional effect of second treatment with ABI+P or ENZ in daily practice.

The Effect of Treatment Sequence on Overall Survival for Men With Metastatic Castration-resistant Prostate Cancer: A Multicenter Retrospective Study

INTRODUCTION

We aimed to evaluate the treatment sequence for patients with metastatic castration-resistant prostate cancer (mCRPC) in real-world practice and compare overall survival in each sequential therapy.

PATIENTS AND METHODS

We retrospectively evaluated 146 patients with mCRPC who were initially treated with androgen deprivation therapy as metastatic hormone-naive prostate cancer in 14 hospitals between January 2010 and March 2019. The agents for the sequential therapy included new androgen receptor-targeted agents (ART: abiraterone acetate or enzalutamide), docetaxel, and/or cabazitaxel. We evaluated the treatment sequence for mCRPC and the effect of sequence patterns on overall survival.

RESULTS

The median age was 71 years. A total of 35 patients received ART-ART, 33 received ART-docetaxel, 68 received docetaxel-ART, and 10 received docetaxel-cabazitaxel sequences. The most prescribed treatment sequence was docetaxel-ART (47%), followed by ART-ART (24%). Overall survival calculated from the initial diagnosis reached 83, 57, 79, and 37 months in the ART-ART, ART-docetaxel, docetaxel-ART, and docetaxel-cabazitaxel, respectively. Multivariate Cox regression analyses showed no significant difference in overall survival between the first-line ART (n = 68) and first-line docetaxel (n = 78) therapies (hazard ratio [HR], 0.84; P = .530), between the ART-ART (n = 35) and docetaxel-mixed (n = 111) sequences (HR, 0.82; P = .650), and between the first-line abiraterone (n = 32) and first-line enzalutamide (n = 36) sequences (HR, 1.58; P = .384).

CONCLUSION

The most prescribed treatment sequence was docetaxel followed by ART. No significant difference was observed in overall survival among the treatment sequences in real-world practice.

Comparison of Radiographic Progression-Free Survival and PSA Response on Sequential Treatment Using Abiraterone and Enzalutamide for Newly Diagnosed Castration-Resistant Prostate Cancer: A Propensity Score Matched Analysis from Multicenter Cohort

Background: There is emerging evidence that radiographic progression-free survival (rPFS) is highly correlated with overall survival (OS), potentially serving as an indicator of treatment outcome for castration-resistant prostate cancer (CRPC). The objective of this study is to assess rPFS and prostate specific antigen (PSA) response in sequential treatment using androgen signaling inhibitors (ASIs) including abiraterone and enzalutamide in newly diagnosed CRPC. Methods: Propensity score matching was performed to reduce bias by confounding factors between first-line ASIs. The primary endpoints of the study included rPFS, time to PSA progression (TTPP), and PSA response. Results: A paired-matched group of 184 patients were identified. From the initiation of first-line ASIs, there was no significant difference in rPFS, TTPP, and PSA response between treatment arms. From the initiation of second-line ASIs, enzalutamide following abiraterone consistently exhibited longer rPFS (median: 7 and 15 months, p = 0.04), TTPP, and better PSA response compared to the reverse, whereas OS did not reach significance (median: 14 and 23 months, p = 0.35). Conclusion: Although the effect of ASIs as the first line was similar, the extent of cross-resistance might differ towards less resistance in enzalutamide following abiraterone than the reverse.

A bypass mechanism of abiraterone-resistant prostate cancer: Accumulating CYP17A1 substrates activate androgen receptor signaling

BACKGROUND

Intratumoral steroidogenesis and its potential relevance in castration-resistant prostate cancer (CRPC) and in cytochrome P450, family 17, subfamily A, polypeptide 1 (CYP17A1)-inhibitor treated hormone-naïve and patients with CRPC are not well established. In this study, we tested if substrates for de novo steroidogenesis accumulating during CYP17A1 inhibition may drive cell growth in relevant preclinical models.

METHODS

PCa cell lines and their respective CRPC sublines were used to model CRPC in vitro. Precursor steroids pregnenolone (Preg) and progesterone (Prog) served as substrate for de novo steroid synthesis. TAK700 (orteronel), abiraterone, and small interfering RNA (siRNA) against CYP17A1 were used to block CYP17A1 enzyme activity. The antiandrogen RD162 was used to assess androgen receptor (AR) involvement. Cell growth was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. AR-target gene expression was quantified by reverse transcription polymerase chain reaction (RT-PCR). Nuclear import studies using cells with green fluorescent protein (GFP)-tagged AR were performed to assess the potential of precursor steroids to directly activate AR.

RESULTS

Preg and Prog stimulated cell proliferation and AR target gene expression in VCaP, DuCaP, LNCaP, and their respective CRPC sublines. The antiandrogen RD162, but not CYP17A1 inhibition with TAK700, abiraterone or siRNA, was able to block Preg- and Prog-induced proliferation. In contrast to TAK700, abiraterone also affected dihydrotestosterone-induced cell growth, indicating direct AR binding. Furthermore, Prog-induced AR translocation was not affected by treatment with TAK700 or abiraterone, while it was effectively blocked by the AR antagonist enzalutamide, further demonstrating the direct AR activation by Prog.

CONCLUSION

Activation of the AR by clinically relevant levels of Preg and Prog accumulating in abiraterone-treated patients may act as a driver for CRPC. These data provide a scientific rationale for combining CYP17A1 inhibitors with antiandrogens, particularly in patients with overexpressed or mutated-AR.

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.