Comparing the clinical efficacy and safety of abiraterone and enzalutamide in metastatic castration-resistant prostate cancer: A systematic review and meta-analysis

Real-life Data on First- and Second-Line Treatment of Metastatic Castration-Resistant Prostate Cancer With Abiraterone, Enzalutamide and Cabazitaxel - A multicentric Study From Portugal

INTRODUCTION AND OBJECTIVES

New drugs for metastatic castrate resistant prostate cancer (mCRPC) were approved, first in the pos-docetaxel and then in the pre-docetaxel setting. We aim to assess the real daily practice benefit of abiraterone (Abi), enzalutamide (Enz) and cabazitaxel (Cab) in patients with mCRPC, compare it with RCT results and compare Abi vs Enz.

MATERIALS AND METHODS

We retrospectively collected the data of all consecutive mCRPC patients treated with Abi, Enz or Cab in the six major oncological hospitals in the north of Portugal until December 2020.

RESULTS

A total of 470 treatments pre-docetaxel (163 Abi and 307 Enz) and 373 pos-docetaxel (160 Abi, 148 Enz and 59 Cab) were included, with median follow-up time of 35 months. Mean age was 73.1, 84.4% had ECOG status < 2, ISUP grade was ≥ 4 in 59% and 28.0% had oligometastatic disease. In first line, for Abi and for Enz respectively, the proportion of patients with PSA reduction > 50% was 64.4% and 80.4% (P < .001), the mean duration of treatment (DT) was 10 and 14 months (P = .037) and the median overall survival (OS) was 25 months and 30 months (P = .17). In second line the results for Abi, Enz and Cab were respectively: proportion of patients with PSA reduction > 50% was 40.4%, 57.4% and 24.6% (p for Abi vs Enz=0.004); DT was 7, 8, and 3 months (p for Abi vs Enz = 0.27); OS was 17, 22 and 10 months (p for Abi vs. Enz = 0,07).

CONCLUSION

These drugs have good efficacy in real-world evidence, similar to those reported in randomized clinical trials, with the expected exception of lower OS due to the inclusion of a broader sample of patients. Our results add to the evidence that Enz might have better efficacy in this setting compared with Abi.

Systemic therapy landscape of advanced prostate cancer

Prostate cancer is the most commonly diagnosed cancer in American men and 2nd leading cause of cancer-related deaths in the United States. Androgen deprivation therapy (ADT) is the backbone of treatment for advanced prostate cancer. Over the past several decades a number of new therapeutics, such as novel androgen receptor pathway inhibitors, targeted agents and radionuclide therapies, have been introduced for the treatment of prostate cancers. These agents have been demonstrated to improve clinical outcomes of prostate cancer patients in randomized clinical trials. In addition, new therapeutic strategies, such as early intensification of ADT, novel treatment combinations, and treatment sequencing, are expected to improve outcomes further. In this clinical review, we discuss the changing treatment landscape for advanced prostate cancer with a focus on new therapeutics.

Hospitalizations Among Veterans Treated for Metastatic Prostate Cancer With Abiraterone or Enzalutamide

BACKGROUND

Abiraterone and enzalutamide are second generation androgen receptor pathway inhibitors (ARPIs) used to treat advanced or metastatic prostate cancer. Without head-to-head comparative studies identifying 1 agent as preferred initial therapy, physician preferences guide initial ARPI choice. This study compares hospitalizations among patients treated initially with abiraterone versus enzalutamide.

PATIENTS AND METHODS

United States veterans treated with abiraterone or enzalutamide between May 13, 2011 and December 31, 2019; then compared hospitalization rate during first treatment with ARPI in the Veterans Healthcare Administration. Baseline incidence rate of hospitalization was determined from data 1 year prior to ARPI. Incidence Rate Difference (IRD) was calculated using χ2 test and difference in IRD using Poisson Regression.

RESULTS

19,775 veterans were identified; 13,527 (68.4%) were initially treated with abiraterone and 6248 (31.6%) initially with enzalutamide. The enzalutamide cohort was older (75.8 vs. 74.5 years, P < .001) and had higher baseline comorbidities at ARPI initiation (4.4 vs. 4.0, P < .001). Patients were treated with enzalutamide longer than abiraterone (median 9.0 vs. 8.0 months, P < .001). Total hospitalizations increased from 465 per 1000 person-years in the year prior to treatment with abiraterone to 567 during treatment. Total hospitalizations increased from 417 per 1000 person-years in the year prior to treatment with enzalutamide to 430 during treatment. Total rate of hospitalization increased 22% for abiraterone compared to a 3% increase for enzalutamide in the 12 months after ARPI initiation (P < .0001). Abiraterone was associated with greater increase in rates of acute heart failure, atrial fibrillation, acute kidney injury, urinary tract infections, sepsis, and pneumonia.

CONCLUSION

By comparing the rate of hospitalization before vs. during treatment, real world analyses identified a 22% versus 3% increase in hospitalizations with abiraterone compared to enzalutamide respectively, despite being used in a younger population with less comorbid disease. Abiraterone was also associated with higher risk of infections, a novel finding.

Cost-effectiveness and budget impact analysis of enzalutamide in comparison to abiraterone in treatment of metastatic prostate cancer resistant to castration in Iran

INTRODUCTION

In recent years, enzalutamide and abiraterone have been widely used as treatments for metastatic castration-resistant prostate cancer (mCRPC). However, the cost-effectiveness of these drugs in Iran is unknown. This study evaluated the cost-effectiveness of enzalutamide for the treatment of metastatic prostate cancer resistant to castration in Iran.

METHODS

A 3-state Markov model was developed to evaluate the cost-effectiveness of enzalutamide and abiraterone from a social perspective over 10 years. The clinical inputs were obtained from the meta-analysis studies. The direct medical costs were obtained from the tariffs of the healthcare system, while the direct non-medical and indirect costs were collected from the patients. The data of utilities were derived from the literature. In addition, sensitivity analyses were conducted to assess the uncertainties.

RESULTS

Compared with Abiraterone, enzalutamide was associated with a high incremental cost-effectiveness ratio (ICER) of $6,260 per QALY gained. According to the one-way sensitivity analysis, ICER was most heavily influenced by the prices of enzalutamide and Abiraterone, non-medical costs, and indirect costs. Regardless of the variation, enzalutamide remained cost-effective. The budget impact analysis of enzalutamide in the health system during 5 years was estimated at $6,362,127.

CONCLUSIONS

At current prices, adding enzalutamide to pharmaceutical lists represents the cost-effective use of the healthcare resources in Iran for the treatment of metastatic castration-resistant prostate cancer.

Survival of veterans treated with enzalutamide and abiraterone for metastatic castrate resistant prostate cancer based on comorbid diseases

BACKGROUND

Comorbid diseases influence patient outcomes, yet little is known about how comorbidities interact with treatments for metastatic castrate-resistant prostate cancer (mCRPC). No head-to-head trials have compared the efficacy of abiraterone and enzalutamide - oral androgen-receptor targeted agents (ARTAs) for mCRPC. In patients with comorbid disease, outcomes with ARTAs may differ due to disparate mechanisms of action, adverse events, and drug interactions.

METHODS

Retrospective observational study of US veterans initiating treatment for mCRPC with abiraterone or enzalutamide between September 2014 and June 2017. Treatment duration and overall survival (OS) was compared based on age and comorbid diseases. The association between ARTA and OS was assessed using Cox proportional hazards and propensity-score matched modeling while adjusting for potential confounders. Sensitivity analyses were performed based on patient age, comorbidities, and subsequent treatments for mCRPC.

RESULTS

Of 5822 veterans treated for mCRPC, 43.0% initially received enzalutamide and 57.0% abiraterone. Veterans initially treated with enzalutamide versus abiraterone were older (mean 75.8 vs. 75.0 years) with higher mean Charlson comorbidity index (4.4 vs. 4.1), and higher rates of cardiovascular disease or diabetes (74.2% vs. 70.6%). In the entire population, veterans initially treated with enzalutamide had longer median OS compared to those initially treated with abiraterone (24.2 vs. 22.1 months, p = 0.001). In veterans with cardiovascular disease or diabetes, median treatment duration with enzalutamide was longer (11.4 vs. 8.6 months, p < 0.001) with longer median OS compared to abiraterone (23.2 vs. 20.5 months, p < 0.001). In a propensity score matched cohort, enzalutamide was associated with decreased mortality compared to abiraterone (HR 0.90, 95% CI 0.84-0.96).

CONCLUSIONS

Veterans with cardiovascular disease or diabetes had longer treatment duration and OS with enzalutamide compared to abiraterone. Further study of ARTA selection may benefit men with metastatic castrate resistant prostate cancer and likely hormone sensitive prostate cancer, especially among patients with comorbid diseases.

Clinical Efficacy and Psychological Impact of Omaha-Based Continuing Care for Prostate Cancer Patients

Prostate cancer is a common malignancy elderly male urogenital system, because of the special disease position, and postoperative complications such as urinary retention, urinary incontinence, and sexual dysfunction, if not treated, can increase the patients' physical pain, anxiety, and other psychological burden; endocrine therapy after surgery can affect self-image and quality of life of patients. Omaha system was originally used for community health nurses, which contains three main contents: problem classification, nursing intervention, and outcome evaluation. The problem classification dimension includes four dimensions: environment, physiology, social psychology, and health-related behavior. The nursing intervention dimension is composed of 75 intervention objectives and four behavior types. Omaha system is a nursing intervention model based on individual psychological, physiological, educational level, and family and social background. The model has good clinical application effect. This study aimed to explore the continuous nursing intervention effect in the nursing of patients with prostate cancer and its psychological impact. A total of 96 prostate patients with cancer who were admitted to Taizhou First People's Hospital from November 2019 to May 2021 were divided into Omaha system care group and routine care group with 48 cases each by random number table method. The routine care group received routine care and discharge guidance, and the Omaha system care group on the basis of the routine care group; continuation care based on the Omaha system was implemented. The differences in mental state, life quality score, serum prostate specific antigen (PSA) level, average urine flow rate, and self-care ability score were compared between the routine care and Omaha system care group. The results showed that Omaha-based continuation care for prostate cancer is beneficial to reduce bad mood, improve patients' life quality score and self-care ability, and provide certain reference for clinical care of prostate cancer patients.

Comparative Effectiveness of Abiraterone and Enzalutamide in Patients With Metastatic Castration-Resistant Prostate Cancer in Taiwan

Background

Abiraterone and enzalutamide are widely used as first-line treatment for metastatic castration-resistant prostate cancer (mCRPC); however, their efficacy in mCRPC has been inconsistently demonstrated in other outcome studies from real-world databases. The aim of our study was to assess the comparative effectiveness of abiraterone and enzalutamide in patients with mCRPC using real-world data from Taiwan.

Methods

This retrospective cohort population-based study included patients identified in the Taiwan National Health Insurance Research Database who had been diagnosed with mCRPC and who had taken abiraterone or enzalutamide between December 2014 and August 2017. The study’s outcome evaluated the differences in overall survival (OS) and time to treatment failure (TTF) between abiraterone and enzalutamide over a 15-month follow-up period. The patients were followed from the index date to when the outcome occurred, to December 31, 2018, or to the patients’ withdrawal from the National Health Insurance program. The estimated relative treatment effects of abiraterone and enzalutamide on OS and TTF were adjusted by the inverse probability of treatment weighting (IPTW) using the Kaplan–Meier method and a Cox proportional hazards model.

Results

The abiraterone and enzalutamide groups consisted of 1,046 and 118 patients, respectively. After IPTW adjustment, 1,164 patients in the abiraterone group and 1,158 in the enzalutamide group underwent an outcome evaluation. Enzalutamide showed a similar OS rate to that of abiraterone (57.58% vs. 49.51%, p = 0.095 by log-rank test). Enzalutamide significantly reduced the risk of death for mCRPC when compared with abiraterone [adjusted hazard ratio (aHR), 0.828; 95% CI 0.731–0.938]. However, similar results were not observed in the TTF outcomes (63.84% vs. 67.79%, p = 0.2651 by log-rank test; aHR, 0.902; 95% CI 0.812–1.002).

Conclusion

In conclusion, enzalutamide was associated with better OS for mCRPC than abiraterone in the Taiwan population. Our study showed that there was no statistically significant difference in TTF between enzalutamide and abiraterone. Studies with longer surveillance of enzalutamide and abiraterone using real-world databases are needed.

Co-Inhibition of Androgen Receptor and PARP as a Novel Treatment Paradigm in Prostate Cancer-Where Are We Now?

Metastatic prostate cancer remains lethal with a 5-year survival rate of about 30%, indicating the need for better treatment options. Novel antiandrogens (NAA)-enzalutamide and abiraterone-have been the mainstay of treatment for advanced disease since 2011. In patients who progress on the first NAA, responses to the second NAA are infrequent (25-30%) and short-lasting (median PFS ~3 months). With the growing adoption of NAA therapy in pre-metastatic castration-resistant settings, finding better treatment options for first-line mCRPC has become an urgent clinical need. The regulatory approval of two PARP inhibitors in 2020-rucaparib and olaparib-has provided the first targeted therapy option for patients harboring defects in selected DNA damage response and repair (DDR) pathway genes. However, a growing body of preclinical and clinical data shows that co-inhibition of AR and PARP induces synthetic lethality and could be a promising therapy for patients without any DDR alterations. In this review article, we will investigate the limitations of NAA monotherapy, the mechanistic rationale for synthetic lethality induced by co-inhibition of AR and PARP, the clinical data that have led to the global development of a number of these AR and PARP combination therapies, and how this may impact patient care in the next 2-10 years.

Novel hormonal agents for metastatic Castration-Resistant Prostate Cancer: comparing outcomes. A single-center retrospective study

INTRODUCTION

Prostate cancer is the most common cancer in men, accounting for 15% of all diagnosed cancers and is the sixth leading cause of cancerrelated deaths amongst men worldwide. Abiraterone and enzalutamide were the first two novel hormonal agents approved for the treatment of metastatic prostate cancer but there is a lack of quality evidence regarding which is associated with better outcomes and who would benefit the most with one or another of these drugs.

OBJECTIVE

To evaluate the clinical outcomes of real-world patients submitted to treatment with novel hormonal agents, enzalutamide and abiraterone, for castration resistant metastatic prostate cancer in an academic center.

PATIENTS AND METHODS

We retrospectively reviewed patients treated for castration-resistant prostate cancer with either abiraterone or enzulatamide between January 1, 2016 and December 31, 2019. The primary endpoints were biochemical response, biochemical progression, radiological progression, clinical deterioration (attributed to disease progression) and death.

RESULTS

Enzalutamide had a higher biochemical response rate than abiraterone in patients with mCRPC (77.1% vs 58.1%, p = 0.016). Achieving a biochemical response was associated with a lower risk of biochemical progression (OR: 0.248, p = 0.017) and death (OR: 0.302, p = 0.038).

CONCLUSIONS

Enzalutamide conferred higher biochemical response rate than abiraterone in patients with mCRPC. Despite the trend to better performance of other endpoints in the enzalutamide group, it did not achieve statistical significance. Well-designed prospective studies are needed to elucidate the comparative efficacies of these agents.

Efficacy and Safety of Abiraterone Acetate and Enzalutamide for the Treatment of Metastatic Castration-Resistant Prostate Cancer: A Systematic Review and Meta-Analysis

OBJECTIVE

The androgen receptor-targeting drugs abiraterone acetate and enzalutamide have shown positive results as treatments for metastatic castration-resistant prostate cancer (mCRPC). Therefore, a meta-analysis was conducted to compare the efficacy and safety of abiraterone acetate and enzalutamide in patients with mCRPC.

METHODS

We retrieved relevant articles from PubMed, Cochrane, and EMBASE published before December 31, 2020. Eleven articles were initially selected, and four phase III, double-blind, randomized controlled trials of abiraterone acetate and enzalutamide that involved 5199 patients with mCRPC were included. The end points were time to prostate-specific antigen progression (TTPP), according to the prostate-specific antigen working group criteria; overall survival (OS); and radiographic progression-free survival (rPFS).

RESULTS

Four randomized, controlled clinical trials involving 5199 patients were included in this study. The results of the meta-analysis showed that compared with placebo alone, abiraterone significantly improved OS (HR=0.69, 95% CI: 0.60-0.8, P<0.00001), rPFS (HR=0.64, 95% CI: 0.57-0.71, P < 0.00001), and TTPP (HR=0.52, 95% CI: 0.45-0.59, P < 0.00001) in patients with mCRPC. Compared with placebo, enzalutamide significantly improved OS (HR=0.67, 95% CI: 0.59-0.75, P<0.00001), rPFS (HR=0.33, 95% CI: 0.29-0.37, P< 0.00001), and TTPP (HR=0.19, 95% CI: 0.17-0.22, P < 0.00001). An indirect comparison was performed to compare the efficacy of abiraterone and enzalutamide. The results showed that there was no significant difference between abiraterone and enzalutamide with regard to improving the OS of patients with mCRPC (HR=1.03, 95% CI: 0.854-1.242). Enzalutamide was superior to abiraterone with regard to improving rPFS in patients with mCRPC (HR=0.516, 95% CI: 0.438-0.608). With regard to improving TTPP, the efficacy of enzalutamide was better than that of abiraterone (HR=0.365, 95% CI: 0.303-0.441). In sAE, there was no difference between abiraterone and enzalutamide (P=0.21, I2 = 38%).

CONCLUSIONS

Compared with placebo, both abiraterone and enzalutamide significantly prolonged OS, rPFS, and TTPP in patients with mCRPC. There was no difference in safety between abiraterone and enzalutamide. In addition, enzalutamide had better efficacy than abiraterone with regard to improving rPFS and TTPP but not OS, but the level of evidence was low. Therefore, a large direct comparison trial is needed to compare the efficacy of the two drugs.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, identifier (CRD42021226808).

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

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

NUMB suppression by miR-9-5P enhances CD44+ prostate cancer stem cell growth and metastasis

Experimental and clinical studies over the past two decades have provided overwhelming evidence that human cancers, including prostate cancer (PCa), harbor cancer stem cells (CSCs) that sustain tumor growth, drive tumor progression and mediate therapy resistance and tumor relapse. Recent studies have also implicated NUMB as a PCa suppressor and an inhibitor of PCa stem cells (PCSCs); however, exactly how NUMB functions in these contexts remains unclear. Here, by employing bioinformatics analysis and luciferase assays and by conducting rescue experiments, we first show that NUMB is directly targeted by microRNA-9-5p (miR-9-5p), an oncogenic miR associated with poor prognosis in many malignancies. We further show that miR-9-5p levels are inversely correlated with NUMB expression in CD44+ PCSCs. miR-9-5p reduced NUMB expression and inhibited numerous PCSC properties including proliferation, migration, invasion as well as self-renewal. Strikingly, overexpression of NUMB in CD44+ PCSCs overcame all of the above PCSC properties enforced by miR-9-5p. Taken together, our results suggest that inhibiting the expression of the oncomiR miR-9-5p and overexpressing NUMB may represent novel therapeutic strategies to target PCSCs and PCa metastasis.