Survival by race in men with chemotherapy-naive enzalutamide- or abiraterone-treated metastatic castration-resistant prostate cancer

Prostate cancer metastasis and health disparities: a systematic review

BACKGROUND

Prostate cancer (PCa), one of the most prevalent malignancies affecting men, significantly contributes to increased mortality rates worldwide. While the causative death is due to advanced metastatic disease, this occurrence disproportionately impacts men of African descent compared to men of European descent. In this review, we describe potential mechanisms underlying PCa metastases disparities and current treatments for metastatic disease among these populations, differences in treatment outcomes, and survival rates, in hopes of highlighting a need to address disparities in PCa metastases.

METHODS

We reviewed existing literature using databases such as PubMed, Google Scholar, and Science Direct using the following keywords: "prostate cancer metastases", "metastatic prostate cancer disparity", "metastatic prostate cancer diagnosis and treatment", "prostate cancer genetic differences and mechanisms", "genetic differences and prostate tumor microenvironment", and "men of African descent and access to clinical treatments". The inclusion criteria for literature usage were original research articles and review articles.

RESULTS

Studies indicate unique genetic signatures and molecular mechanisms such as Epithelial-Mesenchymal Transition (EMT), inflammation, and growth hormone signaling involved in metastatic PCa disparities. Clinical studies also demonstrate differences in treatment outcomes that are race-specific, for example, patients of African descent have a better response to enzalutamide and immunotherapy yet have less access to these drugs as compared to patients of European descent.

CONCLUSIONS

Growing evidence suggests a connection between a patient's genetic profile, the prostate tumor microenvironment, and social determinants of health that contribute to the aggressiveness of metastatic disease and treatment outcomes. With several potential pathways highlighted, the limitations in current diagnostic and therapeutic applications that target disparity in PCa metastases warrant rigorous research attention.

Emerging racial disparities among Medicare beneficiaries and Veterans with metastatic castration-sensitive prostate cancer

BACKGROUND

Previous studies have shown that Black men receive worse prostate cancer care than White men. This has not been explored in metastatic castration-sensitive prostate cancer (mCSPC) in the current treatment era.

METHODS

We evaluated treatment intensification (TI) and overall survival (OS) in Medicare (2015-2018) and Veterans Health Administration (VHA; 2015-2019) patients with mCSPC, classifying first-line mCSPC treatment as androgen deprivation therapy (ADT) + novel hormonal therapy; ADT + docetaxel; ADT + first-generation nonsteroidal antiandrogen; or ADT alone.

RESULTS

We analyzed 2226 Black and 16,071 White Medicare, and 1020 Black and 2364 White VHA patients. TI was significantly lower for Black vs White Medicare patients overall (adjusted odds ratio [OR] 0.68; 95% confidence interval [CI] 0.58-0.81) and without Medicaid (adjusted OR 0.70; 95% CI 0.57-0.87). Medicaid patients had less TI irrespective of race. OS was worse for Black vs White Medicare patients overall (adjusted hazard ratio [HR] 1.20; 95% CI 1.09-1.31) and without Medicaid (adjusted HR 1.13; 95% CI 1.01-1.27). OS was worse in Medicaid vs without Medicaid, with no significant OS difference between races. TI was significantly lower for Black vs White VHA patients (adjusted OR 0.75; 95% CI 0.61-0.92), with no significant OS difference between races.

CONCLUSIONS

Guideline-recommended TI was low for all patients with mCSPC, with less TI in Black patients in both Medicare and the VHA. Black race was associated with worse OS in Medicare but not the VHA. Medicaid patients had less TI and worse OS than those without Medicaid, suggesting poverty and race are associated with care and outcomes.

Evaluation of Survival Outcomes Among Black and White Patients with Metastatic Castration-resistant Prostate Cancer: A Systematic Review and Meta-analysis

Context

Data on racial disparities among patients with metastatic castration-resistant prostate cancer (mCRPC) are limited and there is no uniform conclusion on differences by race in this setting.

Objective

To provide the latest evidence on racial disparities in survival outcomes between Black and White patients receiving systemic therapies for mCRPC.

Evidence acquisition

Our study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We systematically searched the PubMed, Web of Science, and Cochrane Library databases up to September 2023 to identify potentially relevant studies. Overall survival (OS) and progression-free survival (PFS) were the outcomes of interest. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were evaluated.

Evidence synthesis

Nine studies involving 9462 patients with mCRPC (2058 Black and 7404 White men) met the eligibility criteria and were included. Pooled estimates demonstrated significantly better OS for Black than for White men (HR 0.75, 95% CI 0.70-0.80; p < 0.0001). The results were similar in a subgroup of men receiving androgen receptor-targeted therapies (HR 0.72, 95% CI 0.66-0.78; p < 0.0001) and a subgroup of men receiving other treatments (HR 0.79, 95% CI 0.71-0.88; p < 0.0001). Likewise, significantly favorable PFS was observed for Black men receiving ARTs in comparison to their White counterparts (HR 0.84, 95% CI 0.71-0.99; p = 0.0373).

Conclusions

Overall, our meta-analysis of survival outcomes for men with mCRPC stratified by race revealed a significant survival benefit for Black men in comparison to their White counterparts, regardless of systemic therapeutic agent.

Patient summary

Both biological and nonbiological factors could account for racial differences in the efficacy of systemic treatments for metastatic prostate cancer that is resistant to hormone therapy. Our review provides the latest reliable evidence showing better survival outcomes for Black than for White men. The results will be helpful in further understanding the molecular mechanisms that might explain racial differences in this disease stage and in planning treatment.

Disparities With Systemic Therapies for Black Men Having Advanced Prostate Cancer: Where Do We Stand?

PURPOSE

Prostate cancer represents the most common cancer diagnosis in Black men and is the second leading cause of cancer death in this population. Multilevel disparities have been well-documented in Black men with prostate cancer and play a role in poorer survival outcomes when compared with White men with prostate cancer. In this review, we highlight the changing trend in disparities for systemic therapy outcomes in Black men diagnosed with metastatic prostate cancer.

METHODS

We reviewed data from real-world registries and prospective clinical trials with a particular focus on equal access settings to compare outcomes to systemic therapies between Black and White men with metastatic prostate cancer.

RESULTS

In metastatic prostate cancer, there is growing evidence to suggest that Black men may have similar, if not better, outcomes to systemic therapies than White men with advanced disease, as corroborated by prospective studies and clinical trials where health care delivery and follow-up are more likely to be standardized.

CONCLUSION

This review illustrates the importance of nonbiological drivers of racial disparities in Black men with advanced prostate cancer. Mitigating barriers to health care access and delivery as well as including participation in clinical trials will be pivotal to ongoing efforts to address disparities in systemic therapy outcomes for Black men with metastatic 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.

Improved Outcomes with Enzalutamide in Biochemically Recurrent Prostate Cancer

BACKGROUND

Patients with prostate cancer who have high-risk biochemical recurrence have an increased risk of progression. The efficacy and safety of enzalutamide plus androgen-deprivation therapy and enzalutamide monotherapy, as compared with androgen-deprivation therapy alone, are unknown.

METHODS

In this phase 3 trial, we enrolled patients with prostate cancer who had high-risk biochemical recurrence with a prostate-specific antigen doubling time of 9 months or less. Patients were randomly assigned, in a 1:1:1 ratio, to receive enzalutamide (160 mg) daily plus leuprolide every 12 weeks (combination group), placebo plus leuprolide (leuprolide-alone group), or enzalutamide monotherapy (monotherapy group). The primary end point was metastasis-free survival, as assessed by blinded independent central review, in the combination group as compared with the leuprolide-alone group. A key secondary end point was metastasis-free survival in the monotherapy group as compared with the leuprolide-alone group. Other secondary end points were patient-reported outcomes and safety.

RESULTS

A total of 1068 patients underwent randomization: 355 were assigned to the combination group, 358 to the leuprolide-alone group, and 355 to the monotherapy group. The patients were followed for a median of 60.7 months. At 5 years, metastasis-free survival was 87.3% (95% confidence interval [CI], 83.0 to 90.6) in the combination group, 71.4% (95% CI, 65.7 to 76.3) in the leuprolide-alone group, and 80.0% (95% CI, 75.0 to 84.1) in the monotherapy group. With respect to metastasis-free survival, enzalutamide plus leuprolide was superior to leuprolide alone (hazard ratio for metastasis or death, 0.42; 95% CI, 0.30 to 0.61; P<0.001); enzalutamide monotherapy was also superior to leuprolide alone (hazard ratio for metastasis or death, 0.63; 95% CI, 0.46 to 0.87; P = 0.005). No new safety signals were observed, with no substantial between-group differences in quality-of-life measures.

CONCLUSIONS

In patients with prostate cancer with high-risk biochemical recurrence, enzalutamide plus leuprolide was superior to leuprolide alone with respect to metastasis-free survival; enzalutamide monotherapy was also superior to leuprolide alone. The safety profile of enzalutamide was consistent with that shown in previous clinical studies, with no apparent detrimental effect on quality of life. (Funded by Pfizer and Astellas Pharma; EMBARK ClinicalTrials.gov number, NCT02319837.).

Real-World Treatment Trends Among Patients with Metastatic Castration-Sensitive Prostate Cancer: Results from an International Study

BACKGROUND

Continuous androgen deprivation therapy ± first-generation non-steroidal antiandrogen was previously the standard-of-care for patients with metastatic castration-sensitive prostate cancer (mCSPC). Treatment intensification with novel hormonal therapy (NHT) or taxane chemotherapy is now approved and guideline-recommended for these patients.

METHODS

Physician-reported data on adult patients with mCSPC from the Adelphi Prostate Cancer Disease Specific Programme were analyzed descriptively. We evaluated real-world treatment trends for patients with mCSPC in 5 European countries (United Kingdom, France, Germany, Spain, and Italy) and the United States (US), looking at differences between patients initiating treatment in 2016-2018 and in 2019-2020. We also investigated treatment trends by ethnicity and insurance status in the US.

RESULTS

This study found that most patients with mCSPC do not receive treatment intensification. However, greater use of treatment intensification with NHT and taxane chemotherapy was observed in 2019-2020 than in 2016-2018 across 5 European countries. In the US, greater use of treatment intensification with NHT in 2019-2020 than in 2016-2018 was observed for all ethnicity groups and those with Medicare and commercial insurance status.

CONCLUSIONS

As the number of patients with mCSPC who receive treatment intensification increases, more patients who progress to metastatic castration-resistant prostate cancer (mCRPC) will have been exposed to intensified treatments. Treatment options for patients with mCSPC and mCRPC overlap, suggesting that an unmet need will emerge for new therapies. Further studies are needed to understand optimal treatment sequencing in mCSPC and mCRPC.

The impact of race on survival in metastatic prostate cancer: a systematic literature review

BACKGROUND

Prostate cancer (PC) is the second most diagnosed cancer in men worldwide. While racial and ethnic differences exist in incidence and mortality, increasing data suggest outcomes by race among men with newly diagnosed PC are similar. However, outcomes among races beyond Black/White have been poorly studied. Moreover, whether outcomes differ by race among men who all have metastatic PC (mPC) is unclear. This systematic literature review (SLR) provides a comprehensive synthesis of current evidence relating race to survival in mPC.

METHODS

An SLR was conducted and reported in accordance with PRISMA guidelines. MEDLINE®, Embase, and Cochrane Library using the Ovid® interface were searched for real-world studies published from January 2012 to July 2022 investigating the impact of race on overall survival (OS) and prostate cancer-specific mortality (PCSM) in patients with mPC. A supplemental search of key congresses was also conducted. Studies were appraised for risk of bias.

RESULTS

Of 3228 unique records identified, 62 records (47 full-text and 15 conference abstracts), corresponding to 54 unique studies (51 United States and 3 ex-United States) reporting on race and survival were included. While most studies showed no difference between Black vs White patients for OS (n = 21/27) or PCSM (n = 8/9), most showed that Black patients demonstrated improved OS on certain mPC treatments (n = 7/10). Most studies found no survival difference between White patients and Hispanic (OS: n = 6/8; PCSM: n = 5/6) or American Indian/Alaskan Native (AI/AN) (OS: n = 2/3; PCSM: n = 5/5). Most studies found Asian patients had improved OS (n = 3/4) and PCSM (n = 6/6) vs White patients.

CONCLUSIONS

Most studies found Black, Hispanic, and AI/AN patients with mPC had similar survival as White patients, while Black patients on certain therapies and Asian patients showed improved survival. Future studies are needed to understand what aspects of race including social determinants of health are driving these findings.

Prostate-specific antigen response and clinical progression-free survival in Black and White men with chemotherapy-naïve metastatic castration-resistant prostate cancer treated with enzalutamide in a real-world setting

BACKGROUND

In the United States, Black men have a higher incidence of prostate cancer (PC)-related mortality than men of other races. Several real-world studies in advanced PC suggest, however, that Black men respond better to novel hormonal therapies than White men. Data on treatment responses to enzalutamide by race are limited. We assessed real-world prostate-specific antigen (PSA) response and clinical progression-free survival (cPFS) of Black vs. White men with chemotherapy-naïve PC treated with enzalutamide.

METHODS

This retrospective cohort study included patients with PC who initiated enzalutamide treatment from 2014 to 2018 in the IntrinsiQ Specialty Solutions™ database, a collection of electronic medical records from community urology practices. Index date was the date of the first prescription for enzalutamide, used as a proxy for metastatic castration-resistant PC (mCRPC). Patients who had undergone chemotherapy and/or abiraterone therapy were excluded. Kaplan-Meier and Cox models adjusted for baseline characteristics were used to estimate PSA response and cPFS by race.

RESULTS

The study included 214 Black and 1332 White men with chemotherapy-naïve PC presumed to have mCRPC based on the enzalutamide indication during the study period. Black men were younger and had higher baseline median PSA levels than White men. Enzalutamide therapy duration, follow-up time, and number of post-index PSA tests were similar between races. In multivariable analyses, the risk of patients achieving a ≥ 50% PSA decline was similar, whereas a numerically higher trend of ≥90% PSA decline was observed in Black men (HR 1.23; 95% CI 0.93-1.62 [P = 0.14]). In the multivariable analysis, Black men had significantly better cPFS (HR 0.82; 95% CI 0.68-0.98 [P = 0.03]).

CONCLUSIONS

Black and White men with presumed chemotherapy-naïve mCRPC had similar PSA responses when treated with enzalutamide, but Black men had better cPFS than White men. Further research is warranted to validate these findings.

Association between concomitant proton pump inhibitor use and survival of patients with metastatic prostate cancer receiving abiraterone acetate: a post-hoc analysis of pooled data from three randomized controlled trials

BACKGROUND

Evidence suggests proton pump inhibitor (PPI) use may attenuate the effect of abiraterone acetate plus prednisone (AAP) in metastatic prostate cancer via the modification of gut microbiota. This study aimed to examine whether concomitant PPI use is associated with survival in patients with metastatic prostate cancer treated with androgen deprivation therapy (ADT) and AAP.

METHODS

Post-hoc analysis was conducted in patients with metastatic castration-sensitive prostate cancer (mCSPC) and metastatic castration-resistant prostate cancer (mCRPC) treated in the LATITUDE, COU-AA-301, and COU-AA-302 trials (ADT vs. ADT plus AAP). PPI users and non-users were compared for restricted mean overall survival time (RMOST) and restricted mean progression-free survival time (RMPFST) based on inverse probability of treatment weight (IPTW)-adjusted Kaplan-Meier curves. IPTW-adjusted Cox regression models were used to assess heterogeneity of treatment effect.

RESULTS

In patients treated with AAP, PPI use was associated with inferior RMOST [difference (95% confidence interval): -4.2 (-7.0 to -1.4)] and RMPFST [-3.5 (-6.6 to -0.4)] compared with non-users. However, RMOST and RMPFST were similar between PPI users and non-users in patients treated with ADT alone [RMOST, -2.6 (-5.8 to 0.6); RMPFST, -1.7 (-4.8 to 1.4)]. Interaction term analyses did not show evidence of heterogeneity in treatment effect between AAP and ADT, despite the prominent treatment effect shown in mCSPC vs. mCRPC.

CONCLUSIONS

PPI use may be associated with inferior survival in patients with metastatic prostate cancer who receive ADT plus AAP. Discontinuing unnecessary PPI use might improve those outcomes.

Analysis of evolutionary dynamics and clonal architecture in prostate cancer

The extent to which clinical and genomic characteristics associate with prostate cancer clonal architecture, tumor evolution, and therapeutic response remains unclear. Here, we reconstructed the clonal architecture and evolutionary trajectories of 845 prostate cancer tumors with harmonized clinical and molecular data. We observed that tumors from patients who self-reported as Black had more linear and monoclonal architectures, despite these men having higher rates of biochemical recurrence. This finding contrasts with prior observations relating polyclonal architecture to adverse clinical outcomes. Additionally, we utilized a novel approach to mutational signature analysis that leverages clonal architecture to uncover additional cases of homologous recombination and mismatch repair deficiency in primary and metastatic tumors and link the origin of mutational signatures to specific subclones. Broadly, prostate cancer clonal architecture analysis reveals novel biological insights that may be immediately clinically actionable and provide multiple opportunities for subsequent investigation.

Statement of significance

Tumors from patients who self-reported as Black demonstrate linear and monoclonal evolutionary trajectories yet experience higher rates of biochemical recurrence. In addition, analysis of clonal and subclonal mutational signatures identifies additional tumors with potentially actionable alterations such as deficiencies in mismatch repair and homologous recombination.

Race and prostate cancer: genomic landscape

In the past 20 years, new insights into the genomic pathogenesis of prostate cancer have been provided. Large-scale integrative genomics approaches enabled researchers to characterize the genetic and epigenetic landscape of prostate cancer and to define different molecular subclasses based on the combination of genetic alterations, gene expression patterns and methylation profiles. Several molecular drivers of prostate cancer have been identified, some of which are different in men of different races. However, the extent to which genomics can explain racial disparities in prostate cancer outcomes is unclear. Future collaborative genomic studies overcoming the underrepresentation of non-white patients and other minority populations are essential.