A prospective trial of abiraterone acetate plus prednisone in Black and White men with metastatic castrate-resistant prostate cancer

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.

The complex interplay of modifiable risk factors affecting prostate cancer disparities in African American men

Prostate cancer is the second most commonly diagnosed non-skin malignancy and the second leading cause of cancer death among men in the USA. However, the mortality rate of African American men aged 40-60 years is almost 2.5-fold greater than that of European American men. Despite screening and diagnostic and therapeutic advances, disparities in prostate cancer incidence and outcomes remain prevalent. The reasons that lead to this disparity in outcomes are complex and multifactorial. Established non-modifiable risk factors such as age and genetic predisposition contribute to this disparity; however, evidence suggests that modifiable risk factors (including social determinants of health, diet, steroid hormones, environment and lack of diversity in enrolment in clinical trials) are prominent contributing factors to the racial disparities observed. Disparities involved in the diagnosis, treatment and survival of African American men with prostate cancer have also been correlated with low socioeconomic status, education and lack of access to health care. The effects and complex interactions of prostate cancer modifiable risk factors are important considerations for mitigating the incidence and outcomes of this disease in African American men.

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.

Genetic and biological drivers of prostate cancer disparities in Black men

Black men with prostate cancer have historically had worse outcomes than white men with prostate cancer. The causes of this disparity in outcomes are multi-factorial, but a potential basis is that prostate cancers in Black men are biologically distinct from prostate cancers in white men. Evidence suggests that genetic and ancestral factors, molecular pathways involving androgen and non-androgen receptor signalling, inflammation, epigenetics, the tumour microenvironment and tumour metabolism are contributing factors to the racial disparities observed. Key genetic and molecular pathways linked to prostate cancer risk and aggressiveness have potential clinical relevance. Describing biological drivers of prostate cancer disparities could inform efforts to improve outcomes for Black men with prostate cancer.

Evaluation of Diversity of Clinical Trials Informing Health Technology Assessments in the United States: A 5-Year Analysis of Institute for Clinical and Economic Review Assessments

OBJECTIVES

This study aimed to evaluate the diversity of clinical trials informing assessments conducted by the Institute for Clinical and Economic Review.

METHODS

This was a cross-sectional study of pivotal trials included in completed Institute for Clinical and Economic Review assessments over 5 years (2017-2021). Representation of racial/ethnic minority groups, females, and older adults was compared with the disease-specific and US population, using a relative representation cutoff of 0.8 for adequate representation.

RESULTS

A total of 208 trials, evaluating 112 interventions for 31 unique conditions, were examined. Race/ethnicity data were inconsistently reported. The median participant-to-disease representative ratio (PDRR) for Blacks/African Americans (0.43 [interquartile range (IQR) 0.24-0.75]), American Indians/Alaska Natives (0.37 [IQR 0.09-0.77]), and Hispanics/Latinos (0.79 [IQR 0.30-1.22]) were below the adequate representation cutoff. In contrast, Whites (1.06 [IQR 0.92-1.2]), Asians (1.71 [IQR 0.50-3.75]), and Native Hawaiian/Other Pacific Islanders (1.61 [IQR 0.77-2.81]) were adequately represented. Findings were similar when compared with the US Census, except for Native Hawaiian/Pacific Islanders, which was substantially worse. Relative to all trials, a higher proportion of US-based trials adequately represented Blacks/African Americans (61% vs 23%, P < .0001) and Hispanics/Latinos (68% vs 50%; P = .047), but a lower proportion adequately represented Asians (15% vs 67%, P < .0001). Females were adequately represented in 74% of trials (PDRR: 1.02 [IQR 0.79-1.14]). Nevertheless, older adults were adequately represented in only 20% of trials (PDRR: 0.30 [IQR 0.13-0.64]).

CONCLUSIONS

The representation of racial/ethnic minorities and older adults was inadequate. Efforts are needed to enhance the diversity of clinical trials. Standardized and transparent evaluation of trial diversity should be part of the health technology assessment process.

Race and Treatment Outcomes in Patients With Metastatic Castration-Sensitive Prostate Cancer: A Secondary Analysis of the SWOG 1216 Phase 3 Trial

Importance

Black patients present with more aggressive disease and experience higher mortality than White patients with prostate cancer. Race and social determinants of health influence prostate cancer-specific mortality and overall survival (OS); however, in a previous trial, Black patients did not have inferior outcomes compared with White patients, possibly because of equitable access to care available in a clinical trial setting.

Objective

To compare differences in survival outcomes of patients with metastatic castration-sensitive prostate cancer (mCSPC) by race in a phase 3 trial with a large proportion of Black patients.

Design, Setting, and Participants

This secondary analysis of patient-level data of a prospective phase 3 randomized clinical trial included patients with newly diagnosed mCSPC enrolled between March 1, 2013, and July 15, 2017. Analysis was conducted between December 2022 and February 2023.

Interventions

Patients receiving androgen deprivation therapy were randomized (1:1) to receive either orteronel 300 mg orally twice daily (experimental group) or bicalutamide 50 mg orally daily (control group).

Main Outcomes and Measures

OS, with progression-free survival (PFS) as a secondary end point.

Results

Among 1313 participants, 135 (10%) identified as Black and 1077 (82%) as White, with an equal racial distribution between groups. Black patients were younger (median [IQR] age, 65.8 [60-70] vs 68.4 [62.5-74.1] years; P = .001) and had a higher median (IQR) baseline prostate-specific antigen response rate than White patients (54.7 [19.8-222.0] vs 26.7 [9.2-96.0] ng/mL; P < .001). At a median follow-up of 4.9 years, Black and White patients had similar median PFS (2.3 years; 95% CI, 1.8-1.4 years vs 2.9 years; 95% CI, 2.5-3.3 years; P = .71) and OS (5.5 years; 95% CI, 4.8-NR vs 6.3 years; 95% CI, 5.7-NR; P = .65). The multivariable analysis confirmed similar PFS and OS after adjusting for known prognostic factors. No interaction between race and treatment was observed.

Conclusions and Relevance

In this secondary analysis of a randomized clinical trial studying androgen deprivation therapy with first- or second-generation androgen receptor pathway inhibitors, both Black and White patients demonstrated similar OS and PFS. Equitable access to care may reduce historical differences in outcomes between Black and White patients with advanced prostate cancer.

Trial Registration

ClinicalTrials.gov Identifier: NCT01809691.

Diversity, equity, and inclusion in genitourinary clinical trials leading to FDA novel drug approval: An assessment of the FDA center for drug evaluation and research drug trials snapshot

To determine the distribution of race and ethnicity among genitourinary oncology trial participants leading to FDA approval of novel molecular entities/biologics. Secondarily, we evaluated whether the proportion of Black participants in clinical trials increased over time. We quired the FDA Center for Drug Evaluation and Research Drug Trials Snapshot (DTS) between 2015 and 2020 for urologic oncology clinical trials leading to FDA approval of novel drugs. Enrollment data was stratified by race and ethnicity. Cochran-Armitage Trend tests were used to examine changes in Black patient participation over years. Nine clinical trials were identified that led to FDA approval of 5 novel molecular entities for prostate and 4 molecular entities for urothelial carcinoma treatment. Trials for prostate cancer included 5202 participants of which 69.8% were White, 4.0% Black, 11.0% Asian, 3.6% Hispanic, <1% American Indian/Alaska Native or Native Hawaiian/Pacific Islander, 3% other. Trials in urothelial carcinoma had 704 participants of which 75.1% were male, 80.8% White, 2.3% Black, 2.4% Hispanic, <1% American Indian/Alaska Native or Native Hawaiian/Pacific Islander, 5% other. Black participation rates over time did not change for urothelial (P = 0.59) or the combined cancer cohort (P = 0.29). Prostate cancer enrollment trends among Black participant declined over time (P = 0.03). Participants in genitourinary clinical trials leading to FDA approval of novel drugs are overwhelmingly white. Involving stakeholders who represent the needs and interests of underrepresented populations in the design and implementation of clinical trials of novel agents may be a strategy to increase diversity, equity, and inclusion among genitourinary clinical trials.

Black Patients with Metastatic Castrate-Resistant Prostate Cancer Have a Shorter Time Interval Between PSA and Clinical Progression on Novel Hormonal Therapies plus Avelumab

BACKGROUND

Black men are at higher risk for prostate cancer death. Previous studies showed a benefit of different therapies, including immune-based therapy, for Black men with metastatic prostate cancer. We sought to explore the efficacy of the PD-L1 inhibitor avelumab in Black men with metastatic castrate-resistant prostate cancer (mCRPC) progressing after abiraterone or enzalutamide.

METHODS

This pilot phase II study enrolled self-identified Black patients who developed mCRPC on next-generation hormonal therapies (NHTs) abiraterone acetate or enzalutamide (NCT03770455). Enrolled patients received avelumab 10mg/kg IV every 2 weeks while remaining on the same NHTs. The primary endpoint of our study was ≥ 50% reduction in prostate specific antigen (PSA) at ≥8 weeks.

RESULTS

A total of eight patients were enrolled. The median duration on NHTs prior to enrollment was 364 days (95% CI, 260.9-467.1). The median time to initiate avelumab was 8 days (3-14). With a median follow-up of 196 days, no patients achieved the primary endpoint. The median time to PSA progression was 35 days (95 CI%, 0-94.8) and the median time to radiographic and/or clinical progression was 44 days (95 CI%, 0-118.5). The study was closed prematurely due to safety concerns related to the rapid clinical progression observed in the patients enrolled on study.

CONCLUSION

In conclusion, the addition of avelumab to NHT did not demonstrate clinical activity in Black men with new mCRPC. The unexpected short interval between PSA and radiographic and/or clinical progression observed in this study has potential clinical implications.ClinicalTrials.gov Identifier: NCT03770455 (IND number 139559).

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.

Outcomes Among African American and Non-Hispanic White Men With Metastatic Castration-Resistant Prostate Cancer With First-Line Abiraterone

IMPORTANCE

Prospective evidence suggests abiraterone is associated with superior progression-free survival for African American men compared with non-Hispanic White men with metastatic castration-resistant prostate cancer (mCRPC).

OBJECTIVE

To investigate differences in outcomes with first-line abiraterone therapy between African American and non-Hispanic White men with mCRPC in a national real-world cohort.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study used a nationwide electronic health record-derived database of 3808 men receiving first-line therapy for mCRPC between January 1, 2012, and December 31, 2018. Data analysis was performed between January 1, 2020, and June 1, 2021. Median follow-up was 13 months (IQR, 7-22 months). Propensity score-based inverse probability of treatment weighting was applied to reduce imbalance in measured confounders between patients receiving first-line abiraterone vs other first-line therapies. Deidentified patient data originated from a geographically diverse set of approximately 280 cancer clinics (approximately 800 sites of care) throughout the United States. Participants had newly diagnosed mCRPC and were receiving first-line systemic therapy during the study period.

EXPOSURES

Receipt of abiraterone for first-line therapy.

MAIN OUTCOMES AND MEASURES

Overall survival from start of first-line treatment. Stratified analyses investigated overall survival within each race group, with first-line enzalutamide as the comparator.

RESULTS

Among 3808 patients with mCRPC, there were 2615 non-Hispanic White men (68.7%; mean [SD] age at diagnosis, 74 [8] years) and 404 African American men (10.6%; mean [SD] age at diagnosis, 69 [9] years), and 1729 patients (45.4%) in the cohort received first-line abiraterone. Among patients receiving first-line abiraterone, African American men had higher median overall survival than non-Hispanic White men (23 months [IQR, 10-37 months] vs 17 months [IQR, 9-32 months], respectively; inverse probability of treatment weighting hazard ratio, 0.76; 95% CI, 0.60-0.98). A race-by-treatment interaction existed for first-line abiraterone vs first-line enzalutamide (hazard ratio for abiraterone vs enzalutamide: non-Hispanic White men, 1.21 [95% CI, 1.06-1.38]; African American men, 1.05 [95% CI, 0.74-1.50]; interaction P = .02). There was no overall survival difference between first-line abiraterone and first-line enzalutamide among African American patients (24 vs 24 months, respectively; inverse probability of treatment weighting hazard ratio, 1.05; 95% CI, 0.74-1.50). First-line abiraterone was associated with decreased median overall survival relative to first-line enzalutamide among non-Hispanic White patients (17 months [IQR, 9-32 months] vs 20 months [IQR, 10-36 months], respectively; inverse probability of treatment weighting hazard ratio, 1.21; 95% CI, 1.06-1.38).

CONCLUSIONS AND RELEVANCE

In this cohort study of patients who received first-line systemic therapy for mCRPC, African American men who received abiraterone had improved overall survival compared with non-Hispanic White men. Future prospective studies should assess drivers of differential abiraterone outcomes in mCRPC between African American and non-Hispanic White men, including differences in genetic factors and socioeconomic status, to inform treatment strategies.

Genetic Contributions to Prostate Cancer Disparities in Men of West African Descent

Prostate cancer (PCa) is the second most frequently diagnosed malignancy and the second leading cause of death in men worldwide, after adjusting for age. According to the International Agency for Research on Cancer, continents such as North America and Europe report higher incidence of PCa; however, mortality rates are highest among men of African ancestry in the western, southern, and central regions of Africa and the Caribbean. The American Cancer Society reports, African Americans (AAs), in the United States, have a 1.7 increased incidence and 2.4 times higher mortality rate, compared to European American's (EAs). Hence, early population history in west Africa and the subsequent African Diaspora may play an important role in understanding the global disproportionate burden of PCa shared among Africans and other men of African descent. Nonetheless, disparities involved in diagnosis, treatment, and survival of PCa patients has also been correlated to socioeconomic status, education and access to healthcare. Although recent studies suggest equal PCa treatments yield equal outcomes among patients, data illuminates an unsettling reality of disparities in treatment and care in both, developed and developing countries, especially for men of African descent. Yet, even after adjusting for the effects of the aforementioned factors; racial disparities in mortality rates remain significant. This suggests that molecular and genomic factors may account for much of PCa disparities.

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

BACKGROUND

Black men are more likely to be diagnosed with aggressive prostate cancer (PC) and die from PC than white men. However, black men with metastatic castration-resistant PC (mCRPC) had longer overall survival (OS) than white men when treated with certain agents in clinical trials. We analyzed claims data from the Veterans Health Administration (VHA) database to evaluate OS in black and white men treated with enzalutamide or abiraterone (novel hormonal therapy [NHT]) for chemotherapy-naïve mCRPC.

METHODS

Patients with mCRPC aged ≥18 years were identified in the VHA database by diagnosis codes, evidence of surgical/medical castration, and a prescription claim for enzalutamide or abiraterone after castration from April 2014-March 2017. Cox models assessed associations between race and OS. Unadjusted and multivariable analyses were performed on the entire population and subsets based on the type of therapy received (if any) after NHT.

RESULTS

In total, 2910 patients were identified (787 black, mean 71.7 years; 2123 white, mean 74.0 years). Median follow-up was 19.0 and 18.7 months in blacks and whites, respectively. Black men had better survival versus white men: hazard ratios (95% CIs) were 0.89 (0.790-0.996; P = 0.044) and 0.67 (0.592-0.758; P < 0.0001) in the unadjusted and multivariable models, respectively. Statistically significantly longer OS was seen in black versus white men regardless of subsequent treatment, including no subsequent treatment.

CONCLUSIONS

In the VHA, black men with chemotherapy-naïve mCRPC initiating NHT may have better outcomes than similarly treated white men.

Differences in Toxicity and Outcomes in Clinical Trial Participants From Minority Populations

Black men have a higher prevalence of and mortality rate from prostate cancer compared with White men and have been shown to present with more aggressive and later-stage disease. How prostate cancer treatment affects these racial disparities is still unclear. Several studies have shown that Black men who receive treatment have a more pronounced decrease in prostate cancer-specific death; however, there remains a large disparity in all-cause mortality. This disparity may be in part related to a higher risk of death resulting from comorbidities, given the higher rates of cardiovascular disease and diabetes in Black men, both of which are complicated by the use of androgen-deprivation therapy. To further understand these disparities, it is important that we analyze the racial differences in adverse event rates and severity. Increasing the percentage of Black men in clinical trials will improve the understanding of the biologic drivers of racial disparities in prostate cancer. To evaluate the potential differences in adverse event reporting and demonstrate the feasibility of enrolling equal numbers of Black and White men in trials, we performed a prospective, multicenter study of abiraterone plus prednisone with androgen-deprivation therapy in men with metastatic castration-resistant prostate cancer, stratified by race. Racial differences in prostate-specific antigen kinetics and toxicity profile were demonstrated. Higher rates and severity of adverse events related to adrenal hormone suppression, including hypertension, hypokalemia, and hypomagnesemia, were seen in the Black cohort, not previously reported. Increased enrollment of Black men in prostate cancer clinical trials is imperative to further understand the impact of race on clinical outcomes and treatment tolerability.