Beyond Frontline Therapy with Abiraterone and Enzalutamide in Metastatic Castration-Resistant Prostate Cancer: A Real-World US Study

Safety and effectiveness of the radium-223-taxane treatment sequence in patients with metastatic castration-resistant prostate cancer in a global observational study (REASSURE)

BACKGROUND

Radium-223 and taxane chemotherapy each improve survival of patients with metastatic castration-resistant prostate cancer (mCRPC). Whether the radium-223-taxane sequence could extend survival without cumulative toxicity was explored.

METHODS

The global, prospective, observational REASSURE study (NCT02141438) assessed real-world safety and effectiveness of radium-223 in patients with mCRPC. Using data from the prespecified second interim analysis (data cutoff, March 20, 2019), hematologic events and overall survival (OS) were evaluated in patients who were chemotherapy-naive at radium-223 initiation and subsequently received taxane chemotherapy starting ≤90 days ("immediate") or >90 days ("delayed") after the last radium-223 dose.

RESULTS

Following radium-223 therapy, 182 patients received docetaxel (172 [95%]) and/or cabazitaxel (44 [24%]); 34 patients (19%) received both. Seventy-three patients (40%) received immediate chemotherapy and 109 patients (60%) received delayed chemotherapy. Median time from last radium-223 dose to first taxane cycle was 3.6 months (range, 0.3-28.4). Median duration of first taxane was 3.7 months (range, 0-22.0). Fourteen patients (10 in the immediate and four in the delayed subgroup) had grade 3/4 hematologic events during taxane chemotherapy, including neutropenia in two patients in the delayed subgroup and thrombocytopenia in one patient in each subgroup. Median OS was 24.3 months from radium-223 initiation and 11.8 months from start of taxane therapy.

CONCLUSIONS

In real-world clinical practice settings, a heterogeneous population of patients who received sequential radium-223-taxane therapy had a low incidence of hematologic events, with a median survival of 1 year from taxane initiation. Thus, taxane chemotherapy is a feasible option for those who progress after radium-223.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT02141438.

PLAIN LANGUAGE SUMMARY

Radium-223 and chemotherapy are treatment options for metastatic prostate cancer, which increase survival but may affect production of blood cells as a side effect. We wanted to know what would happen if patients received chemotherapy after radium-223. Among the 182 men treated with radium-223 who went on to receive chemotherapy, only two men had severe side effects affecting white blood cell production (neutropenia) during chemotherapy. On average, the 182 men lived for 2 years after starting radium-223 and 1 year after starting chemotherapy. In conclusion, patients may benefit from chemotherapy after radium-223 treatment without increasing the risk of side effects.

A global phase II randomized trial comparing oral taxane ModraDoc006/r to intravenous docetaxel in metastatic castration resistant prostate cancer

STUDY AIM

ModraDoc006, an oral formulation of docetaxel, is co-administered with the cytochrome P450-3A4 and P-glycoprotein inhibitor, ritonavir (r): ModraDoc006/r. The preliminary efficacy and safety of oral ModraDoc006/r was evaluated in a global randomized phase II trial and compared to the current standard chemotherapy regimen of intravenous (i.v.) docetaxel and prednisone.

METHODS

103 mCRPC patients, chemotherapy-naïve with/without abiraterone and/or enzalutamide pretreated, with adequate organ function and evaluable disease per RECIST v1.1 and PCWG3 guidelines were randomized 1:1 into two cohorts. In Cohort 1, 49 patients received docetaxel 75 mg/m2 i.v. every 3 weeks (Q3W). In Cohort 2, 52 patients received ModraDoc006/r; 21 patients with a starting dose of ModraDoc006 30 mg with ritonavir 200 mg in the morning and ModraDoc006 20 mg with ritonavir 100 mg in the evening (30-20/200-100 mg) bi-daily-once-weekly (BIDW) on Days 1, 8, and 15 of a 21-day cycle. To alleviate tolerability, the starting dose was amended to ModraDoc006/r 20-20/200-100 mg in another 31 patients. All patients received prednisone 10 mg daily. Primary endpoint was rPFS.

RESULTS

There was no significant difference in rPFS between the 2 arms (p = 0.1465). Median rPFS was 9.5 months and 11.1 months (95% CI) for ModraDoc006/r and i.v. docetaxel, respectively. Partial response was noted in 44.1% and 38.7% measurable disease patients, and 50% decline of PSA was seen in 23 (50%) and 26 (56.5%) evaluable cases treated with ModraDoc006/r and i.v. docetaxel, respectively. The safety profile of ModraDoc006/r 20-20/200-100 mg dose was significantly better than i.v. docetaxel, with mild (mostly Grade 1) gastrointestinal toxicities, no hematologic adverse events, and neuropathy and alopecia incidence of 11.5% and 25%, respectively.

CONCLUSIONS

ModraDoc006/r potentially represents a widely applicable, convenient, effective, and better tolerated oral taxane therapy option for mCRPC. Further investigation of ModraDoc006/r in a large randomized trial is warranted.

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.

Organoids: An Emerging Precision Medicine Model for Prostate Cancer Research

Prostate cancer (PCa) has been known as the most prevalent cancer disease and the second leading cause of cancer mortality in men almost all over the globe. There is an urgent need for establishment of PCa models that can recapitulate the progress of genomic landscapes and molecular alterations during development and progression of this disease. Notably, several organoid models have been developed for assessing the complex interaction between PCa and its surrounding microenvironment. In recent years, PCa organoids have been emerged as powerful in vitro 3D model systems that recapitulate the molecular features (such as genomic/epigenomic changes and tumor microenvironment) of PCa metastatic tumors. In addition, application of organoid technology in mechanistic studies (i.e., for understanding cellular/subcellular and molecular alterations) and translational medicine has been recognized as a promising approach for facilitating the development of potential biomarkers and novel therapeutic strategies. In this review, we summarize the application of PCa organoids in the high-throughput screening and establishment of relevant xenografts for developing novel therapeutics for metastatic, castration resistant, and neuroendocrine PCa. These organoid-based studies are expected to expand our knowledge from basic research to clinical applications for PCa diseases. Furthermore, we also highlight the optimization of PCa cultures and establishment of promising 3D organoid models for in vitro and in vivo investigations, ultimately facilitating mechanistic studies and development of novel clinical diagnosis/prognosis and therapies for PCa.

Real-world economic burden of metastatic castration-resistant prostate cancer before and after first-line therapy initiation

AIMS

To describe healthcare costs of patients with metastatic castration-resistant prostate cancer (mCRPC) initiating first-line (1 L) therapies from a US payer perspective.

METHODS

Patients initiating a Flatiron oncologist-defined 1 L mCRPC therapy (index date) on or after mCRPC diagnosis were identified from linked electronic medical records/claims data from the Flatiron Metastatic Prostate Cancer (PC) Core Registry and Komodo's Healthcare Map. Patients were excluded if they initiated a clinical trial drug in 1 L, had <12 months of insurance eligibility prior to index, or no claims in Komodo's Healthcare Map for the Flatiron oncologist-defined index therapy. All-cause and PC-related total costs per-patient-per-month (PPPM), including costs for services and procedures from medical claims (i.e. medical costs) and costs from pharmacy claims (i.e. pharmacy costs), were described in the 12-month baseline period before 1 L therapy initiation (including the baseline pre- and post- mCRPC progression periods) and during 1 L therapy (follow-up).

RESULTS

Among 459 patients with mCRPC (mean age 70 years, 57% White, 16% Black, 45% commercially-insured, 43% Medicare Advantage-insured, and 12% Medicaid-insured), average baseline all-cause total costs (PPPM) were $4,576 ($4,166 pre-mCRPC progression, $8,278 post-mCRPC progression). Average baseline PC-related total costs were $2,935 ($2,537 pre-mCRPC progression, $6,661 post-mCRPC progression). During an average 1 L duration of 8.5 months, mean total costs were $13,746 (all-cause) and $12,061 (PC-related) PPPM. The cost increase following 1 L therapy initiation was driven by higher PC-related outpatient and pharmacy costs. PC-related medical costs PPPM increased from $1,504 during baseline to $5,585 following 1 L mCRPC therapy initiation.

LIMITATIONS

All analyses were descriptive; statistical testing was not performed.

CONCLUSION

Incremental costs of progression to mCRPC are significant, with the majority of costs driven by higher PC-related costs. Using contemporary data, this study highlights the importance of utilizing effective therapies that slow progression and reduce healthcare resource demands despite the initial investment in treatment costs.

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.

Treatment Patterns, Clinical Outcomes, Health Care Resource Utilization and Costs in Older Patients With Metastatic Castration-Resistant Prostate Cancer in the United States: An Analysis of SEER-Medicare Data

BACKGROUND

Prostate cancer (PC) is more likely to develop in men ≥65 years old than in those <65 years old. This study aimed to generate real-world evidence on treatment patterns, clinical outcomes, health care resource utilization (HCRU), and costs among older patients with metastatic castration-resistant PC (mCRPC).

MATERIALS AND METHODS

A claims algorithm based on treatments expected for mCRPC was used to identify men ≥65 years old with mCRPC in the SEER-Medicare data between 2007 and 2019. The index date was defined as the date of the start of first-line therapy (1L). Treatment patterns and all-cause and PC-specific HCRU and costs were measured in the 12 months preindex period and the postindex follow-up period. Time to next treatment or death (TNTD) and overall survival (OS) were assessed in the follow-up period.

RESULTS

A total of 4758 patients met the eligibility criteria and received 1L treatment. Among these 1L patients, 57.4% subsequently received second-line (2L) treatment; among patients receiving 2L treatment, 49.3% subsequently received third-line (3L) treatment. Abiraterone, enzalutamide, and docetaxel were most common regimens in 1L (41.9%, 22.0%, 22.0%, respectively), 2L (33.3%, 32.7%, 13.6%, respectively), and 3L (17.9%, 25.1%, 22.3%, respectively). On average, patients had 1.2 inpatient admissions, 1.1 emergency room visits, and 27.6 outpatient visits per year during follow-up. The mean total all-cause and PC-related costs during the follow-up period were $111,060 and $99,540 per-patient-per-year, respectively. Median TNTD was 9.3, 6.5, and 5.7 months for 1L, 2L, and 3L, respectively. Median OS from the start of 1L treatment for mCRPC was 21.5 months.

DISCUSSION

Among older patients with mCRPC, high attrition from 1L to subsequent lines of therapy was observed. Median TNTD was <1 year and median OS was <2 years. These results highlight a need to introduce more effective mCRPC therapies in 1L to improve clinical outcomes for older patients.

Use of Structured Template and Reporting Tool for Real-World Evidence for Critical Appraisal of the Quality of Reporting of Real-World Evidence Studies: A Systematic Review

OBJECTIVES

Real-world evidence (RWE) studies are increasingly being used to support healthcare decisions. Various frameworks, tools, and checklists exist for ensuring quality of real-world data, designing robust studies, and assessing potential for bias. In January 2021, Structured Template and Reporting Tool for RWE (STaRT-RWE) was released to further reduce ambiguity, assumptions, and misinterpretation while planning, implementing, and reporting RWE studies of the safety and effectiveness of treatments. The objective of this study was to identify gaps in the reporting quality of published RWE studies by using this template for critical appraisal.

METHODS

Two reviewers conducted a keyword search on PubMed for free-full-text research articles using real-world data, RWE design, and safety with or without effectiveness outcomes of a medicinal product or intervention in humans of any age or gender, published in English between January 13, 2021, and January 13, 2022. Assessment of risk of bias was done using Assessment of Real-World Observational Studies critical appraisal tool. Deficiencies in methods and findings as per STaRT-RWE template were reported as frequencies.

RESULTS

A total of 54 of 2374 retrieved studies were included in the review. Based on the STaRT-RWE template, the studies inadequately reported empirically defined covariates, power and sample size calculation, attrition, sensitivity analyses, index date (day 0) defining criterion, predefined covariates, outcome, metadata about data source and software, objective, inclusion and exclusion criteria, analysis specifications, and follow-up.

CONCLUSIONS

The use of STaRT-RWE template along with its tables, design diagram, and library of published studies has a potential of improving robustness of RWE studies.

Outcomes Following Abiraterone versus Enzalutamide for Prostate Cancer: A Scoping Review

Abiraterone acetate (AA) and enzalutamide (ENZ) are commonly used for metastatic prostate cancer. It is unclear how their outcomes and toxicities vary with patient-specific factors because clinical trials typically exclude patients with significant comorbidities. This study aims to fill this knowledge gap and facilitate informed treatment decision making. A registered protocol utilizing PRISMA scoping review methodology was utilized to identify real-world studies. Of 433 non-duplicated publications, 23 were selected by three independent reviewers. ENZ offered a faster and more frequent biochemical response (30-50% vs. 70-75%), slowed progression (HR 0.66; 95% CI 0.50-0.88), and improved overall survival versus AA. ENZ was associated with more fatigue and neurological adverse effects. Conversely, AA increased risk of cardiovascular- (HR 1.82; 95% CI 1.09-3.05) and heart failure-related (HR 2.88; 95% CI 1.09-7.63) hospitalizations. Ultimately, AA was associated with increased length of hospital stay, emergency department visits, and hospitalizations (HR 1.26; 95% CI 1.04-1.53). Accordingly, total costs were higher for AA, although pharmacy costs alone were higher for ENZ. Existing data suggest that AA and ENZ have important differences in outcomes including toxicities, response, disease progression, and survival. Additionally, adherence, healthcare utilization, and costs differ. Further investigation is warranted to inform treatment decisions which optimize patient outcomes.

Real-World Effectiveness of Sipuleucel-T on Overall Survival in Men with Advanced Prostate Cancer Treated with Androgen Receptor-Targeting Agents

Introduction

The treatment landscape for metastatic castration-resistant prostate cancer (mCRPC) continues to evolve. Sipuleucel-T was the first immunotherapy approved by the US Food and Drug Administration (FDA) to treat asymptomatic or minimally symptomatic mCRPC. The androgen receptor-targeting agents (ARTAs) abiraterone acetate and enzalutamide were initially approved to treat mCRPC. Looking at chemotherapy-naïve men with mCRPC, we compared survival outcomes between the sipuleucel-T + ARTA cohort (men who received either sipuleucel-T or an ARTA in the first line, and then the other in the second line within 6 months) and the ARTA monotherapy cohort (men who only received ARTA monotherapy).

Methods

This retrospective cohort analysis used longitudinal, adjudicated claims data from the US Medicare Fee-for-Service 100% research identifiable dataset that includes both urologic and oncologic practice settings. Eligible men started their first mCRPC treatment with either sipuleucel-T or ARTA in either 2014 or 2015 and had continuous Medicare Parts A, B, and D eligibility for the subsequent 3 years. A multivariable Cox proportional hazards regression model was used to analyze overall survival (OS), both overall and by index year, and to control for differences.

Results

The sipuleucel-T + ARTA and ARTA monotherapy cohorts comprised 773 and 4642 men, respectively, with different characteristics at treatment start. The most commonly used ARTAs were enzalutamide in the former and abiraterone in the latter cohort. Median OS was 30.4 and 14.3 months in the sipuleucel-T + ARTA and ARTA monotherapy cohorts, respectively, with the sipuleucel-T + ARTA cohort having a 28.3% lower risk of death than the ARTA monotherapy cohort (hazard ratio 0.717; 95% CI 0.648, 0.793; p < 0.01).

Conclusions

This real-world study of mCRPC treatment indicates that men receiving sipuleucel-T and ARTAs had a longer median OS than patients receiving treatment with an ARTA alone, suggesting that leveraging mechanisms of action can be beneficial in treating patients with mCRPC.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-022-02085-6.

The treatment landscape for metastatic castration-resistant prostate cancer (mCRPC) continues to evolve. There are multiple treatments for mCRPC, including sipuleucel-T, the first US Food and Drug Administration (FDA)-approved immunotherapy, and the androgen receptor-targeting agents (ARTAs) abiraterone acetate and enzalutamide. Although sipuleucel-T uses a unique mechanism of action that may be useful in developing a treatment strategy for mCRPC, an optimal treatment algorithm for prostate cancer remains undefined. Therefore, survival was compared in men with mCRPC who received sipuleucel-T and an ARTA in the first 6 months of treatment with those who received only ARTA monotherapy. A retrospective longitudinal study was conducted using the US Medicare Fee-for-Service 100% research identifiable dataset linked to the National Death Index. Eligible men started their first mCRPC treatment with either sipuleucel-T or ARTA in either 2014 or 2015 and had continuous Medicare eligibility for the subsequent 3 years. Men who received treatment with both sipuleucel-T and an ARTA had a longer median survival (30.4 months) than men who received an ARTA without sipuleucel-T (14.3 months). This represents a 28% reduced risk of death with sipuleucel-T. This real-world study of mCRPC treatment indicates that men receiving sipuleucel T and an ARTA survive longer than men who only receive an ARTA, suggesting that changing the mechanism of action can be beneficial in treating patients with mCRPC.