A Retrospective Observational Analysis of Overall Survival with Sipuleucel-T in Medicare Beneficiaries Treated for Advanced Prostate Cancer.

INTRODUCTION: Since sipuleucel-T approval in 2010, the treatment landscape for metastatic castration-resistant prostate cancer (mCRPC) now includes the androgen-receptor signaling pathway inhibitors (ASPIs) abiraterone acetate or enzalutamide. In 2013 and 2014, these oral agents were approved for use in men with metastatic prostate cancer who had minimal to no symptoms. We compared overall survival (OS) in men who received their first mCRPC treatment using the Medicare Fee-for-Service 100% administrative claims research dataset with patient-level linkage to the National Death Index. METHODS: This retrospective cohort analysis (January 2013 to December 2017) included men who were chemo-naïve at treatment start in 2014 and who had continuous Medicare Parts A, B, and D eligibility during the 3-year observation period. We compared: first-line sipuleucel-T vs. first-line ASPIs and any-line sipuleucel-T vs. any-line ASPIs (without sipuleucel-T). We used a multivariable regression model to help control for potentially confounding factors while assessing survival outcomes. RESULTS: The model included 6044 eligible men (average age 75-78 years) with similar disease severity; > 80% were white. Median OS, presented as sipuleucel-T vs. ASPI, was 35.2 vs. 20.7 months (n, 906 vs. 5092; any-line cohort) and 34.9 vs. 21.0 months (n, 647 vs. 4810; first-line cohort). Model outcomes indicated sipuleucel-T was associated with significantly prolonged OS compared with ASPIs: adjusted hazard ratio, 0.59 (95% CI 0.527-0.651) and 0.56 (0.494-0.627) for the any-line and first-line cohorts, respectively. CONCLUSION: This analysis suggests use of sipuleucel-T at any time was associated with improved OS compared with ASPI use alone. Of note, these analyses are intended as descriptive rather than definitive as this dataset contains limited data on key clinical factors. While selection bias is a risk in secondary claims data, this research provides important insight into real-world treatment outcomes.

Assessment of STAT5 as a potential therapy target in enzalutamide-resistant prostate cancer.

Despite enzalutamide's efficacy in delaying the progression of metastatic castration-resistant prostate cancer (CRPC), resistance to this anti-androgen inevitably occurs. Several studies have revealed that the signal transducer and activator of transcription (STAT) 5 plays a role in tumour progression and development of drug resistance such as enzalutamide. Data mining revealed heterogeneous expression of STAT5 in enzalutamide-treated mCRPC patients and enzalutamide-resistant prostate cancer (PCa). Isobologram analysis revealed that the STAT5 inhibitor pimozide combined with enzalutamide has? additive and synergistic inhibitory effects on cell viability in the used models. Functional analysis with siRNA-mediated STAT5 knockdown yielded divergent results. The LNCaP-derived cell line MR49F could be resensitised to enzalutamide by siRNA-mediated STAT5b-knock-down. In contrast, neither STAT5a nor STAT5b knockdown resensitised enzalutamide-resistant LAPC4-EnzaR cells to enzalutamide. In conclusion, our results indicate that STAT5 may be a possible target in a subgroup of enzalutamide-resistant PCa. However, based on the data presented here, a general role of STAT5 in enzalutamide-resistance and its potential as a therapeutic target could not be shown.

Economic Outcomes in Patients with Chemotherapy-Naïve Metastatic Castration-Resistant Prostate Cancer Treated with Enzalutamide or Abiraterone Acetate Plus Prednisone.

INTRODUCTION: Prostate cancer (PC) is the second leading cause of cancer death among US men and accounts for considerable healthcare expenditures. We evaluated economic outcomes in men with chemotherapy-naïve metastatic castration-resistant PC (mCRPC) treated with enzalutamide or abiraterone acetate plus prednisone (abiraterone). METHODS: We performed a retrospective analysis on 3174 men (18 years or older) utilizing the Veterans Health Administration (VHA) database from 1 April 2014 to 31 March 2018. Men with mCRPC were included if they had at least one pharmacy claim for enzalutamide or abiraterone (first claim date = index date) following surgical or medical castration, had no chemotherapy treatment within 12 months prior to the index date, and had continuous VHA enrollment for at least 12 months pre- and post-index date. Men were followed until death, disenrollment, or end of study and were 1:1 propensity score matched (PSM). All-cause and PC-related resource use and costs per patient per month (PPPM) in the 12 months post index were compared between matched cohorts. RESULTS: We identified 1229 men with mCRPC prescribed enzalutamide and 1945 prescribed abiraterone with mean ages of 74 and 73 years, respectively. After PSM, each cohort had 1160 patients. The enzalutamide cohort had fewer all-cause (2.51 vs 2.86; p < 0.0001) and PC-related outpatient visits (0.86 vs 1.03; p < 0.0001), with corresponding lower all-cause ($2588 vs $3115; p < 0.0001) and PC-related ($1356 vs $1775; p < 0.0001) PPPM outpatient costs compared with the abiraterone cohort. All-cause total costs (medical and pharmacy) PPPM ($8085 vs $9092; p = 0.0002) and PC-related total costs PPPM ($6321 vs $7280; p < 0.0001) were significantly lower in the enzalutamide cohort compared with the abiraterone cohort. CONCLUSIONS: Enzalutamide-treated men with chemotherapy-naïve mCRPC had significantly lower resource utilization and healthcare costs compared with abiraterone-treated men.

Prostate cancer (PC) is the second leading cause of death among men with cancer in the USA. Healthcare costs associated with PC, including hospitalizations, outpatient visits, and medications prescribed to treat adverse effects, depend on the severity of the disease and intensity of treatment, but are generally very high. Enzalutamide and abiraterone acetate with prednisone (abiraterone) are both approved treatments for men with PC that does not respond to treatments that reduce the male hormone testosterone, known as castration-resistant PC (CRPC). These drugs are associated with varying treatment duration and different adverse effects, and therefore could result in differences in the use of healthcare resources and overall cost of treatment. Here we evaluated the healthcare resource utilization (HCRU), which was calculated as the average number of healthcare encounters, including inpatient stays, outpatient visits, and pharmacy visits, and length of inpatient stays, and treatment costs associated with use of enzalutamide or abiraterone by men with metastatic CRPC (mCRPC), who had not received prior chemotherapy in the Veterans Health Administration. We found that men with chemotherapy-naïve mCRPC treated with enzalutamide used less healthcare resources and incurred lower total healthcare costs than men treated with abiraterone. On average, all-cause total healthcare costs were $1007 per patient per month lower and PC-related total healthcare costs were $959 per patient per month lower for patients treated with enzalutamide than those treated with abiraterone. These results support the hypothesis that the long-term HCRU and costs of enzalutamide may be lower compared with abiraterone.

Budget Impact of Enzalutamide for Nonmetastatic Castration-Resistant Prostate Cancer.

BACKGROUND: Prostate cancer is the most common cancer and second-leading cause of cancer death among men in the United States. Prostate cancer poses a large economic burden, which increases with progression from localized to metastatic disease. Newly approved treatments for non-metastatic castration-resistant prostate cancer (nmCRPC) delay disease progression and reduce the risk of metastatic disease. Quantifying the potential budget impact of these new treatments is of interest to health care decision makers. OBJECTIVE: To estimate the budget impact of enzalutamide for the treatment of patients with nmCRPC in the United States over a 3-year time horizon. METHODS: An Excel-based model was developed to estimate the budget impact to a U.S. health plan of enzalutamide, a second-generation antiandrogen, as an add-on to androgen deprivation therapy (ADT) for the treatment of high-risk nmCRPC patients (prostate-specific antigen doubling time of ≤ 10 months). Comparators include apalutamide + ADT, bicalutamide + ADT, and ADT only. The analysis includes treatment costs for nmCRPC and for treatment after progression to metastatic castration-resistant prostate cancer (mCRPC). The treated population size was estimated from epidemiological data and literature. Dosing, duration of therapy, and adverse event rates were based on package inserts and pivotal studies. RED BOOK, Centers for Medicare & Medicaid Services fee schedules, and literature were used to obtain costs of drugs, adverse events, and health care visits. Market shares were estimated for each comparator before and after enzalutamide adoption. A 1-way sensitivity analysis was performed to quantify the impact of parameter uncertainty. RESULTS: In a hypothetical 1-million-member plan with 3% annual growth, it was estimated that there would be approximately 19 eligible incident nmCRPC patients in year 1, increasing to 20 eligible incident patients in year 3. With an assumed market share of approximately 6% for enzalutamide in year 1, the budget impact would be $106,074 ($0.009 per member per month [PMPM]). With a 26% enzalutamide share in year 3, the budget impact would be $632,729 ($0.048 PMPM). Cumulative budget impact to the health plan over 3 years is estimated to be $1,082,095 ($0.028 PMPM). The increased cost of the treatment regimen is partly offset by reduced postprogression costs. CONCLUSIONS: Treatment of nmCRPC patients with enzalutamide has a modest budget impact that is partly offset by delaying progression to mCRPC. DISCLOSURES: This research was sponsored by Astellas Pharma and Pfizer, the codevelopers of enzalutamide. All authors contributed to the development of the manuscript and maintained control over the final content. Schultz is employed by Astellas Pharma and owns stock in Gilead Sciences and Shire. O'Day and Sugarman are employees of Xcenda, which received consultancy fees from Astellas Pharma. Ramaswamy is employed by Pfizer. A synopsis of the current study was presented in poster format at the AMCP Managed Care & Specialty Pharmacy Annual Meeting 2019, in San Diego, CA, on March 25-28, 2019.

Metastatic Hormone-Sensitive Prostate Cancer: A Review of the Current Treatment Landscape.

PURPOSE: In recent years, the treatment options for metastatic hormone-sensitive prostate cancer (mHSPC) have expanded significantly. In addition to androgen deprivation therapy, the systemic treatments now include docetaxel, abiraterone, enzalutamide, and apalutamide. Radiation to the primary is also an option for select low-volume patients. METHODS: We conducted a review of the pivotal trials that have changed the practice of mHSPC. RESULTS: We describe an overview of the trials that investigated docetaxel (CHAARTED and STAMPEDE-Docetaxel), abiraterone (LATTITUDE and STAMPEDE-Abiraterone), enzalutamide (ARCHES, ENZAMET), apalutamide (TITAN), and radiation to the primary (STAMPEDE-Radiation). DISCUSSION: The treatment of mHSPC is a complex topic, and treatment choice should be individualized. Patient preferences, cost, volume of disease, and side effect profiles are important in determining which option is the best for an individual patient.

Management of patients with high-risk and advanced prostate cancer in the Middle East: resource-stratified consensus recommendations.

PURPOSE: Prostate cancer care in the Middle East is highly variable and access to specialist multidisciplinary management is limited. Academic tertiary referral centers offer cutting-edge diagnosis and treatment; however, in many parts of the region, patients are managed by non-specialists with limited resources. Due to many factors including lack of awareness and lack of prostate-specific antigen (PSA) screening, a high percentage of men present with locally advanced and metastatic prostate cancer at diagnosis. The aim of these recommendations is to assist clinicians in managing patients with different levels of access to diagnostic and treatment modalities. METHODS: The first Advanced Prostate Cancer Consensus Conference (APCCC) satellite meeting for the Middle East was held in Beirut, Lebanon, November 2017. During this meeting a consortium of urologists, medical oncologists, radiation oncologist and imaging specialists practicing in Lebanon, Syria, Iraq, Kuwait and Saudi Arabia voted on a selection of consensus questions. An additional workshop to formulate resource-stratified consensus recommendations was held in March 2019. RESULTS: Variations in practice based on available resources have been proposed to form resource-stratified recommendations for imaging at diagnosis, initial management of localized prostate cancer requiring therapy, treatment of castration-sensitive/naïve advanced prostate cancer and treatment of castration-resistant prostate cancer. CONCLUSION: This is the first regional consensus on prostate cancer management from the Middle East. The following recommendations will be useful to urologists and oncologists practicing in all areas with limited access to specialist multi-disciplinary teams, diagnostic modalities and treatment resources.

Cost-effectiveness analysis of metformin with enzalutamide in the metastatic castrate-resistant prostate cancer setting.

INTRODUCTION: Enzalutamide (Enza) is an effective treatment for metastatic castrate-resistant prostate cancer (mCPRC). However, Enza is not cost-effective (CE) at willingness to pay (WTP) thresholds from $0-$125 000/quality adjusted life years (QALYs) and is therefore a strain on valuable health care dollars. Metformin (Met) is inexpensive (~$8.00/month) and is thought to improve prostate cancer specific and overall survival compared to those not taking Met. We hypothesized that there must be an added effect Met could provide that would make Enza CE thereby alleviating this financial strain on government health care budgets. MATERIALS AND METHODS: We constructed a Markov model and performed a threshold analysis to narrow in on the added effect needed to make such a combination therapy cost-effective at various WTP thresholds. RESULTS: At a WTP threshold of $50 000/QALY Enza + Met is unlikely to be CE unless it increases Enza's efficacy by more than 30%. At a WTP threshold of $100 000, Enza + Met could be CE barring Met adds 18.73% to the efficacy of Enza. CONCLUSIONS: Enza + Met is unlikely to be CE at WTP thresholds less than $100 000/QALY; these results make sense because a therapy that is not CE at these WTP thresholds by itself is unlikely to be CE with an adjuvant therapy that keep a patient on such a treatment for even longer. Finally, our model suggests that the mCRPC setting is not the optimal place to trial adding Met as the relative costs are high and utility values low.

Exposure-Response Assessment of Enzalutamide and Its Major Metabolites in a Real-World Cohort of Patients with Metastatic Castration-Resistant Prostate Cancer.

STUDY OBJECTIVE: Enzalutamide is an oral agent for the treatment of metastatic castration-resistant prostate cancer (mCRPC); N-desmethyl enzalutamide is its active metabolite, which has clinically relevant anti-androgen capacities similar to enzalutamide, and carboxylic acid enzalutamide is an inactive metabolite. The aim of our study was to investigate the relationship between enzalutamide and N-desmethyl enzalutamide exposure and treatment response in a real-world cohort of patients with mCRPC. DESIGN: Retrospective, observational, pharmacokinetic study. SETTING: Outpatient clinic at a tertiary cancer center in Amsterdam, the Netherlands. PATIENTS: Sixty-five patients with mCRPC who were treated with enzalutamide 160 mg daily and had at least one steady-state enzalutamide plasma concentration between May 2015 and June 2018; of these patients, 38 were prostate-specific antigen (PSA) responders and 27 were nonresponders. MEASUREMENTS AND MAIN RESULTS: Plasma concentrations, determined by using liquid chromatography with tandem mass spectrometry (LC-MS/MS), were compared between PSA responders and nonresponders. Three clinical end points were evaluated separately in this study: PSA-independent progression-free survival (PFS), time to PSA progression (TTPP), and rate of PSA response (defined as ≥ 50% decrease in PSA level from baseline). Enzalutamide toxicity was defined as discontinuation due to adverse events, dose reductions due to adverse events, or temporary treatment interruption. For these analyses, plasma concentrations of enzalutamide and N-desmethyl enzalutamide were divided into quartiles. Mean ± SD plasma concentrations in the 65 patients were as follows: enzalutamide 11.2 ± 2.8 µg/ml, N-desmethyl enzalutamide 9.9 ± 2.9 µg/ml, and carboxylic acid enzalutamide 6.1 ± 4.3 µg/ml. Plasma concentrations were not significantly different in the PSA responder versus nonresponder groups for enzalutamide (11.5 vs 10.6 µg/ml, p=0.20), N-desmethyl enzalutamide (10.1 vs 9.6 µg/ml, p=0.48), and carboxylic acid enzalutamide (6.5 vs 5.5 µg/ml, p=0.34). Univariate and multivariate analyses did not show a relationship between plasma concentrations and PSA-independent PFS, TTPP, or toxicity. CONCLUSION: This study confirmed that enzalutamide plasma concentrations were not related to PSA-independent PFS, TTPP, or toxicity in patients with mCRPC, and demonstrated that plasma concentrations of its major metabolites were also not associated with treatment response. Based on these findings, there is no role for therapeutic drug monitoring of enzalutamide in patients with mCRPC in daily practice.

Cost-effectiveness model of abiraterone plus prednisone, cabazitaxel plus prednisone and enzalutamide for visceral metastatic castration resistant prostate cancer therapy after docetaxel therapy resistance.

Aims: Among patients diagnosed with prostate cancer, 10-20% will develop castration-resistant prostate cancer (CRPC) within 5 years; for 70%, CRPC will metastasize, mostly to the lungs and/or liver. We performed a cost-effectiveness model comparing abiraterone plus prednisone (ABI + PRD), cabazitaxel plus prednisone (CAB + PRD) and enzalutamide (ENZ) for visceral metastatic CRPC post-docetaxel therapy resistance. Methods: A three-state (Progression-Free, Progression, Death) lifetime Markov model was constructed to compare ABI + PRD, CAB + PRD, and ENZ from a United States healthcare payer perspective (2019 US$; discount rate 3%/yr.). Effectiveness was measured in life-years (LYs) and quality-adjusted life years (QALYs). Inputs included treatment costs, grade III/IV adverse events with incidence ≥5%, physician follow-up, lab and imaging tests. Phase III trial Kaplan-Meier curves were extrapolated to estimate overall survival and Progression-Free transition probabilities. Incremental cost-effectiveness ratios (ICERs) and utility ratios (ICURs), probabilistic sensitivity analyses (PSAs) and cost-effectiveness acceptability curves at willingness-to-pay (WTP) thresholds were estimated. Results: Models estimated 3-year overall survival rates of 1.3% for patients treated with ABI + PRD, 16.2% for CAB + PRD, and 13.2% for ENZ. Estimated Progression-Free rates at 1.5 years were 0.51% for ABI + PRD, 0.27% for CAB + PRD, and 14.47% for ENZ. LYs and QALYs were 1.20 and 0.58 respectively for ABI + PRD, 1.48 and 0.56 for CAB + PRD, and 1.58 and 0.79 for ENZ. Total treatment costs were: $115,433 for ABI + PRD, $85,337 for CAB + PRD and $109,213 for ENZ. CAB + PRD and ENZ dominated ABI + PRD due to higher LYs gained. Incremental QALYs for ENZ vs. CAB + PRD were larger than incremental LYs. The ICUR for ENZ was $103,674/QALY compared to CAB + PRD. Conclusions: This analysis found ENZ provided greater LYs and QALYs than both ABI + PRD and CAB + PRD, at a lower cost than ABI + PRD, but at a higher cost compared to CAB + PRD. For patients with visceral mCRPC after docetaxel therapy resistance, ENZ was cost-effective 92% of the time with a WTP threshold of $100,000/QALY.

Adoption of Abiraterone and Enzalutamide by Urologists.

OBJECTIVE: To investigate the adoption of abiraterone and enzalutamide by urologists. Abiraterone and enzalutamide are oral therapies approved for the treatment of metastatic castration-resistant prostate cancer, a disease most commonly treated by medical oncologists. METHODS: Using the Medicare Part D Public Use Files from 2013 to 2016, we identified total abiraterone and enzalutamide prescriptions 2013-2016 and urologists who prescribed moderate to high volumes of these drugs. We then characterized the urologist practices of those urologists according to practice context (eg, single-specialty group) using data from the Centers for Medicare and Medicaid Services, and the geographic distribution of those providers. RESULTS: We found abiraterone prescriptions increased from 71,423 in 2013 to a peak of 100,371 in 2015 and enzalutamide prescriptions continued to increase from 29,572 in 2013 to 100,980 in 2016. Prescriptions by urologists increased between 2013 and 2016 while prescriptions by other specialties plateaued. The number of moderate-high prescribing urologists increased from 98 (abiraterone) and 22 (enzalutamide) in 2013, to 301 (abiraterone) and 671 (enzalutamide) by 2016 with 1063 unique urologists prescribing moderate-high volumes of either drug between 2013 and 2016. Among urologists who prescribe androgen deprivation therapy, 5% were moderate-high prescribers of abiraterone and 12% of enzalutamide in 2016. The majority of moderate-high prescribing urologists were in single-specialty groups (70%). CONCLUSION: Urologists are increasingly prescribing oral therapies for metastatic castration-resistant prostate cancer. Understanding the distribution of urologists specializing in castration-resistant prostate cancer therapeutics will help guide future interventions to optimize the care for this important patient population.

Comparative assessment of prognostic outcomes between first-generation antiandrogens and novel androgen-receptor-axis-targeted agents in patients with non-metastatic castration-resistant prostate cancer.

BACKGROUND: To compare the prognostic outcomes between first-generation antiandrogen (FGA) and novel androgen-receptor-axis-targeted agent (ARATA) as first-line therapy in patients with non-metastatic castration-resistant prostate cancer (nmCRPC). METHODS: This study retrospectively included a total of 103 consecutive nmCRPC patients consisting of 47 (45.6%) and 56 (54.4%) who received FGA (bicalutamide or flutamide) and ARATA (abiraterone acetate or enzalutamide), respectively, as the first-line agent after the failure of primary androgen deprivation therapy (ADT). RESULTS: There were no significant differences in the major clinicopathological parameters and previous therapeutic histories between the FGA and ARATA groups. During the observation period, 31 (66.0%) and 29 (51.8%) discontinued first-line therapy in the FGA and ARATA groups, respectively, and of these, 27 (87.1%) and 23 (79.3%) in the FGA and ARATA groups, respectively, were subsequently treated with approved agents as second-line therapy. The prostate-specific antigen (PSA) response rate in the FGA group was significantly lower than that in the ARATA group. Although no significant difference in overall survival was noted between the FGA and ARATA groups, there were significant differences in the PSA progression-free survival on first-line therapy and metastasis-free survival between the two groups, favoring the ARATA group compared with FGA group. CONCLUSIONS: Collectively, these findings suggest that among nmCRPC patients who progressed following treatment with the primary ADT, the introduction of ARATA may result in the delay of disease progression compared with FGA.

Treatment Duration, Healthcare Resource Utilization, and Costs Among Chemotherapy-Naïve Patients with Metastatic Castration-Resistant Prostate Cancer Treated with Enzalutamide or Abiraterone Acetate: A Retrospective Claims Analysis.

INTRODUCTION: Enzalutamide and abiraterone acetate (plus prednisone) are new hormonal treatments for metastatic castration-resistant prostate cancer (mCRPC). This study compared treatment duration, healthcare resource utilization (HRU), and treatment costs for chemotherapy-naïve mCRPC patients treated with enzalutamide or abiraterone acetate in the USA. METHODS: Chemotherapy-naïve mCRPC patients initiating treatment with enzalutamide or abiraterone acetate were identified from administrative claims. Continuous enrollment ≥ 6 months before and ≥ 3 months after the index date (initiation date of enzalutamide or abiraterone acetate) was required. Treatment duration, all-cause and prostate cancer-related HRU, and costs were estimated during the post-index period. Multivariable analyses compared HRU and costs between cohorts, adjusting for baseline characteristics. RESULTS: Overall, 920 chemotherapy-naïve patients initiated enzalutamide and 2310 initiated abiraterone acetate (median follow-up, 10.7 and 13.5 months, respectively). More enzalutamide-treated patients had corticosteroid-sensitive comorbidities at baseline. Treatment duration was longer with enzalutamide versus abiraterone acetate (median, 10.7 vs. 8.8 months; P = 0.008). Enzalutamide was associated with fewer all-cause inpatient admissions [adjusted incidence rate ratio (95% confidence interval) 0.87 (0.76, 0.99)], days of hospitalization [0.84 (0.70, 1.02)], and outpatient visits [0.94 (0.90, 0.98)], and fewer prostate cancer-related outpatient visits [0.92 (0.87, 0.96)] compared with abiraterone acetate. Enzalutamide was also associated with lower prostate cancer-related inpatient and emergency department costs [adjusted differences, $122 (P = 0.024) and $28 (P = 0.009), respectively]. CONCLUSION: Chemotherapy-naïve mCRPC patients treated with enzalutamide versus abiraterone acetate had longer treatment duration and incurred lower HRU and prostate cancer-related inpatient and emergency department costs. FUNDING: Astellas Pharma Inc.

Dutch Economic Value of Radium-223 in Metastatic Castration-Resistant Prostate Cancer.

BACKGROUND: The treatment of metastatic castration-resistant prostate cancer has changed with the introduction of radium-223, cabazitaxel, abiraterone and enzalutamide. To assess value for money, their cost effectiveness in patients with metastatic castration-resistant prostate cancer previously treated with docetaxel from the Dutch societal perspective was investigated. METHODS: A cost-effectiveness analysis was conducted using efficacy, symptomatic skeletal-related event and safety data obtained from indirect treatment comparisons. Missing skeletal-related event data for cabazitaxel were conservatively assumed to be identical to radium-223. A Markov model combined these clinical inputs with Dutch-specific resource use and costs for metastatic castration-resistant prostate cancer treatment from a societal perspective. Total quality-adjusted life-years and costs in 2017 euros were calculated over a 5-year (lifetime) time horizon. RESULTS: Radium-223 resulted in €6092 and €4465 lower costs and 0.02 and 0.01 higher quality-adjusted life-years compared with abiraterone and cabazitaxel, respectively, demonstrating dominance of radium-223. Sensitivity analyses reveal a 64% (54%) chance of radium-223 being cost effective compared with abiraterone (cabazitaxel) at the informal €80,000 willingness-to-pay threshold. Compared with enzalutamide, radium-223 resulted in slightly lower quality-adjusted life-years (-0.06) and €7390 lower costs, revealing a 61% chance of radium-223 being cost effective compared with enzalutamide. The lower costs of radium-223 compared with abiraterone and enzalutamide are driven by lower drug costs and prevention of expensive skeletal-related events. Compared with cabazitaxel, the lower costs of radium-223 are driven by lower costs of the drug, administration and adverse events. CONCLUSION: Radium-223 may be a less costly treatment strategy offering similar gains in health benefits compared with abiraterone, cabazitaxel and enzalutamide in patients with metastatic castration-resistant prostate cancer previously treated with docetaxel from the Dutch societal perspective.

Impact of prior androgen receptor-axis-targeted agents on the clinical activity of subsequent docetaxel in patients with metastatic castration-resistant prostate cancer: comparative assessment between abiraterone acetate and enzalutamide.

The objective of this study was to investigate the impact of prior treatment with androgen receptor-axis-targeted (ARAT) agents, abiraterone acetate (AA) and enzalutamide (Enz), on the activity of subsequently introduced docetaxel in patients with metastatic castration-resistant prostate cancer (mCRPC). This study included a total of 114 mCRPC patients consisting of 54 and 60 who progressed following treatment with AA and Enz, respectively, prior to the introduction of docetaxel, and compared oncological outcomes with docetaxel between these two groups. There were no significant differences in the major clinicopathological characteristics before treatment with docetaxel between the AA and Enz groups. The prostate-specific antigen (PSA) response rates to docetaxel in the AA and Enz groups were 40.7 and 43.3%, respectively, with no significant differences in the rates between these two groups. Following the introduction of docetaxel, the median PSA progression-free survival (PFS) and overall survival (OS) in the 114 patients were 7.2 and 17.5 months, respectively. There was no significant difference in the PSA PFS or OS between the AA and Enz groups. Despite the lack of a significant impact of the type of ARAT agent on PSA PFS or OS by univariate analysis, multivariate analyses identified the following independent prognostic predictors: performance status (PS) for PSA PFS and PS and visceral metastasis for OS. Collectively, these findings suggest that the type of ARAT agent may not have a significant impact on disease control by subsequent docetaxel therapy in mCRPC patients.

Letter--Corrected Net Health Benefit Calculations for Enzalutamide Using ASCO Value Framework Guidelines and NCCN Evidence Blocks.

DISCLOSURES: This research was funded by Astellas Pharma and Medivation, which was acquired by Pfizer in 2016. Astellas Pharma and Medivation are the co-developers of enzalutamide. Flanders, Brown, Massoudi, and Schultz are employees of Astellas Pharma. Ramaswamy is an employee of Pfizer and holds stock in Johnson & Johnson. Flanders holds stock in Johnson & Johnson, AbbVie, and Abbott Labs.

The lack of a relationship between physician payments from drug manufacturers and Medicare claims for abiraterone and enzalutamide.

BACKGROUND: Interactions between industry and prescribers have raised concerns regarding conflicts of interest. To the best of the authors' knowledge, quantitative data measuring these interactions have been limited until recently. In the current study, the authors sought to determine whether an association exists between industry payments and prescriber behavior with regard to abiraterone and enzalutamide. METHODS: Two Centers for Medicare and Medicaid Services databases were combined to analyze oncologists and urologists who received industry payments and/or prescribed abiraterone and enzalutamide. Correlation analysis was constructed on prescription count and industry payments. Multivariable median regression examined predictors of change in prescription count per dollar of industry payment. Stratifying prescribers by quantile evaluated threshold effects on prescribers. RESULTS: The number of prescriptions was similar between prescribers who did and those who did not receive industry payment for both drugs. The median industry payment amount to prescribers differed between prescribers and nonprescribers for abiraterone ($72 vs $56) and enzalutamide ($59 vs $31). Although no statistical association was found to exist between industry payment amount and prescription count for abiraterone prescribers, an association was found to exist for enzalutamide prescribers (rho = 0.31). A small change was found with regard to prescription count per dollar of industry payment for abiraterone (0.0007 prescriptions) and enzalutamide (0.0006 prescriptions). The amount of industry payment needed to predict one additional prescription was found to be lower in the fourth and fifth quantiles compared with the first through third quantiles. CONCLUSIONS: No difference in prescription count was found to exist between prescribers who received industry payments and those who did not. A positive correlation was noted between industry payments and prescription count for enzalutamide. Ease of adoption may affect differences between the 2 drugs. Cancer 2017;123:4356-62. © 2017 American Cancer Society.

Early National Dissemination of Abiraterone and Enzalutamide for Advanced Prostate Cancer in Medicare Part D.

INTRODUCTION: Abiraterone and enzalutamide were approved by the Food and Drug Administration in 2011 and 2012 to treat men with metastatic castration-resistant prostate cancer (mCRPC). Most men with mCRPC are > 65 years of age and thus eligible for Medicare Part D. We conducted a study to better understand the early dissemination of these drugs across the United States using national Medicare Part D data. METHODS: We evaluated the number of prescriptions for abiraterone and enzalutamide by provider specialty and hospital referral region (HRR) using Medicare Part D and Dartmouth Atlas data. We categorized HRRs by abiraterone and enzalutamide prescriptions, adjusted for prostate cancer incidence, and examined factors associated with regional variation using multilevel regression models. RESULTS: Among providers who wrote the majority of prescriptions for abiraterone or enzalutamide in 2013 (n = 2,121), 87.5% were medical oncologists, 3.3% were urologists, and 9.2% were other provider specialties. Among prescribers, approximately 30% were responsible for three quarters of the claims for abiraterone and 20% were responsible for more than half the claims for enzalutamide. Some HRRs demonstrated low-prescribing rates despite average medical oncology and urology physician workforce density. Our multilevel model demonstrated that regional factors potentially influenced variation in care. CONCLUSION: The majority of prescriptions written for abiraterone and enzalutamide through Medicare Part D in 2013 were written by a minority of providers, with marked regional variation across the United States. Better understanding of the early national dissemination of these effective but expensive drugs can help inform strategies to optimize introduction of new, evidence-based mCRPC treatments.

Docetaxel chemotherapy in metastatic castration-resistant prostate cancer: cost of care in Medicare and commercial populations.

OBJECTIVE: To estimate the healthcare costs and characteristics of docetaxel chemotherapy episodes of care for men with metastatic castration-resistant prostate cancer (mCRPC). METHODS: This study used the Medicare 5% sample and MarketScan Commercial (2010-2013) claims data sets to identify men with mCRPC and initial episodes of docetaxel treatment. Docetaxel episodes included docetaxel claim costs from the first claim until 30 days after the last claim, with earlier termination for death, insurance disenrollment, or the end of a 24-month look-forward period from initial docetaxel index date. Docetaxel drug claim costs were adjusted for 2011 generic docetaxel introduction, while other costs were adjusted to 2015 values using the national average annual unit cost increase. RESULTS: This study identified 281 Medicare-insured and 155 commercially insured men, with 325 and 172 docetaxel episodes, respectively. The average number of cycles (unique docetaxel infusion days) per episode was 6.9 for Medicare and 6.3 for commercial cohorts. The average cost per episode was $28,792 for Medicare and $67,958 for commercial cohorts, with docetaxel drug costs contributing $2,588 and $13,169 per episode, respectively. The average cost per episode on docetaxel infusion days was $8,577 (30%) for Medicare and $28,412 (42%) for commercial. Non-docetaxel infusion day costs included $7,074 (25%) for infused or injected drugs for Medicare, $10,838 (16%) for commercial cohorts, and $6,875 (24%) and $9,324 (14%) for inpatient admissions, respectively. LIMITATIONS: The applicability is only to the metastatic castration-resistance clinical setting, rather than the metastatic hormone-sensitive setting, and the lack of data on the cost effectiveness of different sequencing strategies of a range of systemic therapies including enzalutamide, abiraterone, radium-223, and taxane chemotherapy. CONCLUSION: The majority of docetaxel episode costs in Medicare and commercial mCRPC populations were non-docetaxel drug costs. Future research should evaluate the total cost of care in mCPRC.

Comparative Assessment of Efficacies Between 2 Alternative Therapeutic Sequences With Novel Androgen Receptor-Axis-Targeted Agents in Patients With Chemotherapy-Naïve Metastatic Castration-Resistant Prostate Cancer.

BACKGROUND: The objective of this study was to compare the efficacies of sequential therapies with novel androgen receptor-axis-targeted (ARAT) agents in patients with docetaxel-naïve metastatic castration-resistant prostate cancer (mCRPC). PATIENTS AND METHODS: This study included 108 consecutive patients with mCRPC who sequentially received abiraterone acetate (AA) and enzalutamide (Enz), in either order, without prior treatment with docetaxel. The combined prostate-specific antigen (PSA) progression-free survival (PFS) was defined as the sum of PFS1 and PFS2, representing PSA PFSs on the first and second ARAT agents, respectively. RESULTS: Of these patients, 49 and 59 received ARAT therapy with the AA-to-Enz sequence (AA-to-Enz group) and with the reverse sequence (Enz-to-AA group), respectively. No significant differences in the baseline characteristics were noted between the 2 groups. In the overall patient population, the PSA response rate to the second-line ARAT agent (21.3%) was significantly lower than that of the first-line ARAT agent (58.3%). The combined PSA PFS in the AA-to-Enz group (median, 18.4 months) was significantly superior to that of the Enz-to-AA group (median, 12.8 months). Furthermore, multivariate analysis identified the treatment sequence (ie, AA-to-Enz vs. Enz-to-AA group) in addition to performance status as an independent predictor of combined PSA PFS in these patients. However, there was no significant difference in overall survival (OS) between the 2 groups. CONCLUSIONS: Although cross-resistance between ARAT agents is a common phenomenon in docetaxel-naïve patients with mCRPC, different efficacies were observed favoring the AA-to-Enz rather than Enz-to-AA sequence in this series with respect to combined PSA PFS but not OS.

Comparative Assessment of Clinical Outcomes Between Abiraterone Acetate and Enzalutamide in Patients With Docetaxel-Naive Metastatic Castration-Resistant Prostate Cancer: Experience in Real-World Clinical Practice in Japan.

BACKGROUND: The objective of the present study was to comprehensively compare the clinical outcomes between abiraterone acetate (AA) and enzalutamide (Enz) in Japanese patients with docetaxel-naive metastatic castration-resistant prostate cancer (mCRPC). PATIENTS AND METHODS: The present study retrospectively included 280 consecutive mCRPC patients, consisting of 113 and 167 who had received AA and Enz, respectively, without previous treatment with docetaxel. RESULTS: Of the several baseline characteristics examined, some parameters, including performance status (PS), prostate-specific antigen (PSA) value, and incidence of lymph node metastasis, significantly favored the Enz over the AA group. The PSA response rate in the Enz group was significantly greater than that in the AA group, and the PSA progression-free survival in the Enz group was significantly superior to that in the AA group. Multivariate analyses of several parameters identified the following independent predictors of PSA progression-free survival: duration of androgen deprivation therapy and PS for the AA group, age and PS for the Enz group, and PS but not the introduced agent (ie, AA vs. Enz) for the overall patients. The common adverse events observed in the present series were fatigue (19.4%) and liver toxicity (11.5%) in the AA group and fatigue (32.3%) and appetite loss (19.2%) in the Enz group. In addition, the proportion of patients with adverse events grade ≥ 3 in the Enz group (11.4%) was significantly greater than that in the AA group (4.4%). CONCLUSION: Both AA and Enz were effective and tolerable for patients with docetaxel-naive mCRPC in the routine clinical setting.