Medication adherence among patients with advanced prostate cancer using oral therapies.

Aims: In light of the extended overall survival and improved quality of life provided by advanced prostate cancer (PC) oral therapies, this study aimed to describe treatment adherence to advanced PC oral therapies and evaluate associated patient characteristics and subsequent healthcare resource utilization (HRU). Patients & methods: Patients with advanced PC initiating apalutamide, enzalutamide or abiraterone acetate were identified from administrative data (October 1, 2014-September 30, 2019). Adherence and persistence at six months postinitiation were used to evaluate patient factors and HRU. Results: Aged ≥75 years, Black race, chemotherapy use and higher pharmacy paid amounts were associated with poor adherence/persistence, which translated to higher HRU. Conclusions: Strategies to increase adherence and persistence may improve patient outcomes and associated HRU.

Lay abstract This study included 27,262 patients with advanced prostate cancer who started taking one of three oral cancer medications (apalutamide, enzalutamide or abiraterone acetate) between October 2014 and September 2019. Patients who were black, aged 75 years or older, who had chemotherapy or who had higher prescription costs had the most difficulty following dosing guidelines or staying on treatment. Patients who did not follow dosing guidelines required more healthcare services. In light of the extended survival and improved quality of life that oral cancer medication for advanced prostate cancer provides, helping patients to take the correct medication dose, at the right time, and for the recommended length of time may improve their outcomes and reduce medical costs.

ENZA-p trial protocol: a randomized phase II trial using prostate-specific membrane antigen as a therapeutic target and prognostic indicator in men with metastatic castration-resistant prostate cancer treated with enzalutamide (ANZUP 1901).

OBJECTIVES: To determine the activity and safety of lutetium-177 (177 Lu)-prostate-specific membrane antigen (PSMA)-617 in men with metastatic castration-resistant prostate cancer (mCRPC) commencing enzalutamide, who are at high risk of early progression, and to identify potential prognostic and predictive biomarkers from imaging, blood and tissue. PARTICIPANTS AND METHODS: ENZA-p (ANZUP 1901) is an open-label, randomized, two-arm, multicentre, phase 2 trial. Participants are randomly assigned (1:1) to treatment with enzalutamide 160 mg daily alone or enzalutamide plus 177 Lu-PSMA-617 7.5 GBq on Days 15 and 57. Two additional 177 Lu-PSMA-617 doses are allowed, informed by Day-92 Gallium-68 (68 Ga)-PSMA positron emission tomography (PET; up to four doses in total). The primary endpoint is prostate-specific antigen (PSA) progression-free survival (PFS). Other major endpoints include radiological PFS, PSA response rate, overall survival, health-related quality of life, adverse events and cost-effectiveness. Key eligibility criteria include: biochemical and/or clinical progression; 68 Ga-PSMA PET-avid disease; no prior androgen signalling inhibitor, excepting abiraterone; no prior chemotherapy for mCRPC; and ≥2 high-risk features for early enzalutamide failure. Assessments are 4 weekly during study treatment, then 6 weekly until radiographic progression. Response Evaluation Criteria in Solid Tumours (RECIST) are used to assess imaging conducted every 12 weeks, 68 Ga-PSMA PET at baseline, Days 15 and 92, and at progression, and 18 F-fluorine deoxyglucose (18 F-FDG) PET at baseline and progression. Translational samples include blood (and optional biopsies) at baseline, Day 92, and first progression. Correlative studies include identification of prognostic and predictive biomarkers from 68 Ga-PSMA and 18 F-FDG PET/CT, circulating tumour cells and circulating tumour DNA. The trial will enrol 160 participants, providing 80% power with a two-sided type-1 error rate of 5% to detect a hazard ratio of 0.625 assuming a median PSA-PFS of 5 months with enzalutamide alone. RESULTS AND CONCLUSION: The combination of 177 Lu-PSMA-617 and enzalutamide may be synergistic. ENZA-p will determine the safety and efficacy of the combination in addition to developing predictive and prognostic biomarkers to better guide treatment decisions.

Adherence and out-of-pocket costs among Medicare beneficiaries who are prescribed oral targeted therapies for advanced prostate cancer.

BACKGROUND: Abiraterone and enzalutamide are high-cost oral therapies that increasingly are used to treat patients with advanced prostate cancer; these agents carry the potential for significant financial consequences to patients. In the current study, the authors investigated coping and material measures of the financial hardship of these therapies among patients with Medicare Part D coverage. METHODS: The authors performed a retrospective cohort study on a 20% sample of Medicare Part D enrollees who underwent treatment with abiraterone or enzalutamide between July 2013 and June 2015. The authors described the variability in adherence rates and out-of-pocket payments among hospital referral regions in the first 6 months of therapy and determined whether adherence and out-of-pocket payments were associated with patient factors and the socioeconomic characteristics of where a patient was treated. RESULTS: There were 4153 patients who filled abiraterone or enzalutamide prescriptions through Medicare Part D in 228 hospital referral regions. The mean adherence rate was 75%. The median monthly out-of-pocket payment for abiraterone and enzalutamide was $706 (range, $0-$3505). After multilevel, multivariable adjustment for patient and regional factors, adherence was found to be lower in patients who were older (69% for patients aged ≥85 years vs 76% for patients aged <70 years; P < .01) and in those with low-income subsidies (69% in those with a subsidy vs 76% in those without a subsidy; P < .01). Both Hispanic ethnicity and living in a hospital referral region with a higher percentage of Hispanic beneficiaries were found to be independently associated with higher out-of-pocket payments for abiraterone and enzalutamide. CONCLUSIONS: There were substantial variations in the adherence rate and out-of-pocket payments among Medicare Part D beneficiaries who were prescribed abiraterone and enzalutamide. Sociodemographic patient and regional factors were found to be associated with both adherence and out-of-pocket payments.

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.

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.

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.

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 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.