Association of CYP1A1 and CYP1B1 inhibition in in vitro assays with drug-induced liver injury.

Drug-induced liver injury (DILI) is one of the major causes for the discontinuation of drug development and withdrawal of drugs from the market. Since it is known that reactive metabolite formation and being substrates or inhibitors of cytochrome P450s (P450s) are associated with DILI, we systematically investigated the association between human P450 inhibition and DILI. The inhibitory activity of 266 DILI-positive drugs (DILI drugs) and 92 DILI-negative drugs (no-DILI drugs), which were selected from Liver Toxicity Knowledge Base (US Food and Drug Administration), against 8 human P450 forms was assessed using recombinant enzymes and luminescent substrates, and the threshold values showing the highest balanced accuracy for DILI discrimination were determined for each P450 enzyme using receiver operating characteristic analyses. The results showed that among the P450s tested, CYP1A1 and CYP1B1 were inhibited by DILI drugs more than no-DILI drugs with a statistical significance. We found that 91% of drugs that showed inhibitory activity greater than the threshold values against CYP1A1 or CYP1B1 were DILI drugs. The results of internal 5-fold cross-validation confirmed the usefulness of CYP1A1 and CYP1B1 inhibition data for the threshold-based discrimination of DILI drugs. Although the contribution of these P450s to drug metabolism in the liver is considered minimal, our present findings suggest that the assessment of CYP1A1 and CYP1B1 inhibition is useful for screening DILI risk of drug candidates at the early stage of drug development.

The Complex Management of Atrial Fibrillation and Cancer in the COVID-19 Era: Drug Interactions, Thromboembolic Risk, and Proarrhythmia.

PURPOSE OF REVIEW: Cardiotoxicity by anticancer agents has emerged as a multifaceted issue and is expected to affect both mortality and morbidity. This review summarizes clinical challenges in the management of oncological patients requiring anticoagulants for atrial fibrillation (AF) also considering the current outbreak of the COVID-19 (coronavirus disease 2019) pandemic, since this infection can add challenges to the management of both conditions. Specifically, the aims are manyfold: (1) describe the evolving use of direct oral anticoagulants (DOACs) in AF patients with cancer; (2) critically appraise the risk of clinically important drug-drug interactions (DDIs) between DOACs and oral targeted anticancer agents; (3) address expected DDIs between DOACs and candidate anti-COVID drugs, with implications on management of the underlying thrombotic risk; and (4) characterize the proarrhythmic liability in cardio-oncology in the setting of COVID-19, focusing on QT prolongation. RECENT FINDINGS: AF in cardio-oncology poses diagnostic and management challenges, also due to the number of anticancer drugs recently associated with AF onset/worsening. Oral targeted drugs can potentially interact with DOACs, with increased bleeding risk mainly due to pharmacokinetic DDIs. Moreover, the vast majority of oral anticancer agents cause QT prolongation with direct and indirect mechanisms, potentially resulting in the occurrence of torsade de pointes, especially in susceptible patients with COVID-19 receiving additional drugs with QT liability. Oncologists and cardiologists must be aware of the increased bleeding risk and arrhythmic susceptibility of patients with AF and cancer due to DDIs. High-risk individuals with COVID-19 should be prioritized to target preventive strategies, including optimal antithrombotic management, medication review, and stringent monitoring.

Administration of a long-acting antipsychotic injection to a child while managing contraindicated polypharmacy interactions and transition between services.

Second-generation antipsychotics are used to treat a variety of psychiatric symptoms and illnesses as well as the behavioural aspects of various neurodevelopmental disorders. However, there is reluctance in using second-generation long-acting injectable antipsychotics in child psychiatry services. We present a case of a 12-year-old child whose presentation and medication regime warranted the use of aripiprazole long-acting injection against a backdrop of potential CYP P450 enzyme interactions as a consequence of polypharmacy. The case also describes the difficulties encountered working across different health sectors and agencies and highlights the ongoing need for skills-based Continuous Professional Development for Child and Adolescent Mental Health Services-based nursing staff.

Expert consensus on the management of breakthrough cancer pain in older patients. A Delphi study.

OBJECTIVES: We aimed to generate expert-based recommendations on the management of breakthrough cancer pain (BTcP) in older patients with cancer. MATERIAL AND METHODS: A two-round multidisciplinary Delphi study. Specialists rated their agreement with a set of statements using a nine-point Likert scale (one = totally disagree and nine = totally agree). Statements were classified as appropriate (median ranged from seven to nine), irrelevant (median ranged from four to six) or inappropriate (median ranged from one to three). Consensus was established when at least two thirds of the panel scored within any of the ranges. RESULTS: A total of 64 specialists from pain units (44.4%), palliative care units (25.4%), medical oncology (19.1%), geriatric medicine (7.9%) and others (3.2%), participated in two consultation rounds. Specialists agreed that effective coordination between the different specialties and levels of care is essential for proper management of BTcP. Most participants (81.3%) supported the assessment of frailty and resolved (96.8%) that frailty status is a better indicator of patient needs than biological age. Participants agreed (75.8%) in the application of the Davies algorithm for diagnosis of BTcP in older patients. A strong consensus was achieved regarding which pharmacological treatment (transmucosal fentanyl) and dosing method (start low and go slow) are the most suitable for the older population. No agreement was reached on how interventionist techniques should be integrated into the therapeutic strategy for BTcP. CONCLUSIONS: The present Delphi has generated a set of recommendations that will help healthcare professionals in the management of BTcP in older patients.

Steroidogenic disruptive effects of the serotonin-noradrenaline reuptake inhibitors duloxetine, venlafaxine and tramadol in the H295R cell assay and in a recombinant CYP17 assay.

The aim of this study was to determine the steroidogenic endocrine disrupting effect of three widely used serotonin-noradrenaline reuptake inhibitors duloxetine, venlafaxine and tramadol, using two in vitro models, the H295R assay and a recombinant CYP17 enzyme assay. Steroid hormones were quantified using LC-MS/MS. Duloxetine showed endocrine disrupting effects at 5-20µM with CYP17 being the main target. Venlafaxine also affected the steroidogenesis, mainly by affecting the CYP17 lyase reaction, although at much higher concentrations i.e. 100µM. Tramadol only exerted minor effects on the steroidogenesis with the lowest observed effect at 314µM. Based on the H295R results, the inhibition of CYP17 by duloxetine and venlafaxine was investigated in a recombinant CYP17 assay with the use of the 4 major CYP17 substrates pregnenolone, progesterone, 17α-hydroxypregnenolone and 17α-hydroxyprogesterone. Both duloxetine and venlafaxine inhibited CYP17 enzyme activity, but duloxetine was most potent. IC50-values were in the range 5.3-21µM for duloxetine and 1318-2750µM for venlafaxine. Overall, results from the recombinant CYP17 assay confirmed the results from the H295R cell assay. Using testosterone as end point, the margin of safety (defined as NOAEL/Cmax) for duloxetine was 1.6 indicating that duloxetine may have endocrine disrupting effects. In contrast, venlafaxine and tramadol showed higher margins of safety (venlafaxine: 24; tramadol: 157) indicating a lower potential to disrupt the human steroidogenesis.

A Chemoproteomic Platform To Assess Bioactivation Potential of Drugs.

Reactive metabolites (RM) formed from bioactivation of drugs can covalently modify liver proteins and cause mechanism-based inactivation of major cytochrome P450 (CYP450) enzymes. Risk of bioactivation of a test compound is routinely examined as part of lead optimization efforts in drug discovery. Here we described a chemoproteomic platform to assess in vitro and in vivo bioactivation potential of drugs. This platform enabled us to determine reactivity of thousands of proteomic cysteines toward RMs of diclofenac formed in human liver microsomes and living animals. We pinpointed numerous reactive cysteines as the targets of RMs of diclofenac, including the active (heme-binding) sites on several key CYP450 isoforms (1A2, 2E1 and 3A4 for human, 2C39 and 3A11 for mouse). This general platform should be applied to other drugs, drug candidates, and xenobiotics with potential hepatoxicity, including environmental organic substances, bioactive natural products, and traditional Chinese medicine.

Population pharmacokinetics of ospemifene and safety evaluation of pharmacokinetic alterations caused by intrinsic and extrinsic factors
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PURPOSE: To develop a population pharmacokinetic (PPK) model to assess factors influencing ospemifene pharmacokinetics and to assess safety for pharmacokinetic alteration observed in drug development. METHOD: A PPK model was constructed using pooled ospemifene concentrations. Covariates considered before start of the analysis were: age, race, body weight, BMI, albumin, alanine amino-transferase, bilirubin, and creatinine clearance. The expected distribution of ospemifene concentration was derived for the 4 cases in phase-1 studies that increased ospemifene exposure: administration to severe renal impairment subjects (case 1), administration to moderate hepatic impairment subjects (case 2), coadministration with ketoconazole (case 3), or coadministration with fluconazole (case 4). Safety information in a long-term safety trial was used to assess the potential changes in risk of adverse events with ospemifene-exposure increase. RESULTS: The PPK parameter estimates were 9.16 L/h for CL/F, 34.3 L for V2/F, 16.4 L/h for Q/F, 250 L for V3/F, and 0.522 h-1 for ka, based on the final model. Distributions of estimated AUC in a phase-3 study largely covered the expected distribution for case 1, case 2, or case 3, but did not overlap the expected distribution for case 4. The incidences of adverse events were not associated with ospemifene exposure in the long-term safety study. CONCLUSIONS: We developed an ospemifene PPK model and identified no relevant covariate in the PPK analysis. The drug appears safe to use in renal impairment, moderate hepatic impairment, and when coadministered with ketoconazole. Ospemifene should not be administered with fluconazole.
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Absorption, Distribution, and Excretion of the Investigational Agent Orteronel (TAK-700) in Healthy Male Subjects: A Phase 1, Open-Label, Single-Dose Study.

This study evaluated the absorption, distribution, and excretion of orteronel, an investigational, nonsteroidal, reversible, selective 17,20-lyase inhibitor. Six healthy male subjects received a single 400-mg dose of radiolabeled [(14) C]-orteronel (18.5 kBq). The pharmacokinetics of [(14) C]-radioactivity, orteronel, and the primary metabolite M-I were characterized by ultra-performance liquid chromatography-tandem mass spectrometry, and mass balance recovery of [(14) C]-radioactivity was determined by liquid scintillation counting and accelerator mass spectrometry. Median time to maximum observed concentration of [(14) C]-radioactivity was 2.5 hours (plasma/whole blood) and of orteronel was 1 hour (plasma). Mean terminal half-life for [(14) C]-radioactivity in plasma and whole blood was 9.46 and 7.39 hours, respectively. For [(14) C]-radioactivity, the geometric mean whole blood-to-plasma ratios for maximum observed plasma/whole-blood concentration, area under the plasma concentration-time curve from time 0 to last quantifiable concentration (AUC0-last ), and AUC0-inf (AUC from time 0 to infinity) were 1.04, 0.92, and 0.93, respectively. Dose recovery accounted for 95.9% of the administered orteronel dose; the majority of excretion occurred by 96 hours postdose. The principal excretion route was via urine (mean, 77.5%; including 49.7% unchanged drug and 16.3% M-I) compared with 18.4% via feces. Three mild adverse events were reported; none were considered serious or related to orteronel.

A Phase 1, Randomized, Single-Dose Crossover Pharmacokinetic Study to Investigate the Effect of Food Intake on Absorption of Orteronel (TAK-700) in Healthy Male Subjects.

This study aimed to determine the impact of food on the pharmacokinetics of orteronel, an investigational nonsteroidal, reversible selective inhibitor of 17,20-lyase. In this open-label, randomized crossover study, healthy subjects received single doses of orteronel 400 mg with a low-fat meal, a high-fat meal, and under fasting conditions in a randomized sequence. Plasma concentrations of orteronel and its primary M-I metabolite were determined by ultra-performance liquid chromatography, and pharmacokinetic parameters were evaluated using mixed-effects analysis of variance model. Compared with fasting conditions, the oral bioavailability of orteronel was increased under fed conditions. The least-squares mean ratio for area under the plasma concentration-time curve after a low-fat breakfast was 135% (90% confidence interval [CI], 126%-145%) compared with fasting conditions. Similarly, after a high-fat breakfast, the corresponding value was 142% (90%CI, 132%-152%). No unexpected safety concerns were raised with orteronel 400 mg administered in the fasted state or after either a high-fat or a low-fat meal; mild adverse events were experienced by 36% of the healthy male subjects.

A Physiologically Based Pharmacokinetic Model of Amiodarone and its Metabolite Desethylamiodarone in Rats: Pooled Analysis of Published Data.

BACKGROUND AND OBJECTIVE: Amiodarone (AMD) is one of the most effective drugs for rhythm control of atrial fibrillation. The use of AMD is also associated with adverse effects in multiple tissues. Both the parent compound and its major metabolite desethylamiodarone (DEA) contribute to the drug's therapeutic and toxic action. The present study aimed to build a whole-body physiologically based pharmacokinetic (PBPK) model for AMD and DEA in rats. METHODS: Pharmacokinetic data from multiple studies were collected. Some of the data were pooled together to develop the PBPK model; others were used to evaluate the model. Development of the model also involved in vitro to in vivo extrapolation based on in vitro metabolism data. RESULTS: The final model consisted of 11 tissue compartments, including therapeutic target organs and those to which AMD and DEA may be harmful. Model simulations were in good agreement with the observed time courses of the drug-metabolite pair in tissues, under various dosing scenarios. The key pharmacokinetic properties of AMD, such as extensive tissue distribution, substantial storage in the fat tissue, and long half-lives in many tissues, were closely reflected. CONCLUSION: The developed PBPK model can be regarded as the first step towards a PBPK-pharmacodynamic model that can used to mechanistically evaluate and explain the high adverse event rate and potentially to determine which factors are the primary drives for experiencing an adverse event.

Food effects on abiraterone pharmacokinetics in healthy subjects and patients with metastatic castration-resistant prostate cancer.

Food effect on abiraterone pharmacokinetics and safety on abiraterone acetate coadministration with low-fat or high-fat meals was examined in healthy subjects and metastatic castration-resistant prostate cancer (mCRPC) patients. Healthy subjects (n = 36) were randomized to abiraterone acetate (single dose, 1000 mg) + low-fat meal, + high-fat meal, and fasted state. mCRPC patients received repeated doses (abiraterone acetate 1000 mg + 5 mg prednisone twice daily; days 1-7) in a modified fasting state followed by abiraterone acetate plus prednisone within 0.5 hours post-low-fat (n = 6) or high-fat meal (n = 18; days 8-14). In healthy subjects, geometric mean (GM) abiraterone area under plasma concentration-time curve (AUC) increased ∼5- and ∼10-fold, respectively, with low-fat and high-fat meals versus fasted state (GM [coefficient of variation], 1942 [48] and 4077 [37] ng · h/mL vs 421 [67] ng · h/mL, respectively). In mCRPC patients, abiraterone AUC was ∼2-fold higher with a high-fat meal and similar with a low-fat meal versus modified fasting state (GM [coefficient of variation]: 1992 [34] vs 973 [58] ng · h/mL and 1264 [65] vs 1185 [90] ng · h/mL, respectively). Adverse events (all grade ≤ 3) were similar, with high-fat/low-fat meals or fasted/modified fasting state. Short-term dosing with food did not alter abiraterone acetate safety.

Identification and Mechanistic Investigation of Drug-Drug Interactions Associated With Myopathy: A Translational Approach.

Myopathy is a group of muscle diseases that can be induced or exacerbated by drug-drug interactions (DDIs). We sought to identify clinically important myopathic DDIs and elucidate their underlying mechanisms. Five DDIs were found to increase the risk of myopathy based on analysis of observational data from the Indiana Network of Patient Care. Loratadine interacted with simvastatin (relative risk 95% confidence interval [CI] = [1.39, 2.06]), alprazolam (1.50, 2.31), ropinirole (2.06, 5.00), and omeprazole (1.15, 1.38). Promethazine interacted with tegaserod (1.94, 4.64). In vitro investigation showed that these DDIs were unlikely to result from inhibition of drug metabolism by CYP450 enzymes or from inhibition of hepatic uptake via the membrane transporter OATP1B1/1B3. However, we did observe in vitro synergistic myotoxicity of simvastatin and desloratadine, suggesting a role in loratadine-simvastatin interaction. This interaction was epidemiologically confirmed (odds ratio 95% CI = [2.02, 3.65]) using the data from the US Food and Drug Administration Adverse Event Reporting System.

Pharmacokinetics of abiraterone in healthy Japanese men: dose-proportionality and effect of food timing.

PURPOSE: Abiraterone acetate (AA) was recently approved for castration-resistant prostate cancer in Japan. Two phase 1 studies were conducted to assess the pharmacokinetics of abiraterone after single-dose administration in Japanese healthy men and to evaluate the effects of food timing on abiraterone pharmacokinetics after single-dose administration of AA in Japanese and Caucasian healthy men. METHODS: In the dose-proportionality study, subjects (n = 30 Japanese) were randomly assigned to receive single doses of 250, 500, and 1,000 mg AA, and in the food-timing study, subjects (n = 22 Japanese and n = 23 Caucasian) randomly received single doses of 1,000 mg AA under fasted (overnight) and three different modified fasting conditions. RESULTS: Mean C(max) and AUC(∞) for abiraterone increased dose-dependently in Japanese healthy men; however, 90 % confidential interval (CI) was outside the predefined dose-proportionality criteria. Based on geometric mean ratios and 90 % CIs (versus overnight fasting condition), abiraterone exposure (AUC) increased significantly with dosing 1 h premeal, 2 h postmeal, or in between two meals 4 h apart by 57 %, 595 %, and 649 %, respectively. CONCLUSION: No clinically meaningful difference was observed in the pharmacokinetics of abiraterone between Caucasian and Japanese subjects.

Outcomes with abiraterone acetate in metastatic castration-resistant prostate cancer patients who have poor performance status.

BACKGROUND: Although abiraterone acetate (abiraterone) has proven efficacy in two randomised phase 3 trials in metastatic castration-resistant prostate cancer (mCRPC), patients who had an Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≥2 were either excluded or under-represented in these trials. OBJECTIVE: To compare outcomes in ECOG PS 0-1 and ≥2 in mCRPC patients treated with abiraterone. DESIGN, SETTING, AND PARTICIPANTS: Cancer registries from three Canadian centres were used to retrospectively identify mCRPC patients (postdocetaxel and docetaxel-naïve) treated with abiraterone. ECOG PS, clinicopathologic characteristics, prostate-specific antigen (PSA) response, and survival data were collected. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Survival outcomes were estimated using the Kaplan-Meier method and compared using the log-rank test. Cox proportional hazards modelling was used to examine the effect of clinicopathologic characteristics on overall survival (OS) and time to PSA progression. RESULTS AND LIMITATIONS: A total of 519 patients were identified; 61% (n=318) and 39% (n=201) were ECOG PS 0-1 and ≥2, respectively. ECOG PS 0-1 patients were significantly more likely than PS ≥2 patients to achieve a PSA decline ≥50% from baseline (45% vs 32%; p=0.003, Fisher exact test) and had significantly longer median time to PSA progression (5.2 mo vs 4.1 mo; p=0.023), median treatment duration (7.4 mo vs 4.5 mo; p<0.001), and median OS (20.0 mo vs 9.1 mo; p<0.001). On multivariate analysis, ECOG PS was a significant factor for OS (p<0.001), time to PSA progression (p=0.043), and PSA decline (p=0.002). Potential limitations include the retrospective study design and subjective nature of ECOG PS classification. CONCLUSIONS: ECOG PS ≥2 mCRPC patients treated with abiraterone have inferior outcomes compared with ECOG 0-1 patients, especially in regard to OS. These data indicate that early initiation of abiraterone prior to a decline in PS may be warranted. PATIENT SUMMARY: We found that advanced prostate cancer patients who have worse performance status (PS) derive less benefit from abiraterone, indicating that earlier treatment before PS declines could improve outcomes.

Inhibitory effects of curcumin on activity of cytochrome P450 2C9 enzyme in human and 2C11 in rat liver microsomes.

Cytochrome P450 2C9 (CYP2C9), one of the most important phase I drug metabolizing enzymes, could catalyze the reactions that convert diclofenanc into diclofenac 4'-hydroxylation. Evaluation of the inhibitory effects of compounds on CYP2C9 is clinically important because inhibition of CYP2C9 could result in serious drug-drug interactions. The objective of this work was to investigate the effects of curcumin on CYP2C9 in human and cytochrome P450 2C11 (CYP2C11) in rat liver microsomes. The results showed that curcumin inhibited CYP2C9 activity (10 µmol L(-1) diclofenac) with half-maximal inhibition or a half-maximal inhibitory concentration (IC50) of 15.25 µmol L(-1) and Ki = 4.473 µmol L(-1) in human liver microsomes. Curcumin's mode of action on CYP2C9 activity was noncompetitive for the substrate diclofenanc and uncompetitive for the cofactor NADPH. In contrast to its potent inhibition of CYP2C9 in human, diclofenanc had lesser effects on CYP2C11 in rat, with an IC50 ≥100 µmol L(-1). The observations imply that curcumin has the inhibitory effects on CYP2C9 activity in human. These in vitro findings suggest that more attention should be paid to special clinical caution when intake of curcumin combined with other drugs in treatment.

The prevalence of opioid-related major potential drug-drug interactions and their impact on health care costs in chronic pain patients.

BACKGROUND: Literature has shown that chronic pain patients prescribed opioids are at an increased risk for experiencing drug-drug interactions as a result of polypharmacy. In addition, chronic, noncancer pain patients who experience drug-drug interactions have been shown to have greater health care utilization and costs. However, no study has focused on the health economics of major clinically significant drug-drug interactions associated with long-acting opioids. OBJECTIVES: To (a) estimate the prevalence of major drug-drug interactions among patients prescribed a long-acting opioid and (b) evaluate the potential impact of major drug-drug interactions on health care costs. METHODS: This study was a retrospective cohort analysis using claims data from the MarketScan Commercial Claims and Encounter Database between 2008 and 2010. Patients with at least 1 prescription for a long-acting opioid for ≥ 30 days were placed into cohorts according to the expected clinical impact of the potential drug-drug interaction: major versus none. Propensity score matching was used to mitigate differences in baseline characteristics between the cohorts. Health care costs were based on payments for all covered health care services, which consisted of inpatient and outpatient medical, emergency department, and outpatient prescription costs. RESULTS: Among 57,752 chronic, noncancer pain patients who met all inclusion and exclusion criteria, 5.7% (3,302) were exposed to a potential major drug-drug interaction. The costs associated with a potential interaction versus no potential interaction were significantly more after baseline characteristics of the cohorts were normalized by propensity score matching. Monthly health care costs in the 90-day post-index period were significantly greater ($3,366 vs. $2,757, a $609 difference) in patients exposed to a potential drug-drug interaction of major clinical significance, compared with those not exposed to a drug-drug interaction. The higher health care costs were mainly driven by outpatient and inpatient medical costs. CONCLUSIONS: Exposure to potential drug-drug interactions may result in unnecessary and unintended health care costs. Physicians should be made aware of commonly administered cytochrome P450 (CYP450) metabolized drugs in the chronic pain patient and consider prescribing non-CYP450 metabolized opioid and nonopioid analgesics. Managed care's use of utilization management tools to avoid these exposures may reduce costs.

Updated interim efficacy analysis and long-term safety of abiraterone acetate in metastatic castration-resistant prostate cancer patients without prior chemotherapy (COU-AA-302).

BACKGROUND: Abiraterone acetate (an androgen biosynthesis inhibitor) plus prednisone is approved for treating patients with metastatic castration-resistant prostate cancer (mCRPC). Study COU-AA-302 evaluated abiraterone acetate plus prednisone versus prednisone alone in mildly symptomatic or asymptomatic patients with progressive mCRPC without prior chemotherapy. OBJECTIVE: Report the prespecified third interim analysis (IA) of efficacy and safety outcomes in study COU-AA-302. DESIGN, SETTING, AND PARTICIPANTS: Study COU-AA-302, a double-blind placebo-controlled study, enrolled patients with mCRPC from April 2009 to June 2010. A total of 1088 patients were stratified by Eastern Cooperative Oncology Group performance status (0 vs 1). INTERVENTION: Patients were randomised 1:1 to abiraterone 1000mg plus prednisone 5mg twice daily by mouth versus prednisone. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Co-primary end points were radiographic progression-free survival (rPFS) and overall survival (OS). Median times to event outcomes were estimated using the Kaplan-Meier method. Hazard ratios (HRs) and 95% confidence intervals (CIs) were derived using the Cox model, and treatment comparison used the log-rank test. The O'Brien-Fleming Lan-DeMets α-spending function was used for OS. Adverse events were summarised descriptively. RESULTS AND LIMITATIONS: With a median follow-up duration of 27.1 mo, improvement in rPFS was statistically significant with abiraterone treatment versus prednisone (median: 16.5 vs 8.2 mo; HR: 0.52 [95% CI, 0.45-0.61]; p<0.0001). Abiraterone improved OS (median: 35.3 vs 30.1 mo; HR: 0.79 [95% CI, 0.66-0.95]; p=0.0151) but did not reach the prespecified statistical efficacy boundary (α-level: 0.0035). A post hoc multivariate analysis for OS using known prognostic factors supported the primary results (HR: 0.74 [95% CI, 0.61-0.89]; p=0.0017), and all clinically relevant secondary end points and patient-reported outcomes improved. While the post hoc nature of the long-term safety analysis is a limitation, the safety profile with longer treatment exposure was consistent with prior reports. CONCLUSIONS: The updated IA of study COU-AA-302 in patients with mCRPC without prior chemotherapy confirms that abiraterone delays disease progression, pain, and functional deterioration and has clinical benefit with a favourable safety profile, including in patients treated for ≥24 mo. TRIAL REGISTRATION: Study COU-AA-302, ClinicalTrials.gov number, NCT00887198. PATIENT SUMMARY: The updated results of this ongoing study showed that disease progression was delayed in patients with advanced prostate cancer who were treated with abiraterone acetate and prednisone, and there was a continued trend in prolongation of life compared with patients treated with prednisone alone. Treatment with abiraterone acetate and prednisone was well tolerated by patients who were treated for >2 yr.

Single-dose pharmacokinetic studies of abiraterone acetate in men with hepatic or renal impairment.

Three open-label, single-dose studies investigated the impact of hepatic or renal impairment on abiraterone acetate pharmacokinetics and safety/tolerability in non-cancer patients. Patients (n = 8 each group) with mild/moderate hepatic impairment or end-stage renal disease (ESRD), and age-, BMI-matched healthy controls received a single oral 1,000 mg abiraterone acetate (tablet dose); while patients (n = 8 each) with severe hepatic impairment and matched healthy controls received 125- and 2,000-mg abiraterone acetate (suspension doses), respectively (systemic exposure of abiraterone acetate suspension is approximately half to that of tablet formulation). Blood was sampled at specified timepoints up to 72 or 96 hours postdose to measure plasma abiraterone concentrations. Abiraterone exposure was comparable between healthy controls and patients with mild hepatic impairment or ESRD, but increased by 4-fold in patients with moderate hepatic impairment. Despite a 16-fold reduction in dose, abiraterone exposure in patients with severe hepatic impairment was about 22% and 44% of the Cmax and AUC∞ of healthy controls, respectively. These results suggest that abiraterone pharmacokinetics were not changed markedly in patients with ESRD or mild hepatic impairment. However, the capacity to eliminate abiraterone was substantially compromised in patients with moderate or severe hepatic impairment. A single-dose administration of abiraterone acetate was well-tolerated.