Clinical improvement in psoriasis with specific targeting of interleukin-23.

Psoriasis is a chronic inflammatory skin disorder that affects approximately 2-3% of the population worldwide and has severe effects on patients' physical and psychological well-being. The discovery that psoriasis is an immune-mediated disease has led to more targeted, effective therapies; recent advances have focused on the interleukin (IL)-12/23p40 subunit shared by IL-12 and IL-23. Evidence suggests that specific inhibition of IL-23 would result in improvement in psoriasis. Here we evaluate tildrakizumab, a monoclonal antibody that targets the IL-23p19 subunit, in a three-part, randomized, placebo-controlled, sequential, rising multiple-dose phase I study in patients with moderate-to-severe psoriasis to provide clinical proof that specific targeting of IL-23p19 results in symptomatic improvement of disease severity in human subjects. A 75% reduction in the psoriasis area and severity index (PASI) score (PASI75) was achieved by all subjects in parts 1 and 3 (pooled) in the 3 and 10 mg kg(-1) groups by day 196. In part 2, 10 out of 15 subjects in the 3 mg kg(-1) group and 13 out of 14 subjects in the 10 mg kg(-1) group achieved a PASI75 by day 112. Tildrakizumab demonstrated important clinical improvement in moderate-to-severe psoriasis patients as demonstrated by improvements in PASI scores and histological samples.

Food-effect study of nilotinib in chronic myeloid leukaemia (NiFo study): Enabling dose reduction and relief of treatment burden.

OBJECTIVES: Taking advantage of its food-dependent bioavailability, the present study investigated the effect of a reduced dose taken with real-life meals on the pharmacokinetics (PK) of nilotinib in chronic myeloid leukaemia (CML) patients. METHODS: Nilotinib was taken fasted (300 mg BID, days 1-4) or with real-life meals (200 mg BID, days 5-11). Rich sampling (days 1, 3, 8, 11) allowed for non-compartmental PK analysis. Nilotinib exposure (AUC0-12 h  -Cmin -Cmax ) and its intra- and interpatient variability were compared between the two regimens. Adverse events were recorded by means of a patient diary and ECG monitoring. RESULTS: Fifteen patients aged 40-74 years participated. Nilotinib PK following 200 mg BID taken with a meal strongly resembled that of 300 mg BID taken fasted (Cmin percentile (P)10-P90: 665-1404 ng/mL and 557-1743 ng/mL, respectively). Meals delayed nilotinib absorption. Intra- and interpatient variability were not increased by intake with meals. Nilotinib with food was well tolerated. CONCLUSION: With support of therapeutic drug monitoring, the use of a reduced 200 mg nilotinib dose with real-life meals seems feasible and safe. Future (confirmatory) studies should further explore the usefulness of nilotinib dosing together with food, including the relationship with treatment efficacy as well as long-term effects on quality of life. CLINICAL TRIAL REGISTRATION: NTR5000 (Netherlands Trial Register, www.trialregister.nl).

Impact of patient characteristics on the pharmacokinetics of corifollitropin alfa during controlled ovarian stimulation.

AIM: The aim of the present study was to characterize the pharmacokinetic profile of corifollitropin alfa and examine the relationships between dose, intrinsic factors [body weight, body mass index (BMI), age and race] and corifollitropin alfa pharmacokinetics. METHODS: Data from five phase II and III clinical trials of corifollitropin alfa were evaluated. All subjects included in the analysis received 60 - 180 µg corifollitropin alfa for controlled ovarian stimulation in a gonadotrophin-releasing hormone antagonist protocol followed by daily recombinant follicle stimulating hormone (rFSH) from day 8 onwards. Serum corifollitropin alfa levels (across the entire range of treatment) and total follicle stimulating hormone immunoreactivity levels (up to the start of rFSH treatment) were indicators of drug exposure. The analyses were performed using a nonlinear mixed-effects modelling approach. RESULTS: A total of 2630 subjects were treated with corifollitropin alfa, and 2557 subjects were evaluable for analysis. Body weight, BMI and race (Asian and Black vs. Caucasian) were significant determinants of corifollitropin alfa exposure. Dose-normalized corifollitropin alfa exposure was ~89% higher in women with a body weight of 50 kg vs. 90 kg (in subjects with a similar BMI of 24 kg m(-2) ); 14% higher in women with a BMI of 18 kg m(-2) vs. 32 kg m(-2) (provided they were of similar body weight); and ~15.7% lower in Asian subjects and 13% higher in Black subjects vs. Caucasian subjects. CONCLUSIONS: Body weight was the major determinant of corifollitropin alfa exposure; BMI and race (Asian and Black) were also determinants but to a lesser extent and without associated effects on clinical outcomes. Corifollitropin alfa dose adjustment is indicated, based on body weight but not for BMI or race. These recommendations are consistent with the product label.

Single therapeutic and supratherapeutic doses of corifollitropin alfa, a sustained follicle stimulant, do not prolong the QTcF-interval in healthy postmenopausal volunteers.

OBJECTIVE: Corifollitropin alfa (Elonva®) is the first hybrid follicle-stimulating hormone molecule with demonstrated sustained follicle-stimulating activity after a single subcutaneous injection. This trial evaluated if corifollitropin alfa is associated with QT/QTc prolongation and/ or proarrhythmic potential as compared to placebo in healthy post-menopausal women. MATERIALS: Participants were healthy, postmenopausal women. Study treatments were corifollitropin alfa 150 µg, corifollitropin alfa 240 µg, and moxifloxacin 400 mg with placebo. METHODS: This randomized, double blind, double-dummy, 4-period crossover trial compared single doses of corifollitropin alfa 150 µg (therapeutic dose), corifollitropin alfa 240 µg (supratherapeutic dose), and moxifloxacin 400 mg (positive control) with placebo. Corifollitropin alfa was administered on day 1 and moxifloxacin on day 2. RESULTS: The largest time-matched mean QTcF difference versus placebo for the therapeutic dose of corifollitropin alfa was 1.4 ms (upper limit of 1-sided 95% confidence interval (UL 95% CI) = 3.4 ms), and for the supratherapeutic dose was 1.2 ms (UL 95% CI = 3.6 ms). CONCLUSIONS: For both the therapeutic and the supratherapeutic dose of corifollitropin alfa and at all time points, the UL 95% CI for the time matched QTcF differences compared with placebo was below 10 ms, the threshold of relevance defined by the ICH E14 guideline. Single therapeutic and supratherapeutic doses of corifollitropin alfa are not associated with clinically relevant QT/QTc-interval prolongation in healthy post-menopausal women.

Two-stage model-based design of cancer phase I dose escalation trials: evaluation using the phase I program of barasertib (AZD1152).

INTRODUCTION: Modeling and simulation of pharmacokinetics and pharmacodynamics has previously been shown to be potentially useful in designing Phase I programs of novel anti-cancer agents that show hematological toxicity. In this analysis, a two-stage model-based trial design was evaluated retrospectively using data from the Phase I program with the aurora kinase inhibitor barasertib. METHODS: Data from two Phase I trials and four regimens were used (n = 79). Using barasertib-hydroxy QPA plasma concentrations and neutrophil count data from only study 1A, a PKPD model was developed and subsequently used to predict the MTD and a safe starting dose for the other trials. RESULTS: The PKPD model based on data from the first study adequately described the time course of neutrophil count fluctuation. The two-stage model-based design provided safe starting doses for subsequent phase I trials for barasertib. Predicted safe starting dose levels were higher than those used in two subsequent trials, but lower than used in the other trial. DISCUSSION: The two-stage approach could have been applied safely to define starting doses for alternative dosing strategies with barasertib. The limited improvement in efficiency for the phase I program of barasertib may have been due to the fact that starting doses for the studied phase I trials were already nearly optimal. CONCLUSION: Application of the two-stage model-based trial design in Phase I programs with novel anti-cancer drugs that cause haematological toxicity is feasible, safe, and may lead to a reduction in the number of patient treated at sub-therapeutic dose-levels.

Corifollitropin alfa doses based on body weight: clinical overview of drug exposure and ovarian response.

Corifollitropin alfa is a new recombinant gonadotrophin with a different pharmacokinetic profile but similar pharmacodynamic properties to conventional recombinant FSH. A single dose of corifollitropin alfa sustains multiple follicular development during the first 7 days of ovarian stimulation. This review is based on results of phase II and III trials testing the selected dose of 150 µg corifollitropin alfa in subjects >60 kg and 100 µg in subjects ≤60 kg. Exposure to corifollitropin alfa is inversely related to bodyweight. The selected doses of 100 and 150 µg in subjects weighing ≤60 and >60 kg, respectively, provide, on average, equal drug exposure producing similar ovarian responses in terms of the number of growing follicles, serum oestradiol, inhibin B and number of oocytes retrieved. Clinicians treating IVF patients with corifollitropin alfa should alter their treatment paradigm as a lower or higher dose than recommended according to body weight does not affect the ovarian response, which depends mainly on the ovarian reserve. After decades of daily dosing with FSH preparations, corifollitropin alfa allows a simpler IVF treatment regime with fewer injections. Successful use of corifollitropin alfa requires assessment of patient suitability and dosing before the start of stimulation.

Two-stage model-based clinical trial design to optimize phase I development of novel anticancer agents.

BACKGROUND: The phase I program of anticancer agents usually consists of multiple dose escalation studies to select a safe dose for various administration schedules. We hypothesized that pharmacokinetic and pharmacodynamic (PK-PD) modeling of an initial phase I study (stage 1) can be used for selection of an optimal starting dose for subsequent studies (stage 2) and that a post-hoc PK-PD analysis enhances the selection of a recommended dose for phase II evaluation. The aim of this analysis was to demonstrate that this two-stage model-based design, which does not interfere in the conduct of trials, is safe, efficient and effective. METHODS: PK and PD data of dose escalation studies were simulated for nine compounds and for five administration regimens (stage 1) for drugs with neutropenia as dose-limiting toxicity. PK-PD models were developed for each simulated study and were used to determine a starting dose for additional phase I studies (stage 2). The model-based design was compared to a conventional study design regarding safety (number of dose-limiting toxicities (DLTs)), efficiency (number of patients treated with a dose below the recommended dose) and effectiveness (precision of dose selection). Retrospective data of the investigational anticancer drug indisulam were used to show the applicability of the model-based design. RESULTS: The model-based design was as safe as the conventional design (median number of DLTs = 3) and resulted in a reduction of the number of patients who were treated with a dose below the recommended dose (-27%, power 89%). A post-hoc model-based determination of the recommended dose for future phase II studies was more precise than the conventional selection of the recommended dose (root mean squared error 8.3% versus 30%). CONCLUSIONS: A two-stage model-based phase I design is safe for anticancer agents with dose-limiting myelosuppression and may enhance the efficiency of dose escalation studies by reducing the number of patients treated with a dose below the recommended dose and by increasing the precision of dose selection for phase II evaluation.

Artificial Intelligence and Machine Learning Applied at the Point of Care.

INTRODUCTION: The increasing availability of healthcare data and rapid development of big data analytic methods has opened new avenues for use of Artificial Intelligence (AI)- and Machine Learning (ML)-based technology in medical practice. However, applications at the point of care are still scarce. OBJECTIVE: Review and discuss case studies to understand current capabilities for applying AI/ML in the healthcare setting, and regulatory requirements in the US, Europe and China. METHODS: A targeted narrative literature review of AI/ML based digital tools was performed. Scientific publications (identified in PubMed) and grey literature (identified on the websites of regulatory agencies) were reviewed and analyzed. RESULTS: From the regulatory perspective, AI/ML-based solutions can be considered medical devices (i.e., Software as Medical Device, SaMD). A case series of SaMD is presented. First, tools for monitoring and remote management of chronic diseases are presented. Second, imaging applications for diagnostic support are discussed. Finally, clinical decision support tools to facilitate the choice of treatment and precision dosing are reviewed. While tested and validated algorithms for precision dosing exist, their implementation at the point of care is limited, and their regulatory and commercialization pathway is not clear. Regulatory requirements depend on the level of risk associated with the use of the device in medical practice, and can be classified into administrative (manufacturing and quality control), software-related (design, specification, hazard analysis, architecture, traceability, software risk analysis, cybersecurity, etc.), clinical evidence (including patient perspectives in some cases), non-clinical evidence (dosing validation and biocompatibility/toxicology) and other, such as e.g. benefit-to-risk determination, risk assessment and mitigation. There generally is an alignment between the US and Europe. China additionally requires that the clinical evidence is applicable to the Chinese population and recommends that a third-party central laboratory evaluates the clinical trial results. CONCLUSIONS: The number of promising AI/ML-based technologies is increasing, but few have been implemented widely at the point of care. The need for external validation, implementation logistics, and data exchange and privacy remain the main obstacles.

Covariate-based dose individualization of the cytotoxic drug indisulam to reduce the risk of severe myelosuppression.

AIM: Chemotherapy with indisulam causes myelosuppression. This study aimed to evaluate the influence of patient-related covariates on pharmacokinetics and pharmacodynamics, to identify patients at risk for severe myelosuppression and to develop a dosing algorithm for treatment optimization. METHODS: Pharmacokinetic and pharmacodynamic data of 412 patients were available. Non-linear mixed effects modeling was used to determine the relative risk of dose-limiting myelosuppression for various covariates (demographics, physical condition, prior treatment, comedication, CYP2C genotype and biochemistry). RESULTS: Body surface area (BSA), race and CYP2C genotype had a significant impact on indisulam elimination (P < 0.001). Low BSA, Japanese race, variant CYP2C genotype, low baseline neutrophil and thrombocyte counts and female sex were clinically relevant risk factors of dose-limiting myelosuppression (RR > 1.1). A dosing strategy was developed to optimize treatment for patient subgroups. CONCLUSIONS: This study has identified covariates related to an increased risk of myelosuppression after indisulam therapy. Dose individualization may contribute to treatment optimization.

Population pharmacokinetics and pharmacodynamics for treatment optimization in clinical oncology.

Population pharmacokinetic and pharmacodynamic analysis is an important tool to support optimal treatment in clinical oncology. The population approach is suitable to explain variability between patients and to establish relationships between drug exposure and a relevant pharmacodynamic parameter. This can facilitate the selection of dosing schedules, the development of strategies for dose individualization and the application of therapeutic drug monitoring of anticancer agents. This review discusses the role of population pharmacokinetics and pharmacodynamics in clinical oncology to enhance the efficiency of drug development and to support the development of safe and effective dosing regimens for optimal treatment of cancer patients. An overview of published population studies of investigational anticancer agents and established treatment regimens is presented.

Population pharmacokinetic and pharmacodynamic analysis to support treatment optimization of combination chemotherapy with indisulam and carboplatin.

AIMS: Indisulam and carboplatin have shown synergistic activity in preclinical studies. In a dose escalation study of the combination, a treatment delay was frequently required in a 3-weekly regimen to allow recovery from myelosuppression from previous cycles. A 4-weekly regimen was better tolerated, but had a decreased dose-intensity which may compromise efficacy. The aims of this study were (i) to develop a pharmacokinetic-pharmacodynamic (PK-PD) model to describe the myelosuppressive effect of the combination, and (ii) to use this model to select a dosing regimen for Phase II evaluation. METHODS: Sixteen patients were treated at four different dose levels of indisulam (1-h infusion on day 1) and carboplatin (30-min infusion on day 2). Pharmacokinetic data were analysed with nonlinear mixed effects modelling. A semiphysiological model describing chemotherapy-induced myelosuppression characterized the relationship between the pharmacokinetics and the haematological toxicity of indisulam and carboplatin. A simulation study was performed to evaluate the tolerability and dose-intensity for 3-weekly and 4-weekly treatment regimens. RESULTS: The PK-PD model described the pharmacokinetics and the myelosuppressive effect of indisulam and carboplatin. The risk of a treatment delay at cycle 2 due to myelosuppression was unacceptably high (34-65%) in a 3-weekly regimen for various dose levels (350-600 mg m(-2) indisulam in combination with carboplatin to achieve an AUC of 4-6 mg min(-1) ml(-1)). This risk was acceptable for a 4-weekly regimen (9-24%), which is in line with the clinical study results. CONCLUSIONS: This PK-PD study supports the selection of indisulam 500 mg m(-2) and a dose of carboplatin to achieve an AUC of 6 mg min(-1) ml(-1) in a 4-weekly regimen as the recommended dose for future studies.

CYP2C9 and CYP2C19 polymorphic forms are related to increased indisulam exposure and higher risk of severe hematologic toxicity.

PURPOSE: The anticancer agent indisulam is metabolized by the cytochrome P450 of enzymes CYP2C9 and CYP2C19. Polymorphisms of these enzymes may affect the elimination rate of indisulam. Consequently, variant genotypes may be clinically relevant predictors for the risk of developing severe hematologic toxicity. The purposes of this study were to evaluate the effect of genetic variants of CYP2C9 and CYP2C19 on the pharmacokinetics of indisulam and on clinical outcome and to assess the need for pharmacogenetically guided dose adaptation. EXPERIMENTAL DESIGN: Pharmacogenetic screening of CYP2C polymorphisms was done in 67 patients treated with indisulam. Pharmacokinetic data were analyzed with a population pharmacokinetic model, in which drug elimination was described by a linear and a Michaelis-Menten pathway. The relationships between allelic variants and the elimination pharmacokinetic parameters (CL, V(max), K(m)) were tested using nonlinear mixed-effects modeling. Polymorphisms causing a high risk of dose-limiting neutropenia were identified in a simulation study. RESULTS: The Michaelis-Menten elimination rate (V(max)) was decreased by 27% (P<0.0001) for heterozygous CYP2C9*3 mutants. Heterozygous CYP2C19*2 and CYP2C19*3 mutations reduced the linear elimination rate (CL) by 38% (P < 0.0001). The risk of severe neutropenia was significantly increased by these mutations and dose reductions of 50 to 100 mg/m(2) per mutated allele may be required to normalize this risk. CONCLUSIONS: CYP2C9*3, CYP2C19*2, and CYP2C19*3 polymorphisms resulted in a reduced elimination rate of indisulam. Screening for these CYP2C polymorphisms and subsequent pharmacogenetically guided dose adaptation may assist in the selection of an optimized initial indisulam dosage.

A randomized phase II pharmacokinetic and pharmacodynamic study of indisulam as second-line therapy in patients with advanced non-small cell lung cancer.

PURPOSE: The primary aim of this study was to measure the objective tumor response rate following treatment with indisulam [E7070; N-(3-chloro-7-indolyl)-1,4-benzenedisulfonamide] as second-line therapy in patients with advanced non-small cell lung cancer. The secondary aims were to determine progression-free survival, to assess the safety and tolerability of indisulam, and to study its pharmacokinetic and pharmacodynamic profile. EXPERIMENTAL DESIGN: Patients were randomized to receive indisulam every 3 weeks either as a single i.v. dose of 700 mg/m(2) on day one (dx1) or 130 mg/m(2) given on days 1 to 5 inclusive as a daily infusion (dx5). All patients had previously received platinum-based chemotherapy. RESULTS: Forty-four patients were randomized. Only minor responses were seen. Myelosuppression, gastrointestinal symptoms, and lethargy were the most common toxicities and were more frequent in the dx1 arm. The pharmacokinetics of indisulam in each treatment schedule were adequately described using a previously developed population pharmacokinetic model and were mostly consistent with the results of the phase I program. Flow cytometric analysis of endobronchial and metastatic disease revealed a reduction in the fraction of cycling cells and an increase in apoptosis following indisulam compared with pretreatment levels. CONCLUSIONS: We conclude that, despite evidence of tumor-specific indisulam-induced apoptosis, neither of these treatment schedules has single-agent activity as second-line treatment of non-small cell lung cancer.

Vitamin C Pharmacokinetics in Critically Ill Patients: A Randomized Trial of Four IV Regimens.

BACKGROUND: Early high-dose IV vitamin C is being investigated as adjuvant therapy in patients who are critically ill, but the optimal dose and infusion method are unclear. The primary aim of this study was to describe the dose-plasma concentration relationship and safety of four different dosing regimens. METHODS: This was a four-group randomized pharmacokinetic trial. Patients who were critically ill with multiple organ dysfunction were randomized to receive 2 or 10 g/d vitamin C as a twice daily bolus infusion or continuous infusion for 48 h. End points were plasma vitamin C concentrations during 96 h, 12-h urine excretion of vitamin C, and oxalate excretion and base excess. A population pharmacokinetic model was developed using NONMEM. RESULTS: Twenty patients were included. A two-compartment pharmacokinetic model with creatinine clearance and weight as independent covariates described all four regimens best. With 2 g/d bolus, plasma vitamin C concentrations at 1 h were 29 to 50 mg/L and trough concentrations were 5.6 to 16 mg/L. With 2 g/d continuous, steady-state concentrations were 7 to 37 mg/L at 48 h. With 10 g/d bolus, 1-h concentrations were 186 to 244 mg/L and trough concentrations were 14 to 55 mg/L. With 10 g/d continuous, steady-state concentrations were 40 to 295 mg/L at 48 h. Oxalate excretion and base excess were increased in the 10 g/d dose. Forty-eight hours after discontinuation, plasma concentrations declined to hypovitaminosis levels in 15% of patients. CONCLUSIONS: The 2 g/d dose was associated with normal plasma concentrations, and the 10 g/d dose was associated with supranormal plasma concentrations, increased oxalate excretion, and metabolic alkalosis. Sustained therapy is needed to prevent hypovitaminosis. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT02455180; URL: www.clinicaltrials.gov.

Optimization of anti-infective dosing regimens during online haemodiafiltration.

Online haemodiafiltration (HDF) is increasingly used in clinical practice as a routine intermittent dialysis modality. It is well known that renal impairment and renal replacement therapy can substantially affect the pharmacokinetic behaviour of several drugs. However, surprisingly few data are available on the need for specific dose adjustments during HDF. Due to convection, drug clearance may be increased during HDF as compared with standard haemodialysis. This may be of particular interest in patients undergoing anti-infective therapy, since under-dosing may compromise patient outcomes and promote the emergence of bacterial resistance. Drug clearance during HDF is determined by (i) dialysis characteristics, (ii) drug characteristics and (iii) patient characteristics. In this review, we will discuss these different determinants of drug clearance during HDF and advise on how to adjust the dose of antibacterial, antimycotic and antiviral agents in patients undergoing HDF. In addition, the possible added value of therapeutic drug monitoring is discussed. The review provides guidance for optimization of anti-infective dosing regimens in HDF patients.

Population pharmacokinetics of caffeine and its metabolites theobromine, paraxanthine and theophylline after inhalation in combination with diacetylmorphine.

The stimulant effect of caffeine, as an additive in diacetylmorphine preparations for study purposes, may interfere with the pharmacodynamic effects of diacetylmorphine. In order to obtain insight into the pharmacology of caffeine after inhalation in heroin users, the pharmacokinetics of caffeine and its dimethylxanthine metabolites were studied. The objectives were to establish the population pharmacokinetics under these exceptional circumstances and to compare the results to published data regarding intravenous and oral administration in healthy volunteers. Diacetylmorphine preparations containing 100 mg of caffeine were used by 10 persons by inhalation. Plasma concentrations of caffeine, theobromine, paraxanthine and theophylline were measured by high performance liquid chromatography. Non-linear mixed effects modelling was used to estimate population pharmacokinetic parameters. The model was evaluated by the jack-knife procedure. Caffeine was rapidly and effectively absorbed after inhalation. Population pharmacokinetics of caffeine and its dimethylxanthine metabolites could adequately and simultaneously be described by a linear multi-compartment model. The volume of distribution for the central compartment was estimated to be 45.7 l and the apparent elimination rate constant of caffeine at 8 hr after inhalation was 0.150 hr(-1) for a typical individual. The bioavailability was approximately 60%. The presented model adequately describes the population pharmacokinetics of caffeine and its dimethylxanthine metabolites after inhalation of the caffeine sublimate of a 100 mg tablet. Validation proved the stability of the model. Pharmacokinetics of caffeine after inhalation and intravenous administration are to a large extent similar. The bioavailability of inhaled caffeine is approximately 60% in experienced smokers.

A phase I study of ridaforolimus in adult Chinese patients with advanced solid tumors.

PURPOSE: Ridaforolimus (AP23573, MK-8669 or deforolimus) is an inhibitor of mammalian target of rapamycin (mTOR), an important regulator in the cell survival pathway. This open-label, single center phase I study aimed to investigate the pharmacokinetic (PK) and safety profiles of ridaforolimus in Chinese patients with treatment-refractory advanced or relapsed solid tumors. The PK data generated from these Chinese patients were further compared with those previously reported in Caucasian and Japanese patient populations. EXPERIMENTAL DESIGN: The patients were given an oral dose of 40 mg of ridaforolimus on Day 1 of the study. On Day 8, patients were initiated on a treatment regimen that comprised a once daily dose of 40 mg of ridaforolimus for five consecutive days, followed by a 2-day off-drug interval. Patients repeated this regimen until disease progression or intolerance. Blood samples were collected at specific times pre- and post-treatment to establish the PK profile of ridaforolimus in all patients. RESULTS: Fifteen patients were given at least one dose of 40 mg of ridaforolimus. The median absorption lag-time was 2 hours, the median Tmax was 4 hours and the mean elimination half-life was 53 hours. The accumulation ratio for AUC(0-24hr) was 1.3 on day 19 (steady state)/day 1 (after a single dose). The most common drug-related adverse events (AEs) that occurred in ≥40% of patients were stomatitis, proteinuria, leukopenia, hyperglycemia, and pyrexia. Grade 3/4 drug-related AEs were anemia, stomatitis, fatigue, thrombocytopenia, constipation, gamma glutamyltransferase increase, and proteinuria. All 11 evaluable patients achieved stable disease. CONCLUSIONS: Oral ridaforolimus at a daily dose of 40 mg were generally well tolerated in Chinese patients with advanced or refractory solid tumors. Adverse events and PK profiles of ridaforolimus in this study were similar to those from Caucasian and Japanese patients reported previously.

Tolerability, safety and pharmacokinetics of ridaforolimus in combination with bicalutamide in patients with asymptomatic, metastatic castration-resistant prostate cancer (CRPC).

PURPOSE: Recent data indicate that there is a significant cross-talk between the PI3K/Akt/mTOR and androgen receptor signaling pathways. We evaluated safety and tolerability as well as potential drug-drug interaction of ridaforolimus, a mammalian target of rapamycin (mTOR) inhibitor, when combined with the androgen receptor inhibitor bicalutamide in patients with asymptomatic, metastatic castration-resistant prostate cancer. PATIENTS AND METHODS: Patients were treated with the combination of ridaforolimus 30 mg/day for 5 consecutive days each week and bicalutamide 50 mg/day. Ridaforolimus pharmacokinetics was assessed with and without bicalutamide. RESULTS: Twelve patients were enrolled including 1 screen failure. Dose reductions were required in 7 patients. Three of the 11 patients experienced a dose-limited toxicity, 1 with Grade 3 hyperglycemia and 2 with Grade 2 stomatitis leading to <75 % of planned ridaforolimus dose during the first 35 days of study treatment. The pharmacokinetic results showed no differences in exposures to ridaforolimus with and without concomitant bicalutamide administration. CONCLUSIONS: Although there was no evidence of a clinically relevant pharmacological drug-drug interaction, the occurrence of dose-limiting toxicities in 3 of 11 evaluable patients at a reduced dose of ridaforolimus of 30 mg/day suggests that this combination may not be well suited for asymptomatic or minimally symptomatic prostate cancer patients.

Performance of methods for handling missing categorical covariate data in population pharmacokinetic analyses.

In population pharmacokinetic analyses, missing categorical data are often encountered. We evaluated several methods of performing covariate analyses with partially missing categorical covariate data. Missing data methods consisted of discarding data (DROP), additional effect parameter for the group with missing data (EXTRA), and mixture methods in which the mixing probability was fixed to the observed fraction of categories (MIX(obs)), based on the likelihood of the concentration data (MIX(conc)), or combined likelihood of observed covariate data and concentration data (MIX(joint)). Simulations were implemented to study bias and imprecision of the methods in datasets with equal-sized and unbalanced category ratios for a binary covariate as well as datasets with non-random missingness (MNAR). Additionally, the performance and feasibility of implementation was assessed in two real datasets. At either low (10%) or high (50%) levels of missingness, all methods performed similarly well. Performance was similar for situations with unbalanced datasets (3:1 covariate distribution) and balanced datasets. In the MNAR scenario, the MIX methods showed a higher bias in the estimation of CL and covariate effect than EXTRA. All methods could be applied to real datasets, except DROP. All methods perform similarly at the studied levels of missingness, but the DROP and EXTRA methods provided less bias than the mixture methods in the case of MNAR. However, EXTRA was associated with inflated type I error rates of covariate selection, while DROP handled data inefficiently.

Marginal increase of sunitinib exposure by grapefruit juice.

PURPOSE: The drug label of sunitinib includes a warning for concomitant use of grapefruit juice (GJ) but clinical evidence for this drug interaction is lacking. The aim of this study is to determine the effect of GJ, a potent intestinal cytochrome P450 (CYP) 3A4 inhibitor, on steady-state sunitinib pharmacokinetics (PK). METHODS: Sunitinib PK was evaluated in eight cancer patients receiving sunitinib monotherapy in a "4 weeks on-2 weeks off" dose regimen. Serial blood samples for PK analysis of sunitinib were collected on two separate days. On both PK days, patients received a single oral dose of 7.5-mg midazolam as a phenotypic probe for assessment of intestinal CYP3A4 activity. The first PK day was at steady-state sunitinib PK (between days 14-20), the second PK day was on day 28. On days 25, 26 and 27, 200-mL GJ was consumed 3 times a day. The effect of GJ on sunitinib exposure was assessed by comparing sunitinib PK with and without GJ. RESULTS: Concomitant use of GJ and sunitinib resulted in an 11% increase of the relative bioavailability of sunitinib (P < 0.05). The effect of GJ on CYP3A4 activity was confirmed by an increase of ~50% of mean midazolam exposure (AUC(0-24 h)) from 122.1 to 182.0 ng h/mL (P = 0.034). CONCLUSION: GJ consumption results in a marginal increase in sunitinib exposure which is not considered clinically relevant. There is no clinical evidence underscoring the warning in the sunitinib drug label regarding concomitant use of GJ.